DE2917568A1 - METHOD FOR PRODUCING AROMATIC DI- AND POLYURETHANES - Google Patents

Description

process for the production of aromatic di- and

Polyurethanes The invention relates to a method of production of aromatic di- and / or polyurethanes from primary aromatic di- and / or Polyamines and carbamic acid esters in the presence of alcohols and optionally Alcoholates as catalysts at elevated temperatures.

N-aryl urethanes are usually produced industrially by reacting Alcohols with aromatic isocyanates or of aromatic amines with chlorocarbonic acid esters produced, with both the isocyanates and the chlorocarbonic acid esters by Phosgenation of the corresponding amines and elimination of hydrogen chloride or can be obtained by phosgenation of the alcohols. (Methods of organic chemistry, Houben-Weyl, Volume 8, Pages 137, 120 and 101, Georg Thieme Verlag, Stuttgart, log52) These processes are technically very complex; also brings the use of Phosgene is considerable because of the associated safety and environmental protection measures Disadvantages with itself.

N-aryl urethanes are used as intermediate and end products. According to DE-OS 26 35 kl.90 or US-PS 3,919,278 are for example for the production of Isocyanates suitable. Other manufacturing processes for N-substituted urethanes are therefore becoming increasingly important.

rsO describes the DE-OS 21 60 111 a process for the production of N-substituted urethanes by reacting an organic carbonate with a primary or secondary aromatic amine in the presence of a Lewis acid.

The disadvantage of this process is that the reaction rate quite short and the response times are correspondingly long; also be N-alkyl-arylamines are always additionally obtained as by-products.

According to US Pat. No. 2,834,799, carbamic acid and carbonic acid esters are used produced by reacting ureas with alcohols in the presence of boron trifluoride. The disadvantage here is that the boron trifluoride is used as a catalyst in equimolar amounts is required, so that per molecule produced carbamic acid ester at least one and At least two molecules of boron trifluoride are consumed per molecule of carbonic acid ester. This not only makes the process expensive; but it also represents one significant environmental pollution, since the boron trifluoride in the form of the H3N. BF3 adduct accrues.

Methyl-N-phenylurethane can also be made from carbon monoxide, sulfur, aniline and methanol (R.A. Franz et al, J. Org. Chem. 28, 585 (1963)). Particularly disadvantageous here are the low yields, even with long yields Response times do not exceed 25%.

According to US Pat. No. 2,409,712, N-alkyl and N-aryl monourethanes can be used by reacting monoamines with urea, N, N'-dialkyl or N, N'-diaryl urea and alcohols at temperatures from 150.degree. C. to 350.degree. C., optionally at elevated temperatures Pressure, to be produced. However, only the production is described by way of example of N-alkylmonourethanes by the method mentioned, While N-phenyl urethane is produced by alcoholysis of diphenyl urea.

Urea is used to produce N-substituted monourethanes according to US Pat. No. 2,677,698 initially with monoamines in the corresponding N, N'-disubstituted ones Urea transferred, this is purified and then reacted with alcohol brought.

Disadvantages of the processes mentioned are, in addition to a costly one Technology, especially the low yields, which are also due to the production and Purification of N, N'-disubstituted ureas cannot be improved.

These disadvantages can also be avoided with the aid of the method according to US Pat 806 051 cannot be eliminated. According to this patent specification, for example Aniline with urea and alcohol in a molar ratio of 1.0: 1.2: 2.0 at temperatures below 2000C, preferably from 1200 to 1750C implemented. Also in the preferred ones Temperature ranges are in technically appropriate reaction times according to this Procedure N-phenylmonourethane obtained only in low yields. It is therefore not surprisingly that in subsequent US Pat. No. 3,076,007 for the preparation of N-alkyl and N-cycloalkyl urethanes using the above methods unsubstituted or substituted ureas are not described; mentioned however, the reaction of phosgene with alcohols to chloroalkylformates and the subsequent further reaction with amines to form urethanes, while being special the reaction of amines with ethylene carbonate is advantageous for the production of urethanes is recommended. According to a more recent variant of the method (DE-OS 27 16 540) are for Production of aromatic urethanes dialkyl carbonates with N-acylamines for reaction brought.

