Conventionally, several methods have been known as methods for producing hydrogenated biphenol. In PTL 1, a portion of 4,4′-bicyclohexanol, which is the target hydrogenated bisphenol, is obtained using isopropanol as a solvent by hydrogenating bisphenol in the presence of 5% by weight of a Pd—C catalyst, filtering the reaction mixture, and removing the isopropanol from the filtrate by distillation under reduced pressure. At the same time, 4,4′-bicyclohexanol is also obtained by dissolving the crystals obtained during filtering in 500 mL of tetrahydrofuran when heating, then filtering and removing the tetrahydrofuran from the filtrate by distillation under reduced pressure. Further, the crystals from both of these processes are combined, suspended in n-hexane during heating, left to stand for 1 hour at 5 to 6° C., and the precipitated crystals are collected and dried under reduced pressure to obtain 4,4′-bicyclohexanol in a yield of 87%. Although the yield is sufficient, this method suffers from the drawback of complex operation.
On the other hand, PTLs 2 and 3 disclose a method in which, using one or two or more of glycol monoalkyl ethers having seven or less carbon atoms as a solvent, bisphenol is hydrogenated in the presence of a hydrogenation catalyst, the hydrogenation catalyst is then removed by filtering, and the solvent is removed from the filtrate by distillation under ordinary pressure or reduced pressure to produce hydrogenated biphenol. However, in this method, since a glycol monoalkyl ether having seven or less carbon atoms, which is a high-boiling point compound, is used as the solvent, the reaction system has to be put under reduced pressure and high temperature for the distillation, and thus as an industrial production method there is a problem of increased costs due to the large amount of energy required and the need to prepare high-performance equipment.
USPTO Backgrounds
USPTO Backgrounds