Chloromethyl polystyrene chemical modification

Widespread chlorine-containing polymers would include, 1) stable molding material for practical use such as polyvinyl chloride (PVC), polyvinylidene chloride and poly(epichlorohydrin)(PECH) and, 2) reactive polymers capable to introduce additional functional groups via their active chlorines such as chloromethyl polystyrene, poly (3-chloroethyl vinyl-ether) and poly (vinyl chloroacetate). While the latter, especially the chloromethyl polystyrene, has been widely used recently for the synthesis of variety of functional polymers, we should like to talk in this article about the chemical modification of the former, mainly of PVC and PECH, which was developed in our laboratory. 

Polystyrene, chloromethylated PS, and lithiated PS rings are used in the modification of PS resins for the preparation of new functional polymers because they provide a method of attaching a wide variety of both electrophilic and nucleophilic species. However, the use of commercial PS beads in chemical modifications requires the removal of surface impurities such as suspending or stabilizing agents which remain from the polymerization process, since surface contaminants can prevent the penetration of reagents into the swollen beads or lead to the need for more drastic reaction conditions. 

Due to its ready availability, high reactivity and other interesting properties, chloromethyl substituted polystyrene (I) has been the most extensively studied substrate in chemical modification via phase transfer catalysis. Reactions have been carried out both on soluble poly(chloromethyl styrene) (Ref. 12,... 

Table 4. Chemical Modification of Chloromethyl Polystyrene ( -CH2C1 under Phase Transfer Catalysis Structure of the Polymers after Modification. (Reference)...

Although phase transfer catalysis is certainly an important and extremely versatile tool for the chemical modification of chloromethyl polystyrene, it is not necessarily always the best method as excellent results can also be obtained for some nucleophilic displacements when DMF or even DMSO (at low temperature to avoid oxidation to the carboxaldehyde polymer) are used as solvent for the nucleophile. For example, we prefer to use a solution of sodium cyanide in DMF to prepare cyanomethyl polystyrene from I rather than using a different solvent and phase transfer conditions, and we routinely prepare iodomethyl polystyrene from I by reaction with sodium or potassium iodide in acetone rather than under the conditions of Gozdz (Ref. 25). Recent work by Bied-Charreton et al. (Ref. 32) has also shown that excellent results could be obtained even under classical conditions in the transformation of I into its malononitrile derivative if the chloromethylated polymer is first transformed into the more reactive iodomethyl derivative this is in sharp contrast with earlier data from the same laboratory (Ref. 33). 

CHEMICAL MODIFICATION OF CHLOROMETHYLATED POLYSTYRENE WITH PHOSPHINE OXIDES USING PHASE-TRANSFER CATALYSIS... 

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