It is also known that ethyl carbamate in boiling dioxane do not react with amines (D.G. Crosby and C. Niemann, J. Am. Chem. Soc. 76 4458 (1954)), and that N-alkyl urethanes with alcoholic ammonia solution at temperatures from 160 to 1800C result in an alkaline solution, from which after neutralization with Hydrochloric acid amine hydrochloride, urea, alkyl urea and alkyl urethane isolated can be (M. Brander, Rec. trav. Chim 37 88-91 (1917).

Since already the production of N-monosubstituted carbamic acid esters from monoamines, urea and alcohols or the exchange of the amino group in carbamic acid esters only succeeds in moderate yields, it is not surprising that in none of the above Patents the production of di- and / or polyurethanes, starting from weak basic aromatic di- and / or polyamines, according to these process variants is also only mentioned.

The object of the present invention was to produce aromatic Di- and / or polyurethanes from easily accessible starting components, if possible in one reaction stage under economically justifiable conditions in good yields to manufacture. The use of highly toxic starting materials, for example of phosgene, carbon monoxide, or catalysts that are toxic or in the course of form toxic compounds, e.g. hydrogen sulfide, should be largely avoided.

This object was achieved by a process for the production of aromatic Di- and / or polyurethanes, which is characterized in that one carbamic acid ester with primary aromatic di- and / or polyamines in the presence of alcohols and if necessary, converts catalysts at elevated temperatures and the resulting the Separates ammonia if necessary.

The reaction can be illustrated by the following equation: The formation of aromatic di- and / or polyurethanes, in particular in one process step and in good yields, was particularly surprising since, according to known doctrine, N, N'-diarylureas are obtained from carbamic acid esters and aromatic amines, which are usually recrystallized from alcohol. Unsubstituted urethanes react very easily in the presence of aromatic amines, even in alcohol, to form N, N'-diarylureas. (Methods of organic chemistry, Houben-Weyl, Volume 8, pages 152, 140 and 161, Georg Thieme Verlag, Stuttgart, 1952).

Correspondingly, diamines and urea not only become N, N'-disubstituted Ureas, but rather high-molecular, spinnable condensation products at temperatures above 1000C obtained (DE-PS 896 412). High molecular weight polyureas, for example with molecular weights 8000 to 10000 and larger are also obtained using diurethanes with diamines condensed at temperatures of about 150 ° C. to 3000 ° C. (US Pat. No. 2,181,663 and U.S. Patent 2,568,885). Since mono- and polyurethanes are also thermally converted into isocyanates, alcohols and optionally olefins, carbon dioxide, urea and carbodiimides are split, the resulting cleavage products again numerous secondary products, e.g.

Biurets, allophanates, isocyanurates, polycarbodiimides, etc.

can form, (J.A.C.S. 80, 5495 (1958) and J.A.C.S. 2, 1946 (1956)) could not be expected under very similar reaction conditions after the process of the invention di- and / or polyurethanes in good yields obtain will. This was particularly surprising given attempts to make diurethanes from the above-mentioned products according to the reaction conditions according to the invention did not lead to the goal.

For the reaction according to the invention with carbamic acid esters in the presence of alcohols are optionally substituted primary aromatic di- and / or Polyamines, the primary aromatic diamines being preferred. in the individual examples are: aromatic diamines, such as 1,3- and 1,4-diaminobenzene; by a nitro, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, Isobutoxy, sec-butoxy, tert-butoxy or a halogen atom, preferably a fluorine and / or chlorine atom, 1,3-diaminobenzene substituted in the 2- and / or 4-position or 1,4-diaminobenzene, 1,5- and 1,8-diaminonaphthalene substituted in the 2-position, 4,4'-diaminodiphenyl, 2,2'-, 2,4dz and 4,4'-diamino-diphenylmethane and the corresponding Mixtures of isomers and polyphenyl-polymethylene-polyamines and mixtures of diamino-diphenylmethanes and polyphenyl-polymethylene-polyamines, which are produced by known methods by condensation of aniline and formaldehyde in the presence of preferably mineral acids as catalysts can be obtained.

