Method for controlling the temperature of an exothermic reaction and apparatus therefor

1,132,689. Adipic acid. VICKERS-ZIMMER PLANTING UND BAU VON INDUSTRIEANLAGEN A.G. 14 June, 1967 [14 June, 1966], No. 27475/67. Heading C2C. [Also in Division B1] Adipic acid is produced by the aqueous nitric acid oxidation of a mixture of cyclohexanol and cyclohexanone in the liquid phase at a temperature of less than 90‹ C. (optimum 75‹ C.) in which control and isothermal maintenance of the reaction is accomplished by continuously bleeding a portion of the reaction mixture from the reaction zone during the course of the reaction and indirectly contacting it with a boiling heat exchange medium, of boiling point not more than 100‹ C. as measured at a pressure of 760 mm. Hg, the temperature of the boiling heat exchange medium being controlled so that adipic acid does not crystallize from the bled portion of the reaction mixture and returning the bled portion to the reaction zone. The temperature of the boiling heat exchange medium, which may be, e.g. water, methanol, ethanol or isopropanol, may be controlled by adjusting the pressure thereon, in response to the temperature of the reaction mixture.