JP7594368B2 - Method for producing bifunctional cyclic carbonate having a spiro structure and method for producing polyhydroxyurethane - Google Patents

Description

The present invention relates to a method for producing a bifunctional cyclic carbonate having a spiro structure and a method for producing polyhydroxyurethane.

Polyhydroxyurethane (PHU), synthesized by ring-opening polyaddition reaction of bifunctional cyclic carbonate with diamine, has attracted attention in recent years as a new method for synthesizing polyurethane (PU) without using diisocyanate. In addition, this reaction generates primary to tertiary hydroxyl groups in the side chain due to the structure of the ring-opening cyclic carbonate, so the side chain of PHU can be modified in various ways. However, most bifunctional five-membered and six-membered cyclic carbonates require two cyclic carbonates to be linked with a linker, and their synthesis requires several steps. It is also known that six-membered cyclic carbonates are more reactive with amines than five-membered cyclic carbonates.

On the other hand, the bifunctional cyclic carbonate 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione, which can be synthesized in one step by reacting the inexpensive polyol pentaerythritol (PE) with diethyl carbonate (dimethyl carbonate; DMC), does not require a linker moiety because it has a spiro structure consisting of two six-membered cyclic carbonates. Furthermore, in the ring-opening reaction of 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione with an amine, only primary hydroxyl groups are produced, unlike less symmetrical bifunctional cyclic carbonates. For example, Patent Document 1 discloses that PE is reacted with 2,2,2-Trichloroethyl Chloroformate (TrocCl) to obtain 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione.

International Publication No. 2018/109714

However, the reaction between PE and DMC requires a catalyst and a complicated purification procedure. In the reaction between PE and TrocCl, TrocCl is derived from toxic phosgene and contains chlorine components, which can cause discoloration.

The present invention has been made in consideration of the above circumstances, and provides a simple method for producing a bifunctional cyclic carbonate with improved yield, and a novel method for producing polyhydroxyurethane using the bifunctional cyclic carbonate.

That is, the present invention includes the following aspects.
(1) A reaction step of reacting pentaerythritol with a diaryl carbonate to obtain a bifunctional cyclic carbonate having a spiro structure,
The bifunctional cyclic carbonate having a spiro structure is 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione,
A method for producing a bifunctional cyclic carbonate having a spiro structure, the method comprising the step of :
(2 ) The method according to (1) , wherein the reaction is carried out at a temperature of 40° C. or higher and 100° C. or lower in the reaction step.
( 3 ) The method according to (1) or (2) , wherein the reaction is carried out at a temperature of 50° C. or higher and 100° C. or lower in the reaction step.
( 4 ) The method according to any one of (1) to ( 3 ), wherein in the reaction step, a molar ratio of the diaryl carbonate to pentaerythritol is 2/1 or more and 10/1 or less.
( 5 ) The method according to any one of (1) to ( 4 ), wherein in the reaction step, a molar ratio of the diaryl carbonate to pentaerythritol is 4/1 or more and 10/1 or less.
( 6 ) The method according to any one of (1) to ( 5 ), wherein in the reaction step, the concentration of pentaerythritol is 10 mmol/L or more and 100 mmol/L or less with respect to the total volume of the reaction solution.
( 7 ) The method according to any one of (1) to ( 6 ), wherein in the reaction step, the concentration of pentaerythritol is 10 mmol/L or more and 80 mmol/L or less with respect to the total volume of the reaction solution.
( 8 ) The method according to any one of (1) to ( 7 ), wherein the diaryl carbonate is diphenyl carbonate.
( 9 ) A method for producing a bifunctional cyclic carbonate having a spiro structure by the method according to any one of (1) to (8), and reacting the bifunctional cyclic carbonate having a spiro structure with a diamine represented by the following general formula (Ia) to obtain a polyhydroxyurethane,
The method for producing polyhydroxyurethane, wherein the bifunctional cyclic carbonate having a spiro structure is 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione.

(In general formula (Ia), X is an alkylene group, an aralkylene group, or a group represented by -R ¹¹ -Ar ¹¹ -R ¹² -. ^{Ar 11} is a divalent aromatic hydrocarbon group, and R ¹¹ and R ¹² are each independently an alkylene group having 1 to 20 carbon atoms.)

( 10 ) The method according to ( 9 ), wherein in the polymerization step, the polymerization reaction is carried out at 5° C. or less, and the content of polyhydroxyurethane having a branched structure is controlled to be 4 mol % or less based on the total molar amount of polyhydroxyurethane.
( 11 ) The method according to ( 9 ), wherein in the polymerization step, the polymerization reaction is carried out at 50° C. or higher, and the content of polyhydroxyurethane having a branched structure is controlled to be 11 mol % or higher relative to the total molar amount of polyhydroxyurethane.

The above-described method for producing a bifunctional cyclic carbonate can provide a method for producing a bifunctional cyclic carbonate that is simple and has an improved yield. The above-described method for producing a polyhydroxyurethane can produce a novel polyhydroxyurethane.

1 is a ¹ H-NMR spectrum of compound (I) in Example 1. 1 is a ¹³ C-NMR spectrum of compound (I) in Example 1. 1 is a ¹ H-NMR spectrum of the product in Example 2. 1 is a graph showing the relationship between the yield (selectivity) of compound (I) and the initial PE concentration. 1 is a graph showing the relationship between the yield (selectivity) of compound (I) and the reaction temperature. 1 is a graph showing the relationship between the yield (selectivity) of compound (I) and the molar ratio of DPC to PE. FIG. 1H-NMR spectra of a mixture (A) of compound (I) and compound (IV), a reaction product (B) of compound (IV) with a monoamine, a reaction product (C) of compound (I) with a monoamine, and a reaction product (D) of a mixture of compound (I) and compound (IV) with a monoamine in Example ¹⁶ . 1 shows gel permeation chromatograms of the reaction product of compound (I) and 1,6-diaminohexane in Example 17 (reaction times: 1, 2, 3, 4, 5, 7 and 9 hours). 1 is a graph showing the relationship between the reaction time of compound (I) and 1,6-diaminohexane in Example 17 and the number average molecular weight or molecular weight distribution of the product. 22 is a graph showing the results of thermogravimetric analysis of each of the polyhydroxyurethanes obtained in Examples 18 to 21 in Example 22. 22 is a graph showing the results of differential scanning calorimetry of each of the polyhydroxyurethanes obtained in Examples 18 to 21 in Example 22. 1 is a ¹ H-NMR spectrum of compound (V) in Example 23. 1 shows ¹ H-NMR spectra of the reaction product (crude product) of compound (I) with 1-hexylamine and the purified by-product (compound V′) in Example 24. ¹ H-NMR spectrum of the reaction product of compound (I) and 1,6-diaminohexane in Example 25 (reaction temperature: 50° C.). ¹ H-NMR spectrum of the reaction product of compound (I) and 1,6-diaminohexane in Example 26 (reaction temperature: 0° C.).

The following describes in detail the form for carrying out the present invention (hereinafter abbreviated as "the present embodiment"). Note that the present invention is not limited to the following embodiment, and can be carried out in various modifications within the scope of the gist of the invention.

<Method for producing bifunctional cyclic carbonate>
The method for producing a bifunctional cyclic carbonate having a spiro structure according to the present embodiment (hereinafter also referred to as "the method for producing a bifunctional cyclic carbonate according to the present embodiment") includes a reaction step of reacting pentaerythritol (PE) with a diaryl carbonate to obtain a bifunctional cyclic carbonate having a spiro structure. The bifunctional cyclic carbonate having a spiro structure is 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione. 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione is a compound represented by the following formula (I) (hereinafter sometimes referred to as "compound (I)"). The CAS number of compound (I) is 84056-48-4.

In a conventional method for producing a difunctional cyclic carbonate, PE and dimethyl carbonate are reacted in the presence of a catalyst (1,4-Diazabicyclo[2.2.2]octane; DABCO) to obtain a difunctional cyclic carbonate having a spiro structure.
In contrast, in the method for producing a bifunctional cyclic carbonate of the present embodiment, 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione, which is a bifunctional cyclic carbonate having a spiro structure, is obtained in a one-step reaction without using a catalyst.