Have proven particularly useful and are therefore preferably used 2,4- and 2,6-diaminotoluene and the corresponding isomer mixtures, 2,2'-, 2,4'- and 4,4'-diamino-diphenylmethane and the corresponding mixture of isomers, 1,5-diamino-naphthalene and, as polyamines, mixtures of diamino-diphenylmethanes and polyphenyl-polymethylene-polyamines.

Suitable carbamic acid esters have the formula H2N-COOR, in which R is an optionally substituted aliphatic, cycloaliphatic or aromatic-aliphatic Rest means. Carbamic acid esters based on, for example, come into consideration primary aliphatic monoalcohols having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, such as carbamic acid methyl ester, ethyl ester, propyl ester, -n-butyl ester, -isobutyl ester, -2- and -3-methylbutyl ester, -neopentyl ester, -pentyl ester, -2-methyl-pentyl ester, -n-hexyl ester, -2-ethylhexyl ester, -heptyl ester, -n-octyl ester, -n-nonyl ester, -n-decyl ester and -n-dodecyl ester, 2-phenylpropyl ester and -benzyl ester, based on secondary aliphatic and cycloaliphatic monoalcohols with 3 to 15 carbon atoms, preferably 3 to 6 carbon atoms, such as carbamic acid isopropyl ester, -sec-butyl ester, -sec-iso-amyl ester, -cyclopentyl ester, -cyclohexyl ester and tert-butyl-cyclohexyl ester. Carbamic acid methyl ester, ethyl ester, propyl ester are preferably used, -isopropylester, -butylester, -isobutylester, -2- and -3-methylbutylester, -pentylester, -hexylester, -2-ethylhexylester, -heptylester, -octylester and -cyclohexylester.

For the production of the aromatic di- and / or polyurethanes according to the Process according to the invention, the 'abovementioned' primary, aromatic di- and / or polyamines reacted with the carbamic acid ester in such amounts, that the ratio of NH2 groups of the primary aromatic amines to carbamic acid ester 1: 0.8 to 10, preferably 1: 0.9 to 5 and in particular 1: 1 to 3.

The reaction is carried out in the presence of alcohol and in the absence or optionally in the presence of catalysts at elevated temperatures and optionally ver reduced or increased pressure carried out, whereby it is has proven advantageous to remove the ammonia formed immediately from the reaction mixture, for example by distillation to separate.

As alcohols for the process according to the invention, any optionally substituted primary or secondary aliphatic alcohols as well Mixtures thereof can be used. The carbamic acid esters are preferably used appropriate alcohol used, in an amount that the ratio of NH2 groups of the aromatic amines to OH groups of the alcohols 1: 2.0 to 100, preferably 1: 2.5 to 50 and especially 1: 2.5 to 30.

Primary aliphatic alcohols, for example, are also suitable 1 to 20 carbon atoms, preferably 1 to 10 raw material atoms, such as methanol, ethanol, propanol, n-butanol, n-pentanol, neopentyl alcohol, 2-methyl-pentanol, n-hexanol, n-heptanol, n-octanol, nonanol; n-decanol and n-dodecanol, secondary aliphatic and cycloaliphatic alcohols having 3 to 15 carbon atoms, preferably 3 to 6 carbon atoms, such as isopropanol, sec-butanol> sec-isoamyl alcohol, cyclopentanol, 2,3- or 4-methyl - cyclohexanol and cyclohexanol. Preferably used as monoalcohols methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, 2-ethylbutanol, 2- and 3-methylbutanol, n-pentanol, n-hexanol, 2-ethylhexanol, Heptanol, octanol and cyclohexanol.

The alcohols can optionally be mixed with others under the reaction conditions inert organic solvents are mixed.

For example, alcohol-solvent mixtures that contain at least 20% by weight, preferably more than 50% by weight, L J 'based on the Total weight, alcohol included.

The preparation of the aromatic di- and / or polyurethanes according to the The process according to the invention is expediently carried out in the absence of catalysts carried out, provided the implementation of the selected reactants in economical acceptable reaction times with good yields. That way it will be costly Purification operations to separate the catalysts from the end products obtained avoided.

