Models for Polyesterification Kinetics. III. Preliminary Studies on the Catalysis by Titanium(IV) Tetraalkoxides

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Abstract
The catalytic behavior of tetrabutoxytitanium in polyesterification between diacids and diols is studied with the help of two model reactions. One is the esterification between two mono-functional oligomers. The second is the reaction of 1-octa-decanol with octadecanoic acid either in octadecanyl octadecano-ate or in an excess of octadecanol. The behavior of this catalyst is complex since it depends on the reaction medium. A decrease of the vacuum and an increase of the acid concentration lead to poor catalytic efficiency which is also observed when the reaction is carried out in a hydrophilic medium such as polyoxy-ethylene. When the alcohol is in excess, the catalyst is much more efficient and experimental results fit with a zero overall order, although deviations are observed at the highest conversions. The existence of a complex between carboxyl groups and titanium is postulated.