Synthesis and Polymerizability of Cyclic Acetals

There are a few general methods of-preparing cyclic acetals described in the literature 2 . The most frequently used method is based on the reaction of the corresponding diols with aldehydes or ketones  

Some of these reactions are essentially quantitative and are even used in analytical chemistry (e.g. benzal of pentaerithritol)3) or to introduce protective groups in the synthesis of nucleic acids or sugars (reactions of hydroxyl groups at adjacent carbon atoms in sugar with acetone or benzaldehyde)4). 

The conformations of cyclic acetals have been discussed by us in Adv. Polymer Sci. 37 (1980). 

The scope of application of cyclic acetals for the synthesis of polymers is very much limited because substitution (particularly at the C-2) position, retards polymerization. Earlier observations have been recently complemented by the unsuccessful attempts directed toward the polymerization of a large variety of higher substituted cyclic acetals5). 

The general thermodynamics of polymerization of cyclic acetals and the influence of substitution are discussed in Chapt. 2 of this volume (Thermodynamics). It may suffice to state here, that the monomers used to date for polymer synthesis are mostly derivatives of 1,2-glycols or 1,4-glycols and formaldehyde (i.e. 5- and 7-membered formals). 6-membered formals (1,3-dioxane and its derivatives) are nonpolymeri-zable due to the thermodynamic restrictions. 

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