WO1993016030A1

WO1993016030A1 - Promoters for hydrogenation of aromatic amines

Info

Publication number: WO1993016030A1
Application number: PCT/US1993/000630
Authority: WO
Inventors: Peter John Whitman
Original assignee: Olin Corporation
Priority date: 1992-02-05
Filing date: 1993-01-25
Publication date: 1993-08-19
Also published as: AU3590693A

Abstract

A process for increasing the rate of catalytic hydrogenation of aromatic amines by reacting aromatic amines with hydrogen in the presence of a noble metal catalyst, an organic solvent or a mixture of solvents, and at least one salt of a transition or lanthanide metal as a promoter, in an effective amount to increase the rate of the hydrogenation reaction, decrease the induction period, and decrease the amount of higher boiler by-products.

Description

PROMOTERS FOR HYDROGENATION OF AROMATIC AMINES

This invention relates to a process using transition or lanthanide metal salt promoters in the catalytic hydrogenation of aromatic amines to produce their cycloaliphatic counterparts. Substantial literature exists with respect to the catalytic hydrogenation of aromatic amines to prepare the corresponding cycloaliphatic amines. Illustrative of this type of reaction is the hydrogenation of methylenedianiline [4,4 '-diaminodiphenylmethane, MDA] to the cycloaliphatic amine which is bis(4-aminocyclohexyl)methane, also called PACM, H₁₂ DA.

The hydrogenation follows a step-wise reaction sequence, giving first the half hydrogenated cis and trans isomers [p-(4-aminocyclohexylmethyl)aniline, 4-(ρ-aminobenzyl)aminocyclohexane, H,MDA] , then reacting further to yield the three bis(4-aminocyclohexyl)methane isomers (cis, cis; cis, trans; and trans, trans) represented by the formulas and reactions as follows:

cia , cia-bis (4-aminocyclohexyl ) methane

Some of the early hydrogenation work to produce bis(4-aminocyclohexyl)methanes was done by Whitman and Barkdoll, et al and their work is set forth in a series of US Patents Nos.2,511,028; 2,606,924; 2,606.925; and 2,606,928. Basically the processes described in these patents involve the hydrogenation of methylenedianiline at pressures in excess of 200 psig, preferably in excess of 1,000 psig at temperatures within a range of 80* to 275^βC utilizing a ruthenium catalyst for the hydrogenation. The hydrogenation is carried out under liquid phase conditions and an inert organic solvent is used. Most of the references utilize a noble metal such -as ruthenium, rhodium, iridium, or mixtures of any of

SUBSTITUTE these or with platinum or palladium, either as the hydroxide, oxide, or the metal itself on an inert support. Examples of ruthenium catalysts utilized for the hydrogenation process include ruthenium oxides, such as ruthenium sesquioxide and ruthenium dioxide; ruthenium hydroxide; and ruthenium salts.

US Patent No. 3,959,374 discloses a process for the preparation of bis(4-aminocyclohexyl)methane by pretreating a mixed methylenedianiline system with a nickel-containing hydrogenation catalyst prior to hydrogenation with ruthenium. The pretreatment was used to overcome low yields (52.4%) and long reaction time associated with nickel and cobalt catalysts. Ruthenium catalysts, although commonly used for hydrogenation, were not suited for hydrogenation of a feed containing impurities. Impurities in the feed caused a rapid decline in activity and hydrogenation efficiency.

In the continued development of processes for manufacturing bis(4-aminocyclohexyl)methanes by hydrogenating methylenedianiline it was found that if the ruthenium was loaded upon a support and the support was alkali-moderated, the catalyst was much more active and catalytically effective in producing the desired hydrogenated bis(4-aminocyclohexyl)methane product. Alkali moderation was effected by contacting the catalyst with an alkali metal hydroxide or alkoxide; also, such alkali moderation of the catalyst could be effected prior to hydrogenation or in situ during the hydrogenation. Representative patents showing the utilization of alkali moderated ruthenium catalysts to hydrogenate methylenedianiline include US Patent Nos. 3,636,108; 3,644,522; and 3,697,449. Alkali metal and alkaline earth metal nitrates and sulfates have similarly been shown effective in US Patent No. 4,448,995 under high pressure (4000 psig) hydrogenation conditions. Representative supports disclosed in US Patent No. 3,697,449 include bauxite, periclase, zirconia, titania, diatomaceous earth, etc. US Patent Nos. 3,347,917; 3,711,550; 3,679,746; 3,155,724; 3,766,272 and British Patent No. 1,122,609 disclose various isomerization and hydrogenation processes to produce bis(4-aminocyclohexyl)methane containing a high trans,trans-isomer content; i.e. an isomer content near equilibrium typically 50% trans,trans, 43% cis,trans and 7% cis,cis. Ruthenium catalysts were used to effect isomerization.

