HU198680B - Process for production of biscarbamates - Google Patents

Abstract

New bis-carbamates of the formula (I) R=1-8C alkyl gp., X= 2-60C atom-contg. hydrocarbon gp. in which 1 or more C atoms can be replaced by heteroatoms and which can contain halogen atoms, ester, carbonyl or nitro gps. are prepd. by electrochemical oxidn. of a formamide of formula (II) in the presence of an alcohol of formula ROH and an inorganic halide. - Pref. a salt of hydrobromic acid is used as the ionogenic halide, the anode is of graphite and methanol, is used as the alkanol. An electrolyte contg. 1-50 wt.% formamide of formula (II), 40-90 wt.% of the alkanol and 0.1-10 wt.% of the ionogenic halide is used for the electrochemical oxidn.

Description

It is known that carbamic acid esters are prepared by converting alcohols to phosphorus into chloroformic acid esters and then aminolizing them. Working with highly toxic and corrosive starting materials and intermediates requires considerable technical effort. In addition, this process produces hydrochloric acid or a halogen-containing waste salt, which is often technically very expensive to separate (Ullmann, Enzyklopadie dér Techn. Chemie, 4th Edition, Vol. 9, pp. 118-119).

In a production process that does not use phosgene, urea is reacted with alkanols. In this case, the high reaction temperature and the long reaction time as well as the technically difficult handling of solids are disadvantageous (Houben-Weyl, Methoden dérorganchen Chemie, 1952 / Vol. 8, p. 140).

Thus, the object of the present invention was to provide a technically simpler and particularly environmentally friendly process for the preparation of bis-carbamic acid esters.

According to the present invention, this object is solved by a process wherein the bis-carbamates of formula I, wherein R is a C 1-4 alkyl group, X is a C 2-12 alkylene group, wherein 1-3 methylene groups can be oxygen or a methylene group may be replaced by an -N (CHO) - group, or X (a), (b), (c) or (d) or 3,5,5-trimethyl-3-methylene-1-dclohexyl can be prepared by electrochemically oxidizing a formamide of Formula 11, wherein X is as defined above, an alkanol of formula ROH, wherein R is as defined above, and an ionic halide.

The present invention also relates to the preparation of novel bis-carbamates of formula (I) wherein R ¹ is C 1 -C 4 alkyl, Y is - (CH ₂ ) j -, 3,5,5-. trimethyl-3-methylene-1-dclohexyl, - (CH ₂ ) ₃ -O- (CH ₂ ) 4 -O- (CH ₂ ) ₃ -, - (CH ₂ hO- (CH ₂ ) j O- (CH ₂ ) ₃ -, 2,2-bis (4-cyclohexyl) -n-propyl of formula (d), -CH ₂ -CH (CH ₃ ) (CH ₃ ) ₃ - or - (CH ₂ ) _2- N (CHO> (CH ₂ ) _{2 -} ).

For the preparation of the bis-carbamates of formula (1), the bivalent X group is as defined above.

In the formula (11) used as starting material for the preparation of bis-carbamates of formula (1), the divalent X group is as defined above.

In the alcohols of the formula ROH, R is a C 1-4 alkyl group. Suitable alkanols are, for example, n- or i-propanol, n-butanol, but especially methanol and ethanol.

Salts such as the alkali metal, alkaline earth metal or ammonium salts of hydrogen iodide, hydrobromic acid or hydrogen chloride may be used as your ionogenic halogen. Hydrogen bromide salts, such as alkali metal and alkaline earth metal bromides, and quaternary ammonium bromides, especially tetraalkylammonium bromides, are particularly preferred. The nature of the cation is not critical to the invention, so other ionic metal halides may be used. It is advisable to choose a cheap halide. For example, sodium, potassium, calcium or ammonium bromide and di-, tri- or tetramethyl- or tetraethyl-ammonium bromide may be used.

The process of the present invention does not require a special electrolysis cell, preferably an undivided flow cell. The anode may be any conventional anode material which is stable under electrolysis conditions, such as precious metals such as gold or platinum. The preferred anode material is graphite. The material of the cathode may be, for example, a metal such as lead, iron, steel, nickel or precious metal such as platinum. Graphite is also preferably used as the cathode material.

