GB1589887A - Preparation of arylamines by reduction or reductive alkylation of p-nitroarylamines - Google Patents

Description

(54) PREPARATION OF ARYLAMINES BY REDUCTION OR REDUCTIVE ALKYLATION OF P-NITROSOARYLAMINES (71) We, UNIROYAL, INC., a corporation organised and existing under the laws of the State of New Jersey, one of the United States of America, of 1230 Avenue of the Americas, New York, New York 10020, United States of America, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a process for making a p-aminoarylamine or a p-alkylaminoarylamine.

According to the present invention there is provided a process for preparing a compound having the structural formula

wherein: X is alkyl having up to 3 carbon atoms and n is an integer of from 1 to 4, R is hydrogen, alkyl having 1 to 18 carbon atoms, cycloalkyl having. 5 to 8 carbon atoms, aralkyl having 7 to 9 carbon atoms, alkaryl having 7 to 10 carbon atoms or phenyl; R1 is hydrogen or a group having the formula CHR2Rs wherein R2 and R3 are the same or different and are alkyl having 1 to 10 carbon atoms, cycloalkyl having 5 to 8 carbon atoms, aryl having 6 to 10 carbon atoms, or R2 and Rd combined represent polymethylene having 4 to 5 carbon atoms and attached to the same carbon atom, by contacting a p-nitrosoarylamine compound of the structural formula

wherein R, X and n have the meanings above, with hydrogen in the absence or presence of a ketone of the formula O=CR2R3 wherein R2 and R are as defined above, under a pressure of from 70 to 35,000 kPa (preferably from 700 to 20,000 kPa, more preferably from 700 to 10,000 kPa), at a temperature of from 5 to 250"C. in the presence of a catalytically effective amount of platinum metal sulfide, the reaction temperature in the case where the reaction is carried out in the presence of a ketone being at least 50"C during at least the latter part of the reaction.

This invention comprises the use of the sulfides of the platinum metals, ruthenium, rhodium, palladium, osmium, iridium, and platinum, as heterogeneous hydrogenation catalysts for the hydrogenation of p-nitrosoarylamines to p-aminoarylamines, and for the reductive alkylation of p-nitrosoarylamines with ketones to p-alkylaminoarylamines.

This invention is valuable because of a combination of two factors, one, the economical availability of p-nitrosoarylamines, and two, the efficiency and selectivity of the sulfides of the platinum metals for the desired transformation of the p-nitrosoarylamines to paminoarylamines and to p-alkylaminoarylamines.

The p-nitrosoarylamines are well known in the art.

The platinum metal sulfide catalysts are important in this invention because they make the desired hydrogenations possible with little or none of the side reactions, such as nuclear hydrogenation, cleavage or carbon-nitrogen bonds, and reduction of ketones to alcohols, that are commonly found with such non-suffided catalysts as platinum, palladium, nickel, and copper chromite. In addition, they are relatively insensitive to poisons that severely inhibit these other catalysts. Furthermore, they are much more active than the base metal sulfides, such as the sulfides of nickel, cobalt, iron, and molybdenum, and can therefore be used under milder conditions of temperature and pressure that are economically desirable and tend to avoid undesirable side reactions.

The catalyst may be prepared in situ or added to the reaction mixture after prior preparation and isolation. Commercial catalysts are available. The catalyst may be prepared and used as a bulk powder or supported on a suitable carrier, such as carbon or alumina. The catalyst may be prepared and used as a powder for liquid phase slurry and for vapor phase fluidized reactions, or as a pellet or granule for liquid or vapor phase fixed bed operations.

The reactions may be carried out in either batch or continuous systems, with either tank or pipe-line type reactors, in the liquid phase with either slurry or fixed bed catalysts, or in the vapor phase with either fluidized or fixed bed catalysts, operating in a manner well known to those skilled in the art.

