3,847,990 United States Patent Office Patented Nov. 12, 1974 1 2 both by reacting corresponding phenols with isocyanates, 3,847,990 as described by McKinley in Ind. Eng. Chem. Anal. 16, PROCESS FOR THE PRODUCTION OF NTROD. PHENYL AMINEDERVATIVES 304 (1944), and by reacting chlorocarbonic acid esters Johannes Blahak, Cologne, Germany, assignor to Bayer and amines (S. Petersen, A. 562, 207 et seq. (1949)). In Aktiengesellschaft, Leverkusen, Germany 5 addition, decarboxylation can preferably be carried out No Drawing. Filed Sept. 26, 1972, Ser. No. 292,445 wtihout previous isolation of the urethanes by directly Claims priority, application Germany, Sept. 28, 1971, combining the nitrophenol and phenyl isocyanate com P 21. 48 223.5 ponents and subsequently heating them to a temperature Int, C. G07c87/60 in the range of from 100 to 250° C. in the presence of a U.S. C. 260-576 13 Claims 10 catalytic quantity of a strong base. Solvents which boil at temperatures of from 150 to 220 C. and which do not react with the isocyanates can be used as the ABSTRACT OF THE DISCLOSURE solvents but are not essential. Where the nitrophenols Object of the invention is a process for the production and isocyanates are directly combined, a quantitative ratio of nitrodiphenyl amine compounds by decarboxylating the 15 of isocyanate to nitrophenol of 0.5:1 to 5:1, but prefer corresponding urethanes in the presence of a catalyst at ably from 1:1 to 2:1, is applied. temperatures of from 100 to 250 C. either in the pres The urethanes used in accordance with the invention ence or in the absence of a solvent. Nitrodiphenyl amine can be obtained, for example, by reacting paranitro compounds are important intermediates for the synthesis phenol, orthonitrophenol, 2,4-dinitrophenol, 4-nitro-2- of anti-agers of the p-alkylaminodiphenyl amine type. chlorophenol, 4-nitro-3-chlorophenol, 3-chloro-2-nitro 20 phenol, 4-chloro-2-nitrophenol, 5-chloro-2-nitrophenol, German Auslegeschrift No. 1,030,834 describes a proc 6-chloro-2-nitrophenol, 2,6-dichloro-4-nitrophenol, 4-ni ess for the production of 4-nitrodiphenyl amine by react tro orthocresol, 4-nitrometa cresol, 6-nitro ortho cresol, ing paranitrochlorobenzene with aniline in the presence 6-nitrometa cresol, 4-nitro-2-isopropyl phenol, 4-nitro-2- of a molar quantity of potassium carbonate as a binding 25 isobutyl phenol, 4-nitro-2-cyclohexyl phenol, with the fol agent for the hydrochloric acid liberated and a copper lowing isocyanates: phenyl isocyanate, metamethylphenyl salt as a catalyst. In order to obtain commercially de isocyanate, paramethylphenyl isocyanate, metaisobutyl sirable yields, the water formed during neutralisation also phenyl isocyanate, meta-2-ethyl hexylphenyl isocyanate, has to be removed. German Auslegeschrift No. 1,056,619 metacyclohexyl phenyl isocyanate, metachlorophenyl iso discloses the use of acylated anilines as starting compo 30 cyanate, parachlorophenyl isocyanate, metanitrophenyl nents. A molar quantity of an acid-binding agent is also isocyanate and paranitrophenyl isocyanate. added in this process, always resulting in the accumula Where the urethanes according to the invention are tion of relatively large quantities of salt which have to be synthesised from chlorocarbonic acid esters and aniline removed during working up. derivatives, the following compounds for example are 35 reacted: paranitrophenyl chlorocarbonic acid ester, or The present invention relates to a chemically unique thonitrophenyl chlorocarbonic acid ester, 2,4-dinitro process for the production of a nitrodiphenyl amine phenyl chlorocarbonic acid ester, 4-nitro-2-chlorophenyl derivative corresponding to the general formula: chlorocarbonic acid ester, 4-nitro-3-chlorophenyl chloro carbonic acid ester, 3-chloro-2-nitrophenyl chlorocarbonic 40 acid ester, 4-chloro-2-nitrophenyl chlorocarbonic acid es ON ter, 5-chloro-2-nitrophenyl chlorocarbonic acid ester, 6 chloro-2-nitrophenyl chlorocarbonic acid ester, 2,6-di Y chloro-4-nitrophenyl chlorocarbonic acid ester, 4-nitro-2- methylphenyl chlorocarbonic acid ester, 4-nitro-3-methyl in which the symbols X can be the same or different 45 phenyl chlorocarbonic acid ester, 6-nitro-2-methylphenyl from each other and represents hydrogen, alkyl, isoalkyl chlorocarbonic acid ester, 6-nitro-3-methylphenyl chloro or cycloalkyl having up to 6 carbon atoms, halogen or carbonic acid ester, 4-nitro-2-isopropylphenyl chlorocar nitro groups, whilst Y represents hydrogen, alkyl, iso bonic acid ester, 4-nitro-2-diisobutylphenyl chlorocarbonic alkyl or cycloalkyl having up to 6 carbon atoms, wherein acid ester and 4-nitro-2-cyclohexylphenyl chlorocarbonic a urethane corresponding to the general formula: 50 acid ester. The following compounds are mentioned as examples of aniline derivatives: aniline, N-methylaniline, N-isopropyl aniline, N-cyclo hexyl aniline, 4-methyl aniline, N-ethyl-4-methyl ani in which X and Y are as just defined, is decarboxylated 55 line, N-isobutyl-3-cyclohexyl aniline, 3-chloroaniline, in the presence of a catalytic quantity of a strong base 4-chloroaniline, N-methyl-2-chloroaniline, N-ethyl-2- at a temperature in the range of from 100° C. to 250° C., chloroaniline, metanitraniline, paranitraniline, N-meth but preferably at a temperature in the range of from ylmetanitro aniline and N-isopropyl metanitro aniline. 