Use of RLi to Prepare Terminally Functional Diene Olefin Polymers

USE OF RLi TO PREPARE TERMINALLY FUNCTIONAL DIENE (OLEFIN) POLYMERS 

The utility of functionally terminated ( telechelic ) polymers, particularly difunctional materials, rests with the ability of such materials to be chain-extended to afford a high molecular weight and useful physical properties. In general, there are two organolithium-based methods for 

Reaction of live polymers with protic agents (e.g., HsO, ROH, and RNH2) results in simple protonation of the live ends and cessation of formation of the kinetic polymer chain. On the other hand, reaction of live polymers with some electrophiles can produce end-group substitution, as well as chain termination, as shown. 

For example, polymers having hydroxyl end groups can be prepared by reaction of polymer lithium with epoxides, aldehydes, and ketones III-113). Carboxylated polymers result when living polymers are treated with carbon dioxide (///) or anhydrides (114). When sulfur (115, 116), cyclic sulfides (117), or disulfides (118) are added to lithium macromolecules, thiol-substituted polymers are produced. Chlorine-terminus polymers have reportedly been prepared from polymer lithium and chlorine (1/9). Although lithium polymers react with primary and secondary amines to produce unsubstituted polymers (120), tertiary amines can be introduced by use of p-(dimethylamino)benzaldehyde (121). 

One drawback to the treatment of dilithium polymers with certain electrophilic agents is the formation of an intractable anionic association or gel. The degree of association is related to the charge density of the electrophile and increases in the following order  

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