However, the reaction is used to increase the reaction rate carried out in the presence of alcoholates as catalysts, these are expediently in amounts of 0.1 to 20% by weight, preferably 0.1 to 10% by weight and in particular Q, 1 Up to 5% by weight, based on the weight of the aromatic primary amine, is used. Alkaline earth metal and alkali metal alcoholates are preferably used as catalysts, in particular sodium alcoholates of the alcohols functioning as reaction components or of volatile aliphatic alcohols with 1 to 4 carbon atoms, for example sodium methylate, sodium ethylate and potassium isopropylate. Have proven however, there are also alcoholates of other metals, for example aluminum, Titans et al. The corresponding alcoholates can be obtained, for example, directly from the alcohol and the (earth) alkali metal, the corresponding alkali and alkaline earth metal hydrides, -amides, e.g. sodium hydride, calcium hydride or sodium amide or optionally another (earth) alkali metal alcoholate can be produced.

The reaction is carried out at elevated temperatures, for example at temperatures from 1600 to 3000 ° C., preferably from 1800 to 250 ° C. and in particular from 1850 to 2300C and pressures of 0.1 to 120 bar, preferably 0.5 to 60 bar, especially 1 to 40 bar. Result for this temperature range Reaction times from 0.5 to 50 hours, preferably from 10 to 30 hours. At a given temperature, the reaction is then preferably carried out under a pressure in which the ammonia formed is selectively distilled off from the reaction mixture can be. The corresponding values can be found in tables with physical characteristics the ammonia and the alcohols are removed.

The di- and / or polyurethanes are produced in the process according to the invention expediently prepared as follows: The primary aromatic di- and / or Polyamines and the carbamic acid esters are advantageously used in the molar ratios mentioned mixed with the alcohol corresponding to the carbamic acid ester and in the absence or optionally the presence of catalysts in a reaction vessel heated with a device for separating the ammonia '. The resulting ammonia can be separated off after the reaction has ended; however, preferably it will already distilled off in the course of the reaction. It can be useful here, especially in the reaction of low molecular weight alcohols under pressure, the ammonia with Using an entrainer which is inert under the reaction conditions, for example a gas such as nitrogen.

According to another embodiment, which in general leads to a considerable Reduction of the reaction time leads and used advantageously in these cases the primary aromatic di- and / or polyamines, the urea and the alcohol initially in a ratio of NH2 groups of the amines to urea to alcohol from 1: 1.5-3: 2-10, preferably 1: 1.5-2: 4-8 0.5 to 3, preferably 0.5 to 2 hours reacted afterwards is added to the reaction mixture Alcohol incorporated in such an amount that per NH2 group used the Amines 10 to 30, preferably 15 to 30 mol of alcohol are present, and the reaction in a period of 4 to 20 hours in total, preferably 4 to 10 hours brought to the end. The reaction mixture obtained then becomes, if appropriate after neutralizing the catalyst and / or filtering off the substances, the di- and / or Polyurethane isolated, for example by distilling off the alcohol and / or the solvent and any O-alkyl carbamates used in excess, by partially distilling off the alcohol and crystallizing out, by crystallizing out, by precipitation with or also by recrystallization from other solvents.

The aromatic di- and / or polyurethanes obtained are valuable End and intermediate products. For example, they are used as pesticides used. As intermediate products, they are used as components for polycondensation and polymer systems are used, but especially with the elimination of alcohol converted into the corresponding isocyanates, with di- and polyisocyanates for production of polyurethanes are used.

The parts mentioned in the examples are based on weight. The elemental compositions and structures are determined by elemental analysis, mass spectroscopy as well as JR and NMR spectra confirmed.

Example 1 20.0 parts of 4,4'-diamino-diphenylmethane are combined with 44 parts N-hexyl carbamic acid in 60 parts of n-hexanol heated to boiling for 12 hours, a pressure of 2 to 3 bar being set via a pressure valve in the reaction vessel so that the boiling point of the hexanol is about 195 °.

The ammonia formed during the reaction is used of 25 liters of nitrogen per 1 reaction mixture per hour as stripping gas continuously distilled off. On cooling, 18.4 parts of 4,4'-di (hexoxycarbonylamino) diphenylmethane crystallize (64> 0% of theory, based on converted 4,4'-diaminodiphenylmethane) with a melting point of 142-143 ° C from C27H3604N2 (molecular weight 452). sales of 4,4'-diaminodiphenylmethane is 63.0%. There is still in the mother liquor 4-amino-4 '- (hexoxyearbonylamino) diphenylmethane.