The steps constituting the method for producing the bifunctional cyclic carbonate of this embodiment are described in detail below.

[Reaction step]
In the reaction step, as shown in the following reaction formula, pentaerythritol is reacted with a diaryl carbonate to obtain the above-mentioned compound (I), which is a bifunctional cyclic carbonate having a spiro structure. This reaction to obtain compound (I) is a known intramolecular cyclization reaction.

(Pentaerythritol (PE))
Pentaerythritol (PE) is a compound having the structure shown in the above reaction formula. PE can be synthesized, for example, by condensing acetaldehyde and formaldehyde in a basic environment. Commercially available PE may also be used. The CAS number of PE is 115-77-5.

(Diaryl carbonate)
Examples of diaryl carbonates include a compound represented by the following general formula (III) (hereinafter, sometimes referred to as "compound (III)").

In formula (III), Ar ³¹ and Ar ³² each independently represent a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

Ar ³¹ and Ar ³² are aromatic hydrocarbon groups having 6 to 20 carbon atoms, preferably aromatic hydrocarbon groups having 6 to 12 carbon atoms, more preferably aromatic hydrocarbon groups having 6 to 10 carbon atoms. The aromatic hydrocarbon group may have a substituent. Examples of the substituent in the aromatic hydrocarbon group include an alkyl group, an alkoxy group, a dialkylamino group, a halogen group, a nitro group, a trifluoromethyl group, and a cyano group.
Specific examples of such Ar ³¹ and Ar ³² include a phenyl group, a methylphenyl group (each isomer), an ethylphenyl group (each isomer), a propylphenyl group (each isomer), a butylphenyl group (each isomer), a pentylphenyl group (each isomer), a hexylphenyl group (each isomer), a dimethylphenyl group (each isomer), a methylethylphenyl group (each isomer), a methylpropylphenyl group (each isomer), a methylbutylphenyl group (each isomer), a methylpentylphenyl group (each isomer), a diethylphenyl group (each isomer), an ethylpropylphenyl group (each isomer), an ethyl Examples of such groups include a phenylbutylphenyl group (each isomer), a dipropylphenyl group (each isomer), a trimethylphenyl group (each isomer), a triethylphenyl group (each isomer), a naphthyl group (each isomer), a methoxyphenyl group, a dimethoxyphenyl group, a trimethoxyphenyl group, a dimethylaminophenyl group, a chlorophenyl group, a dichlorophenyl group, a trichlorophenyl group, a fluorophenyl group, a difluorophenyl group, a trifluorophenyl group, a perfluorophenyl group, a nitrophenyl group, a dinitrophenyl group, and a trinitrophenyl group. Among these, a phenyl group is preferable as Ar ³¹ and Ar ³² .
Ar ³¹ and Ar ³² may be the same or different, but from the viewpoint of ease of production, it is preferable that they are the same.

Preferred diaryl carbonates include diaryl carbonates in which Ar ³¹ and Ar ³² are aromatic hydrocarbon groups having 6 to 10 carbon atoms. Specific examples of such diaryl carbonates include diphenyl carbonate, di(methylphenyl) carbonate (each isomer), di(diethylphenyl) carbonate (each isomer), and di(methylethylphenyl) carbonate (each isomer). Note that these compounds are merely examples of preferred diaryl carbonates, and preferred diaryl carbonates are not limited to these. Furthermore, these diaryl carbonates may be used alone or in combination of two or more.
Among these, diphenyl carbonate is particularly preferred as the diaryl carbonate.

A known method can be used to produce diaryl carbonate. Among them, the method described in WO 2009/139061 (Reference 1) in which an organotin compound having a tin-oxygen-carbon bond is reacted with carbon dioxide to produce an aliphatic carbonate, and an aromatic carbonate (i.e., diaryl carbonate) is produced from the aliphatic carbonate and an aromatic hydroxy compound is preferred. The diaryl carbonate can be produced, for example, by using the production apparatus described in WO 2009/139061 (Reference 1). Commercially available diaryl carbonate may also be used.

The reaction process can be carried out in the presence or absence of a solvent. The solvent may be any solvent capable of dissolving PE, and is preferably a highly polar solvent that does not have a hydroxyl group. Specific examples of such solvents include the following:

(1) Ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone;
(2) Nitriles such as acetonitrile, butyronitrile, and caprylnitrile;
(3) Esters such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dibutyl phthalate, diamyl phthalate, dibutyl fumarate, dimethyl maleate, diethyl maleate, and dibutyl maleate;
(4) Ethers such as furan, tetrahydrofuran, propyl oxide, dioxane, dibenzyl ether, and diphenyl ether;
(5) Glycol ether esters such as ethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, cyclohexanol acetate, propylene glycol diacetate, 1,4-butanediol diacetate, 1,3-butylene glycol diacetate, and 1,6-hexanediol diacetate;
(6) Phosphite esters such as triphenyl phosphite;
(7) Sulfur compounds such as dimethyl sulfide, thiophene, and carbon disulfide;
(8) Halogenated hydrocarbons such as methyl chloride, ethyl chloride, dichloropropane, dichloroethylene, trichloroethylene, tetrachloroethylene, pentachloroethane, chloroform, methyl bromide, ethyl bromide, methyl iodide, and ethyl iodide;
(9) N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N,N-dimethylpropionamide, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1,5-dimethyl-2-pyrrolidone;
(10) Pyrrolidines such as 1-acetylpyrrolidine;
(11) Ureas such as 1,3-dimethyl-2-imidazolidinone;
(12) Sulfoxide compounds such as dimethyl sulfoxide (DMSO), diethyl sulfoxide, dipropyl sulfoxide, dibutyl sulfoxide, diphenyl sulfoxide, methyl ethyl sulfoxide, methyl propyl sulfoxide, methyl butyl sulfoxide, and methyl phenyl sulfoxide.

These solvents may be used alone or in combination of two or more. When two or more types are used in combination, the combination and ratio of the solvents may be selected arbitrarily.

The reaction step is preferably carried out, for example, under an inert gas atmosphere.
Examples of the inert gas include argon gas, helium gas, and nitrogen gas.

In the reaction step, the amount of PE used, i.e., the concentration of PE in the reaction solution, is preferably from 10 mmol/L to 100 mmol/L, more preferably from 10 mmol/L to 80 mmol/L, even more preferably from 10 mmol/L to 60 mmol/L, particularly preferably from 10 mmol/L to 40 mmol/L, and most preferably from 10 mmol/L to 30 mmol/L, relative to the total volume of the reaction solution.
When the concentration of PE is equal to or higher than the lower limit, the PE can be reacted more thoroughly with the diaryl carbonate. On the other hand, when the concentration of PE is equal to or lower than the upper limit, the carbonation of PE can be preferentially caused intramolecularly rather than intermolecularly, and the yield (selectivity) of compound (I) can be further improved.

In the reaction step, the amount of diaryl carbonate used can be expressed as a molar ratio of diaryl carbonate to PE. The molar ratio of diaryl carbonate to PE is preferably 2/1 or more and 10/1 or less, more preferably 4/1 or more and 10/1 or less.
When the molar ratio of diaryl carbonate to PE is equal to or greater than the lower limit, carbonation of PE can occur preferentially intramolecularly rather than intermolecularly, and the yield (selectivity) of compound (I) can be further improved. When the molar ratio of diaryl carbonate to PE is equal to or less than the upper limit, the abundance ratio of diaryl carbonate can be prevented from becoming excessive, and compound (I) can be produced more efficiently while suppressing production costs.

In the reaction step, the reaction temperature can be 20° C. or higher and 100° C. or lower, preferably 40° C. or higher and 100° C. or lower, more preferably 50° C. or higher and 100° C. or lower, and even more preferably 75° C. or higher and 100° C. or lower.
By setting the reaction temperature to the above lower limit, the carbonation of PE can be preferentially caused intramolecularly rather than intermolecularly, and the yield (selectivity) of compound (I) can be further improved. On the other hand, by setting the reaction temperature to the above upper limit or less, the application of excess heat can be suppressed, and compound (I) can be produced more efficiently while suppressing production costs.