The composition of the electrolytes can be chosen within wide limits. The electrolyte preferably contains the starting materials in the following weight percentages: 1-50% by weight of formamide 11, 40-90% by weight of alkanol, 0.1-10% by weight of halide.

If desired, a solvent may be added to the electrolyte to improve the solubility of the formamide or halide. Suitable solvents are, for example, a nitrile such as acetonitrile, a carbonate such as dimethyl carbonate, an ether such as tetrahydrofuran or a dialkylformamide such as dimethylformamide. The current density in the process according to the invention is not limited and can be electrolyzed at a current density of 1 to 25 A / dm ² , preferably 3 to 12 A / dm ² . Electrolysis is carried out at temperatures up to 120 ° C. When the electrolysis is carried out at the pressure of the cavity, a temperature range which is preferably within the range of 5 to 10 ° C below the boiling point of the electrolyte is selected. When methanol or ethanol is used, the electrolysis is preferably carried out at a temperature of 20-50 ° C.

Workup of the mixture obtained by electrolysis can be carried out by methods known per se, preferably by distillation first. Distill the excess alkanol and any co-solvent that may be present. The halides are separated by known methods, such as filtration or extraction. Thereafter, the bis-carbamate is often recovered in a very pure form and, if necessary, can be further purified, for example, by precipitation or by recrystallization. The alkanol, any unreacted formamide present, the co-solvent and the halide may be recycled to the electrolysis. The process of the present invention may be carried out batchwise or continuously.

The process of the present invention is particularly advantageous for the preparation of bis-carbamates. Surprisingly, the new process allows large-scale conversion of formamide without loss of yield. The current utilization of the process according to the invention is also unusually high. Thus, in the case of electrolysis with a capacity of 4-5 F / mole formamide, most of the fortification is already complete. These favorable results were not expected, since formamides have long been known. electrochemical conversion to alcohols in the presence of conductive salts, such as tetraalammonium ammonium thiafluoroborate, leads to oxyformamides (Tetrahedron, 32, 2185-2206, (1983)), and that the bis ( -Sulfonate is electrochemical when used

198,680 (J. Org. Chem., 48, 3338-3339, 1983).

Bis-carbamates are versatile intermediates for the production of isocyanates. The new bis-carbamates are mainly used for the production of special polyurethanes.

Example 1

Preparation of CH ₃ COOCHN- (CH ₂ ) ₆ NHCOOCH 3 by Electrolysis

Equipment:

Anode:

electrolyte:

300 g formamide of formula IV (n = 6) g sodium bromide 3204 g methanol Cathode.

Current density:

Temperature:

undivided cell with 11 electrodes graphite

8.5 wt% 1.0 wt% 90.5 wt% graphite 3.3 A / dm ^{2 at} 25 ° C

Electrolysis with a capacity of 5.3 F / mol formamide

Flow through cell: 200 rpm

Workup: After completion of the electrolysis, methanol is distilled off at atmospheric pressure and the residue is dissolved in hot ethyl ethyl ketone. Sodium bromide (36 g) was filtered through a spin. The reaction product was crystallized from the filtrate to give 385 g of CH ₃ OOC-NH- (CH ₂ ) ₆ -NHCOOCH ₃ , m.p. 112 ° C and pure by ¹ H NMR. Yield 95.1%.

Example 2

Preparation of CH ₃ OCONH- (CH ₂ ) ₄ NHCOOCH ₃ by Electrolysis

Equipment:

Anode.

electrolyte:

300 g of formamide IV (n = 4).

g sodium bromide 2670 g methanol Cathode:

Current density:

Temperature:

undivided cell with 6 electrodes graphite

10.0% by weight

1.0% by weight

89.0% by weight graphite 3.3 A / dm ^{2 at} 25 ° C

Electrolysis with a capacitance of 4.75 F / mole formamide

Flow through the cell, 2001 / h

Workup: analogous to Example 1 to obtain 356 g of CH ₃ OCONH- (CH ₂ ) ₄ -NHCOOCH ₃ with 27 g of sodium bromide, m.p. 126-128 ° C. .

Yield 83.8%.