In US Patents Nos. 4,394,522 and 4,394,523, a process is disclosed for producing bis(4-aminocyclohexyl)methane by carrying out the hydrogenation of methylenedianiline in the presence of unsupported ruthenium dioxide at pressures of at least 2500 psig or in the presence of ruthenium on alumina under pressures of at least 500 psig and preferably from 1500 psig to 4000 psig in the presence of an aliphatic alcohol and ammonia. Other catalysts have been utilized for the hydrogenation of methylenedianiline and examples are shown in US Patents Nos. 3,591,635 and 3,856,862 which disclose the use of a rhodium component as a catalytic material and each require the use of an alcohol as a solvent. The rhodium is alkali moderated using ammonium hydroxide as a pretreatment or by carrying out the reaction in the presence of ammonia.

The isomeric cycloaliphatic diamines are useful in the preparation of the corresponding aliphatic diisocyanates suitable for forming light stable urethane coatings and lacquers.

In earlier experiments involving the hydrogenation of aniline, it was shown that addition of ammonia not only suppresses by-product formation mainly from hydrogenolysis and condensation reactions, but also poisons the catalyst. However, addition of lithium hydroxide and sometimes sodium hydroxide suppresses the hydrogenolysis without the detrimental poisoning of the catalyst. A similar phenomenon has been reported with the hydrogenation of methylenedianiline using lithium hydroxide, and to a lesser extent, with other alkali or alkaline earth hydroxides or alkoxides. Common by-products formed during the hydrogenation of methylenedianiline include the hydrogenolysis products 4-aminodicyclohexylmethane and

4-aminocyclohexylcyclohexenylmethane, the hydrolysis product 4-amino- '-hydroxydicyclohexylmethane, and higher boilers, mainly, but not exclusively, higher molecular weight secondary amine condensation products. All of these products exist as a number of isomers.

U.S. Patent No. 4,448,995 teaches that this hydrogenation reaction should be maintained in an anhydrous state or at least maintained so that water concentration is less than 0.5% by weight because failure to do so results in an increase in both the amount of alcohol by-products and higher molecular weight condensation products. In addition, the patent states that alkali nitrates and sulfates, especially those of lithium reduce by-products.

In some comparisons, the presence of lithium hydroxide has been shown to actually result in an increase in the production of higher molecular weight products. (See U.S. Patent No. 4,946,998.)

U.S. Patent Nos. 4,960,491 and 4,754,070 disclose the hydrogenation of aromatic amines to their hydrogenated counterparts. In these patents, it is stated that "Although in some processes water can be used as a co-solvent, it is preferred that the system be in an anhydrous state or at least maintained so that the water concentration is less than 0.5 percent by weight. Water, when present in the system, tends to increase the amount of by-product alcohols and heavy condensation products during the hydrogenation process and tends to deactivate the catalyst system."

New aqueous and non-aqueous processes for hydrogenating aromatic amines at an improved rate would be highly desired by the isocyanates manufacturing community.

In one aspect, the present invention relates to a process for the catalytic hydrogenation of an aromatic amine represented by the formula:

in which: R, is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and NH₂;

R₂ is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and C CHH,.-^---^ NH, and

R„ and R. are independently selected from the group consisting of H, and an alkyl or cycloalkyl group having 1-6 carbon atoms; which process comprises reacting said aromatic amine with hydrogen in a reaction mixture containing an organic solvent, a noble metal catalyst and a promoter admixed with said reaction mixture, said promoter being -1-

a metal salt selected from the group consisting of a sulfate, a phosphate and a carboxylate, wherein the metal is selected from the group consisting of transition metals Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, and Hg, and lanthanide metals, said promoter being used in an effective amount to increase the rate of said hydrogenation reaction, decrease the induction period, and decrease the amount of high boiler by-products.

