Poly vinylacetophenone

Photodegradation of poly(vinylacetophenone) (or poly(p-acetyl-styrene) (3.22) occurs by the Norrish Type I reactions [2233, 2249, 2260]  

A methyl radical ( CH3) can abstract hydrogen from the tertiary carbon in a polymer backbone molecule  

The photodegradation of poly(vinylacetophenone) films exposed to 254 nm radiation causes the formation of H2 and small amounts of CH4, CjHg, acetaldehyde and carbon monoxide (CO). 

All of these reactions are accompanied by crosslinking, which prevail in concentrated solutions or in a solid film [522]. 

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The reduction of poly(vinylacetophenone) with lithium aluminum hydride (LiAlH4) and quinine led to a product which was estimated to contain about 9% of (+ )-poly-[4-(2-hydroxyethyl)styrene. This asymmetric reduction is described in Preparation 13-2. 

The preparation of the starting material, poly(vinylacetophenone), may be carried out by a Friedel-Krafts reaction of polystyrene in carbon disulfide with acetyl chloride and aluminum chloride by the method of Kenyon and Waugh [95a]. 

Up to now only very few examples of asymmetric synthesis with macromolecules are known that means reactions on prachiral base units in zwactive polymers under formation of optically active polymers. One of such a reaction is the, asymmetric reduction of poly-vinylacetophenone to poly(4- [2-hydroxyethyl] styrene) [24]. 

Extension of the use of the cinnamoyl unit to photocrosslinkable polymers is found in the numerous chalcone-type polymers prepared by Unruh and Smith 34>. Typical is a group of chalcone polymers which were prepared by reaction of poly(4-vinylacetophenone) with aromatic aldehydes such as benzaldehyde. 

C.C. Unruh and A.C. Smith, Condensation of poly(4 vinylacetophenone) with various aralde hydes, J. Appl. Polym. Sci. 3, 310 (1960). 

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