Patent ID: 6673975
Filing Date: 2004-01-06
Classification: C07C

Abstract:
A process for production of high purity 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane which comprises:(a) a reaction step wherein phenol is reacted with 3,3,5-trimethylcyclohexanone in a slurry containing phenol adduct crystals of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane in the presence of an acid catalyst; (b) a neutralization step wherein after the reaction, the resulting reaction mixture in the form of slurry is neutralized with an alkali to a pH of 5 to 8 while it is heated so that it is converted to a solution; (c) a primary crystallization and filtration step wherein the resulting solution is cooled and the resulting phenol adduct crystals of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane are collected by filtration; (d) a secondary crystallization and filtration step wherein the adduct crystals obtained in the primary crystallization and filtration step are heated in a crystallization solvent to dissolve the adduct crystals therein to prepare a solution and then the solution is cooled to crystallize the 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane out of the solution, followed by collecting the crystals by filtration; (e) a filtrate recycling step wherein at least a part of the secondary crystallization filtrate obtained in the secondary crystallization and filtration step is returned to the reaction step.