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Abstract

A process for purifying a polyol (per)fluoropolyether derivative [polyol (P)] from a mixture of hydroxyl (per)fluoropolyether derivatives [mixture (M)]. Such polyol (P) comprising one or more hydroxyl (per)fluoropolyether derivatives [PFPE (OH)] comprising at least one (per)fluoropolyoxyalkylene chain (chain R_f) and at least one end-group having formula (t₃) —CF₂CH₂OCH₂CH(OH)CH₂OCH₂CH(OH)CH₂OH. Such mixture (M) comprising the polyol (P) and at least one PFPE (OH) different from the polyol (P) and comprising at least one chain R_f and at least one end-group selected from end-groups having formula (t₁) —CF₂CH₂OH and formula (t₂) —CF₂CH₂OCH₂CH(OH)CH₂OH. The process comprises the steps of: 1) reacting the mixture (M) with a ketone, an aldehyde or a combination thereof to yield corresponding mixture of cyclic ketal/acetal (per)fluoropolyether derivatives [PFPEs (OH)_p] [protected mixture (P)]; 2) carrying out a molecular distillation of the protected mixture (P) to isolate a protected product heavy residue [product (P_r)]; 3) hydrolyzing the product (P_r) to yield deprotected product [product (P_d)]; and 4) carrying out a distillation under reduced pressure of the product (P_d) to obtain polyol (P).

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