DE3326723A1 - AMINE SALTS OF P-NITROSOPHENOLATES - Google Patents

Description

Sandoz AG

4000 Basel Case 155-2059

Amine salts of p-nitrosophenols

The present invention relates to amine salts of p-nitrosophenols and their use as a polymerization inhibitor,

Preventing the undesirable polymerization of polymerizable Monomers during manufacture, especially during manufacture, purification or storage of the monomers, still cease An important problem. Inhibitors are used in large numbers in order to prevent or delay undesired polymerization. Many However, these inhibitors only work for a short time or are insufficiently effective at elevated temperatures, which very often leads to polymerization of the monomers to be stabilized, interruption of the manufacturing process and expensive cleaning of the equipment. It has now been found that amine salts of p-nitrosophenol act as polymerization inhibitors can be used and that these salts prevent the polymerization of monomers for a considerably longer period of time than conventional inhibitors such as sodium p-nitrosophenolate.

The present invention relates in particular to amine salts of p-nitrosophenols, characterized in that these salts are protonated of an amine or PolyaT.ins were obtained with a p-nitrosophenol and in this amine salt each protonated nitrogen atom corresponds to one p-nitrosophenolate anion each.

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The amine contained in such an amine salt of the present invention is preferable a mono-, di-, tri- or tetramine. The compound according to the invention is preferably derived from a mono-, di-, trioder Tetramine, the nitrogen atoms of which represent primary, secondary or tertiary amino groups. The nitrogen atoms present are in the amine salt partially or all protonated, so that a p-nitrosophenolation can be assigned to each protonated nitrogen atom.

In particular, the invention relates to compounds of the formula I.

R \, R2 and R3 independently of one another are hydrogen, alkyl ((4.4) or

R hydrogen, alkyl (q_ ₂₀ ), alkanol C ₂ _4), cycloalkyl (C ₃ _ ₇ ),

Cycloalkyl (C ₃ _ ₆₎ alkyl (C _1-4), aryl or Arylalykl (Ci_4), B are independently alkylene ^ .g) or

D-UA)) wherein each D and E independently of one another the direct bond or alkylene (C ^ _4),
m 0, 1, 2 or 3 and
η is an integer from 1-4, where n <m + 1 and the benzene rings A, independently of one another, can be unsubstituted or can carry up to 2 substituents selected from chlorine, methyl, methoxy or ethyl. Each protonated nitrogen atom of the amine corresponds to a p-nitrosophenolatani on.

R, R 1 and R3 can be straight-chain or branched; With the meaning of alkanol, these substituents bear the hydroxyl group in the β, γ or cf position relative to the nitrogen atom to which this substituent is attached. Such an alkanol radical preferably has 2 or 3-C

Case 155-2059

* so B is preferably unsubstituted

Atoms and is preferably ß-Hydroxyaethyl.

If B is alkylene, it is straight-chain or branched, preferably straight chain.

R \, R2 or R3 in the meaning of alkyl ((4.4) are preferably methyl, ethyl, isopropyl or butyl. R as alkyl is preferably alkyl (Ci_ig), preferably methyl, ethyl, isopropyl, butyl, hexyl, n-octyl, tertiary octyl, decyl, dodecyl or hexadecyl, R as cycloalkyl is preferably cyclohexyl and as cycloalkylalkyl is preferably cyclohexylmethyl.

The term aryl preferably denotes phenyl. R is aralkyl preferably phenyl alkyl (C ^) and preferably benzyl or phenylaethyl.

If B means a remainder D
Phenylenes.

m preferably denotes zero, 1, 2, or 3, the molecule preferably having the same number of p-nitrosophenolate anions as the amine nitrogen atoms, ie all nitrogen atoms of the amine are preferably protonated. R preferably denotes R ', ie hydrogen, alkyl (C ^. ^ G), alkenol (C2,3), cyclohexyl, phenyl or benzyl. R ^ preferably denotes Rl ¹ , ie hydrogen, alkyl (Ci_ ₄ ) or alkanol (C2-3). R3, independently of one another, preferably denotes R3 ¹ , ie hydrogen, alkyl (Ci_4) or alkanol (C2> 3). R2 preferably denotes hydrogen. B, independently of one another, preferably denotes B ', ie straight-chain alkylene (C ^ _g) or phenylene. It is preferably in the para position to D. The benzene ring A is preferably unsubstituted. m preferably denotes zero.