The reaction time can be, for example, from 1 hour to 24 hours, and can be from 6 hours to 18 hours.

[Other steps]
The method for producing a bifunctional cyclic carbonate of this embodiment may further include a purification step of compound (I) after the reaction step, i.e., after completion of the reaction.

In the purification step, post-treatment is performed as necessary using known techniques to extract compound (I). Specifically, post-treatment operations such as filtration, washing, extraction, pH adjustment, dehydration, and concentration are performed alone or in combination as necessary, and compound (I) is roughly purified by concentration, crystallization, reprecipitation, column chromatography, etc.

In addition, in order to increase the purity of the crudely purified compound (I), it is preferable to perform operations such as crystallization, reprecipitation, column chromatography, extraction, stirring and washing of the crystals with a solvent, either alone or in combination of two or more types, at least once, as necessary.

In the method for producing a bifunctional cyclic carbonate of this embodiment, the reaction step may be followed by the method for producing polyhydroxyurethane described below without carrying out a purification step, but from the viewpoint of improving the yield of polyhydroxyurethane, it is preferable to carry out a purification step of compound (I).

The structure of compound (I) can be confirmed by known methods such as nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), and infrared spectroscopy (IR).

<Use of compound (I)>
Compound (I) obtained by the production method of the present embodiment can be suitably used, for example, as a raw material for polyhydroxyurethane described later, a raw material for a diol having two urethane groups obtained by a reaction of compound (I) with a monoamine, a raw material for a polycarbonate, a raw material for copolymerization with lactone or lactide, a raw material for a crosslinking agent, and the like.

<Method of producing polyhydroxyurethane>
The method for producing polyhydroxyurethane of the present embodiment includes a polymerization step of reacting a bifunctional cyclic carbonate having a spiro structure with a diamine represented by the above general formula (Ia) to obtain polyhydroxyurethane.
The bifunctional cyclic carbonate having a spiro structure is 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione.

The method for producing polyhydroxyurethane according to this embodiment makes it possible to obtain a new polyhydroxyurethane.

[Polymerization process]
In the polymerization step, as shown in the reaction formula below, a bifunctional cyclic carbonate having a spiro structure is reacted with a diamine represented by the following general formula (Ia) to obtain polyhydroxyurethane.
This reaction to give polyhydroxyurethane is a known ring-opening polyaddition reaction.

In the above reaction formula, X is an alkylene group, an aralkylene group, or a group represented by -R ¹¹ -Ar ¹¹ -R ¹² -. ^{Ar 11} is a divalent aromatic hydrocarbon group, and R ¹¹ and R ¹² are each independently an alkylene group having 1 to 20 carbon atoms. n is an integer of 1 or more.

(Bifunctional cyclic carbonate having a spiro structure)
The bifunctional cyclic carbonate having a spiro structure is 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione (compound (I)). Compound (I) may be a commercially available product or may be synthesized by a known method. However, compound (I) is preferably obtained by the above-mentioned method for producing a bifunctional cyclic carbonate, since compound (I) can be obtained easily and in good yield.

(Diamine)
The diamine is a compound represented by the following general formula (Ia) (hereinafter, sometimes referred to as "diamine (Ia)").

(In general formula (Ia), X is an alkylene group, an aralkylene group, or a group represented by -R ¹¹ -Ar ¹¹ -R ¹² -. ^{Ar 11} is a divalent aromatic hydrocarbon group, and R ¹¹ and R ¹² are each independently an alkylene group having 1 to 20 carbon atoms.)

As the alkylene group in X, a linear alkylene group having 2 to 20 carbon atoms is preferred, and specific examples thereof include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tetradecylene group, a hexadecylene group, an octadecylene group, a nonylene group, or a decylene group. Among these, as the alkylene group in X, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, or a decylene group is preferred, and a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, or an octylene group is more preferred.

As the aralkylene group in X, an aralkylene group having 3 to 20 carbon atoms is preferred, and specific examples include a benzylene group, a phenethylene group, a phenylbutylene group, a naphthylmethylene group, and a naphthylethylene group. Of these, as the aralkylene group in X, a benzylene group or a phenethylene group is preferred.

In the group represented by -R ¹¹ -Ar ¹¹ -R ¹² - in X, R ¹¹ and R ¹² may be the same or different, but are preferably the same.
Examples of the alkylene group having 1 to 20 carbon atoms in R ¹¹ and R ¹² include a methylene group and the same as those exemplified in the alkylene group in X. Among them, the alkylene group having 1 to 20 carbon atoms in R ¹¹ and R ¹² is preferably a methylene group or an ethylene group.

Specific examples of the group represented by -R ¹¹ -Ar ¹¹ -R ¹² - in X include a group represented by -CH ₂ -Ph-CH ₂ - (Ph is a phenylene group, the same applies below) and a group represented by -CH ₂ CH ₂ -Ph-CH ₂ CH ₂ -. Of these, the group represented by -R ¹¹ -Ar ¹¹ -R ¹² - in X is preferably a group represented by -CH ₂ -Ph-CH ₂ -.

Preferred diamines (Ia) include, for example, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, p-xylylenediamine, etc. Among them, preferred diamines (Ia) are 1,3-diaminopropane, 1,6-diaminohexane, 1,8-diaminooctane, and p-xylylenediamine.

The polymerization step can be carried out in the presence or absence of a solvent. Examples of the solvent include the same solvents as those exemplified in the reaction step of the above-mentioned method for producing a bifunctional cyclic carbonate.
The solvent may be used alone or in combination of two or more. When two or more types are used in combination, the combination and ratio thereof can be arbitrarily selected.

The polymerization process can be carried out without the use of a catalyst.

The reaction step is preferably carried out, for example, under an inert gas atmosphere.
Examples of the inert gas include argon gas, helium gas, and nitrogen gas.

In the polymerization step, the amount of diamine (Ia) used is preferably 0.5 to 1.5 times the molar amount of compound (I) used, and more preferably 0.7 to 1.3 times the molar amount.

In the polymerization step, as shown in the examples described later, in the latter stage of the reaction, the molar concentration of the amino group at the polymer chain end of the polyhydroxyurethane produced is significantly lower than the molar concentration of the hydroxy group end produced. Therefore, there is a risk that the compound (I) reacts with the hydroxy group instead of the amino group, crosslinking the polymer chain, and gelling of the polyhydroxyurethane occurs. Therefore, in order to suppress the gelling of the polyhydroxyurethane, it is preferable to add diamine (Ia) in an amount of 0.05 times or more and 0.3 times or less, preferably 0.07 times or more and 0.2 times or less, of the amount of compound (I) used during the reaction, for example, 30 minutes, 1 hour, 2 hours, and 3 hours after the start of the reaction. This can prevent the formation of a crosslinked structure in the polyhydroxyurethane, and can effectively suppress the gelling of the polyhydroxyurethane produced.
In addition, it is sufficient that the amount of diamine (Ia) used throughout the entire reaction is within the above range, and for example, at the start of the reaction, diamine (Ia) is added in an amount of more than half the amount of diamine (Ia) used throughout the entire reaction, and during the reaction, diamine (Ia) in an amount less than half the amount of diamine (Ia) used throughout the entire reaction can be further added. Also, for example, it is preferable to add diamine (Ia) in an amount equimolar to the amount of compound (I) used at the start of the reaction, and then add diamine (Ia) in an amount 0.1 times the amount of compound (I) used 3 hours after the start of the reaction.