Example 3

Preparation of CH ₃ OCONH- (CH ₂ ) j -NHCOOCH 3 by Electrolysis

H15

On:

Anode:

electrolyte:

140 g undivided cell of formula IV with 6 electrodes graphite formamide (n = 5) 4.7 wt% sodium bromide 1.0 wt%

2830 g of methanol 94.3% by weight

Cathode: graphite

Current density: 3.3 A / dm ²

Temperature: 25 ° C

Electrolysis with a capacity of 4.4 F / mol formamide

Flow through the cell. 2001 / h

Preparation: The procedure is analogous to Example 1. is repeated, and in addition, 30 g sodium bromide in 175 g of CH ₂ OCONH (CH _{2) 5} -NHCOOCH compound of Formula ₃ with a melting point of 104 from 112 C and ¹ H-NMR spectrum clear. Yield 90.6%.

Example 4

Preparation of 3,5,5-Trimethyl-1- (methoxycarbonylamino) -3- (methoxycarbonylaminomethyl) cyclohexane by electrolysis

Equipment:

Anode:

electrolyte:

279.2 g formamide X 8.8 wt% sodium bromide 1.0 wt%

2848 g of methanol 90.2% by weight. Cathode: graphite

Current density: 3.3 A / dm ²

Temperature. 20-22 ° C

Electrolysis with a capacity of 4.5 F / mole formamide

Flow through the cell. 2001 / h

Workup: After completion of the electrolysis, methanol is distilled off at atmospheric pressure. The solid residue was taken up in methyl ethyl ketone and the resulting solid (32 g of sodium bromide) was filtered off. The filtrate was stripped of methyl ethyl ketone. The residue was recrystallized from a small amount of methyl ethyl ketone to provide 282 g of biscarbamate obtained, melting at 103 117 ° C and ¹H-NMR and pure ^carbon-13 NMR spectrum alapiján, ace-trans mixture. Yield 79.8%.

Example 5 '

Preparation of CH ³ OCONH- (CH ₂ X -N (CHO> (CH ₂ h nhcooch ₃ ) by electrolysis, unbroken cell with 11 electrodes, graphite, undivided cell, with 11 electrodes, graphite

Equipment Anode:

electrolyte:

330 g formamide of formula XVI (n = m = 2) g sodium bromide 2937 g methanol Cathode:

Current density:

Electrolysis with a yield of 4.5 F / mol formamide

Flow through cell: 2001 / h.

Workup: After completion of the electrolysis, methanol is distilled off at room temperature. The residue was taken up in methylene chloride and the sodium bromide (28 g) was filtered off. The filtrate was stripped of methylene chloride. The residue (408 g) is then recrystallized from methyl ethyl ketone to give 248.2 g of bis-carbamate, m.p.

3.3 A / dm ²

198.680, 90-92 ° C, and pure by ¹ H-NMR and ¹³ C-NMR. An additional 128.5 g of bicarbamate can be isolated from the mother liquor. Total yield 86.4%.

Example 6

Preparation of CH ₃ 00CHN- (CH ₂ ) ₃ -O- (CH ₂ ) ₄ -0 <CH ₂ ) ₃ -NHCOOCH ₃ by Electrolysis

Equipment: Undivided cell with 11 electrodes

Anode: graphite

electrolyte:

330 g formamide of formula XVII (n = m = 3, q = 4, p = 1) 10% by weight of sodium bromide 1% by weight

2937 g of methanol 89% by weight

Cathode: graphite

Current density: 3.3 A / dm ²

Temperature. 25 ° C

Electrolysis with a capacitance of 4.75 F / mole formamide

Flow through cell: 2001 / h

Workup: After completion of the electrolysis, methanol is distilled off at atmospheric pressure. The residue was taken up in methyl ethyl ketone, filtered off with sodium bromide (32 g) and the methyl ethyl ketone distilled off. 357 g of CH ₃ OC0NH- (CH ₂ ) ₄ -O- (CH ₂ ) ₃ -NH-COOCH ₃ are obtained, m.p. 45-46 ° C and ¹ H-NMR spectrum and ¹³ C-NMR spectrum. clean. Yield 87.9%.