Of the compounds of the formula I, those of the formula Ia are preferred

B _ NH) R ₃ ¹ n-1 °

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wherein η R ¹ , R ^ ¹ , R ₃ 'and B ^{1 have} the meaning given above and each protonated nitrogen atom of the amine corresponds to a p-nitrosophenolate group.

Preferred compounds of formula I are those in which the amine the formula

R ¹
J> R ₃ '

is equivalent to. Preferred of these compounds are dimethyl ami η, Diethylamine, triethylamine, isopropylamine, n-butylamine, n-octylamine, tert-octylamine, hexadecylamine, cyclohexylamine, benzylamine, Triethanolamine, ethylenediamine, 1,6-hexanediainine, p-phenylenediamine and Hexamethylenetetramine.

Preference is given to compounds of the formula I in which R = alkyl, cycloalkyl, preferably alkyl (Ci-iß), Ri = hydrogen or alkyl (C ^) ₅ R = hydrogen and m = zero.

The process for preparing the compounds of the present invention is characterized in that one mole of an amine which contains at least one primary, secondary or tertiary nitrogen atom, preferably a mono-, di-, tri- or tetramine or a mixture of two or more such compounds, with one optionally substituted p-nitrosophenol or a mixture of such compounds, the number of moles of des used in the reaction p-nitrosophenols is the same or lower, and preferably the same, like the number of protonizable nitrogen atoms of the amine. The process for making the compounds of Formula 1 is thereby characterized in that one mole of an amine of the formula II

RR ₂

\ (^ R ₃ II

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wherein m, R, R ^, R2, R3 and B have the above meaning or one Mixture of two or more such compounds with a compound of the formula III

N = O III

wherein the benzene ring A can be unsubstituted or substituted or a mixture of such compounds in a molar ratio of 1: 1 to 1: n, preferably 1: n.

The reaction is carried out in a liquid medium such as water or an inert organic solvent such as dimethylformamide or toluene. If the amine is liquid, there is no need to use a solvent. The reaction mixture is stirred at a temperature of 0-40 ^e C, preferably at room temperature, is completed until the reaction, which may take from 10 minutes to 15 hours.

It is preferred to use the same number of moles of p-nitrosophenol as the amine contains nitrogen atoms or amino groups, so that each nitrogen atom is assigned a p-nitrosophenol group. That The reaction product is isolated and purified in a manner known per se.

The compounds of the present invention are according to the invention as Polymerization inhibitors used. In particular, they prevent the polymerization of those that polymerize by means of radical polymerization Monomers. The compounds according to the invention are particularly useful to prevent the polymerization of vinyl monomers such as acrolein, acrylonitrile, styrene, chlorostyrene, vinyl acetate, acrylic acid esters, such as methyl, ethyl, butyl or 2-ethylhexyl acrylate, Methacrylic acid esters, such as methyl or ethyl methacrylate and acrylic acid, preferably butyl acryl at.

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To prevent the polymerization of such polymers, the inventive Compound added to the monomers in a manner known per se. E.g. by mixing or dissolving in the monomer to prevent it premature polymerization during manufacture, purification and especially during distillation of the monomeric material as well as during storage or transport under predominantly air-free conditions. The amount of the compound added for this purpose Formula I is 0.00001 to 1 percent by weight based on the weight of the monomer.

The polymerization inhibitor according to the invention can be used in purified form or in the form of the partially purified reaction mixture, e.g., after dissolving it in water and filtration. This Reaction mixture can contain a proportion of unreacted p-nitrosophencl and Contain sodium p-nitrosophenolate, e.g. up to 15% each of the reactant product. The polymerization inhibitor according to the invention can also be used in a mixture with other polymerization inhibitors.

