Esterification, transesterification and ester hydrolysis - over solid titanium and silicon catalysts, pref. prepd. using polymeric pptn. aids

摘要

The parent patent describes an esterification method using a solid catalyst of SiO2 and TiO2 made by dissolving Si and Ti cpds. in an aq. medium to Si, Ti atom ratio 0.1-100, then adjusting pH to ppte. the Si-Ti component, drying and calcining. In this addition the following processes are carried out in the presence of such as catalyst: (a) esterification of a is not > 30 C carboxylic acid (Ie or its anhydride (excluding methacrylic acid) with a >30 C alcohol (IIef (b) transesterification of an ester (III) of (I) and (II) with a different (I) or (II); and (c) hydrolysis of (III). Pref. the aq. medium in which the catalyst is made contains a dispersed OH-contg. cpd. (IV) of mol. wt.>300, specifically starch; crystalline cellulose; methylcellulose polyethyleneglycol of mol. wt.>400 or polyvinyl alcohol of mol. wt. >500. The catalyst is more strongly acid than other solid catalysts so gives better yields and selectivities. It can be used at relatively low temp. and is much stronger and thermally more stable than conventional ion exchange catalysts. Addition of (IV) as pptn. aid increases activity further.