Examples of p-nitrosoarylamines useful in the invention include: 4-nitrosoaniline 4-nitroso-N-methylaniline 4-nitroso-N-ethylaniline 4-nitroso-N-propylaniline 4-nitroso-N-isopropylaniline 4-nitroso-N-butylaniline 4-nitroso-N-sec-butylaniline 4-nitroso-N-isoamylaniline 4-nitroso-N-dodecylaniline 4-nitroso-N-octadecylaniline 4-nitroso-N-benzylaniline 4-nitroso-N-(alpha-methylbenzyl)aniline 4-nitroso-N-phenethylaniline 4-nitroso-N-(3-phenylpropyl)aniline 4-nitroso-N-( 1 -ethyl-4-methylpentyl)aniline 4-nitroso-N-( 1 ,4-dimethyipentyl)aniline 4-nitroso-N-cyclohexylanil ine 4-nitroso-N-3,3,5-trimethylcyclohexylaniline 4-nitroso-N-cyclooctylaniline 4-nitroso-N-ethyl-2-toluidine 4-nitroso-N-methyl-3-toluidine 4-nitroso-N-benzyl-2-toluidine 4-nitroso-N-benzyl-3-toluidine 4-nitroso-N-(3-phenylpropyl)-3-toluidine 4-nitroso-N-ethyl-2,6-diethylaniline 4-nitroso-N-methyl-3,5-dimethylaniline 4-nitrosodiphenylamine 4-nitroso-4'-t-butyldiphenylamine and 4-nitroso-3 -methyldiphenylamine The ketones used for the reductive alkylation may be of any type, dialkyl, alkylaryl, and diaryl, and the alkyl groups may be cyclic as in cyclohexanone and substituted cyclohexanones. In the reductive alkylation, the molar ratio of ketone/nitroso compound is suitably at least 1/1 and generally may be from 1/1 to 20/1. Usually a ratio of 1/1 to 3/1 is sufficient although a ratio range of from 1/1 to 1.1/1 is also suitable. The excess ketone serves primarily as a solvent medium, and ordinarily in plant operations the ketone/nitroso ratio is kept relatively low, whereas when carrying out the process of this invention on a laboratory type scale higher ketone/nitroso molar ratios may be in order.

Examples of useful ketones are acetone, 2-butanone, di-n-hexyl ketone, 2,6-di methyl-3-heptanone, 2,6-dimethyl-4-heptanone, 3,5 -dimethyl-4-heptanone, 2,4-dimethyl 3 -pentanone, 4,4-dimethyl-2-pentanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexa none, 3-hexanone, mesityl oxide, 4-methyl-3-heptanone, S-methyl-2-hexanone, 3-methyl 2-pentanone, 10-nonadecanone, 2-nonanone, 5-nonanone, 2-octanone, 3-octanone, 4 octanone, 2-pentanone, 3-pentanone, 2-undecanone, 6-undecanone, 2-dodecanone, iso phorone, methyl cyclopentyl ketone, ethyl cyclohexyl ketone, benzophenone, 4-methoxy benzophenone, 2-methylbenzophenone, 4-methylbenzophenone, 2,4,5 -trimethoxybenzo- phenone, 2,4,6-trimethoxybenzophenone, acetophenone, 2-chloroacetophenone, 4-chloro acetophenone, 2-methoxyacetophenone, 3-methoxyacetophenone, 4-methoxyaceto phenone, 2-methylacetophenone, 3-methylacetophenone, 4-methylacetophenone, cyclo hexanone, cyclopentanone, 3-methylcyclohexanone and methylnaphtyl ketone.

The hydrogenation process is usually carried out in the presence of an inert organic solvent, said solvent being present in an amount effective to maintain the nitroso com pound at least partially in solution if the nitroso compound is a solid at the desired pro cess temperature. Generally it is sufficient to employ a volume of the solvent .2 to 10 times greater than the volume of the nitroso compound. If a reductive alkylation is carried out, a solvent may be present in addition to an excess of the ketone. Such solvents include, for example, aliphatic or cycloaliphatic alcohols, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, isobutyl and n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl alcohol, tert-amyl alcohol, n-hexyl alcohol, cyclohexanol, n-octyl alcohol, 2-ethylhexanol, n-decyl alcohol, ndodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol, ethylene glycol, propylene glycol and glycerol; ethers, such as diethyl ether, di-n-propyl ether, diisopropyl ether, methyl n-butyl ether, ethyl n-butyl ether, di-n-butyl ether, di-n-amyl ether, diisoamyl ether, di-n-hexyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,3-dioxolane, 1,4-dioxane and tetrahydrofuran; alcoholethers, such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, 2-butoxyethanol and tetrahydrofurfurfyl alcohol; esters, such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, methyl amyl acetate, 2-ethylhexyl acetate and diethyl succinate; nitriles, such as acetonitrile, propionitrile and butyronitrile; amides, such as formamide, acetamide, propionamide, N,N-diethylformamide, N,N-dimethylformamide, N,N-dimethylacetamide and N,Ndiethylacetamide and hydrocarbons, such n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclohexane, n-heptane, 3-methylhexane, noctane, 2,2,4-trimethylpentane, 2,3,4-trimethylpentane, n-decane, decalin, benzene, toluene and xylenes.