In the polymerization step, as shown in the examples described later, the structure of the resulting polyhydroxyurethane can be controlled by adjusting the polymerization temperature.
When producing polyhydroxyurethane having a branched structure in a relatively large amount, specifically when producing polyhydroxyurethane having a branched structure in an amount of 11 mol % or more relative to the total molar amount of polyhydroxyurethane obtained, the polymerization temperature is preferably 50° C. or higher, and more preferably 60° C. or higher.
By setting the polymerization temperature at or above the lower limit, the production of polyhydroxyurethane having a linear structure can be more effectively suppressed, and the yield of polyhydroxyurethane having a branched structure can be further improved. On the other hand, the upper limit of the reaction temperature is not particularly limited, and can be set to, for example, 100°C.

On the other hand, when polyhydroxyurethane having a linear structure is produced in a relatively large amount, specifically, when the content of polyhydroxyurethane having a branched structure is produced to be 4 mol % or less of the total molar amount of polyhydroxyurethane obtained, the polymerization temperature is preferably 5° C. or less, and more preferably 0° C.
By setting the polymerization temperature to the above upper limit or lower, the production of polyhydroxyurethane having a branched structure can be more effectively suppressed, and the yield of polyhydroxyurethane having a linear structure can be further improved. On the other hand, the lower limit of the reaction temperature is not particularly limited, and can be, for example, 0°C.

In addition, when using a diamine (Ia) having an alkenyl group with 7 or more carbon atoms, if the diamine (Ia) has low solubility in the solvent, the polymerization temperature can be temporarily raised to a temperature between more than 60°C and 100°C and maintained for a short period of time, such as between 10 minutes and 1 hour, to dissolve the diamine (Ia) and homogenize the reaction solution, and then the polymerization temperature can be lowered to a temperature below the upper limit value.

The polymerization time can be, for example, from 1 hour to 24 hours, and can be from 6 hours to 20 hours.

[Other steps]
The method for producing polyhydroxyurethane of the present embodiment may further include a step of purifying the polyhydroxyurethane after the polymerization step, i.e., after completion of the reaction.

In the purification process, post-treatment is carried out as necessary using known techniques to extract polyhydroxyurethane. Specifically, post-treatment procedures such as filtration, washing, extraction, pH adjustment, dehydration, and concentration are carried out alone or in combination as necessary, and the polyhydroxyurethane is roughly purified by concentration, crystallization, reprecipitation, column chromatography, etc.

In order to increase the purity of the crudely refined polyhydroxyurethane, it is preferable to carry out one or more of the following operations, such as crystallization, reprecipitation, column chromatography, extraction, and stirring and washing of the crystals with a solvent, either alone or in combination as necessary.

In the method for producing polyhydroxyurethane of this embodiment, a purification step does not have to be performed after the reaction step, but it is preferable to perform a purification step of polyhydroxyurethane from the viewpoint of the storage stability of polyhydroxyurethane and the use of polyhydroxyurethane in various applications.

The structure of polyhydroxyurethane can be confirmed by known techniques, such as nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), and infrared spectroscopy (IR).

<Applications of polyhydroxyurethane>
The polyhydroxyurethane obtained by the production method of this embodiment is suitable for use as an industrial material, such as a molding material or a binder for paint.

The present embodiment will be described in more detail below with reference to specific examples and comparative examples. However, the present embodiment is not limited in any way by the following examples and comparative examples as long as the gist of the embodiment is not exceeded. The various analyses performed in the examples and comparative examples described below were measured by the following methods.

[Evaluation 1]
(Yield of Compound (I))
The yield (also referred to as selectivity) of compound (I) was determined by ¹ H-NMR analysis under the following analysis conditions.

(Analysis conditions)
Equipment: JEOL ECS-400 spectrometer
Sample preparation: A portion of the reaction solution (about 0.1 mL) was concentrated under reduced pressure and dissolved in deuterated DMSO (DMSO-d ₆ ) (about 0.55 mL).

Specifically, as a method for analyzing the yield (selectivity) using ¹ H-NMR analysis, the sample prepared above was subjected to ¹ H-NMR measurement, and the yield (selectivity) of compound (I) was calculated from the integral ratio of the ¹ H signals corresponding to the target compound, 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione (compound (I)) and the by-products (impurities).

[Example 1]
As shown in the reaction formula below, pentaerythritol (PE) and diphenyl carbonate (DPC) were reacted to obtain 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione (compound (I)).

Detailed reaction conditions are as follows.
DPC (29.15 g, 0.136 mol) and N,N-dimethylformamide (DMF) (800 mL) were added to a 1000 mL flask and heated to 100 ° C. A DMF solution (40 mL) of PE (3.09 g, 0.023 mol) was quickly added thereto, the flask was replaced with nitrogen, and the mixture was stirred at 100 ° C. for 12 hours. After returning to room temperature, DMF was distilled off under reduced pressure, and ethyl acetate (EtOAc) / n-hexane (about 100 mL / about 100 mL) was added to the residue, and the precipitated white solid was collected. Furthermore, the obtained white solid was dissolved in hot DMF (about 60 mL), and recrystallized by adding diethyl ether (Et ₂ O) (about 120 mL), to obtain compound (I) (yield 3.16 g, yield 74%) as a white solid.

The analytical results of compound (I) by ¹ H-NMR, ¹³ C-NMR, melting point measuring instrument, and infrared spectrophotometer (IR) are shown below. ^{The 1} H-NMR spectrum is shown in Figure 1A, and the ¹³ C-NMR spectrum is shown in Figure 1B.

^1H NMR (400 MHz, DMSO- _d6 , rt): δ 4.42 (s, 8H, _CH2 ).
^13C NMR (100 MHz, DMSO-d ₆ , rt): δ 147.056 (C=O), 68.84 (CH ₂ -O-), 29.67 (-C-).
Mp: 220-225℃(dec.).
IR (ATR, cm ^-1 ): 1737 (ν _C=O ), 1254 (ν _CO ), 1171 (ν _CO ), 1125 (ν _CO ), 1094 ν _CO ).

The DMF used as the reaction solvent was recovered and reused as a solvent, but this had almost no effect on the yield or purity, and it was confirmed that it could be reused at least five times.

<Study on Pentaerythritol (PE) Concentration>
Next, in the presence of an excess amount of DPC (10 molar equivalents) relative to 1 molar equivalent of PE, the initial pentaerythritol (PE) concentration in the reaction solution was changed from 100 mM (mmol/L) to 20 mM (mmol/L) and the reaction was carried out at 100° C., and the yield of compound (I) was examined.

[Example 2]
(Initial PE concentration: 100mM)
DPC (428 mg, 2.0 mmol) and DMF (1.5 mL) were added to a 10 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (27.2 mg, 0.20 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 43.8%. The results of the ¹ H-NMR measurement are shown in FIG. 2.

[Example 3]
(Initial PE concentration: 80mM)
DPC (428 mg, 2.0 mmol) and DMF (2.0 mL) were added to a 10 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (27.2 mg, 0.20 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 55.0%.

[Example 4]
(Initial PE concentration: 60mM)
DPC (428 mg, 2.0 mmol) and DMF (2.8 mL) were added to a 10 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (27.2 mg, 0.20 mmol) was quickly added thereto, the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 64.0%.

[Example 5]
(Initial PE concentration: 40mM)
DPC (428 mg, 2.0 mmol) and DMF (4.5 mL) were added to a 10 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (27.2 mg, 0.20 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 78.3%.

[Example 6]
(Initial PE concentration: 20mM)
DPC (428 mg, 2.0 mmol) and DMF (9.5 mL) were added to a 25 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (27.2 mg, 0.20 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 86.8%.

Figure 3 is a graph showing the relationship between the yield (selectivity) of compound (I) obtained in Examples 2 to 6 and the initial PE concentration. As shown in Figure 3, the selectivity of compound (I) increased from 43.8% to 86.8% as the initial PE concentration decreased, and a linear relationship was observed between the initial PE concentration and the production ratio of compound (I). From this result, it is believed that at low concentrations, carbonation of PE occurs preferentially intramolecularly rather than intermolecularly, resulting in more selective production of compound (I).