In another aspect, the present invention relates to a process for the catalytic hydrogenation of an aromatic amine represented by the formula:

in which: R, is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and NH-; R is selected from the group consisting of

H, an-alkyl or cycloalkyl group having 1-6 carbon atoms, and CH_—-^) ^NH ₂' ^an-~

R_ and R. are selected from the group consisting of H, and an alkyl or cycloalkyl group having 1-6 carbon atoms; which process comprises reacting said aromatic amine with hydrogen in the presence of a noble metal catalyst, an alkali metal hydroxide catalyst promoter and a solvent mixture of a water miscible organic solvent and water; said water being used in an effective amount to increase the rate of said hydrogenation reaction without an appreciable increase in total amounts of by-products.

The present invention relates to a process for increasing the rate of conventional ring hydrogenation of aromatic amines to their cycloaliphatic counterparts and these aromatic amines are represented by the formula:

in which R, is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and NH„;

R_ is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and ^CH ₂"~γ /—^NH ' ^and ₃ and R. are independently selected from the group consisting of H, and an alkyl or cycloalkyl group having 1-6 carbon atoms. By the practice of this invention, one is able to increase the rate of hydrogenation of aromatic amines to their cycloaliphatic counterparts, decrease or eliminate the induction period, and decrease the amounts of higher boiler by-products formed during reaction. The aromatic amines useful in the practice of the process can be bridged polynuclear or mononuclear aromatic amines. These can be substituted with various substituents such as an alkyl group or cycloalkyl group containing from 1-6 carbon atoms. Further, the amine group can be substituted with alkyl or cycloalkyl groups having 1-6 carbon atoms resulting in secondary and tertiary amine substituents. Examples of bridged aromatic amines include methylenedianiline (R, is H and R_ is

' ^{bis( -araino~2}~^raethy¹P^{hen 1})^methane' tolidine, and alkyl or cycloalkyl secondary and tertiary amine derivatives of above bridged aromatic amines. Examples of mononuclear aromatic amines include 2,4- and 2,6-toluenediamine, aniline, l-methyl-3,5-diethyl-2,4- or 2,6-diaminobenzene (diethyltoluenediamine) , diisopropyltoluenediamine, tert-butyl-2,4- or 2,6-toluenediamine, cyclopentyltoluenediamine, ortho-toluidine, ethyltoluidine, xylenediamine, mesitylenediamine, mono-isopropyltoluenediamine, phenylenediamine, and alkyl and cycloalkyl secondary and tertiary amine derivatives of the aromatic amines mentioned above. As with conventional processes the hydrogenation process is carried out under liquid phase conditions being maintained typically by carrying out the hydrogenation in the presence of a solvent. Any solvent or solvent mixture that dissolves and is inert to the reactant and product, should be equally usable.

Representative solvents suitable for practicing the invention include low molecular weight alcohols, such as methanol, ethanol, isopropanol, tert-butyl alcohol and methoxyethanol; and low molecular weight aliphatic and alicyclic hydrocarbon ethers, such as n-propyl ether, isopropyl ether, glyme, tetrahydrofuran, and dioxane. Dioxane is preferred. A mixed solvent system may also be used such as an alcohol or an ether mixed together, or either of these with another solvent such as a hydrocarbon or water.