As mentioned above, the invention provides a process for preparing a compound having the structural formula

where R is alkyl it may be primary, secondary or tertiary, linear or branched and preferably has from 1 to 12 carbon atoms. Where R is cycloalkyl, it preferably has from 5 to 6 carbon atoms. Where R is alkaryl, it is frequently alkylphenyl and preferably has from 7 to 8 carbon atoms. Where R is aralkyl having from 7 to 9 carbon atoms, it is preferably benzyl.

Where R1 is a group having the formula - CHR2R', RZ and R3 may be linear or branched alkyl groups, (preferably having from 1 to 5 carbon atoms). Preferred cycloalkyl groups have from 5 to 6 carbon atoms, and aryl is preferably phenyl. In the case where R2 and R3 combined represent polymethylene having 4 or 5 carbon atoms and attached to the same carbon atom, the resultant group may be, for instance, cyclopentyl or cyclohexyl.

From the foregoing it will be apparent that the process of the invention includes two embodiments: I) Hydrogenation of the nitroso compounds of the formula stated to the corresponding amines, II) Reductive alkylation of the nitroso compounds to N-substituted anilines.

In particular, the first embodimen: proceeds according to the following scheme:

whereas the second embodiment may be written as follows:

(Il) The process temperatures vary somewhat depending on whether hydrogenation (I) or reductive alkylation (II) is desired, i.e.: Temperature, C I II broad 5250 50--250 preferred 5-100 100--220 most preferred 30-100 125-200 However, for all practical purposes steps I and II may be combined, i.e. the reductive alkylation may be started at relatively low temperature (ca. 20"C) and eventually the temperature may be raised to a level more effective for sustaining reductive alkylation (ca. 1SO"C).

The conditions may be varied to provide an optimum economic combination of temperature, pressure, catalyst level, and cycle time for any given starting material and catalyst.

In one preferred aspect, the invention is directed to a hydrogenation process as described (in which said ketone is absent) carried out in the presence of a solvent.

In another preferred aspect, the invention is directed to a reductive alkylation process as described (in which said ketone is present) wherein, in the formulas given above: R is hydrogen, alkyl having 1 to 12 carbon atoms, cycloalkyl having 5 or 6 carbon atoms, alkaryl having 7 or 8 carbon atoms, benzyl or phenyl.

R' is a group having the formula -CHR2R wherein R2 and R3 are the same or different and are alkyl having 1 to 5 carbon atoms, cycloalkyl having 5 or 6 carbon atoms, or phenyl, or R2 and R' combined represent pentamethylene, the pressure being from 700 to 20,000 kPa, the temperature being from 50 to 250"C, and the molar ratio of said ketone to said p-nitrosoarylamine compound being from 1/1 to 20/1.

The following Examples will serve to illustrate the practice of the invention in more detail.

Example 1.

Hydrogenation of 4-nitrosodiphenylamine to N-phenyl-p-phenylenediamine.

A. In a 265-ml Magne Dash (trademark) autoclave were placed 19.8 g (0.10 mole) of 4-nitrosodiphenylamine, 145 ml of 2-propanol, and 1.65 g of S 5 platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen was added to a pressure of 400 psig. The reaction mixture was heated with agitation for 0.7 hr. at 25-35 (all temperatures are expressed herein in C) and 300-500 psig, at which point gas absorption abruptly stopped at about 102% of theory.

The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite (trademark) filter-aid to remove the catalyst. The filtrate was shown by gas-liquid phase chromatography (glpc) and infrared analyses to contain N-phenyl-p-phenylenediamine.

B. Example IA was repeated using benzene instead of 2-propanol as solvent. Gas absorption stopped at about the theoretical value after 1.3 hr at 2540 and 500-800 psig. N-phenyl-p-phenylenediamine was identified by glpc and infrared analyses.