Example 2 10.0 parts of 4,4'-diaminodiphenylmethane are mixed with 43.7 parts Carbamic acid octyl ester in 26.3 parts of octanol for 2 hours to the boil (200 - 205 ° C). A further 105 parts of octanol are then added to the reaction mixture and boil for a further 15 hours at reflux temperature, during the reaction ammonia formed using 10 l of nitrogen per liter of reaction mixture and hour is continuously distilled off as a stripping agent. After cooling down 7.4 parts of 4,4'-di- (octoxycarbonylamino) -diphenylmethane crystallize (75> 6 % of theory) C31H4604Ng (molecular weight 510) with a melting point of 117-119 ° C. The conversion of 4,4'-diaminodiphenylmethane is 38%. There is in the mother liquor nor 4-amino-4 '- (octoxyearbonylamino) -diphenylmethane.

Example 3 61 parts of 2,4-diaminotoluene are mixed with 432 parts of octyl carbamic acid and 1.5 parts of sodium methoxide in 1950 parts of octanol heated to boiling (1950C). After 23 hours, the mixture is allowed to cool and excess octanol and excess are distilled off Carbamic acid octyl ester up to a bottom temperature of 180 ° C. The residue is carried out with the help of high pressure liquid chromatography according to the "external" method Standards "analyzed. It turns out that 57% of the 2,4-diaminotpluene is converted where 101 parts (81.7% of theory) of 2,4-di- (octoxycarbonylamino) toluene C25H4204N2 (molecular weight 434) and 10.9 parts (13.8% of theory) of a mixture of 2-amino-4 - (octoxycarbonylamino) toluene and 4-amino-2- (octoxycarbonylamino) toluene.

Example 4 12.2 parts of 2,4-diaminotoluene are mixed with 22.3 parts of ethyl carbamate and 28 parts of ethanol heated to boiling for 2 hours, using a pressure valve a pressure of 23 to 24 bar is set in the reaction vessel, so that the boiling point of the ethanol is at 2000C.

The ammonia formed during the reaction is used of 30 liters of nitrogen per liter of reaction mixture per hour as stripping gas continuously distilled off. Thereafter, a further 140 parts of ethanol are added to the reaction mixture and reflux for another 15 hours. After the reaction has ended to cool and place the reaction vessel in an ice-common salt mixture, where 13.2 Parts (66.6% of theory) 2,4-di- (ethoxycarbonylamino) toluene C13H1804N2 (molecular weight 266) with a melting point of 105-108 C. The high pressure liquid chromatography analysis according to the "external" method 'Standards' shows that 74.5 % of the 2,4-diaminotoluene used have reacted, and that there are still residues of 2,4-di- (ethoxyearbonylamino) toluene and a mixture of 2-amino-4- (ethoxycarbonylamino) toluene and 4-amino-2 - (ethoxycarbonylamino) toluene are present in the mother liquor.

Example 5 10 parts of 4,4'-diaminodiphenylmethane are mixed with 15.2 parts Carbamic acid methyl ester in 65 parts of methanol heated to boiling for 18 hours, wherein A pressure of 35 to 37 bar is set via a pressure valve in the reaction vessel, so that the boiling temperature of the methanol is 180 - 1900C.

The ammonia formed during the reaction is used of 30 l of nitrogen per liter of reaction mixture per hour as stripping gas continuously distilled off. After cooling, 10.6 parts (83> 6% of theory) crystallize 4,4 -Di- (methoxycarbonylamino) diphenylmethane C17Hl804N2 (molecular weight 314) from a melting point of 184-186 ° C. 80% of 4,4-diaminodiphenylmethane have reacted.

Example 6 7.9 parts of 1,5-diaminonaphthalene are mixed with 43 parts of octyl carbamic acid heated to boiling (195 ° C) in 195 parts of octanol for 20 hours. Crystallizes after cooling a precipitate, from which 6.7 parts by recrystallization from ethyl acetate (75.0% of theory) 1,5-di (oetoxyearbonylamino) naphthalene with a melting point of 70 - 72 ° C can be obtained. The conversion of 1,5-diaminonaphthalene is 38%.