<Temperature considerations>
Based on the results of Examples 2 to 6 above, the yield of compound (I) was examined when the reaction was carried out at an initial PE concentration of 20 mM, which had the highest selectivity among the initial PE concentrations, in the presence of an excess amount of DPC (10 molar equivalents) relative to 1 molar equivalent of PE, and at a reaction temperature changed from 20° C. to 100° C.

[Example 7]
(Reaction temperature: 20° C.)
DPC (428 mg, 2.0 mmol) and DMF (9.5 mL) were added to a 25 mL flask and the temperature was adjusted to 20° C. A DMF solution (0.5 mL) of PE (27.2 mg, 0.20 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 20° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO- _d6 , whereupon an insoluble portion was observed. As a result of performing ¹ H-NMR measurement using the soluble portion of the solution, the yield (selectivity) of compound (I) was 8.5%.

[Example 8]
(Reaction temperature: 50° C.)
DPC (428 mg, 2.0 mmol) and DMF (9.5 mL) were added to a 25 mL flask and heated to 50° C. A DMF solution (0.5 mL) of PE (27.2 mg, 0.20 mmol) was quickly added thereto, the flask was replaced with nitrogen, and the mixture was stirred at 50° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 69.1%.

[Example 9]
(Reaction temperature: 75° C.)
DPC (428 mg, 2.0 mmol) and DMF (9.5 mL) were added to a 25 mL flask and heated to 75° C. A DMF solution (0.5 mL) of PE (27.2 mg, 0.20 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 75° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 84.5%.

[Example 10]
(Reaction temperature: 100° C.)
DPC (428 mg, 2.0 mmol) and DMF (9.5 mL) were added to a 25 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (27.2 mg, 0.20 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 86.8%.

Figure 4 is a graph showing the relationship between the yield (selectivity) of compound (I) obtained in Examples 7 to 10 and the reaction temperature. As shown in Figure 4, the selectivity of compound (I) increased with increasing temperature and leveled off at around 75°C. Furthermore, no unreacted PE was observed in any of the cases. From this, as shown in the reaction formula below, at high temperatures, the intermediate produced by the reaction of some of the OH groups of PE with DPC is likely to form an entropically disadvantageous cyclic carbonate, whereas at low temperatures, the intermediate prioritizes the formation of an intermolecular chain carbonate, which is entropically advantageous, and therefore the selectivity of compound (I) decreased with decreasing temperature.

<Study on the molar ratio of DPC to PE ([DPC] ₀ /[PE] ₀ )>
From the results of Examples 2 to 10 above, the yield of compound (I) was investigated when the reaction was carried out with an initial PE concentration of 20 mM, a fixed reaction temperature of 100° C., and the molar ratio of DPC to PE varied from 10/1 to 2/1.

[Example 11]
([DPC] ₀ / [PE] ₀ :10/1)
DPC (214 mg, 1.0 mmol) and DMF (4.5 mL) were added to a 10 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (13.6 mg, 0.10 mmol) was quickly added thereto, the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 86.8%.

[Example 12]
([DPC] ₀ / [PE] ₀ :8/1)
DPC (171.4 mg, 0.80 mmol) and DMF (4.5 mL) were added to a 10 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (13.6 mg, 0.10 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 94.2%.

[Example 13]
([DPC] ₀ / [PE] ₀ :6/1)
DPC (128.5 mg, 0.60 mmol) and DMF (4.5 mL) were added to a 10 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (13.6 mg, 0.10 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 93.9%.

[Example 14]
([DPC] ₀ / [PE] ₀ :4/1)
DPC (85.7 mg, 0.40 mmol) and DMF (4.5 mL) were added to a 10 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (13.6 mg, 0.10 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO-d ₆ and subjected to ¹ H-NMR measurement. As a result, the yield (selectivity) of compound (I) was 91.2%.

[Example 15]
([DPC] ₀ / [PE] ₀ :2/1)
DPC (42.8 mg, 0.20 mmol) and DMF (4.5 mL) were added to a 10 mL flask and heated to 100° C. A DMF solution (0.5 mL) of PE (13.6 mg, 0.10 mmol) was quickly added thereto, the atmosphere in the flask was replaced with nitrogen, and the mixture was stirred at 100° C. for 12 hours. A part of the solution was distilled off under reduced pressure, and the residue was dissolved in DMSO- _d6 , whereupon an insoluble portion was observed. As a result of performing ¹ H-NMR measurement using the soluble portion of the solution, the yield (selectivity) of compound (I) was 86.6%.

In the ¹ H-NMR measurements of the products of Examples 11 to 15, no signals of unreacted OH groups were observed in any of the measurements.
5 is a graph showing the relationship between the yield (selectivity) of compound (I) obtained in Examples 11 to 15 and the molar ratio of DPC to PE. As shown in FIG. 5, an insoluble portion was observed when the molar ratio of DPC to PE was 2/1, but the selectivity of compound (I) in the soluble portion did not differ significantly from that when the molar ratio of DPC to PE was from 10/1 to 4/1. On the other hand, when the molar ratio of DPC to PE was from 10/1 to 4/1, no insoluble portion was observed, and no significant difference was observed in the selectivity.
From the above results, it is considered that when the molar ratio of DPC to PE was 2/1, as in the case of reaction at a low temperature of about 20°C in the above reaction temperature study, unreacted PE became excessive relative to the intermediate produced by the reaction of some of the OH groups of PE with DPC, and as a result, by-products such as oligomers were produced by reacting with the OH groups of PE or the intermediate before the intermediate could undergo an intramolecular cyclization reaction.

[Example 16]
(Reactivity of Compound (I))
Since compound (I) has a spiro structure consisting of two six-membered cyclic carbonates, it was expected that the ring strain would be larger and the reactivity would be higher than similar six-membered cyclic carbonates. Therefore, 5,5-dimethyl-1,3-dioxan-2-one (hereinafter sometimes referred to as "compound (IV)") was used as a model compound, and in the presence of compound (I) and compound (IV) (molar ratio: [compound (I)] _0/ [compound (IV)] ₀ = 1/1), the compound was reacted with 0.9 molar equivalent of monoamine (1-hexylamine) in DMSO-d ₆ at room temperature to compare the reactivity of compound (I) and compound (IV). The ¹ H-NMR measurement results of the products in each reaction are shown in Figure 6.

As can be seen from Figure 6, compound (I) selectively reacted with monoamine (1-hexylamine), whereas compound (IV) was hardly consumed (yield: 1% or less). In other words, it was revealed that the reactivity of compound (I) with amines is more than 100 times higher than that of compound (IV).

<Production of Polyhydroxyurethane>
[Example 17]
(Ring-opening polyaddition behavior of compound (I) and diamine)
As shown in the following reaction formula, polyhydroxyurethane can be obtained by reacting compound (I) with a diamine.

In the following reaction formula, X is an alkylene group, an aralkylene group, or a group represented by -R ¹¹ -Ar ¹¹ -R ¹² -. ^{Ar 11} is a divalent aromatic hydrocarbon group, and R ¹¹ and R ¹² are each independently an alkylene group having 1 to 20 carbon atoms. n is an integer of 1 or more. n is an integer of 1 or more.

The synthesis of polyhydroxyurethane (C6) was attempted by polyaddition of compound (I), which is a spiro-type biscarbonate, with 1,6-diaminohexane in DMSO at 85° C. As a result, gelation occurred after 24 hours of reaction.
In order to verify the polyaddition behavior of compound (I) and 1,6-diaminohexane, the polyaddition behavior was monitored by gel permeation chromatography (GPC) measurement in DMSO at 50°C (see the reaction formula below). The results of the GPC measurement are shown in Figure 7. Figure 8 is a graph showing the relationship between the reaction time of compound (I) and 1,6-diaminohexane and the number average molecular weight or molecular weight distribution of the product.