150° C. to 220 C., either in the presence or in the ab sence of a solvent. The fact that nitrodiphenylamine de 60 Solvents which do not contain a Zerewitinoff-active rivatives can be prepared from nitrophenyl urethanes or hydrogen atom can be used as the solvents according to directly from the non-isolated reaction products of nitro the invention with boiling points in the range from 100 phenols and phenyl isocyanates is surprising because ure to 250° C., preferably from 150 to 220 C. In the classes thanes obtained in this way readily decompose into phe of substances listed in the following, polar members are nols and isocyanates, as described by S. Petersen A. 65 particularly favourable. 562,207 (1949). According to J. M. Lyons, R. H. Thom 1. Hydrocarbons and chlorinated hydrocarbons: n-nonane, son, Soc. 1950, 1971, acid phenols in particular, such as n-butyl cyclohexane, decahydronaphthalene, n-undec 2,4-dinitrophenol for example, "cannot under any circum ane, n-dodecane, n-hexyl cyclohexane, dipentene, 1 stances be reacted with phenyl isocyanate.” dodecene, isopropyl benzene, 1,3-diethyl benzene, in The urethanes which can be used for the decarboxylat 70 dene, n-butylbenzene, tetralin, chlorobenzene, 4-chloro ing reaction according to the invention can be obtained toluene, 1,2-dichlorobenzene, 2,4-dichlorotoluene, 1,2,4- 3,847,990 3 4 trichlorobenzene, 2-chloro-4-isopropyl-1-methyl ben water is removed by the brief application of a water-jet Zee, vacuum. Thereafter 500 ml. of nitrobenzene are added 2. Ethers such as anisol, cyclohexyl ethyl ether, diethyl and the resulting mixture is heated to reflux. 179 g. (1.5 ene glycol dimethyl ether, benzyl methyl ether, 4 mol) of phenyl isocyanate are then added, and refluxing methoxy toluene, parachloroanisol, di-n-hexyl ether. is continued for 8 hours. 23.7 litres of carbon dioxide 3. Ketones such as 2-heptanone, cyclohexanone, 2-propyl escape. The yield of 4-nitrodiphenyl amine melting at 130 cyclohexanone, phenyl-n-propyl ketone, 2-undecanone. 131° C. isolated after removal of the nitrobenzene by dis 4. Substituted acid amides such as N,N-dimethyl forma tillation and working up as in. Example 1, amounts to mide, N,N-diethyl formamide. 80.6% of the theoretical yield. 5. Esters such as ethylene glycol monomethyl ether ace O tate, di-n-propy carbonate, cyclohexyl acetate, diiso EXAMPLE 3 butyl carbonate, diethylene glycol monomethyl ether The procedure is as described in Example 1 except that acetate, diisoamyl carbonate. a molar ratio of phenyl isocyanate to paranitrophenol of 6. Substituted amines such as 2-ethyl pyridine, N,N-di 2:1 is used. In this case, the yield of 4-nitrodiphenyl methyl-2-methyl aniline, N,N-dimethyl aniline, N amine amounts to 83.5% of the theoretical yield. methyl-N-ethyl aniline, N,N-dimethyl-2-chloro aniline, EXAMPLE 4 N,N-diethyl aniline, quinoline. 7. Nitro compounds such as 1-nitrobutane, nitrocyclo The procedure is as described in Example 2 except that hexane, -nitroheptane, nitrobenzene, 2-nitrotoluene, 5.3 g. of sodium carbonate are used as catalyst. The yield 2,4-dimethyl-1-nitrobenzene. 20 of 4-nitrodiphenyl amine amounts to 72% of the theo 8. Nitriles such as N-capronitrile, benzonitrile, tolunitrile retical yield. and phenyl acetonitrile. EXAMPLE 5 Suitable catalysts include alkali salts of organic acids The procedure is as described in Example 1 except that for example lithium acetate, sodium acetate, potassium 4.1 g. of potassium carbonate are used as catalyst. The acetate, rubidium and caesium acetate, sodium formate, 25 yield of 4-nitrodiphenyl amine amounts to 75.5% of the potassium benzoate and potassium phthalate. Also alkali theoretical yield. metal carbonates, preferably sodium or potassium carbo EXAMPLE 6 nate and oxides and hydroxides of alkali metals, pref 92 g. of 2,4-dinitrophenol (0.5 mol), 5 g. of potassium erably sodium or potassium hydroxide. Nitrophenolates acetate and 250 ml. of nitrobenzene are brought to the and basic compounds which are able to convert the nitro 30 boil and 59.5 g. (0.5 mol) of phenyl isocyanate are added phenols into nitrophenolates are also suitable. Another dropwise at 210° C. After 6 hours, the gas meter in class of catalytically active substances include Lewis dicates that 12.8 litres of carbon dioxide have evolved. bases such as tertiary high-boiling amines and phosphines A sample is analysed by preparative thin-layer chro for example N-methyl-di-6-hydroxy diphenyl ether and matography (benzene-silica gel system). The yield of 2,4- tri-n-butyl phosphine.