4-acetoxystyrene:Uses and Purification

4-acetoxystyrene, which is typically obtained through the elimination of water from 4-acetoxyphenylmethyl carbinol, represents an important intermediate from which a variety of compounds are produced.

Uses

The 4-acetoxystyrene is used as a monomer for the manufacture of poly(4-acetoxystyrene) from which poly(4-hydroxystyrene) and various copolymers are produced. In addition, 4-acetoxystyrene can be used to prepare 4-hydroxystyrene from which numerous derivatives having medical applications are produced.

Polymers and copolymers of the kind described above are applied, for example, in the electronic industry as a binder in photoresists, in adhesives to improve their temperature stability, and in the surface treatment of metals, for the replacement of toxic chromate as a subcoating on the metals. The poly(4-hydroxystyrene) polymers and copolymers are also used as a UV absorber and flame-retardant additive that cannot be extracted from the plastic and as an additive in other polymers such as polyesters, nylon, polyurethanes, etc. in order to substantially improve their adhesive properties to glass and mineral fillers.

Process for the purification

A process for purifying 4-acetoxystyrene from a crude mixture comprising 4-acetoxystyrene by melt crystallization, the process comprising the steps of:

a) cooling a crude liquid mixture comprising 4-acetoxystyrene to a temperature ranging from about +8° C. to about -50° C., whereby a first portion of the mixture is crystallized;

b) removing at least substantial amounts of the liquid mixture remaining after step a); and

c) subsequently slowly heating the crystallized first portion while simultaneously removing liquid which forms due to the heating, whereby impurities contained in the liquid which forms are removed from the crystallized first portion, producing a crystallized second portion.

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