Figures 7 and 8 show that a new peak appeared on the high molecular weight side after about 3 hours of reaction, and as the reaction time increased, the peak area increased and shifted to the high molecular weight side. This is probably because in the later stages of the reaction, the concentration of the amino groups at the polymer chain ends was significantly lower than the concentration of the hydroxyl groups produced, and the six-membered cyclic carbonate groups at the polymer chain ends reacted with the hydroxyl groups in the side chains instead of the amino groups, resulting in crosslinking of the polymer chains. Similar gelation has also been reported in the polyaddition of other bifunctional six-membered cyclic carbonates with diamines. To prevent this side reaction, 0.1 molar equivalents of 1,6-diaminohexane was added to the reaction system after 3 hours of reaction, but no gelation was observed even overnight.

Based on the above results, the polyaddition reaction conditions were standardized as shown in the reaction formula below: DMSO, 50°C, 0.1 molar equivalent of diamine was added after 3 hours of reaction, and a total of four types of polyhydroxyurethanes (PHUs) with different diamines (C3, C6, C8, p-Xyl) were produced.

Specific manufacturing methods are shown in Examples 18 to 21 below.

[Example 18]
(Production of polyhydroxyurethane (C3))
Compound (I) (250 mg, 1.33 mmol) was added to a 5 mL vial, the vial was capped with a silicon septum, and the inside of the vial was replaced with nitrogen. Dry DMSO (2 mL) was added thereto to suspend the solution, and then 1,3-diaminopropane (112 μL, 1.33 mmol) was added at room temperature (immediately became a homogeneous solution). This solution was heated to 50° C. and stirred under a nitrogen atmosphere. After 3 hours, 1,3-diaminopropane (11 μL, 0.13 mmol) was added, and the solution was stirred at 50° C. for 16 hours. After cooling to room temperature, the solution was added dropwise to CHCl ₃ (about 125 mL) and allowed to stand at about 4° C. for 4 hours. The precipitated solid was collected, dissolved in DMF (about 4 mL), and added dropwise to CHCl ₃ (about 100 mL) to collect the precipitated solid, which was then dried under reduced pressure to obtain polyhydroxyurethane (C3) (330 mg, yield 95%) as a white solid. The structure of polyhydroxyurethane (C3) was confirmed by ¹ H-NMR spectrum and ¹³ C-NMR spectrum. The proportion of side reactions calculated from the integral ratio of the ¹ H-NMR spectrum of polyhydroxyurethane (C3) was about 22%, and the content of polyhydroxyurethane (C3) having a branched structure relative to the total molar amount of polyhydroxyurethane (C3) was about 11 mol%.

[Example 19]
(Production of polyhydroxyurethane (C6))
Compound (I) (250 mg, 1.33 mmol) and 1,6-diaminohexane (154 mg, 1.33 mmol) were added to a 5 mL vial, the vial was capped with a silicon septum, and the inside of the vial was replaced with nitrogen. Dry DMSO (2 mL) was added thereto at room temperature (immediately became a homogeneous solution), and the mixture was heated to 50°C and stirred under a nitrogen atmosphere. After 3 hours, 1,6-diaminohexane (15.4 mg, 0.13 mmol) was added, and the mixture was stirred at 50°C for 12 hours. After cooling to room temperature, the solution was added dropwise to CHCl ₃ (about 125 mL) and allowed to stand at about 4°C for 1 hour. The precipitated solid was collected, dissolved in MeOH (about 5 mL) and added dropwise to CHCl ₃ (about 100 mL), and the precipitated solid was collected and dried under reduced pressure to obtain polyhydroxyurethane (C6) (356 mg, yield 88%) as a white solid. The structure of polyhydroxyurethane (C6) was confirmed by ¹ H-NMR spectrum and ¹³ C-NMR spectrum.

[Example 20]
(Production of polyhydroxyurethane (C8))
Compound (I) (250 mg, 1.33 mmol) and 1,8-diaminooctane (191.7 mg, 1.33 mmol) were added to a 5 mL vial, the vial was capped with a silicon septum, and the inside of the vial was replaced with nitrogen. Dry DMSO (3 mL) was added thereto at room temperature (partially insoluble), and the mixture was heated to 95° C. and stirred under a nitrogen atmosphere for 0.5 hours and at 50° C. for 2.5 hours. 1,8-diaminooctane (19.7 mg, 0.13 mmol) was added thereto, and the mixture was stirred at 95° C. for 3.5 hours and at 50° C. for 2.5 hours. After cooling to room temperature, the solution was added dropwise to CHCl ₃ (about 125 mL) and allowed to stand at about 4° C. for 3 hours. The precipitated solid was collected, dissolved in MeOH (about 5 mL) and added dropwise to CHCl ₃ /n-hexane (about 100 mL/about 50 mL), and the precipitated solid was collected and dried under reduced pressure to obtain polyhydroxyurethane (C8) (375 mg, yield 85%) as a white solid. The structure of polyhydroxyurethane (C8) was confirmed by ¹ H-NMR spectrum and ¹³ C-NMR spectrum.

[Example 21]
(Production of polyhydroxyurethane (p-Xyl))
Compound (I) (250 mg, 1.33 mmol) and p-xylylenediamine (181 mg, 1.33 mmol) were added to a 5 mL vial, the vial was capped with a silicon septum, and the inside of the vial was replaced with nitrogen. Dry DMSO (2 mL) was added thereto at room temperature (partially insoluble), and after stirring for 5 minutes, the mixture was heated to 50° C. and stirred under a nitrogen atmosphere for 3 hours. p-xylylenediamine (18.1 mg, 0.13 mmol) was added thereto, and the mixture was stirred at 50° C. for 12.5 hours. After cooling to room temperature, the solution was added dropwise to CHCl ₃ (about 125 mL) and allowed to stand at about 4° C. for 1 hour. The precipitated solid was collected, dissolved in DMF (about 5 mL), and added dropwise to CHCl ₃ (about 125 mL) to collect the precipitated solid, which was then dried under reduced pressure to obtain polyhydroxyurethane (p-Xyl) (407 mg, yield 94%) as a pale yellow solid. The structure of polyhydroxyurethane (p-Xyl) was confirmed by ¹ H-NMR spectrum and ¹³ C-NMR spectrum. The proportion of side reactions calculated from the integral ratio of the ¹ H-NMR spectrum of polyhydroxyurethane (p-Xyl) was about 22%, and the content of polyhydroxyurethane (p-Xyl) having a branched structure relative to the total molar amount of polyhydroxyurethane (p-Xyl) was about 11 mol%.

The polyhydroxyurethanes obtained in Examples 18 to 21 were identified by GPC measurement and Fourier transform infrared spectroscopy (FT-IR). The polymerization conditions, yield, number average molecular weight (Mn), and molecular weight distribution (Mw/Mn) are summarized in Table 1.

The FT-IR results showed that in all polyhydroxyurethanes, the peak at 1737 cm ⁻¹ due to the C═O stretching vibration of compound (I), which is a spiro-type cyclic carbonate, completely disappeared, and a peak due to the C═O stretching vibration of urethane was observed between 1686 cm ⁻¹ and 1690 cm ⁻¹ , as well as a peak due to the N-H/O-H stretching vibration near 3310 cm ⁻¹ .
In the ¹ H-NMR spectrum, signals corresponding to the NH of the urethane group (cis/trans mixture: 6.8 ppm to 7.1 ppm), the OH of the hydroxyl group (4.3 ppm to 4.7 ppm), and other protons were observed in all polyhydroxyurethanes, and in the ¹³ C-NMR spectrum, a ¹³ C signal due to the C═O of the urethane group was observed around 156 ppm in all polyhydroxyurethanes.
The number average molecular weight Mn of each of the obtained polyhydroxyurethanes was 3.5×10 ³ or more and 14.2×10 ³ or less, and the molecular weight distribution Mw/Mn was 2.0 or more and 5.8 or less.
From these results, it was found that each of the produced polyhydroxyurethanes was a polyurethane having a hydroxy group in the side chain, and the desired polyhydroxyurethane was produced.