C. In a 265-ml Magne Dash autoclave were placed 59.5 g (0.30 mole) of 4-nitrosodiphenylamine, 110 ml of benzene, and 1.65 g of 5% platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen heated without agiration was added to a pressure of 600 psig. The reaction mixture was heated without agitation to about 90 . Agitation was then sarted, and the pressure was maintained at 500-800 psig. The temperature rose to about 1500 in less than 0.2 hr., when the gas absorption abruptly stopped at about the theoretical value. The reaction product was treated and N-phenyl-p-phenylenediamine identified as in 1A.

Example 2.

Reductive alkylation of 4-nitrosodiphenylamine with acetone.

A. In a 265-ml Magne Dash autoclave were placed 19.8 g (0.10 mole) of 4-nitrosodiphenylamine, 145 ml (2.0 mole) of acetone, and 1.65 g of 5% platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen was added to a pressure of 400 psig. The reaction mixture was heated with agitation for 10.5 hr. at 2030 and 300-500 psig. A relatively rapid gas absorp tion of about 0.2 mole was over in about 1 hr., and was followed by a slow absorption of about 0.1 mole. The autoclave was depressurized, and the reaction product was removed and filtered through Celite filter-aid to remove the catalyst. After removal of the unreacted ketone on a rotary evaporator, a residue was obtained that melted at 7377" and was shown by infrared analysis to contain 19.7 g (87 yicld) of N-isopropyl-N' phenyl-p-phenylene-diamine.

B. In a 600-ml Magne Dash autoclave were placed 59.4 g (0.30 mole) of 4-nitrosodiphenylamine, 175 ml (2.4 mole) of acetone, and 2.5 g of platinum oxide. The autoclave was sealed, purged first with nitrogen and then with hydrogen. Hydrogen sulfide was added to a pressure of 50 psig, followed by the addition of hydrogen to a pressure of 1300 psig. The reaction mixture was heated with agitation at 1200--1400 psig for 0.5 hr. at 90 , followed by 1 hr. at 110 . There was little or no gas absorption in the last 0.3 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. The excess acetone was removed by distillation under reduced pressure. The residue was shown by colorimetric analysis to contain 1.5 g (3% yield) of N-phenyl-p-phenylenediamine, and N isopropyl-N'-phenyl-p-phenylenediamine was identified by infrared analysis.

C. Example 2A was repeated using 1.65 g of a 5% rhodium sulfide on carbon catalyst. The reaction mixture was heated with agitation for 12 hr. at 75" and 300-500 psig. Infrared analysis of the residue product after removal of catalyst and of solvent indicated the presence of 18.5 g (82% yield) of N-isopropyl-N'-phenyl-p-phenylenediamine.

D. Example 2A was repeated using 1.65 g of a 5% ruthenium sulfide on carbon catalyst. The reaction mixture was heated with agitation for 5.5 hr. at 175 and 400 600 psig. N-isopropyl-N'-phenyl-p-phenylenediamine was identified in the reaction product by infrared analysis.

Example 3.

Reductive alkylation of 4-nitrosodiphenylamine with cyclohexanone.

In a 265-ml Magne Dash autoclave were placed 19.8 g (0.10 mole) of 4-nitrosodiphenylamine, 145 ml (1.4 mole) of cyclohexanone, and 1.65 g of 5% platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen was added to a pressure of 400 psig. The reaction mixture was heated with agitation at 300-500 psig for 1.3 hr. at 2530 , followed by 5.8 hr. at 75". The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. After removal of the solvent on a rotary evaporator, a residue was obtained that was shown by infrared analysis to contain 22 g (83% yield) of N-cyclohexyl-N'-phenyl-p-phenylenediamine.

Example 4.

Reductive alkylation of 4-nitrosodiphenylamine with methyl isobutyl ketone.

In a 265-ml Magne Dash autoclave were placed 19.8 g (0.10 mole) of 4-nitrosodiphenylamine, 145 ml (1.2 mole) of methyl isobutyl ketone, and 1.65 g of 5% platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen was added to a pressure of 400 psig. The reaction mixture was heated with agitation at 300-500 psig for 1.8 hr. at 2030 , 0.7 hr. at 3090 and 1 hr. at 9095 , with no gas absorption in the last 0.5 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filteraid to remove the catalyst. After removal of the solvent on a rotary evaporator, a residue was obtained that was shown by relative area percent glpe analysis to contain about 21.5 g of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine.

