Vinyl acetate, from ethylidene diacetate

Owing to the tendency for ethylidene diacetate to be formed at elevated temperatures, care is taken for the rapid removal of vinyl acetate from the reaction vessel as soon as it is formed (Figure 14.1). 

In 1953 the Celanese Corporation of America introduced a route for the production of vinyl acetate from light petroleum gases. This involved the oxidation of butane which yields such products as acetic acid and acetone. Two derivatives of these products are acetic anhydride and acetaldehyde, which then react together to give ethylidene diacetate (Figure 14.2.)... 

Moiseev et al., who proposed initially that ethylidene diacetate was produced from addition of acetic acid to vinyl acetate, later showed this to be impossible from the result of reaction in CH3CO2D, preferring the following mechanism ... 

Starting from acetic anhydride, according to Equation 7, vinyl acetate can be obtained via ethylidene diacetate (22). 

This report describes a process to produce vinyl acetate with high selectivity from exclusively methanol, carbon monoxide, and hydrogen. The simplest scheme for this process involves esterifying acetic acid with methanol, converting the methyl acetate with syn gas directly to ethylidene diacetate and acetic acid, and finally, thermal elimination of acetic acid. Produced acetic acid is recycled. Each step proceeds in high conversion and selectivity. 

In some of the studies on the vinyl acetate synthesis from ethylene, high boiling products were reported (9, 10, 24, 25, 26). These included ethylidene diacetate (III), ethylene glycol monoacetate (IV) and ethylene glycol diacetate (V). Little attention has been given to the reactions by which these products are formed. No dioxygenated products have been reported previously when higher olefins have been used. 

Although vinyl alcohol itself is very unstable, its esters are stable. Klatte found in 1912 that vinyl acetate is formed as a by-product in the course of the manufacture of ethylidene diacetate from acetylene and acetic acid [1]. 

Expanding on the mercuric sulfate - sulfuric acid technology, it was known as early as 1912 that addition of a single equivalent of acetic acid to acetylene in the presence of mercuric sulfate and sulfuric acid resulted in the generation of vinyl acetate (a mere laboratory curiosity at the time) whereas addition of two or more equivalents of acetic acid provided ethylidene diacetate (1,1-diacetoxyethane, EDA). EDA was known to evolve acetaldehyde upon heating in the presence of acids. Upon complete removal of a mole of acetaldehyde, an equimolar amount of acetic anhydride could then be distilled from the residue. If one balances the sequential processes as shown in equations [3] through [6], one finds that the process is in stoichiometric balance for conversion of acetylene and air to cellulose acetate without by-products. (In practice there is some net acetic acid production since cellulose is never completely dry.)... 

From acetylene and acetic acid. The direct addition of acetylene to acetic acid occurs in the liquid or the gas phase. The liquid-phase reaction is carried out at 75-80°C with HgS04 catalyst. The vinyl acetate must be removed from the reaction mixture as quickly as possible otherwise too much ethylidene diacetate will result. However, the formation of the diester can be inhibited by the addition of HgS04/BF3/HF. This method has the commercial disadvantage that the residual deposits of poly(vinyl acetate), metallic mercury, etc., produced can only be removed by burning. The gas-phase method proceeds at 180°C with zinc acetate as catalyst. Only 5-10% of vinyl acetate can be formed per cycle, since otherwise large amounts of by-products occur. The theoretically possible total yield... 

Vinyl Acetate. An alternative and possibly more attractive use for ethylidene diacetate derived from methyl acetate is thermal cracking, and de-aceto lation, over a heterogeneous metal oxide catalyst, to give vinyl acetate with the coproduction of acetic acid ... 

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