Example 7 12.2 parts of 2,4-diaminotoluene are mixed with 42.9 parts of cyclohexyl carbamic acid and 200 parts of cyclohexanol heated to boiling for 15 hours, using a pressure valve a pressure of 2 to 3 bar is set in the reaction vessel, so that the boiling point of cyclohexanol at approx.

200 ° C. The ammonia formed during the reaction is under Use of 15 liters of nitrogen per liter of reaction mixture per hour as stripping gas continuously distilled off.

After cooling, the reaction mixture is made using high pressure liquid chromatography analyzed according to the "external standard" method. This shows that 4.1 Parts (29.6% of theory) 2,4-di (cyclohexoxycarbonylamino) toluene and 6.2 parts (67.6% of theory) of a mixture of 2-amino-4- (cyclohexoxycarbonylamino) toluene and 4-amino-2- (cyclohexoxycarbonylamino) toluene were formed.

The conversion of 2,4-diaminotoluene is 37%.

Example 8 10.0 parts of a commercially available mixture of 2,2'-, 2,4'- and 4,4'-Diaminodiphenylmethane and polyphenyl-polymethylene-polyamines are with 23 Parts of ethyl carbamic acid in 30 parts of ethanol heated to boiling for 15 hours, a pressure of 23 to 25 bar being set via a pressure valve in the reaction vessel so that the boiling point of the ethanol is around 1950C. The during the Ammonia formed in the reaction is generated using 25 liters of nitrogen per liter of reaction mixture and continuously distilled off as stripping gas for an hour. It is allowed to cool and distilled Excess ethanol and excess carbamic acid ethyl ester in vacuo to to a sump temperature of 1900C. The residue is mixed with 100 parts of cyclohexane added and stirred, using a powder shaped precipitate which is separated and analyzed by high pressure liquid chromatography. It turns out that a mixture of 2,4'-, 2,2'- and 4,4'-di- (ethoxycarbonylamino ) -diphenylmethane and polyphenyl-polymethylene-polySthylurethanen.

Claims (11)

iatent claims 4½ process for the production of aromatic di- and / or polyurethanes, characterized in that carbamic acid esters with primary aromatic di- and / or polyamines in the presence of alcohols and optionally Reacts catalysts at elevated temperatures and the ammonia formed, if necessary separates. 2. The method according to claim 1, characterized in that the ratio from NH2 groups of the primary aromatic di- and / or polyamines to carbamic acid esters 1: 0.8-10. 3. The method according to claim 1, characterized in that the ratio from NH2 groups of the aromatic di- and / or polyamines to OH groups of the alcohols 1: 2.0 to 100. 4. The method according to claim 1 to 3, characterized in that the reaction is carried out at temperatures from 160.degree. C. to 300.degree. 5. The method according to claim 1 to 4, characterized in that the ammonia formed is separated off at the same time. 6. The method according to claim 1, characterized in that the Implementation at pressures from 0.1 to 120 bar. 7. The method according to claim 1, characterized in that as aromatic diamines 2,4- and 2,6-diamines no-toluene and the corresponding Mixtures of isomers, 1,5-diamino-naphthalene, 2,2'-, 2,4'- and 4,4'-diamino-diphenylmethane and the corresponding isomer mixtures and, as polyamines, mixtures of diamino-diphenylmethanes and polyphenyl-polymethylene-polyamines are used. 8. The method according to claim 1, characterized in that as Carbamic acid esters those of carbamic acid and aliphatic and cycloaliphatic Monoalcohols with 1 to 10 carbon atoms in the alcohol residue are used. 9. The method according to claim 1, characterized in that as Alcohols used the alcohols corresponding to the carbamic acid esters. 10. The method according to claim 1, characterized in that as Catalysts used alcoholates. 11. The method according to claim 1, characterized in that the Starting components in the ratio of NH2 groups of the amines to carbamic acid ester Alcohol of 1: 1.5-3: 2-10 reacts for 0.5 to 3 hours, the reaction mixture additional Alcohol incorporated in an amount that the ratio of the amines to NH2 groups Alcohol is 1: 10-30 and the reaction ends.