In one aspect of this invention, water is used as a co-solvent. The amount of water depends on the following factors: organic solvent, starting aromatic amine, resulting corresponding hydrogenated amine counterpart, and temperature. Thus, the minimum water concentrations to be effective to increase the rate of the hydrogenation reaction should be in amounts greater than 1.0% by weight of organic solvent. However, the maximum amount of water added can be up to the solubility limits of the starting aromatic amine or the corresponding hydrogenated reaction product in the resultant water-organic solvent mixture thereby preventing the adverse effect of separation of layers or precipitation in the solvent mixture which slows down the rate of hydrogenation dramatically. That is to say, the maximum amount of water used according to the invention is just below that amount which would result in separation of the starting aromatic amine or the corresponding hydrogenated reaction product, whichever is less soluble in the water-organic solvent mixture. Thus, as used in the specification and claims hereof, the term "effective amount" is intended to include any such amount. By way of illustration, an effective amount of the water is a range of from about 1.0% up to solubility limits of the starting product and/or the reaction product in the resultant mixed water-organic solvent, preferably from about 2% to about 20% and most preferably from about 3% to about 10% by weight of organic solvent.

A noble metal catalyst such as ruthenium, rhodium, iridium, or mixtures of any of these or with platinum or palladium, either as the hydroxide, oxide or, the metal itself on an inert support may be utilized for the hydrogenation process. The catalysts used are supported upon an inert carrier and representative carriers include carbon; calcium carbonate; rare earth oxides such as cerium, praseodymium, or lanthanum; rare earth carbonates; alumina; barium sulfate; kieselguhr; pumice; titania; diatomaceous earth; and other alkaline earth componds such as calcium sulfate, calcium oxide, barium oxide, and barium sulfate. Preferred support material is alumina. The preferred catalyst is ruthenium on alumina carrier (Ru/Al_0₃). A 5% ruthenium on alumina loading, a commercial product available from the Aldrich Chemical Co., is illustrative, but any percent loading can be utilized. To maintain high activity of the catalyst system in the hydrogenation process, a transition and/or lanthanide metal salt promoter is added to the reaction system in an effective amount to increase the hydrogenation rate, eliminate the induction period of the hydrogenation reaction, and decrease the amount of higher boiler by-products and thus, the term "effective amount" is intended to include any such amount which accomplishes this. By way of illustration, an effective amount of the transition or lanthaide metal salt promoter is in the range from about 0.1% to about 15% by weight based on the starting aromatic amine. Preferred range is from about 0.3% to about 10.0%. These metal salt promoters can be used alone or in combination with other additives. The transition metal salts that can be used according to the invention are salts of the following transition metals: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, and Hg. Preferred salts are those of the metals: Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ru, and Hf. Most preferred is Fe.

The lanthanide metal salts that can be used according to the invention are salts of the following lanthanide metals: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Preferred metal salts are those of La, Ce, Pr, Nd, Sm, Tb, Er, and Yb. Most preferred are metal salts of La and Ce.

Counter-ions such as the sulfate and phosphate can be used because they do not have non-bonded electrons on the sulfur and phosphorus respectively. Thus, ferrous and cerous sulfates (either as the anhydrous salt or as a hydrate) are illustrative. Other anions that satisfy these criteria such as carboxylates (eg. acetates) can be used.

Promoters of the invention are used to enhance the reaction by decreasing by-products, increasing the reaction rate, and decreasing or eliminating the induction period in the hydrogenation reaction. The reaction can be carried out at any suitable temperature range, preferably from about 80°C to about 240°C. In the case of methylenedianiline, the optimum temperature is dependent on the desired bis(4-aminocyclohexyl)methane isomer ratio. In order to achieve a 20% trans, trans content or less the lower end of the temperature range is desirable. To achieve a 48% trans,trans content, this reaction must take place in the midrange or above 170°C.

Also the reaction may be operated at any suitable pressure, preferably from about 500 to about 4000 psig with the more preferred range from about 1000 to about 3000 psig, most preferably from about 500 to about 1500 psig.

The concentration of starting aromatic amine in solution can vary from 1% to neat (without solvent), preferably from 3% to 50% are utilized.

The progress of the hydrogenation reaction is followed readily by observation of the amount of hydrogen taken up by the reaction mixture and the hydrogenation is terminated at the point at which the theoretical quantity of hydrogen has been consumed. Following the hydrogenation, the catalyst can be filtered through celite and can be optionally reused. The solvent is distilled and also can be optionally reused. The residual cycloaliphatic amine can be either used as is, or purified by vacuum distillation or crystallization.