Example 5.

Reductive alkylation of 2-isopropyl-4'-nitrosodiphenylamine with acetone.

In a 2-liter Magne Drive (trademark) autoclave were placed 370 g (1.52 mole) of 2-isopropyl-4'-nitrosodiphenylamine, 475 ml (6.5 mole) of acetone, and 4.0 g of 5% platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen was added to a pressure of 700 psig. The reaction mixture was heated with agitation at 500--800 psig for 2.5 hr. at 35-85', followed by 3 hr. at 85-90", with little or no gas absorption in the last 0.8 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. The filtrate was distilled, and a fraction boiling from 156 at 0.3 mm to 160 at 0.15 mm was recrystallized from hexane to yield 305 g (75 (;O yield) of N-isopropyl-N'-(2-isopropylphenyl)-p-phenylenediamine, melting at 56-57'. Another 27.5 g (7/c, yield) was recovered from the hexane mother liquors.

Material purified by a second distillation followed by recrystallization from hexane melted at 57-58'.

Example 6.

Reductive alkylation of 2-sec-butyl-4'-nitrosodiphenylamine with acetone.

In a 1-liter Magne Drive autoclave were placed 76 g (0.30 mole) of 2-sec-butyl-4'nitrosodiphenylamine, 330 ml (4.5 mole) of acetone, and 4.0 g of 5 platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 800 pslg. The reaction mixture was heated with agitation at 400-800 psig for 0.8 hr. at 25-70', followed by 3 hr. at 70--75", with little or no gas absorption in the last 1 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. Distillation of the filtrate yielded 77 g (91 Z:, yield) boiling from 180 at 1.5 mm to 174" at 0.9 mm. After two recrystallization from hexane, this N-isopropyl-N'-(2- sec-butyl- phenyl)-p-phenylenediamine melted at 32.5-33'.

Example 7.

Reductive alkylation of 2,2'-diisopropyl-4-nitrosodiphenylamine with acetone.

In a 1-liter Magne Drive autoclave were placed 100 g (0.354 mole) of 2,2'-diisopropyl-4-nitrosodiphenylamine, 300 ml (4.1 mole) of acetone, and 4.0 g of 5% platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 800 psig. The reaction mixture was heated with agitation at 400-800 psig for 0.5 hr. at 2585 , followed by 2.5 hr. at 85-90', with little or no gas absorption in the last 1.5 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. Distillation of the filtrate yielded 101 g (92% yield) boiling at 169-171 at 0.6--0.8 mm. After two recrystallizations of this fraction from hexane, the 2,2'-diisopropyl-4-isopropylaminodiphenylamine melted at 887'.

Example 8.

Conversion of aniline to N-(1,3- dimethylbutyl)- N' -(l-ethyl- 4-methylpentyl) p - phenylenediamine.

A. In a 2-liter Magne Drive autoclave were placed 279.4 g (3.00 mole) of aniline, 424 g (3.30 mole) of ethyl isoamyl ketone and 8.0 g of 5% platinum sulfide on carbon.

The autoclave was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 700 psig. The reaction mixture was heated with agitation at 500--800 psig for 6.3 hr. at 100--105", followed by 5.8 hr. at 125130 . The auto dave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. The filtrate was distilled. A fraction of 114 g boiling at 7488 at 0.5 mm consisted of N-(1-ethyl-4-methylpentyl) aniline and a small amount of ketone, and was discarded. A second fraction of 455 g boiled at 89103 at 0.5 mm and was shown by glpc to consist of N-(1-ethyl-4-methylpentyl) aniline of about 99% purity.

B. A mixture of 205 g (1.0 mole) of N-(1-ethyl-4-methylpentyl) aniline, 300 ml of toluene, and a solution of 76 g (1.1 mole) of sodlum nitrite in 150 ml of water was cooled to 15 in a 2-liter, 3-necked flask equipped with a stirrer, thermometer, and addition funnel. To the stirred mixture was added dropwise 184 ml of 6N sulfuric acid over a period of 0.8 hr. at about 15 . Stirring was continued for an additional 2 hr. The mixture was transferred to a separatory funnel, and the toluene solution separated from the aqueous phase and washed several times with water until neutral.

