# US 5,344,987 A · Process for preparing diphenylamines > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,344,987 A - Document ID: US5344987A - Status: Granted - Kind: A - Application number: 08/092,735 - Filed: 1993-07-16 - Granted: 1994-09-06 - Earliest claimed: 1992-07-23 - Assignees: Bayer Aktiengesellschaft - Inventors: Otto Immel; Gerhard Darsow; Hans-Josef Buysch - Web page: https://patentgrep.com/patent/US5344987A ## CPC - C07C 209/26: by reduction with hydrogen - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS ## Abstract Optionally substituted diphenylamines can be obtained by reacting optionally substituted anilines with optionally substituted cyclohexanones over a supported catalyst at 200.degree.-450.degree. C. and 0.1-20 bar, the supported catalyst containing one or more metals having a dehydrogenating action selected from the group Ru, Pd, Os, Ir, Pt, Fe, Co, Ni, Re, Mn, Cu, Ag, Cr and Ce. ## Claims ### Claim 1 A process for preparing a diphenylamine of the formula ##STR4## in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4 denote, independently of one another, hydrogen, C.sub.1 -C.sub.4 -alkyl or C.sub.1 -C.sub.4 -alkoxy, wherein an aniline of the formula ##STR5## is reacted with a cyclohexanone of the formula ##STR6## which may be present mixed with recycled reaction products, in the formulae the radicals R.sup.1 to R.sup.4 having the above meaning and aniline and cyclohexanone being present in a molar ratio of 1:4-6:1 over a supported catalyst containing 0.05-5% by weight, based on the total weight of the catalyst, of one or more metals having a dehydrogenating action, in the gaseous phase at 200.degree.-450.degree. C. and at 0.1-20 bar, and the metal(s) is/are selected from the group consisting of Ru, Pd, Os, Ir, Pt, Fe, Co, Ni, Re, Mn, Ce, Cu, Ag and Cr. ### Claim 2 (depends on 1) The process of claim 1, wherein the reaction is carried out at 200.degree.-400.degree. C. ### Claim 3 (depends on 1) The process of claim 1, wherein the reaction is carried out at 0.1-6 bar. ### Claim 4 (depends on 1) The process of claim 1, wherein the metal(s) is/are selected from the group consisting of Pd, Ir, Pt, Co, Ni, Re, Mn, Ce and Cr. ### Claim 5 (depends on 4) The process of claim 4, wherein Pt is used in combination with Pd, Ir, Ru, Os or Re. ### Claim 6 (depends on 1) The process of claim 1, wherein aniline and cyclohexanone are present in a molar ratio of 1:2-5:1. ### Claim 7 (depends on 1) The process of claim 1, wherein the supported catalyst contains 0.04-4% by weight, based on the total weight of the catalyst, of one or more of the metals. ### Claim 8 (depends on 7) The process of claim 7, wherein the supported catalyst contains 0.1-3% by weight, based on the total weight of the catalyst, of one or more of the metals. ### Claim 9 (depends on 1) The process of claim 1, wherein the support is aluminium oxide. ### Claim 10 (depends on 9) The process of claim 9, wherein the support is an aluminium oxide treated with manganese and chromium or cerium. ### Claim 11 (depends on 1) The process of claim 1, wherein the catalyst additionally contains 1-12% by weight, based on the total weight of the catalyst, of one or more alkali metal hydroxides and/or alkali metal sulphates, the hydroxides and sulphates in each case being present in an amount of at most 6% by weight. ### Claim 12 (depends on 1) The process of claim 1, wherein the cyclohexanone is replaced in an amount of 0-20 mol-% by the corresponding phenol. ### Claim 13 (depends on 5) The process of claim 5, wherein Pt is used in combination with Pd, Ir or Re. ### Claim 14 (depends on 13) The process of claim 13, wherein the proportion of Pt in the combination is 10-90% of the total weight of the noble metals and Re. ### Claim 15 (depends on 14) The process of claim 14, wherein the proportion of Pt in the combination is 15-80% of the total weight of the noble metals and Re. ### Claim 16 (depends on 15) The process of claim 15, wherein the proportion of Pt in the combination is 20-70% of the total weight of the noble metals and Re. ### Claim 17 (depends on 11) The process of claim 11, wherein the catalyst additionally contains 2-10% by weight, based on the total weight of the catalyst, of one or more alkali metal hydroxides and/or alkali metal sulphates, the hydroxides and sulphates in each case being present in an amount of at most 5% by weight. ### Claim 18 (depends on 10) The process of claim 10, wherein the support contains chromium and manganese together in an amount of about 0.05-8% by weight, based on the total weight of the catalyst, the weight ratio of chromium to manganese being 5:1-1:5. ### Claim 19 (depends on 10) The process of claim 10 wherein another rare earth element besides chromium or cerium is employed. ### Claim 20 (depends on 1) The process according to claim 1, wherein the substituents are H, C.sub.1 -C.sub.2 alkyl, or C.sub.1 -C.sub.2 -alkoxy.