The compounds according to the invention show a particularly interesting one inhibiting effect. They are suitable to protect monomers, especially acrylic acid esters and very especially butyl acrylate, against premature polymerization to protect, especially over a very long period of time, even at temperatures above room temperature. In the further they have good solubility in these monomers, especially in butyl acrylate. The polymerization inhibitors according to the invention show nor do they have the disadvantages of sodium p-nitrosophenolate. she have improved stability and are significantly less ignitable than sodium p-nitrosophenolate.

The salts of p-nitrosophenol with isopropylamine, dimethylamine and Tertiary octylamine are particularly preferred, especially for use in the mentioned acrylic acid esters and preferably for butyl acrylate, Acrylonitrile and acrolein.

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The following examples illustrate the invention. Parts are parts by weight and degrees are degrees Celsius.

example 1

The p-nitrosophenol salt of hexadecyiamine is prepared by slowly adding, at room temperature, 21 parts of hexadecyiamine to 10.7 parts of p-nitrosophenol, which is suspended in 400 parts of water, with stirring. The mixture is stirred for 3 \ hours, the salt formed is filtered off, washed with 80 parts of water and dried in air at 20-30 ° C. 31.7 parts of a greenish powder of the salt mentioned are obtained with a melting point of 60.5 -62 ^e C.

Example 2

An aqueous solution of the salt formed from ρ-nitrosophenol and Benzylamine is made by adding 4.3 parts of benzylamine at room temperature to 4.92 parts of p-nitrosophenol, which is suspended in 100 parts of water, are added dropwise with stirring. The mixture is stirred for a further 2 Hours and filter the reaction mixture. The filtrate obtained is an aqueous solution containing about 8.3 parts of the p-nitrosophenol salt of Contains benzylamine.

Example 3

An aqueous solution of the p-nitrosophenol salt of cyclohexyl amiη is Prepared analogously to Example 2 by using 3.96 parts of cyclohexyl amine instead of benzylamine. The resulting filtrate is a aqueous solution containing approx. 8.65 parts of the p-nitrosophenol salt of cyclohexyl amine.

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Example 4

An aqueous solution containing about 7 parts of the bis-p-nitrosophenol salt of 1,6-hexanediamine is obtained if one proceeds in an analogous manner to Example 2, but benzylamine by 2.35 parts of 1,6-hexanediamine replaced.

Example 5

An aqueous solution containing about 7.4 parts of the p-nitrosophenol salt of Contains n-butylamine is obtained in a manner analogous to Example 2, if 2.92 parts of n-butylamine are used instead of benzylamine.

Example 6

An aqueous solution containing about 7.2 parts of the p-nitrosophenol salt of Diethylamine is obtained in a manner analogous to Example 2 if benzylamine is replaced by 3 parts of diethylamine.

Example 7

25.4 parts of p-Nitrosophenolsal zes-n-octylamine obtained as a dark oil when 13 parts of p-nitrosophenol to 13.65 parts of n-octylamine is added with stirring and then a further 2 hours to react at 15-20 ⁰ C leaves.

Example 8

The p-Nitrosophenolsalz of tert-octylamine is obtained by reacting p ~ 6.85 parts nitrosophenol at 15-2o ^C C to 7.2 parts of tert-octylamine dissolved in 25 parts of toluene is added with stirring and further 4th

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Hours stirs. The product obtained is filtered off and dried. This gives 14 parts of a pale violet powder with a melting point of 53-58 ^e C.

Example 9

The bis-p-nitrosophenol salt of ethylenediamine is prepared by one 4.4 parts of p-nitrosophenol at 20-25 ° C with stirring to a solution 1.3 parts of ethylenediamine in 50 parts of toluene are added and a further 5 Stirred hours at room temperature. It is filtered and dried. You get 5j5 parts of an olive-colored powder with a melting point. 73.5-75 ° C.

Example 10

A solution of the bis-p-nitrosophenol salt of ethylenediamine is prepared by dissolving 1.84 parts of ethylenediamine in 12 parts of dimethylformamide and adding 9 parts of a moist presscake of p-nitrosophenol, 7.38 parts of p-nitrosphenol and 1, Contains 62 parts of water, added and stirred for 2 \ hours at room temperature. The resulting dark solution contains 22.8 parts of the reaction product.

