The preparation of perfluorinated carboxylic esters and perfluoro carbonates

Aliphatic perfluorinated carboxylic esters have been prepared by two methods; (i) the reaction of the potassium salt of perfluoro 3-ethyl pent-3-ol, KOC(C₂F₅)₃, with perfluoro acid chlorides R_fCOCl, to yield perfluorinated esters of composition R_fCOOC(C₂F₅)₃, and (ii) the reaction of carbonyl chloride or thionyl chloride with a mixture of the potassium salt KOC(C₂F₅)₃ and perfluoro acid salts of the general formula KOCOR_f in a polar solvent. The product ester has the composition R_fCOOC(C₂F₅)₃, and in this instance carbon dioxide or sulphur dioxide is liberated during the reaction. A qualitative study of the thermal decomposition of a perfluoro ester has been made.A tertiary perfluoro carbonate of composition (C₂F₅)₂CF₃CO]₂CO has been prepared by the reaction of phosgene with the potassium salt KOC(C₂F₅)₂CF₃ in a polar solvent. The intermediate acid chloride (C₂F₅)₂CF₃COCOCl can be isolated.