Reacetylation of Poly vinyl Alcohol

Poly(vinyl Alcohol) by Transesterification of Poly(vinyl Acetate) Reacetylation of Poly(vinyl Aicohol) 

Safetyprecautions More this experiment is carried out,Sect.2.2.5 must be read as well as the material safety data sheets (MSDS) for all chemicals and products used. 

50 ml of 1% methanolic NaOH are placed in a 500 ml three-necked flask,fitted with stirrer, reflux condenser and dropping funnel, and heated to 50 °C on a water bath. A solution of 15 g of poly (vinyl acetate) (see Example 3-4) in 100 ml of methanol are added dropwise with vigorous stirring over a period of 30 min.The transesterification sets in immediately as indicated by the precipitation of poly(vinyl alcohol). After the addition is complete, stirring is continued for further 30 min the powdery precipitate is then filtered off, washed with methanol, and finally dried in vacuum at 30-40 °C. Po-ly(vinyl alcohol) is soluble or swellable in only a few organic solvents (e.g., in warm dimethylformamide), but dissolves easily in warm water. 

5 g of the poly(vinyl alcohol) obtained above are placed in a 100 ml round-bottomed flask fitted with a reflux condenser, together with 75 ml of the acetylating reagent (consisting of a mixture of pyridine, acetic anhydride, and acetic acid in the volume ratio 1 10 10).The mixture is then heated to 100 °C and kept at this temperature for 24 h. The excess reagent is then removed in a rotary evaporator under vacuum at room temperature and the polymer precipitated from methanol into water. 

The acetyl group content of the polymer is compared with that of the original poly(vinyl acetate), and the solubility behavior is also examined. 

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