As shown in Table 1, polyhydroxyurethane (C8) had the highest number-average molecular weight Mn. However, the molecular weight distribution Mw/Mn was broad at 5.5, and a bimodal peak was observed in the GPC measurement. From these findings, it is believed that polyhydroxyurethane (C8) partially contains a branched structure, and this is presumed to be due to heating at 95°C at the beginning of the reaction. In addition, polyhydroxyurethane (p-Xyl), which was not heated at 95°C, also showed a wide molecular weight distribution (Mw/Mn = 5.8). The reason for this is unclear, but it is thought that the nucleophilicity of the amino group at the benzyl position of p-xylenediamine is lower than that of other diamines, which makes it easier for the reaction to occur between the six-membered cyclic carbonate group at the end of the polymer chain and the hydroxy group in the side chain.

[Example 22]
(Thermal properties of polyhydroxyurethane)
Thermogravimetric and differential thermal analysis (TGA-DTA) and differential scanning calorimetry (DSC) were performed on each of the polyhydroxyurethanes obtained in Examples 18 to 21. The results of TGA-DTA are shown in Figure 9, and the results of DSC are shown in Figure 10.

From FIG. 9, the 5% mass reduction temperature (T _d5 ) rose from 236° C. to 286° C. with an increase in the carbon number of the diamine, except for polyhydroxyurethane (p-Xyl). This is probably because the polyhydroxyurethane depolymerized by heating and converted to the corresponding monomer (compound (I) and diamine), and the polyhydroxyurethane that produces a diamine with a high boiling point had a higher T _d5 . On the other hand, although the boiling point of p-xylylenediamine, the diamine produced by depolymerization of polyhydroxyurethane (p-Xyl), is higher than that of other aliphatic diamines, it showed a lower T _d5 of 269° C. than that of polyhydroxyurethane (C8). In addition, the mass reduction of polyhydroxyurethane (p-Xyl) did not reach 100% even at 500° C. From these facts, it is considered that p-xylylenediamine produced by heating was carbonized, and as a result, _Td5 of polyhydroxyurethane (p-Xyl) became lower than that of polyhydroxyurethane (C8). In fact, when the sample of polyhydroxyurethane (p-Xyl) after TGA-DTA was confirmed, black solid matter was observed.

As shown in Figure 10, the glass transition temperatures Tg of polyhydroxyurethanes (C3), (C6) and (C8) were 42.5°C or higher and 47.4°C or lower, and no particular correlation was observed between the number of carbon chains in the diamine residue and Tg. Considering that Tg is affected by the molecular weight of the polymer, the reason for the lack of correlation may be that the number average molecular weights Mn of polyhydroxyurethanes (C3), (C6) and (C8) are different. On the other hand, polyhydroxyurethane (p-Xyl) having an aromatic group in the main chain showed a higher Tg (85.7°C) than polyhydroxyurethanes (C3), (C6) and (C8). Furthermore, no melting point was observed in any of the polyhydroxyurethanes, indicating that they were amorphous.

[Example 23]
(Conversion of compound (I) into dihydroxyurethane derivative)
By reacting 1 molar equivalent of compound (I) with 2 molar equivalents of monoamine, it is possible to derive the corresponding dihydroxyurethane. By polyaddition of this dihydroxyurethane derivative with diisocyanate, it is possible to synthesize polyurethane having urethane groups in the side chain. In addition, the dihydroxyurethane derivative has the possibility of being converted into a novel six-membered cyclic carbonate having two urethane groups by reaction with DPC.
Based on these findings, the synthesis of a dihydroxyurethane derivative of compound (I) was investigated.

As shown in the reaction formula below, a dihydroxyurethane derivative (hereinafter sometimes referred to as "compound (V)") was obtained by reacting 1 molar equivalent of compound (I) with 2 molar equivalents of monoamine. The specific synthesis procedure is described below.

Compound (I) (500 mg, 2.66 mmol) was suspended in dry DMF (5 mL), 1-hexylamine (592 mg, 5.85 mmol) was slowly added at room temperature, and the mixture was stirred at room temperature for 14.5 hours. DMF was removed under reduced pressure, and the residue was purified with a silica gel column (eluent: EtOAc/n-hexane = 3/1, vol/vol) to obtain compound (V) (744 mg, yield 72%) as a white solid.

The analytical results of compound (V) by electrospray ionization mass spectrometry (ESI-MS), ¹ H-NMR, ¹³ C-NMR, melting point analyzer, and infrared spectrophotometer (IR) are shown below. The ¹ H-NMR spectrum is shown in FIG.

HRMS (ESI-MS) (positive): m/z calcd for [M + Na]+, 413.2628, found, 413.2629.
¹ H NMR (400 MHz, DMSO-d6, rt): δ (trans-urethane isomer) 7.06 (t, J = 5.7 Hz, 2H, NH), 4.46 (t, J = 5.0 Hz, 2H, OH), 3.87 (s, 4H, -NHCOOCH ₂ -), 3.36 (d, J = 5.3 Hz, partially overlapping with residual H ₂ O signal, -CH ₂ OH), 2.93 (q, J = 6.7 Hz, 4H, -NHCH ₂ -), 1.37 (t, J = 6.7 Hz, 4H, -NHCH ₂ CH ₂ -), 1.29-1.21 (m, 12H, -CH ₂ -(CH ₂ ) ₃ -CH ₃ ), 0.85 (t, J = 6.8 Hz, 6H, _-CH3 ).
^13C NMR (100 MHz, DMSO-d6, rt): δ (trans-urethane isomer) 156.46, 62.59, 59.69, 44.39, 40.26, 31.06, 29.45, 26.00, 22.13, 13.97.
Mp: 79.0-81.0℃.
IR (ATR, cm ^-1 ): 3278 (ν _NH and/or ν _OH ), 1687 (ν _C=O ), 1545 (ν _NH ), 1252 (ν _CO ), 1048(ν _CO ).

[Example 24]
(Identification of by-products from model reactions of compound (I) with monoamines)
A model reaction was carried out using compound (I) and a monoamine. The specific synthesis procedure is as follows.
Compound (I) (500 mg, 2.66 mmol) was suspended in dry DMF (5 mL), 1-hexylamine (592 mg, 5.85 mmol) was slowly added at room temperature, and the mixture was stirred at 50° C. for 14.5 hours. DMF was removed from a part of the reaction solution by vacuum distillation, and the residue was dissolved in DMSO-d ₆ , and ¹ H-NMR measurement was performed. In addition, the residue of the remaining reaction solution was purified with a silica gel column (eluent: CHCl ₃ /EtOAc = 2/8, vol/vol), and the obtained solid was dissolved in DMSO-d ₆ , and ¹ H-NMR measurement was performed. The results of the ¹ H-NMR measurement are shown in FIG. 12. In addition, the reaction product was identified by ESI-MS analysis. As a result, it was revealed that in addition to the target product compound (V), compound (V') and compound (V'') were produced as by-products, as shown in the following reaction formula. In the reaction formula, R is a hexyl group.

<Study of manufacturing conditions for polyhydroxyurethane>
[Example 25]
(Reaction temperature: 50° C.)
Compound (I) (250 mg, 1.33 mmol) and 1,6-diaminohexane (154 mg, 1.33 mmol) were added to a 5 mL vial, the vial was capped with a silicon septum, and the inside of the vial was replaced with nitrogen. Dry DMSO (2 mL) was added thereto at room temperature, and the mixture was heated to 50° C. and stirred under a nitrogen atmosphere. After 3 hours, 1,6-diaminohexane (15.4 mg, 0.13 mmol) was added and stirred at 50° C. for 12 hours. After cooling to room temperature, the solution was added dropwise to CHCl ₃ (about 125 mL) and allowed to stand at about 4° C. for 1 hour. The precipitated solid was collected, dissolved in MeOH (about 5 mL), and added dropwise to CHCl ₃ (about 100 mL), and the precipitated solid was collected and dried under reduced pressure to obtain polyhydroxyurethane (C6) (356 mg, yield 88%) as a white solid. ^{The 1} H-NMR spectrum of polyhydroxyurethane (C6) is shown in FIG.

