Method for the Production of Amines from Compounds Comprising Carbodiimide Groups, by Hydrolysis With Water

Abstract

The invention relates to a one-stage or multistage process for preparing mono-, di- and/or polyamines from compounds having carbodiimide groups and optionally also other groups of isocyanate chemistry by hydrolysis with water.

Description

EXAMPLE 1

Conversion of dicyclohexylcarbodiimide to cyclohexylamine

500 g of dicyclohexylcarbodiimide are heated to 190° C. in an autoclave. Subsequently, 900 g of water are added with stirring from a reservoir heated to 190° C. The vapor pressure of the reaction mixture is established in the autoclave. During the reaction, the pressure rises further owing to the evolution of carbon dioxide. After a reaction time of 4 hours, the experiment is ended and the reaction mixture investigated by gas chromatography. A total of 178 g of cyclohexylamine are found, which corresponds to a theoretical yield of 37%, based on the dicyclohexylcarbodiimide used.

EXAMPLE 2

Conversion of dicyclohexylcarbodiimide to cyclohexylamine

500 g of dicyclohexylcarbodiimide are heated to 190° C. in an autoclave. Subsequently, 900 g of an aqueous, 0.25 molar sodium hydroxide solution are added with stirring from a reservoir heated to 190° C. The vapor pressure of the reaction mixture is established in the autoclave. During the reaction, the pressure rises further owing to the evolution of carbon dioxide. After a reaction time of 4 hours, the experiment is ended and the reaction mixture investigated by gas chromatography. A total of 298 g of cyclohexylamine are found, which corresponds to a theoretical yield of 62%, based on the dicyclohexylcarbodiimide used.

EXAMPLE 3

Conversion of dicyclohexylcarbodiimide to cyclohexylamine

The experiment is carried out in a similar manner to Example 2, except that the pressure in the autoclave is adjusted to 55 bar using nitrogen and a nitrogen stream of 50 g/h is passed through the reaction mixture over the entire reaction in order to continuously remove the carbon dioxide formed.

Overall, 399 g of cyclohexylamine are found, which corresponds to a theoretic yield of 83%, based on the dicyclohexylcarbodiimide used.

EXAMPLE 4

Conversion of

where x=4.7to diaminodiphenylmethane

The reactant having the composition

where x=4.7is prepared according to U.S. Pat. No. 2,941,983 from diisocyanatodiphenylmethane and n-butanol (x=4.7; calculated from carbodiimide content and average molar mass). 50 g of this polycarbodiimide are heated to 230° C. in an autoclave with 400 g of n-butanol. Subsequently, 100 g of an aqueous, 0.25 molar sodium hydroxide solution are added with stirring from a reservoir heated to 230° C., and the pressure is adjusted to 55 bar using nitrogen. During the reaction, a nitrogen stream of 30 g/h is passed through the reaction mixture in order to continuously remove the carbon dioxide formed. After a reaction time of 4 hours, the experiment is ended and the reaction mixture investigated by gas chromatography. Overall, 33 g of diaminodiphenylmethane are found, which corresponds to a theoretic yield of 81%, based on the polycarbodiimide used.

EXAMPLE 5

Conversion of

where x=1.1to diaminodicyclohexylmethane

The reactant having the composition

where x=1.1is prepared in a similar manner to Example 4 from diisocyanatodicyclohexylmethane and n-butanol (x=1.1; calculated from carbodiimide content and average molar mass). 50 g of this polycarbodiimide are heated to 230° C. in an autoclave with 400 g of n-butanol. Subsequently, 100 g of an aqueous, 0.25 molar sodium hydroxide solution are added with stirring from a reservoir heated to 230° C., and the pressure is adjusted to 55 bar using nitrogen. During the reaction, a nitrogen stream of 30 g/h is passed through the reaction mixture in order to continuously remove the carbon dioxide formed. After a reaction time of 4 hours, the experiment is ended and the reaction mixture investigated by gas chromatography. Overall, 28 g of diaminodicyclohexylmethane are found, which corresponds to a theoretic yield of 87%, based on the polycarbodiimide used.

Claims

1. A one-stage, continuous or batchwise process for preparing di- and/or polyamines from compounds having carbodiimide groups by hydrolysis with water, the carbon dioxide formed being removed from the reaction mixture continuously or discontinuously, using a stripping gas.

2. The process of claim 1, whereinthe compounds having carbodiimide groups which are used are (poly)carbodiimides which are prepared from (poly)isocyanates, (poly)isocyanate derivatives or (poly)isocyanate homologues having aliphatic or aromatic isocyanate groups.