The promoters of the invention can be used in the hydrogenation of any aromatic amine. The hydrogenation of methylenedianiline is used to demonstrate the invention.

The following examples are presented to further illustrate the invention without any intention of being limited thereby. All parts and percentages are by weight unless otherwise specified except for percent yield which is mole percent.

EXAMPLE 1

In a 600 ml Parr pressure reactor, the following were added: 3.0 g of methylenedianiline, 0.20 g of 5% ruthenium on alumina, 0.15 g of ferrous sulfate heptahydrate (promoter) and 95 g of dioxane. The reactor was flushed with hydrogen and pressurized. The reaction mixture was heated to 125°C for 6 hours at 1500 psig. Essentially no induction period was observed. After cooling and release of pressure, the reaction mixture was filtered through celite and evaporated to dryness under aspirator vacuum to give a crude mixture of 0.1% methylenedianiline, 10.8% p-(4-aminocyclohexylmethyl)aniline and 87.2% bis(4-aminocyclohexyl)methane. Only 0.1 % higher boilers were obtained.

EXAMPLE 2

The same reaction conditions were utilized as in Example 1, except that 0.06 g of cerous sulfate octahydrate was added. The reaction showed no induction period, and gave essentially no methylenedianiline, 11.4% p-(4-aminocyclohexylmethyl)aniline, and 84.3% bis(4-aminocyclohexyl)methane. No higher boilers were observed.

EXAMPLE 3

The same reaction conditions were utilized as in Example 1, except that 0.15 g of ferrous sulfate heptahydrate and 0.06 g of cerous sulfate octahydrate were added. The reaction showed no induction period and gave essentially no methylenedianiline, 8.3% p-(4-aminocyclohexyl)aniline, and 89.4% bis(4-aminocyclohexyl)methane. No higher boilers were observed.

EXAMPLE 4

In a 600 ml Parr pressure reactor, the following were added: 3.0 g of methylenedianiline, 0.20 g of 5% ruthenium on alumina, and 95 g of dioxane. The reactor was flushed with hydrogen and pressurized. The reaction mixture was heated to 125°C for 6 hours at 1500 psig. An induction period of approximately one hour was observed. After cooling and release of pressure, the reaction mixture was filtered through celite and evaporated to dryness under aspirator vacuum to give a crude mixture of essentially no methylenedianiline, 17.6% p-(4-aminocyclohexylmethyl)aniline, and 79.5% bis(4-aminocyclohexyl)methane. Approximately 1.4% higher boilers was observed.

EXAMPLE 5

The same reaction conditions were utilized as in Example 4 except that 0.15 g of stannous chloride dihydrate was added. Essentially no hydrogenation took place; only methylenedianiline starting material was observed.

EXAMPLE 6

The same reaction conditions were utilized as in Example 4 except that 0.01 g of stannous chloride dihydrate was added. Essentially no hydrogenation took place; only methylenedianiline starting material was observed.

Examples 1 - 3 demonstrate an increase in the reaction rate, a decrease or elimination of the induction period, and a decrease of the amount of higher boiler by-products as compared to Example 4. These results were unexpected. Examples 5 and 6 show the effect of catalyst poisoning. Operable and preferred ranges of reaction conditions are presented in the following table:

Non-Aqueous System TABLE 1

Range

Variable Operable Preferred

Temperature 80°-240°C (1)

Pressure 500-4000psig 1000-3000psig

Solvents (2) (2) Concentrations MDA: 1% to neat 3-50% catalyst: 0.005-1.0% (3) 0.05-0.5% (3) promoter: 0.1-15.0% (4) 0.3-10.0% (4)

(1) The "preferred" temperature depends on the desired trans, trans isomer content of the bis(4-aminocyclohexyl)methane. Lower temperatures give a lower (approximate 20% trans, trans) content; increasing the temperature results in a higher (approximate 48% trans, trans) content.

(2) Any organic solvent inert to the starting and product amines and inert to the reaction conditions is usable. Examples include other ethers such as dioxane, glymes, tetrahydrofuran, etc., and alcohols (low molecular weight alcohols, diols, alkoxyalcohols) ; and dioxane is preferred.

