Preparation Of Vinyl Esters Of C3～C4 Alkanoic And Alkenoic Acids

The method to extract and purify vinyl 2-butenoate (VB) from the industrial waste liquid of vinyl acetate (VAc) production was studied in this paper. The obtained vinyl 2-butenoate from the purification was used to the modification of white glue; In addition, vinyl acetate was reacted with C3～C4 of alkanoic and alkenoic acids to produce the corresponding vinyl carboxylates.To extract and purify vinyl 2-butenoate from the industrial waste liquid of VAc which contents 10.71% of VB. Distillation in normal pressure was firstly used and then in reduced pressure, to control an appropriate reflux ratio, the reflux ratio in normal pressure distillation was controlled to be～10, and the reflux ratio in reduced pressure distillation to be～15. VB of 95% was obtained after one of normal pressure and twice of reduced pressure distillations; The effectiveness to purify VB by the azeotropic distillation with water in normal pressure was not obvious.Under normal temperature and normal pressure, Vinyl 2-butenoate, vinyl propionate (VP), vinyl butyrate, vinyl isobutyrate (VI) and vinyl acrylate (VA) were synthesized by the transvinylation reaction of lower content (86%) of VAc with 2-butenoic acid, propanoic acid, butanoic acid, isobutanoic acid and acrylic acid, respectively. Mercury acetate as the catalyst had the highest activity. ZnAc₂ and ZnO had no activity. Using the method of single factor to optimize the experimental conditions, the following optimal reaction conditions were found. For synthesizing VB,VP and vinyl butyrate, the mol ratio of corresponding carboxylic acid to VAc was 1:2, the dosage of mercury acetate was 2% of vinyl acetate (mass), reaction temperature was 25℃, reaction time of synthesizing VB was 10 h, the highest yield of VB was 58.8%. Reaction time of synthesizing VP was 3h, the highest yield of VP was 67.6%. Reaction time of synthesizing vinyl butyrate was 3h, the highest yield of vinyl butyrate was 64.4%. During the separation process of VA, VA was very easily polymerized with VAc and acrylic acid which hadn't reacted yet. It was very difficult to separate VA from the products completely. The yield of synthesizing VI was 54.2%. And the used catalyst HgAc₂ was disposed in a harmless manner.When preparing polyvinyl acetate emulsion (white glue) of low solid content (<22%), adding VB in small amounts (0.03%～0.56% of total mass of the white glue) to copolymerize with vinyl acetate can produce white glue whose apparent viscosity was 19～65 Pa·s, and its adhesive strength and tolerance to boiling water were obviously enhanced compared to the white glue without adding VB in the same preparing conditions. As to improve the existing white glue, adding VB (0.6～12.9% of the mass of white glue) and conducting a heating reaction, the glue's adhesive strength and tolerance to boiling water could also be enhanced markedly. The apparent viscosity and cohesive strength of polyvinyl alcohol water solution were also enhanced markedly after adding VB. It was shown that the vinyl butenoate in the industrial waste liquid has the value to be recovered and utilized.