Example 11

A solution of the p-nitrosophenol salt of triethanolamine is prepared by adding 12 parts of a moist presscake of p-nitrosophenol containing 9.8 parts of p-nitrosophenol and 2.2 parts of water to 100 parts of cold water and stirring 11, are 8 parts of triethanolamine at 5-7 ⁰ C and, afterwards, one hour at 3-4 ° C the mixture is stirred and filtered. 120.2 parts of a dark-colored filtrate which contains the dissolved product are obtained. The 0.45 part filter cake is discarded.

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Example 12

A solution of the p-nitrosphenol salt of triethylamine is prepared by mixing 12 parts of the moist filter cake of p-nitrosophenol, which contains 9.8 parts of p-nitrosophenol and 2.2 parts of water, with 100 parts of cold water. Add to that 8 parts triethylamine at 12-15 ° C, stirred for a further hour at 13-17 ⁰ C for ₅ warmed to 25 ° and stirred for a further 30 minutes, whereupon the mixture is filtered at this temperature. The resulting dark colored filtrate contains the dissolved product. No filter cake is obtained.

Example 13

A solution of the p-Nitrosophenolsalzes of isopropylamine is prepared by dissolving 5.3 parts of isopropylamine in 18 parts of dimethylformamide at 15-20 ° and to this solution in small portions at about 10 ⁰ C, 11 parts of a moist filter cake of p-nitrosophenol, the 82 -85 % solids, add and stir for 3 hours at 5-10'C. 35.4 parts of a dark-colored solution which contains the desired product are obtained.

Example 14

The p-nitrosophenol salt of isopropylamine is prepared by: 13 parts of isopropylamine are added dropwise with stirring to a suspension of 24.6 parts of p-nitrosophenol in 100 parts of water at room temperature, Stirring for a further 2 hours at room temperature, then adding 25 parts of sodium chloride to the mixture, stirring for a further 3 hours and the mixture is filtered. 32.2 parts of a crystalline product are obtained.

Three parts of the product obtained are in 50 parts of water and rapidly dissolved, with 0.26 parts (dry weight) of undissolved material being filtered off. ■

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Analysis shows that the 32.2 parts of the above product are 63.92% Isopropylamine p-nitrosophenol salt, 17.61% NaCl, 9.72% unreacted p-nitrosophenol or foreign material and 8.75% sodium p-nitrosophenolate contain.

Example 15

An aqueous solution of the p-nitrosophenol salt of isopropylamine is used prepared by adding 2.46 parts of isopropylamine dropwise at 15 "C a suspension of 4.92 p-nitrosophenol in water is added with stirring and the mixture is stirred for a further 2 hours. The reaction mixture does not contain any solids. The filtrate contains 7.2 parts of the p-nitrosophenol salt of isopropylamine.

Beis piel 16_

A slurry of tetrakis-p-nitrosophenolsalzes of Hexamethylentetramine in dimethylformamide is prepared by adding 2.3 parts of hexamethylenetetramine to 18 parts of dimethylformamide at 15-20 ⁰ C and p-nitrosophenol then 10.8 parts (calculated at 100%) in the form an 82-85% moist presscake is added in small portions at 10 ° and the mixture is stirred at 5-10 ° C. for 2 hours. A dark-colored slurry is obtained which contains the abovementioned salt.

Example 17

The p-nitrosophenol salt of diethylenamine is prepared by: 15.7 parts of diethylenamine with stirring to form a suspension of 20.6 parts of p-nitrosophenol in 100 parts of water at room temperature

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added dropwise, stirred for a further 2 hours at room temperature, 25 parts of NaCl dem The reaction mixture is added, stirred for a further 15 hours, filtered and the solid obtained is allowed to air dry. You get 31.4 parts of the dry crystals. The analysis shows that 5.48 parts of sodium chloride are still present in the product. 3 parts of the crystals dissolve quickly when treated with 50 parts of water, leaving 0.41 parts (dry weight) insoluble. The 31.4 parts obtained consist of 55.34% of the p-nitrosophenol salt of diethylenediamine, 17,451 NaCl, 15.36% unreacted p-nitrosophenol or foreign matter and 11.85% sodium p-nitrosophenolate.