A solvent system comprising an alcohol or an ether mixed together or with another solvent such as a hydrocarbon or water may be used. (3) Based on weight of noble metal to weight of starting amine.

(4) Based on weight of promoter to weight of starting amine.

EXAMPLE 7

In a 600 ml Parr pressure reactor, the following were added: 3.0 g of methylenedianiline, 0.20 g of 5% ruthenium on alumina, and 95 g of dioxane. The reactor was flushed with hydrogen and pressurized. The reaction mixture was heated to 125°C for 6 hours at 1500 psig (no further decrease in pressure was observed after 5 hours). After cooling and release of pressure, the reaction mixture was filtered through celite and evaporated to dryness under aspirator vacuum to give a crude mixture of essentially no methylenedianiline, <0.1% p-(4-aminocyclohexylmethyl)aniline, and 98.2% bis(4-aminocyclohexyl)methane. The balance consisted primarily of the following by-products: 0.3% monoamines, 0.5% hydroxyamines, and 0.5% higher boilers. Also approximately 0.8%

2,4--diaminodicyclohexylmethane isomers were obtained from the 2, '-methylenedianiline present in the starting material.

EXAMPLE 8

Similar reaction conditions were utilized as in Example 7, except that 0.11 g of lithium hydroxide monohydrate was used as a promoter. The reaction was allowed to run for 6 hours, although no further decreases in pressure were observed after 4.5 hours. The product gave no methylenedianiline or p-(4-aminocyclohexylmethyl)aniline and 98.0% bis(4-aminocyclohexyl)methane. The balance consisted primarily of 0.3% monoamines, 0.5% hydroxyamines, 0.2% higher boilers, and 0.8% 2,4 '-diaminodicyclohexylmethane isomers.

Example 9 below presents a process for the hydrogenation of methylenedianiline.

EXAMPLE 9

In a 600 ml Parr pressure reactor, the following were added: 3.0 g of methylenedianiline, 0.20 g of 5% ruthenium on alumina, 95 g of dioxane, 0.11 g of lithium hydroxide monohydrate (as a promoter), and 5 g of water. The reactor was flushed with hydrogen and pressurized. The reaction mixture was heated to 125°C for 2 hours at 1500 psig. The product gave essentially no methylenedianiline or p-(4-aminocyclohexylmethyl)aniline and 97.5% bis(4-aminocyclohexyl)methane. The balance consisted primarily of 1.5% monoamines, 0.4% hydroxyamines, 0.6% 2,4'-diaminodicyclohexylmethane isomers, and in contrast to examples 7 and 8, no higher boilers.

Thus, water unexpectedly increased the reaction rate. In going from example 7 to example 8, no changes in the amounts of the monoamines and hydroxyamines were observed, although the amount of higher boilers decreased. In going from examples 7 or 8 to example 9, the amounts of monoamines increase, hydroxyamines remain about the same, and higher boilers decrease. No higher boilers were observed in example 9 above. Thus, no appreciable differences in the total amounts of by-products were observed.

The enhancement of the reaction rate due to the presence of water in the reaction mixture was entirely unexpected. Also the elimination of the higher boilers was unexpected.

Operable and preferred ranges of reaction conditions are presented in the following table:

Aque ug System TABLE 2

Range

Variable Operable Preferred

Temperature 80°-240°C (1) Pressure 500-4000psig 1000-3000psig Solvents (2) ( 2 ) Concentrations

MDA: 1% to neat 3-50% catalyst: 0.005%-l% (3) 0 . 05-0 . 5% ( 3 ) metal hydroxide promoter: 0.01-15.0% (4) 0 . 05-5 . 0% ( 4 ) water: >1.0-solubility 2-20% limit

(2) Any solvent miscible with water at the reaction temperature and inert to the reaction conditions is usable. Examples include other ethers such as dioxane, glymes, tetrahydrofuran, etc., and alcohols (low molecular weight alcohols, diols, alkoxyalcohols) .

(3) Based on weight of catalyst to weight of starting amine.

