Vinyl acetate

About: Vinyl acetate is a research topic. Over the lifetime, 15970 publications have been published within this topic receiving 162142 citations. The topic is also known as: Ethenyl acetate & Ethenyl ethanoate.

Controlled Release of Urea Encapsulated by Starch-g-poly(vinyl acetate)

Abstract: A new type of slow-release membrane-encapsulated urea fertilizer was prepared with starch-g-poly(vinyl acetate) (St-g-PVAc) as a biodegradable carrier material. By solution casting and washing rapidly with water the urea was individually encapsulated within the starch matrix modified by vinyl acetate through in situ graft-copolymerization. St-g-PVAc, which exhibits relatively low swellability, was synthesized by the reaction of starch and VAc in the presence of K2S2O8 as the initiator. The chemical structure of the St-g-PVAc and St-g-PVAc/urea composite film was confirmed by FTIR. The release behavior of urea encapsulated in the films was studied. The experimental results indicated that the introduction of hydrophobic PVAc reduced the swellability of the starch matrix; the urea nitrogen slow-release time can reach 28 h in water. The St-g-PVAc/urea composite films could biodegrade in the soil environment.

Co-production of vinyl acetate and ethyl acetate

Abstract: A method of co-producing vinyl acetate and ethyl acetate includes: (a) reacting ethylene, acetic acid and oxygen to form vinyl acetate and at least a minor amount of ethyl acetate; (b) providing a crude product stream containing the vinyl acetate and ethyl acetate of step (a) and acetic acid to a distillation tower; (c) separating the crude product stream into: (i) a vinyl acetate product stream enriched in vinyl acetate with respect to the crude product stream; (ii) an acid recycle stream enriched in acetic acid with respect to the crude product stream; (iii) a mixed sidestream containing vinyl acetate and ethyl acetate, the mixed sidestream being enriched in ethyl acetate with respect to the vinyl acetate product stream; and (d) hydrogenating vinyl acetate in the mixed sidestream to provide an ethyl acetate product stream.

Coverage Effects on the Palladium-Catalyzed Synthesis of Vinyl Acetate: Comparison between Theory and Experiment

Abstract: The high adsorbate coverages that form on the surfaces of many heterogeneous catalysts under steady-state conditions can significantly lower the activation energies for reactions that involve the coupling of two adsorbed intermediates while increasing those which result in adsorbate bond-breaking reactions. The influence of the surface coverage on the kinetics of metal-catalyzed reactions is often ignored in theoretical and even in some ultrahigh vacuum experimental studies. Herein, first principle density functional theoretical calculations are combined with experimental surface titration studies carried out over well-defined Pd(111) surfaces to explicitly examine the influence of coverage on the acetoxylation of ethylene to form vinyl acetate over Pd. The activation energies calculated for elementary steps in the Samanos and Moiseev pathways for vinyl acetate synthesis carried out on acetate-saturated palladium surfaces reveal that the reaction proceeds via the Samanos mechanism which is consistent with experimental results carried out on acetate-saturated Pd(111) surfaces. The rate-limiting step involves a β-hydride elimination from the adsorbed acetoxyethyl intermediate, which proceeds with an apparent calculated activation barrier of 53 kJ/mol which is in very good agreement with the experimental barrier of 55 ± 4 kJ/mol determined from kinetic measurements.