C. To the above toluene solution of N-nitroso-N-(1-ethyl-4-methylpentyl) aniline in a 2-liter, 3-necked flask equipped with a stirrer, thermometer and addition funnel, was added a solution of 73 g (2.0 mole) of dry hydrogen chloride in 124 ml of methanol at 2530 over a period of 1 hr. The reaction mixture was stirred for an additional 3.5 hr. Then 330 ml of 6N sodium hydroxide was slowly added while stirring and cooling. The reaction mixture was transferred to a separatory funnel, the aqueous layer separated, and the toluene layer washed well with water.

D. In a 2-liter Magne Drive autoclave were placed the above toluene solution (500 ml) of 4-nitroso-N-(1-ethyl-4-methylpentyl) aniline, 150 ml (1.2 mole) of methyl isobutyl ketone, and 7.0 g of 5% platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 400 psig. The autoclave was agitated for about 0.1 hr. at 30--50" and 260-400 psig, followed by about 0.1 hr. at 50--95" and 300--600 psig. The reaction mixture was then heated with agitation at 120--125" and 500--600 psig for 5.5 hr., with little or no gas absorption in the last 4 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. The filtrate was distilled and 274 g of a fraction boiling at 155164 at 0.55 mm was collected. Relative area percent glpc analysis indicated that about 95% of this fraction consisted of N-(1,3-dimethylbutyl)-N'-(1-ethyl-4-methylpentyl)-p-phenylenediamine.

Example 9.

Reductive alkylation of 4-nitroso-N-cyclohexylaniline with ethyl isoamyl ketone.

In a 2-liter Magne Drive autoclave were placed 102 g (0.50 mole) of 4-nitroso-Ncyclohexylaniline, 116 ml (0.75 mole) of ethyl isoamyl ketone, and 6.5 g of 5% platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 400 psig. The autoclave was agitated for about 0.1 hr. at 3055 and 200-500 psig, and then heated with agitation for 3.5 hr.

at about 200 and 600-700 psig. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. The filtrate was distilled and yielded a fraction boiling at 184185 at 0.8 mm that was shown by relative area percent glpc analysis to contain about 95 g of N-cyclo hexyl-N'-(1-ethyl-4-methylpentyl)-p-phenylenediamine.

Example 10.

Reductive alkylation of 4-nitroso-N-(1,4-dimethylpentyl)aniline with methyl isoamyl ketone.

A. In a 2-liter Magne Drive autoclave were placed 500 ml of a toluene solution containing 220 g (1.0 mole) of 4-nitroso-N-(1,4-dimethylpentyl)aniline and 136 g (1.19 mole) of methyl isoamyl ketone, and 7.0 g of 5% platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 400 psig. The reaction mixture was heated with agitation for 0.8 hr. at 30--140" and 200-500 psig, followed by 5 hr. at 140 and 500-600 psig, with little or no gas absorption in the last 4.3 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. The filtrate was distilled and yielded 277 g of N,N'-bis(1,4-dimethylpentyl)-p- phenylenediamine boiling mostly at 164169 at 0.9 mm, and shown by relative area percent glpc analysis to be about 98% pure.

B. In a 2-liter Magn cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. After removal of the solvent on a rotary evaporator at reduced pressure, 139 g of a solid residue, m.p. 436 , was obtained that was shown by relative area percent glpc analysis to contain about 95 < , N,N'-diisopropyl-p phenylenediamille.

Example 12.

Reductive alkylation of 4-nitroso-N-sec-butylaniline with methyl ethyl ketone.

In a 2-liter Magne Drive autoclave were placed 655 ml of a toluene solution containing 4-nitroso-N-sec-butylaniline obtained from 0.39 mole of N-sec-butylaniline, 34 g (0.47 mole) of methyl ethyl ketone, and 5.0 g of 5 CXó platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 700 psig. The reaction mixture was heated with agitation at 500-700 psig for 0.5 hr. at 34150 , followed by 1.3 hr. at 150 , with little or no gas absorption in the last 0.8 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. After removal of the solvent in a rotary evaporator at reduced pressure, 82 g of a residue was obtained that was shown by relative area percent glpc analysis to contain about 99% N,N'-di sec-butyl-p-phenylenediamine.