(4) Based on weight of promoter to weight of starting amine. While the specific invention has been described above with reference to specific embodiments thereof, it is apparent that many changes, modifications and variations can be made without departing from the inventive concept disclosed herein. Accordingly, it is intended to embrace all such changes, modifications and variations that fall within the spirit and broad scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A process for the catalytic hydrogenation of an aromatic amine represented by the formula:

in which; R. is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and NH„;

R_ is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and CH₂-C_ V H₂; and

R₃ and R. are independently selected from the group consisting of H, and an alkyl or cycloalkyl group having 1-6 carbon atoms; which process is characterized by reacting said aromatic amine with hydrogen in a reaction mixture containing an organic solvent, a noble metal catalyst and a promoter admixed with said reaction mixture, said promoter being a metal salt selected from the group consisting of a sulfate, a phosphate and a carboxylate, wherein the metal is selected from the group consisting of transition metals Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, and Hg, and lanthanide metals, said promoter being used in an effective amount to increase the rate of said hydrogenation reaction, decrease the induction period, and decrease the amount of high boiler by-products.

2. The process of claim 1 characterized in that the lanthanide metal is selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

5 3. The process of claim 1 characterized in that the transition metal is selected from the group consisting of Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ru, and Hf, and the lanthanide metal is selected from the group consisting of La, Ce, Pr, Nd, Sm, Tb, Er, 10 and Yb.

4. The process of claim 1 characterized in that said promoter is present in an amount from about 0.1% to about 15.0% by weight of the aromatic amine.

5. A process for the catalytic hydrogenation of 15 methylenedianiline to produce bis(4-aminocyclohexyl)methane, which process is characterized by reacting said methylenedianiline with hydrogen in a reaction mixture containing an organic solvent, a noble metal catalyst and a metal salt

20 promoter admixed with said reaction reaction mixture, said promoter being selected from the group consisting of a sulfate, a phosphate and a carboxylate, wherein the metal is selected from the group consisting of transition metals Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn,

25 Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, and Hg, and lanthanide metals, said promoter being used in an effective amount to increase

'} the rate of said hydrogenation reaction, decrease the induction period, and decrease the amount of high boiler

30 by-products.

6. The process of claim 5 characterized in that the transition metal is selected from the group consisting of Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ru, and Hf, and the lanthanide metal is selected from the group consisting of La, Ce, Pr, Nd, Sm, Tb, Er, and Yb.

7. The process of claim 5 characterized in that said promoter is present in an amount from about 0.1% to about 15.0% by weight of the aromatic amine.

8. A process for the catalytic hydrogenation of an aromatic amine represented by the formula:

in which: R, is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and NH_;

R_ is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and and

R₃ and . are selected from the group consisting of H, and an alkyl or cycloalkyl group having 1-6 carbon atoms; which process is characterized by reacting at between 500 psig and 1500 psig of pressure said aromatic amine with hydrogen in the presence of a noble metal catalyst, a lithium catalyst promoter and a solvent mixture of a water miscible organic solvent and water; said water being used in an effective amount to increase the rate of said hydrogenation reaction without an appreciable increase in total amounts of by-products.

9. The process of claim 8 characterized in that the water is present in a concentration of greater than 1.0% by weight of the organic solvent up to the solubility limits of the aromatic amine starting material and/or the corresponding hydrogenated reaction product in the resultant water-organic mixed solvent system.

10. The process of claim 9 characterized in that the water is present in a concentration from about 2% to about 20% by weight of the organic solvent.

11. A process for the catalytic hydrogenation of methylenedianiline to produce bis(4-aminocyclohexyl)methane, which process is characterized by reacting methylenedianiline with hydrogen in the presence of a noble metal catalyst, an alkali metal hydroxide catalyst promoter and a solvent mixture of a water miscible organic solvent and water; said water being used in an effective amount to increase the rate of said hydrogenation reaction without an appreciable increase in total amounts of by-products.

