| 摘要 |
<p>A process that can be used as catalyst in esterification, transesterification or polycondensation is disclosed, which comprises a stable solution comprising (a) titanium in the form of a titanium α-hydroxycarboxylic acid or its salt, (b) a C1-C6 carboxylic acid, and (c) zinc in the form of a water-soluble zinc salt, and (d) water. Also disclosed is an esterification, transesterification or polycondensation process, which comprises contacting, in the presence of the solution process, an organic acid or its ester or its salt with an alcohol, optionally in the presence of a phosphorus compound, an organic or inorganic toning agent such as cobalt acetate, or combinations thereof. The process can also comprise combining aqueous solutions of a titanium α-hydroxycarboxylic acid or its salt and a zinc salt in an alcohol to produce an alcohol solution contacting the alcohol solution with a mixture comprising organic acid or its ester or its salt and a second alcohol, or comprise combining an aqueous solutions of a titanium α-hydroxycarboxylic acid or its salt and aqueous solution of a zinc salt with the mixture.</p> |