The following Example illustrates the advantage of a platinum sulfide over a platinum catalyst for the reductive alkylation of a p-nitrosoarylamine, namely 4-nitrosodiphenylamine, to the corresponding p-alkylaminoarylamine, namely N-(1,3-dimethylbutyl)-N '-phenyl-p-phenylenediamine.

Example 13.

A. In a 1-liter Magne Drive autoclave were placed 19.8 g (0.10 mole) of 4-nitrosodiphenylamine, 20 ml (ca. 0.16 mole) of methyl isobutyl ketone, 220 ml of toluene, and 0.50 g of S )\ platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen was added to a pressure of 500 psig.

After the initial low temperature reaction, the reaction mixture was heated with agitation for 3.9 hr. at 180185^ and 620-685 psig, with little or no gas absorption in the last 0.7 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. The filtrate was concentrated on a hot plate and then taken to dryness on a rotary evaporator at reduced pressure. The residue consisted of 25.3 g (94ç/Ó yield of crude product) of N-(1,3-dimethylbutyl)-N'phenyl-p-phenylenediamine that was shown by relative area percent glpc analysis to be about 96% pure and to contain about 3% of N-phenyl-p-phenylenediamine.

B. In a 600-ml Magne Drive autoclave were placed 19.8 g (0.10 mole) of 4-nitrosodiphenylamine, 20 ml (ca. 0.16 mole) of methyl isobutyl ketone, 220 ml of toluene, and 0.50 g of 5';', platinum on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen was added to a pressure of 700 psig. After an initial rapid reaction at low temperature, the reaction mixture was heated with agitation for 4.0 hr. at about 180 and 640--685 psig, with little or no gas absorption in the last 1.0 hr. Treatment of the reaction product as in part A gave 21.0 g of a residue that was shown by relative area percent glpc analysis to contain about 45% of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and about 50% of N-phenyl-p-phenylenediamine.

Similar results are obtained when using palladium, osmium and iridium sulfides as catalysts.

WHAT WE CLAIM IS:- 1. A process for preparing a compound having the structural formula

wherein: X is alkyl having up to 3 carbon atoms and n is an integer of from 1 to 4, R is a hydrogen, alkyl having 1 to 18 carbon atoms, cycloalkyl having 5 to 8 carbon atoms, aralkyl having 7 to 9 carbon atoms, alkaryl having 7 to 10 carbon atoms or phenyl;

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. After removal of the solvent on a rotary evaporator at reduced pressure, 139 g of a solid residue, m.p. 436 , was obtained that was shown by relative area percent glpc analysis to contain about 95 < , N,N'-diisopropyl-p phenylenediamille. Example 12. Reductive alkylation of 4-nitroso-N-sec-butylaniline with methyl ethyl ketone. In a 2-liter Magne Drive autoclave were placed 655 ml of a toluene solution containing 4-nitroso-N-sec-butylaniline obtained from 0.39 mole of N-sec-butylaniline, 34 g (0.47 mole) of methyl ethyl ketone, and 5.0 g of 5 CXó platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 700 psig. The reaction mixture was heated with agitation at 500-700 psig for 0.5 hr. at 34150 , followed by 1.3 hr. at 150 , with little or no gas absorption in the last 0.8 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. After removal of the solvent in a rotary evaporator at reduced pressure, 82 g of a residue was obtained that was shown by relative area percent glpc analysis to contain about 99% N,N'-di sec-butyl-p-phenylenediamine. The following Example illustrates the advantage of a platinum sulfide over a platinum catalyst for the reductive alkylation of a p-nitrosoarylamine, namely 4-nitrosodiphenylamine, to the corresponding p-alkylaminoarylamine, namely N-(1,3-dimethylbutyl)-N '-phenyl-p-phenylenediamine. Example 13. A. In a 1-liter Magne Drive autoclave were placed 19.8 g (0.10 mole) of 4-nitrosodiphenylamine, 20 ml (ca. 0.16 mole) of methyl isobutyl ketone, 220 ml of toluene, and 0.50 g of S )\ platinum sulfide on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen was added to a pressure of 500 psig. After the initial low temperature reaction, the reaction mixture was heated with agitation for 3.9 hr. at 180185^ and 620-685 psig, with little or no gas absorption in the last 0.7 hr. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter-aid to remove the catalyst. The filtrate was concentrated on a hot plate and then taken to dryness on a rotary evaporator at reduced pressure. The residue consisted of 25.3 g (94ç/Ó yield of crude product) of N-(1,3-dimethylbutyl)-N'phenyl-p-phenylenediamine that was shown by relative area percent glpc analysis to be about 96% pure and to contain about 3% of N-phenyl-p-phenylenediamine. B. In a 600-ml Magne Drive autoclave were placed 19.8 g (0.10 mole) of 4-nitrosodiphenylamine, 20 ml (ca. 0.16 mole) of methyl isobutyl ketone, 220 ml of toluene, and 0.50 g of 5';', platinum on carbon. The autoclave was sealed, purged first with nitrogen and then with hydrogen, and hydrogen was added to a pressure of 700 psig. After an initial rapid reaction at low temperature, the reaction mixture was heated with agitation for 4.0 hr. at about 180 and 640--685 psig, with little or no gas absorption in the last 1.0 hr. Treatment of the reaction product as in part A gave 21.0 g of a residue that was shown by relative area percent glpc analysis to contain about 45% of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and about 50% of N-phenyl-p-phenylenediamine. Similar results are obtained when using palladium, osmium and iridium sulfides as catalysts. WHAT WE CLAIM IS:-