3. The process of claim 1, whereinthe compounds having carbodiimide groups which are used are (poly)carbodiimides which are prepared from the polyisocyanates selected from 1,4-diisocyanatobutane, 1,6-diisocyanatohexane (HDI), 1,12-diisocyanatododecane, 1,4-diisocyanatocyclohexane, 1-isocyanato-5-isocyanatomethyl-3,3,5-trimethylcyclohexane (IPDI), bis(4-isocyanatocyclohexyl)methane (H12MDI), 1,3-bis(1-isocyanato-1-methyl)benzene (XDI), 1,3-bis(1-isocyanato-1-methylethyl)benzene (m-TMXDI), 2,4-diisocyanatotoluene (TDI), bis(4-isocyanatophenyl)methane (MDI), 1,6-diisocyanato-2,2,4(2,4,4)-trimethylhexane (TMDI), or isomers thereof, higher homologues thereof and/or technical-grade mixtures of the individual polyisocyanates.

4. The process of claim 1, wherein(poly)carbodiimides are used which have been modified with groups of isocyanate chemistry.

5. The process of claim 4, wherein(poly)carbodiimides are used which have been modified with groups of isocyanate chemistry, selected from aromatic, cycloaliphatic, (cyclo)aliphatic or aliphatic (poly)carbodiimides which have been modified with urethane, isocyanate, amine, amide, (iso)urea, biuret, isocyanurate, uretdione, guanidine, formamidine, oxamidine, imidazoline, uretonimine and/or allophanate groups.

6. The process of claim 1, whereinthe reaction is effected with an amount of water which is sufficient at least for the hydrolysis of the carbodiimide bonds and any groups of isocyanate chemistry which are also to be converted.

7. The process of claim 1, whereinthe amount of water used is at least 2 mol of water per mole of carbodiimide group and a corresponding amount for the conversion of any additionally present groups of isocyanate chemistry.

8. The process of claim 7, whereinthe amount of water used is from 5 to 100 times the stoichiometric amount, preferably from 5 to 50 times, more preferably 10 times the stoichiometric amount, based on the stoichiometric amount of water required to convert the carbodiimide groups and any additionally present groups of isocyanate chemistry.

9. The process of claim 1, whereinreaction is effected with an acidic or basic, heterogeneous or homogeneous catalyst or mixtures of acidic or basic heterogeneous homogeneous catalysts.

10. The process of claim 1, whereinthe reaction is effected at a temperature of from 0 to 400° C.

11. The process of claim 10, whichis carried out at temperatures of from 150 to 300° C.

12. The process of claim 1, whereinthe reaction is effected at a pressure of from 0 to 500 bar.

13. The process of claim 12, whichis carried out at a pressure of from 20 to 150 bar.

14. The process of claim 1, whereinthe mono-, di- and/or polyamines formed are worked up by separation processes selected from distillation, crystallization, extraction, sorption, permeation, phase separation or combinations thereof.

15. The process of claim 1, whereinthe reaction is effected with or without solvent.

16. The process of claim 15, whereinthe solvent or solvent mixture used comprises alcohols, preferably those alcohols which are formed in the hydrolysis of any urethane groups also present.

17. The process of claim 1, whereinthe working pressure is the vapor pressure of the reaction mixture which is established at reaction temperature.

18. The process of claim 1, whereincarbon dioxide formed in the process is removed from the reaction mixture continuously or discontinuously, using nitrogen.

19. The process of claim 1, whichis carried out continuously or batchwise in reactor systems selected from stirred tank reactors, flow tube reactors, fluidized bed reactors, fixed bed reactors, bubble columns, reactive distillation reactors, microreactors or combinations or batteries of the reactors mentioned.

20. The process of claim 1, whereinpolyamines selected from 1,4-diaminobutane, 1,6-diaminohexane, 1,12-diaminododecane, 1,4-diamionocyclohexane, 1-amino-5-aminomethyl-3,3,5-trimethylcyclohexane (IPDA), bis(4-aminocyclohexyl)methane (H12MDA), 1,3-bis(1-amino-1-methyl benzene (XDA), 1,3-bis(1-amino-1-methylethyl)benzene (m-TMXDA), 2,4-diaminotoluene (TDA), bis(4-aminophenyl)methane (MDA), 1,6-diamino-2,2,4(2,4,4)trimethylhexane (TMDA) and where appropriate isomers, higher homologues and technical-grade mixtures of the individual polyamines are prepared.