13, it was confirmed that in addition to polyhydroxyurethane (C6), by-products corresponding to compound (V') and compound (V''), which were by-products identified in the model reaction in Example 24, were produced. The production ratio of polyhydroxyurethane (C6), compound (V'), and compound (V'') was calculated from the integral ratio of the ¹ H-NMR spectrum. The production ratio was polyhydroxyurethane (C6): compound (V'): compound (V'') = 6.3:1:1, and the proportion of side reactions was approximately 24%.

These results suggest that polyhydroxyurethane (C6) contains a monomer unit having two hydroxy groups in the side chain (corresponding to the structure of compound (V)) and a monomer unit having one hydroxy group and one urethane group in the side chain (corresponding to the structure of compound (V')), and that it has a branched structure. It also suggests that the terminal structures of the main chain and side chain of polyhydroxyurethane (C6) have terminal structures corresponding to the structure of compound (V''), which has three hydroxy groups in addition to the amino terminal.

[Example 26]
(Reaction temperature: 0° C.)
1,6-diaminohexane (154 mg, 1.33 mmol) was added to a 5 mL vial, the vial was capped with a silicon septum, and the inside of the vial was replaced with nitrogen. Dry DMF (2 mL) was added to the vial at room temperature, cooled to 0°C, and compound (I) (250 mg, 1.33 mmol) was added as a powder. After stirring at 0°C for 18 hours, 1,6-diaminohexane (15.4 mg, 0.13 mmol) was added at 0°C, and then stirred at 50°C for 5 hours. After cooling to room temperature, the solution was added dropwise to CHCl ₃ (about 125 mL) and allowed to stand at about 4°C for 1 hour. The precipitated solid was collected, dissolved in MeOH (about 5 mL), and added dropwise to CHCl ₃ (about 100 mL) to collect the precipitated solid, which was then dried under reduced pressure to obtain polyhydroxyurethane (C6) (305 mg, 80%) as a white solid. ^{The 1} H-NMR spectrum of polyhydroxyurethane (C6) is shown in FIG. 14. The production ratio of polyhydroxyurethane (C6), compound (V') and compound (V'') was calculated from the integral ratio of the ¹ H-NMR spectrum. The production ratio was polyhydroxyurethane (C6): compound (V'): compound (V'') = 25:1:1, the proportion of side reactions was about 7%, and the content of polyhydroxyurethane (C6) having a branched structure relative to the total molar amount of polyhydroxyurethane (C6) was about 3.5 mol%.

The above results show that in this example, in which polyhydroxyurethane (C6) was synthesized at 0°C, side reactions were significantly suppressed compared to Example 25, in which polyhydroxyurethane (C6) was synthesized at 50°C (proportion of side reactions: approximately 24%).

[Example 27]
(Production of polyhydroxyurethane (C3): reaction temperature 0° C.)
1,3-diaminopropane (112 μL, 1.33 mmol) and dry DMF (2 mL) were added to a 5 mL vial at room temperature, cooled to 0° C., and compound (I) (250 mg, 1.33 mmol) was added as a powder and stirred at 0° C. for 18 hours. 1,3-diaminopropane (11 μL, 0.13 mmol) was added to this at 0° C., and then stirred at 50° C. for 5 hours. After cooling to room temperature, the solution was added dropwise to CHCl ₃ (about 100 mL), and the precipitated solid was collected, dissolved in DMF (about 4 mL), and added dropwise to CHCl ₃ (about 100 mL), and the precipitated solid was collected and dried under reduced pressure to obtain polyhydroxyurethane (C3) (312 mg, yield 90%) as a white solid. The proportion of side reactions calculated from the integral ratio of the ¹ H-NMR spectrum was about 8%, and the content of polyhydroxyurethane (C3) having a branched structure relative to the total molar amount of polyhydroxyurethane (C3) was about 4 mol %.

[Example 28]
(Production of polyhydroxyurethane (p-Xyl): reaction temperature 0° C.)
Add p-xylylenediamine (181 mg, 1.33 mmol) and dry DMF (2 mL) to a 5 mL vial at room temperature, cool to 0 ° C., add compound (I) (250 mg, 1.33 mmol) as a powder, and stir at 0 ° C. for 18 hours. Add p-xylylenediamine (18.1 mg, 0.13 mmol) to this at 0 ° C., and then stir at 50 ° C. for 5 hours. After cooling to room temperature, the solution was dropped into CHCl ₃ (about 100 mL), and the precipitated solid was collected, dissolved in DMF (about 4 mL), and dropped into CHCl ₃ (about 100 mL), and the precipitated solid was collected and dried under reduced pressure to obtain polyhydroxyurethane (p-Xyl) (396 mg, yield 92%) as a white solid. The proportion of side reactions calculated from the integral ratio of the ¹ H-NMR spectrum was about 8%, and the content of polyhydroxyurethane (p-Xyl) having a branched structure relative to the total molar amount of polyhydroxyurethane (p-Xyl) was about 4 mol %.

The above results show that in Examples 27 and 28, in which polyhydroxyurethane (C3) and polyhydroxyurethane (p-Xyl) were synthesized at 0°C, side reactions were significantly suppressed compared to Examples 18 and 21, in which polyhydroxyurethane (C3) and polyhydroxyurethane (p-Xyl) were synthesized at 50°C (proportion of side reactions: approximately 11%).

According to the production method of this embodiment, it is possible to provide a simple method for producing a bifunctional cyclic carbonate with an improved yield, and a novel method for producing a polyhydroxyurethane using a bifunctional cyclic carbonate.

Claims (11)

The method includes a reaction step of reacting pentaerythritol with a diaryl carbonate to obtain a bifunctional cyclic carbonate having a spiro structure,
The bifunctional cyclic carbonate having a spiro structure is 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione,
A method for producing a bifunctional cyclic carbonate having a spiro structure, the method comprising the step of : The method according to claim 1 , wherein the reaction is carried out at a temperature of 40° C. or higher and 100° C. or lower in the reaction step. The method according to claim 1 or 2 , wherein the reaction is carried out at a temperature of 50° C. or higher and 100° C. or lower in the reaction step. The method according to any one of claims 1 to 3 , wherein in the reaction step, a molar ratio of diaryl carbonate to pentaerythritol is 2/1 or more and 10/1 or less. The process according to any one of claims 1 to 4 , wherein in the reaction step, a molar ratio of diaryl carbonate to pentaerythritol is 4/1 or more and 10/1 or less. The method according to any one of claims 1 to 5 , wherein in the reaction step, a concentration of pentaerythritol is from 10 mmol/L to 100 mmol/L with respect to a total volume of the reaction solution. The method according to any one of claims 1 to 6 , wherein in the reaction step, a concentration of pentaerythritol is from 10 mmol/L to 80 mmol/L with respect to a total volume of the reaction solution. The process according to any one of claims 1 to 7 , wherein the diaryl carbonate is diphenyl carbonate. A bifunctional cyclic carbonate having a spiro structure is produced by the production method according to any one of claims 1 to 8,
The method includes a polymerization step of reacting the bifunctional cyclic carbonate having a spiro structure with a diamine represented by the following general formula (Ia) to obtain polyhydroxyurethane,
The method for producing polyhydroxyurethane, wherein the bifunctional cyclic carbonate having a spiro structure is 2,4,8,10-tetraoxaspiro[5,5]-undecane-3,9-dione.

(In general formula (Ia), X is an alkylene group, an aralkylene group, or a group represented by -R ¹¹ -Ar ¹¹ -R ¹² -. ^{Ar 11} is a divalent aromatic hydrocarbon group, and R ¹¹ and R ¹² are each independently an alkylene group having 1 to 20 carbon atoms.) The method according to claim 9 , wherein in the polymerization step, the polymerization reaction is carried out at 5° C. or less, and the content of polyhydroxyurethane having a branched structure is controlled to be 4 mol % or less based on the total molar amount of polyhydroxyurethane. The method according to claim 9 , wherein in the polymerization step, the polymerization reaction is carried out at 50° C. or higher, and the content of polyhydroxyurethane having a branched structure is controlled to be 11 mol % or higher based on the total molar amount of polyhydroxyurethane.

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