Process for the preparation of perfluoropolyoxyalkylenes with hydroxyl end groups

摘要

A process for preparing perfluoropolyoxyalkylenes with hydroxyl end groups having structure: T1-CFW1-O-Rf-CFW2-T2 (I) wherein: T1, T2, are selected from -CH2OH, -F, -CF3, -CF2CF3 with the proviso that at least one of T1 and T2 is -CH2OH; W1 and W2 are selected from F, CF3; Rf is a perfluoropolyoxyalkylene chain having a number average molecular weight 500-10,000 comprising one or more units of the type -CF2CF2O-, -CF2O-, -C3F6O-, -CF2(CF2)zCF2O- (z=1, 2); -CR4R5CF2CF2O- with R4 and R5 selected from H, Cl, perfluoroalkyl group; said process comprising the following steps: a) adding an ester precursor having structure (I) and T1, T2 end groups selected from -F, -CF3, -CF2CF3, -COOR (R=linear or branched alkyl group having a number of C atoms from 1 to 5), with the proviso that at least one of T1 and T2 is -COOR, in a reaction mixture formed by: an inert or protic reaction solvent; a reducing agent selected from metal hydrides; an unreactive organic base with respect to the ester; b) hydrolysis of the product obtained in step a) for obtaining the compounds of structure (I) with at least a -CH2OH end group.