A first process for producing an optically active perfluoroalklylcarbinol derivative includes (a) reacting an optically active imine with a compound that is a hemiacetal of a perfluoroalkylaldehyde or a hydrate of a perfinoroalkylaldehyde to obtain a condensate; and (b) hydrolyzing the condensate under an acid condition. A second process for increasing optical purity of an optically active 4,4,4-trifluoro-3-hydroxy-1-aryl-1-butanone derivative includes (a) precipitating a racemic crystal of the derivative, from the derivative; and (b) removing the racemic crystal from the derivative. A third process for increasing optical purity of the butanone derivative (includes recrystallizing the derivative. Novel compounds are optically active and inactive 4,4,4-trifluoro-3-hydroxybotanoic aryl ester derivatives. A fourth or fifth process for producing an optically active and inactive 4,4,4-trifloro-3-hydroxybutyric acid aryl ester derivative includes oxidizing an optically active or optically inactive 4,4,4-trifluoro-3-hydroxy-1-aryl-1-butanone derivative. A sixth process for increasing optical purity of the optically active aryl ester derivative includes recrystallizing the derivative. A seventh process for producing an optically active 4,4,4-trifluoro-3-butanediol includes reducing the optically active aryl ester derivative by a hydride. An eighth or ninth process for producing an optically active or inactive 4,4,4-trifluoro-3-hydroxybutyric acid alkyl ester derivative includes reacting under an acid condition the optically active or optically inactive aryl ester derivative with a lower alcohol. It is possible to suitably combine at least two of the first to ninth processes.