12. The process of claim 11 characterized in that the alkali metal hydroxide catalyst promoter is lithium hydroxide.

13. The process of claim 11 characterized in that the water is present in a concentration from about 3% to about 10% by weight of the organic solvent. AMENDED CLAIMS

[received by the International Bureau on 27 July 1993 (27.07.93⁾ ; original claims 1-7 and 12 cancelled; original claim 8 replaced by amended claim new claims added; claims 9-13 unchanged but renumbered as claims 2-5 other claims unchanged (2 pages) ]

1 . A process for the cata lyt ic hydrogenation of an a romat i c amine represented by the formul a :

^R4\N ^*3

in which: is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and NH_ ;

R_ is selected from the group consisting of H, an alkyl or cycloalkyl group having 1-6 carbon atoms, and ; and

R₃ and R. are selected from the group consisting of H, and an alkyl or cycloalkyl group having 1-6 carbon atoms; which process is characterized by reacting at between 500 psig and 1500 psig of pressure said aromatic amine with hydrogen in the presence of a noble metal catalyst, a lithium catalyst promoter and a solvent mixture of a water miscible organic solvent and water; said water being used in an effective amount to increase the rate of said hydrogenation reaction without an appreciable increase in total amounts of by-products. 2. The process of claim 8 characterized in that the water is present in a concentration of greater than 1.0% by weight of the organic solvent up to the solubility limits of the aromatic amine starting material and/or the corresponding hydrogenated reaction product in the resultant water-organic mixed solvent system.

3. The process of claim 9 characterized in that the water is present in a concentration from about 2% to about 20% by weight of the organic solvent.

4. A process for the catalytic hydrogenation of methylenedianiline to produce bis(4-aminocyclohexyl)methane, which process is characterized by reacting methylenedianiline with hydrogen in the presence of a noble metal catalyst, an alkali metal hydroxide catalyst promoter and a solvent mixture of a water miscible organic solvent and water; said water being used in an effective amount to increase the rate of said hydrogenation reaction without an appreciable increase in total amounts of by-products.

5. The process of claim 4 characterized in that the water is present in a concentration from about 3% to about 10% by weight of the organic solvent.

STATEMENTUNDERARTICLE 19

This amendment is made to further clarify the distinctions between the presently claimed invention and the pri art cited in the International Search Report. More specifically a pressure range of between 500 and 1,500 psig. has been incorporated into the process of claim 1, and the alkali metal hydroxide catalyst has been limited to lithium hydroxide, as supported by the disclosures of original process claim 12. This amendment was also made in the corresponding U.S. Patent Application.

Indeed, the only reaction pressures taught in the Brake patent are in the actual working examples, and these are limited to pressures between 3,000 and 5,000 psi. No lower reaction pressure examples are provided by the '449 patent. It is respectfully submitted that alkali moderation pressure is not th same as hydrogenation reaction pressure. Any such a broad readi of the Brake reference is not warranted based upon a careful reading of the specific teaches of this reference.

In contrast to the reaction pressures (not alkali moderation pressures) disclosed in the Brake patent, Example 3 o the instant specification was conducted at a considerably lower pressure of 1,500 psig while still providing excellent product yield. Operation at such a lower pressure provides the instantl claimed invention with a cost savings and process safety advantage vis-a-vis the operating pressures disclosed in the working examples and the pressure range taught by the *108 patent.

The use of the lithium hydroxide catalyst in the process of the instantly claimed invention within the recited range of reaction pressures is nowhere disclosed or suggested by the instant invention. Instead, this patent makes mere mention of lithium in its wish-list of alkali metals employed in the process of the '108 patent. By "wish-list" is meant the large number of compounds recited at column 4, lines 60-67 of the Brake patent, including both recited anions and cations and including the hydroxides and the alkoxides, wherein the preferred alkoxides recited in the patent are methoxides, ethoxides, propoxides and butoxides, and the "most practical" alkali metals are sodium and potassium, according to column 4, lines 66-67 of the reference.

A fair reading of the Brake reference including the working examples appearing therein, that Brake teaches away from the instant invention by explicitly teaching higher reaction pressures utilizing other alkali hydroxides and alkoxides, such as potassium hydroxide, sodium methoxide, and not lithium hydroxide at the instantly employed reaction pressures. Therefore, applicant concludes that the instantly claimed process is not disclosed or suggested by the '108 patent.