1. A process for preparing a compound having the structural formula

wherein: X is alkyl having up to 3 carbon atoms and n is an integer of from 1 to 4, R is a hydrogen, alkyl having 1 to 18 carbon atoms, cycloalkyl having 5 to 8 carbon atoms, aralkyl having 7 to 9 carbon atoms, alkaryl having 7 to 10 carbon atoms or phenyl;

R1 is hydrogen or a group having the formula - CHR2Ra wherein R2 and R3 are the same or different and are alkyl having 1 to 10 carbon atoms, cycloalkyl having 5 to 8 carbon atoms, aryl having 6 to 10 carbon atoms, or R2 and R3 combined represent polymethylene having 4 or 5 carbon atoms and attached to the same carbon atom, by contacting a p-nitrosoarylamine compound of the structural formula

wherein R, X and n have the meanings above, with hydrogen in the absence or presence of a ketone of the formula O=CR2R3 wherein R2 and R3 are as defined above, under a pressure of from 70 to 35,000 kPa, at a temperature of from 5" to 250"C, in the presence of a catalytically effective amount of platinum metal sulfide, the reaction temperature in the case where the reaction is carried out in the presence of a ketone being at least 50"C during at least the latter part of the reaction.

2. A process according to claim 1 wherein the said ketone is absent and the process is carried out in the presence of a solvent.

3. A process according to claim 1 wherein the said ketone is present, R is hydrogen, alkyl having 1 to 12 carbon atoms, cycloalkyl having 5 or 6 carbon atoms, alkaryl having 7 or 8 carbon atoms, benzyl or phenyl, R' is a group having the formula - CHR2R wherein R2 and R3 are the same or different and are alkyl having 1 to 5 carbon atoms, cycloalkyl having 5 or 6 carbon atoms, or phenyl, or R2 and R3 combined represent pentamethylene, the pressure is from 700 to 20,000 kPa, the temperature is from 50 to 250"C., and the molar ratio of said ketone to said p-nitrosoarylamine compound is from 1/1 to 20/1.

4. A process according to claim 1 or claim 3 wherein the said ketone is present and is acetone, cyclohexanone, methyl isobutyl ketone, ethyl isoamyl ketone, methyl isoamyl ketone, or methyl ethyl ketone.

5. A process according to any of the preceding claims wherein the said p-nitrosoarylamine is 4-nitrosodiphenylamine, 2-isopropyl-4'-nitrosophenylamine, 2-sec-butyl-4'nitrosodiphenylamine, 4-nitroso-N-(1-ethyl-4-mehylpentyl)-aniline, 4-nitroso-N-cyclohexylaniline, 4-nitroso-N-( 1,4-dimethylpentyl)-aniline, 4-nitroso-N-isopropylaniline, or 4-nitroso-N-sec-butyl-aniline .

6. A process according to claim 1 and substantially as herein described.

7. A process according to claim 1 and substantially as described in any of the Examples.

8. A compound whenever made by a process according to any of the preceding claims.