Patent ID: 8304515

Claim:
A process for the purification of a tetraol PFPE derivative [tetraol (T)] of formula (I): HO—CH 2 —CH(OH)—CH 2 —O—CH 2 —CF 2 —O—R f —CF 2 —CH 2 O—CH 2 —CH(OH)—CH 2 OH (I), wherein R f represents a fluoropolyoxyalkene chain (chain R f ), said chain R f being a fluorocarbon segment comprising ether linkages in main chain, from a mixture of hydroxyl (per)fluoropolyether derivatives [mixture (M)], said mixture comprising said tetraol (T) and at least one hydroxyl (per)fluoropolyether [PFPE (OH)] comprising a chain R f terminated with at least one end group of formula: —CF 2 CH 2 OH; or —CF 2 CH 2 O—CH(OH)—CH 2 —O—CH 2 —CH(OH)—CH 2 OH; said process comprising: step 1: reacting the mixture (M) with ketones and/or aldehydes so as to selectively protect couples of hydroxyl groups on vicinal carbon atoms by forming corresponding cyclic ketal/acetal derivatives, so as to yield a protected mixture [mixture (P)]; step 2: reacting residual hydroxyl groups of the mixture (P) with suitable functionalizing agents enabling substantial volatility modification, so as to obtain a functionalized protected mixture [mixture (P f )]; step 3: fractional distillation of the mixture (P f ) so as to isolate the cyclic acetal/ketal derivatives of tetraol (T); step 4: hydrolyzing the acetal/ketal derivatives of tetraol (T) so as to recover pure tetraol (T).