For some time now, our research group has been interested in the preparation and use of polymer - immobilized reagents. Our initial work [1,2] centered about the use of divinylbenzene- styrene copolymers. Eventually we reported on the use of polymer bound oxidizing agents,[3] principally those involving polymer bound phenylseleninic acid[4,5] and iodosobenzene[6] (Scheme -I).

We noted polymer degradation with these oxidants, particularly when using the iodosobenzene reagent. Clearly the benzylic positions are susceptible to oxidation, thus making styrene-divinylbenzene a less than optimal choice. As a result, we chose to investigate fluorocarbon polymers, particularly poly(chlorotrifluoroethylene) (PCTFE) as oxidation resistant support materials. Our goal has been to develop methods for replacement of the chlorine with reagent functionality by substitution. In this fashion, an oxidation resistant polymer might be obtained.
In initial work, we[7] and the others [8-10] looked at the reaction of PCTFE with alkyl anions. Reactions proceed via metallation and elimination, followed by further reaction (Scheme - II). McCarthy and coworker [11] have used this reaction to prepare functionalized forms of PCTFE and to analyze the high degree of surface selectivity of such functionalization.

In an important contribution to our work, Cais [12] reported the conversion of PCTFE to poly(trifluoroethylene) using butyltin hydride. The high efficiency of this reaction attests to the stability of the intermediate radical. In the recent past we have been examining methods to generate and trap this radical, using both one electron reduction and homolytic cleavage reactions as methods of generation.
While the strategy of trapping radicals as a means for accomplishing a substitution is somewhat mature; [13] its application to PCTFE is somewhat complicated by two factors :

(1) As a solid, PCTFE can remain inert to a reaction between radical generating agent and trapping agent, and

(2) The strength of the C - Cl bond makes cleavage more difficult.

We have reported, [14] along with the others, [15] on the substitution of chlorine in PCTFE with mercaptide ion (a non surface - selective reaction). Allylation using heterolytic cleavage or Co(II) mediated reduction occurs to about a 50% degree of functionalization (Scheme - III). Limited success was realized in extending this Co(II) chemistry to other alkylations. [16] In addition the use of Zn / SO2 as a method to produce sulfinic and sulfonic acid derivative has been carried out [17] (Scheme IV).

In an intriguing patent report, Lichstein [19] induced transformation of perfluoroalkylbromides and iodides into carboxylic acid derivatives. Presumably, the process involves oxidative addition to the carbon - chlorine bond, carbonyl migration and nucleophilic addition. At high pressure of CO, the reaction was catalytic in Cr. We report herein the extension of this chemistry to PCTFE.