Example 7

Preparation of CH ₃ OCONH- (CH ₂ ) ₃ -O - [(CH ₂ ) ₂ -O] ₂ <CH ₂ ) ₃ -NHCOOCH ₃ by Electrolysis

Equipment: Undivided cell with 6 electrodes

Anode; graphite

Electrolyte.

260 g of formamide (XVII) (n = m = 3, q = 2, p = 2) 10% by weight of sodium bromide 1% by weight

2314 g of methanol 89% by weight

Cathode: gfafit

Current density: 3.3 A / dm ²

Temperature: 20-22 ° C

Electrolysis: 4.75 F / mol formamide

Flow through cell: 2001 / h

Workup: After completion of the electrolysis, methanol is distilled off at atmospheric pressure. The residue was taken up in toluene and filtered to remove sodium bromide (22 g) and the toluene was again distilled off, 275 g 00CNH _{CH3 (CH2) 3} -O- (CH ₂₎ t -O- (CH ₂₎ Compound ₃ NHCOOCH3 of a viscous oil and pure by 1 H-NMR and ¹³ C-NMR. Yield 86.9%.

Analysis for C ₁₄ H _2e N ₂ 0 ₇ based Calcd: C: 50.0, H: 8.3, O: 33.4, N: 8.3% Found: C 50.2, H 8.2, O: 33.3, N: 8.5%.

Example 8

CH ₃ OOC-NH-CH ₃ -CH (CH ₃ ) '(CH ₃ ) ₃ -NH-COOCH ₃ by electrolysis

Equipment: Undivided cell with 6 electrodes Anode: graphite electrolyte: 260 g of the general formula (V) formamide 10% by weight 26 g of sodium bromide 1% by weight 2314 g of methanol 89% by weight Cathode. graphite Current density: 3.3 A / dm ² Temperature: 27 ° C Electrolysis with a capacity of 4.5 F / mole formamide Flow through cell: 2001 / h

Workup: After completion of the electrolysis, methanol is distilled off at atmospheric pressure. The residue was taken up in methyl t-butyl ether and filtered over sodium bromide (24 g). The filtrate was stripped of methyl (t-butyl) ether to give 290 g of CH ₃ OOC-NH-CH ₂ -CH (CH ₃ ) (CH ₂ ) ₃ NHCHOCH ₃ as a yellow liquid and ¹ H-NMR. spectrum and ¹³ C-NMR.

Elemental analysis based on the formula C 10 _{H 2 O} N ₄ O ₂ :

N, 12.1; Found: C, 51.7; H, 8.7; 0: 27.7; N, 12 Found: C, 51.7; 5%.

Yield 82.7%.

Example 9

Preparation of 4,4'-Bis (methoxycarbonylamino) dicyclohexylmethane by electrolysis

Equipment Anode:

electrolyte:

g4,4'-bis (forynyl-amino) -dicyclohexylmethane 26 g of sodium bromide 2314 g of methanol Cathode:

Current density:

Temperature;

Electrolysis Flow through the cell:

undivided cell with 6 electrodes graphite

3.5% by weight 1.1% by weight 95.4% by weight graphite 3.3 A / dm ² 43-50 ° C

With a capacity of 4.5 F / mole formamide 2001 / h

Workup: After completion of the electrolysis, the electrolyte is cooled to 10 ° C to give 38.4 g of the title compound, m.p. 195-200 ° C and ¹ H-NMR and ¹³ C-NMR pure, cis -trans mixture. The methanol is then distilled off at atmospheric pressure, the residue is taken up in dichloromethane, the sodium bromide (24.5 g) is filtered off and the dichloromethane is distilled off. An additional 51 g of bis-carbamate are obtained, m.p. 168-173 ° C. Total yield 84.8%.

Example 10

Preparation of 2,2-Bis / 4- (methoxycarbonylamino) -cyclohexyl / n-propane by electrolysis undivided cell with 6 electrodes

Equipment:"

Anode:

electrolyte:

260 g of 2,2-bis (4-formylamino) -cyclohexyl-n-propane g sodium bromide

2314 g methanol wt% wt%

198 680

Cathode: Beam Density: Temperature: Electrolysis Flow through the cell.

graphite 3.3 A / dm ² ° C

With a capacity of 4.0 F / mole formamide 2001 / h

Processing; after completion of the electrolysis, methanol was distilled off at atmospheric pressure. The residue was dissolved in diethyl ketone and washed with water. The organic phase is dried over sodium sulfate and the diethyl ketone is distilled off. 206.7 g of the title bis-carbamate are obtained, m.p. 137-145 ° C and a pure ace-trans mixture based on 1 H-NMR and ³ C-NMR. Yield: 66%.

