# US 4,398,040 A · Process for producing trimellitic acid > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,398,040 A - Document ID: US4398040A - Status: Granted - Kind: A - Application number: 06/388,234 - Filed: 1982-06-14 - Granted: 1983-08-09 - Earliest claimed: 1979-11-28 - Assignees: Mitsubishi Gas Chemical Company, Inc. - Inventors: Takashi Suzuki; Koichi Kitahara; Susumu Naito; Tomoji Tsuji - Web page: https://patentgrep.com/patent/US4398040A ## CPC - C07C 51/265: having alkyl side chains which are oxidised to carboxyl groups - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS ## Abstract Trimellitic acid is produced in higher yield by liquid phase air oxidation of pseudocumene in acetic acid as a solvent in the presence of cobalt, manganese, and bromine as a catalyst, where the oxidation is carried out at two stages comprising a first stage of reaction at a temperature of 110.degree. to 170.degree. C. and a second stage of reaction at a temperature of 180.degree. to 240.degree. C. while maintaining a reaction pressure under a condition of the following formula throughout the reaction: 1.20 Psolv.ltoreq.P.ltoreq.2.20 Psolv wherein P represents a reaction pressure as absolute pressure and Psolv represents a total vapor pressure of acetic acid and water present in a reaction system at a given reaction temperature. ## Claims ### Claim 1 A process for producing trimellitic acid by liquid phase air oxidation of pseudocumene in an acetic acid reaction medium in the presence of a catalyst consisting of of catalytic forms of cobalt, manganese and bromine, which comprises conducting the reaction at two stages comprising a first stage of reaction at a temperature of 110.degree. to 170.degree. C. and a second stage of reaction at a temperature of 180.degree. to 240.degree. C., while maintaining a reaction pressure under a condition of the following formula throughout the reaction: 1.20Psolv.ltoreq.P.ltoreq.2.20Psolv wherein P represents a reaction pressure as absolute pressure and Psolv represents a total vapor pressure of acetic acid and water present in the reaction system at a given reaction temperature and the first stage of reaction at a lower temperature is continued until the amount of unreacted pseudocumene in the reaction solution becomes 10% or less on the basis of charged pseudocumene. ### Claim 2 (depends on 1) A process according to claim 1, wherein the cobalt and the manganese are used at total atomic concentration of 0.05 to 0.5% by weight on the basis of total of acetic acid and water present at the start of reaction. ### Claim 3 (depends on 1) A process according to claim 1, wherein an atomic ratio of the cobalt to the manganese is 1:4-4:1. ### Claim 4 (depends on 1) A process according to claim 1, wherein an atomic ratio of bromine to total of the cobalt and the manganese is 1.5-2.5:1. ### Claim 5 (depends on 1) A process according to claim 1, wherein 1.0 to 5.0 parts by weight of the acetic acid is used per part by weight of the pseudocumene at the initial charging at the first stage of reaction. ### Claim 6 (depends on 1) A process according to claim 1, wherein the first stage of reaction is carried out at 120.degree. to 150.degree. C. and the second stage of reaction is carried out at 195.degree. to 225.degree. C. ### Claim 7 (depends on 1) A process according to claim 1, wherein the reaction is carried out batchwise, semi-continuously or continuously. ### Claim 8 (depends on 1) A process according to claim 1, wherein the first stage of reaction is carried out batchwise, and the second stage of reaction is carried out continuously. ### Claim 9 (depends on 8) A process according to claim 8, wherein the first stage of batch-wise reaction is carried out at the lower temperature by keeping the temperature only by the heat of reaction, and then the reaction solution is continuously supplied to a tank of complete mixing type kept at the higher temperature at the second stage of continuous reaction, and product solution is continuously withdrawn from the tank. ### Claim 10 (depends on 1) A process according to claim 1, wherein the first stage and second stages of reaction are carried out batchwise. ### Claim 11 (depends on 10) A process according to claim 10, wherein the first stage of batch-wise reaction is started at 110.degree. to 130.degree. C., and the second stage of batchwise reaction is completed by elevating the reaction temperature to 220.degree. to 240.degree. C. in one and same reactor. ### Claim 12 (depends on 11) A process according to claim 11, wherein the first stage of batch-wise reaction is started at 110.degree. to 130.degree. C. and the second stage of batch-wise reaction is completed by elevating the temperature to 220.degree. to 240.degree. C. only by the heat of reaction by controlling a reaction pressure. ### Claim 13 (depends on 1) A process according to claim 1, wherein the second stage of reaction is continued until the total residual amount of dimethylbenzoic acid and methylphthalic acid in reaction solution becomes less than 10% by mole. ### Claim 14 (depends on 1) A process according to claim 1, wherein the air is injected into reaction system, so that the oxygen concentration of effluent gas from the reaction system is less than 8% by volume.