Example 18

The bis-p-nitrosophenol salt of p-phenylenediamine is prepared by one 4.4 parts of p-nitrosophenol to 2 parts of p-phenylenediamine, which in Part of the water is suspended, adds. The mixture is stirred for 5 hours at room temperature and then filtered. Of the Filter cake is washed with water and air-dried, 6.35 parts of the product are obtained.

The following examples 19 and 20 relate to the testing of the inventive Compounds as an inhibitor in butyl acrylate monomers.

Example 19

20 ml of purified butyl acrylate, which 10 ppm by weight of an according to the invention Containing inhibitors are placed in a reaction vessel which has been flushed with nitrogen gas and for the duration of the experiment kept under nitrogen. The reaction vessel is now heated to 90 ", the temperature of the butyl acrylate by means of a thermocouple is measured directly. Once the butyl acrylate

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polymerized, heat is released as a result of the exothermic reaction, which is measured by means of the thermocouple. The time that elapses from the beginning of the experiment to the maximum temperature reached is measured. The experiment is repeated. The compounds from Examples 12, 14 and 17 used in the experiment show ^{an inhibiting effect at 90 °} C. for a very long time.

Example 20

The previous example is repeated with the change that only 5 ppm of the inhibitor (calculated on the pure substance) of Examples 6, 13, 15 and 16 are used. These compounds prevent the indicated concentration polymerization of butyl acrylate at 90 ⁰ C for a long time.

Claims (1)

Claims R ^, R2 and R ₃ independently of one another are hydrogen, alkyl (0χ_ ₄ ) or Alkanol (C2_4),
R hydrogen, alkyl (Cx_2o)> alkanol C2.4), cycloalkyl (C ₃ _ ₇ ), Cycloalkyl (C ₃ _ ₆₎ alkyl (C _1-4), aryl or arylalkyl (C -, _ _4), B are independently alkylene (Cx_g) or m η D- (Qy) where each D and E are independently the direct Bond or alkylene (Ci_4), 0, I ₈ 2 or 3 and mean an integer from 1-4, where η m + 1 and the benzene rings A independently of one another are unsubstituted or have up to 2 substituents selected from Can carry chlorine, methyl, methoxy or ethyl. Case 155-2059 3. Compounds of the formula Ia according to claim 2 of the formula R ¹ <■ ' B - NH N = O Yes wherein R ¹ hydrogen, alkyl (Ci_is, alkanol (C2,3), cyclohexyl, phenyl or benzyl, Rl ^{1 is} hydrogen, alkyl (Ci_4) or alkanol, 3), R3 ^{1 is} hydrogen, alkyl (Ci_4) or alkanol, 3), and B and η have the meaning according to claim 2. Process for the preparation of the compounds according to claim 1, characterized in that 1 mol of an amine which Contains at least one primary, secondary or tertiary nitrogen atom, preferably a mono-, di-, tri- or tetramine or a Mixture of two or more such compounds with an optionally substituted p-nitrosophenol or a mixture converts such compounds, the number of moles of p-nitrosophenol used in the reaction being the same or lower, and is preferably the same as the number of protonizable nitrogen atoms of the amine. 5. Process for the preparation of the compounds of formula I according to claim 2, characterized in that one mole of one Amine of formula II \, ^f2 ^ > N4— BN -} R ₃ II wherein m, R, R ^, R2, R3 and B have the meaning according to claim 2 have or a mixture of two or more such compounds with a compound of the formula III HO - ^) - N = 0 III wherein the benzene ring A can be unsubstituted or substituted or a mixture of such compounds in a molar ratio of 1: 1 to 1: n, preferably 1: n, implements. - 3 - Case 155-2059 6. Use of the amine salts of p-nitrosophenol according to one of the Claims 1-3 as a polymerization inhibitor in monomers polymerizing by means of radical polymerization. 7. Use according to claim 6 in butyl acrylate, or acrylonitrile Acrolein. 8. Monomers that polymerize by means of radical polymerization, characterized in that this is an amine salt according to one of the Claims 1-3 contain in a concentration of 0.00001-1% by weight based on the weight of the monomer.