Example 11 Preparation of 1,4-Bis (methoxycarbonylaminomethyl) -aclohexane by electrolysis

Current density: 3.3 A / dm ²

Temperature: 27 ° C

Electrolysis with a capacity of 6.6 F / mole formamide

Flow through cell: 2001 / h

Workup: After completion of the electrolysis, first methanol is distilled off at atmospheric pressure followed by dimethylformamide at 1500 Pascal head pressure to 110 ° C (bottom temperature). The residue was digested with water at 80 ° C, filtered and dried. 81 g of the title bis-carbamate are obtained, m.p. 186 ° C and pure with 1 H-NMR and ¹³ C-NMR.

Yield 77.1%.

Equipment:

Anode:

electrolyte:

31.6 g 1,4-bis (formylaminomethyl) cyclohexane 26 g sodium bromide 2314 g methanol Cathode:

Current density:

Temperature:

Electrolysis Flow through the cell:

undivided cell with 6 electrodes graphite

1.3% 1.1% 97.6% graphite 3.3 A / dm ² 25-27 ° C

With a capacity of 4.5 F / mole formamide 2001 / h

After working up, electrolysis is complete and methanol is distilled off at atmospheric pressure. The residue was taken up in methylene chloride, the sodium bromide (25 g) was filtered off and the methylene chloride was distilled off. Biscarbamate 29.9 g of the title compound having a melting point range of 144-167 C under ^this, and 'H NMR and ^{F 3} C-NMR of pure cis-trans mixture. Yield 72.6%.

Example 12

Preparation of 1,4-Bis (methoxycarbonylaminomethyl) benzene by electrolysis

Equipment:

Anode:

electrolyte:

g 1,4-bis (formylarranomethyl) benzene g sodium bromide 1357 g Ν, Ν-dimethylformamide 1157 g methanol

Cathode:

undivided cell with 6 electrodes graphite

3.0% by weight 1.0% by weight

51.8% by weight 44.2% by weight graphite

Claims (4)

-15 PATENT CLAIMS 1. Process bis-carbamates of formula I - wherein R is C 1-4 alkyl, X is C 2-12 alkylene, where 1-3 methylene groups can be oxygen. 20 or one methylene group may be replaced by an -N (CHO) group or X (a), (b), (c) or (d) or 3,5,5-trimethyl-3-methylene-1-cyclohexyl characterized in that in the presence of a forminide of formula 11 wherein X is as defined above, an alkanol of formula ROH wherein R is as defined above and an ionic halide, preferably an alkali metal halide, A current of 25 A / dm ² at a temperature of up to 120 ° C of 1-50% by weight of formamide II, 40-90% by weight of alkanol of the general formula ROH and In an electrolyte solution containing from 0.1 to 10% by weight of an ionogenic halide, it is electrochemically oxidized. 2. A process according to claim 1 wherein the ionic halide is the alkali metal salt of hydrobromic acid. 35 The process of claim 1, wherein the anode is graphite. 4. The process of claim 1 wherein the alkanol is methanol. 5. A process according to claim 1 for the preparation of the bis-carbamates of the formula (I) in which R ¹ is C 1 -C 4 alkyl, Y is (CH ₂ ) ₅ , 3,5, 5-trimethyl-3-methylene-lic-dichlohexyl, <CH ₂ ) ₃ -O- (CH ₂ ) 4 -O- (CH ₂ ) ₃ , (CH ₂ ) ₃ -O- (CH ₂₎ ) ₂ -O- (CH ₂ ) ₂ -O (CH ₂ ) ₃ -, 2,2-bis (4-dichlohexyl) -n-propyl, -CH (CH ₃ XCH ₂ ) - or - (CH ₂ ) ₂ -N (CHOXCH 3) ₂ -, characterized in that it is suitably 50 substituted starting compounds are oxidized.