Hoechst Celanese Corporation

Celanese Gmbh

Jack Chosnek

Siegbert Rittner

Donna L Keene

Volker Hautzel

Jerry D Moore

George E Beck

Howard L Pilat

The present invention relates to a process for the purification of 4-acetoxystyrene from a crude product mixture comprising 4-acetoxystyrene and typically 5 or more contaminants in substantial amount. The crude product mixture is purified by melt crystallization by cooling the mixture to a temperature ranging from about +8.degree. C. to about -50.degree. C., whereby at least a first portion of the mixture is crystallized; removing the liquid remaining from contact with the crystallized first portion of the mixture; and, 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. Surprisingly, despite the large number of contaminants present, and use of the process to purify crude product mixtures containing as little as 50% by weight 4-acetoxystyrene, purities as high as 99.9% by weight have been obtained using multiple melt-crystallization steps of the process of the invention.

Process for the purification of 4-acetoxystyrene

Unreacted ethylene contained in a gaseous light ends stream derived from a process for the production of ethyl acrylate from ethylene and acrylic acid utilizing a sulfuric acid catalyst, is recovered by intimately contacting, under controlled conditions of temperature and pressure, the light ends stream with the liquid sulfuric acid catalyst make-up stream which is passed to the ethyl acrylate process. Upon contact of the light ends stream with the sulfuric acid make-up stream, the ethylene reacts with sulfuric acid to form ethyl hydrogen sulfate and diethyl sulfate, both of which remain in solution in the sulfuric acid which is then passed to the ethyl acrylate process as a source of make-up sulfuric acid. Sulfur dioxide contained in the vent-gas stream is not absorbed into the sulfuric acid, and therefore not recycled to the ethyl acrylate process.

Ethylene recovery from ethyl acrylate process

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Corpus Christi, TX, United States of America

Jack Chosnek