Patent ID: 6984759

Claim:
A process for the preparation of perfluoropolyethers of formula: T—CFX′—O—R f —CFX—T′ (I) wherein: T is —F, C 1 -C 3 perfluoroalkyl, —CH 2 OH, —CH 2 NH 2 , or —CHO; T′=T with the proviso that when T is F or C 1 -C 3 perfluoroalkyl, T′ is —CH 2 OH, —CH 2 NH 2 , or —CHO; X and X′ are equal to or different from each other, and are —F or —CF 3 ; R f is selected from: —(C 2 F 4 O) m (CF 2 CF(CF 3 )O) n (CF 2 O) p (CF(CF 3 )O) q — wherein the sum n+m+p+q ranges from 2 to 200, the (p+q)/(m+n+p+q) ratio is lower than or equal to 10:100, the n/m ratio ranges from 0.2 to 6; m, n, p, and q are equal to or different from each other and when m and n range from 1 to 100, then p and q and a range from 0 to 80; the units with n, m, p, and q indexes being statistically distributed along the chain; —(CF 2 CF 2 CF 2 O) r — wherein r ranges from 2 to 200, —(CF(CF 3 )CF 2 O) s — wherein s ranges from 2 to 200, comprising the following steps: A) preparation of perfluoropolyethers of formula T″—CFX′—O—R f —CFX—COF (II) wherein T″ is —COF, —F, or C 1 -C 3 perfluoroalkyl, X, X′, and R f are as above, by reduction of the corresponding perfluoropolyethers containing peroxidic bonds, with gaseous hydrogen in the presence of a catalyst formed by metals of the VIII group supported on metal fluorides, at a temperature from 20° C. to 140° C., and at a pressure between 1 and 50 atm; B) treatment of the formula (II) compounds with inorganic chlorides by heating at a temperature in the range 100°-150° C. and obtaining perfluoropolyethers having acylchloride —COCl end groups; B′) treatment of the formula (II) acylfluoride or of the corresponding ester or of the corresponding acylchloride with gaseous ammonia, obtaining the corresponding amide, which is subsequently dehydrated at a temperature in the range 150°-200° C., and obtaining perfluoropolyethers with nitrile —CN end groups; C) obtaining the compound (I) by reduction of the perfluoropolyethers with acylchloride end groups, obtained in step B), or with nitrile end groups, obtained in step B′), of formula (IIa): T′″—CFX′—O—R f —CFX—T″″ (IIa) wherein: T′″=—F, C 1 -C 3 perfluoroalkyl, —CN, or —COCl, T″″=T′″ with the proviso that when T′″ is —F or C 1 -C 3 perfluoroalkyl, T″″ is —CN or —COCl, with gaseous hydrogen in the presence of a catalyst constituted by metals of the VIII group selected from Pd, Rh, Ru, supported on solid metal fluorides, at a temperature from 20° C. to 150° C., and at a pressure between 1 and 50 atm optionally in the presence of inert solvents.