arylsulfonyloxy group or an aralkylsulfonyloxy group when x is a halogen atom it can be selected from the group consisting of fluorine chorine bromine and iodine preferably 7 4 bromobutoxy 3 4 dihydrocarbostyril is used in some particular embodiments examples of lower alkanesulfonyloxy group include methanesulfonyloxy group ethanesulfonyloxy group isopropanesulfonyloxy group n propanesulfonyloxy group n butanesulfonyloxy group tert butanesulfonyloxy group n pentanesulfonyloxy group or n hexanesulfonyloxy group examples of an arylsulfonyloxy group include phenylsulfonyloxy group 4 methylphenylsulfonyloxy group 2 methylphenylsulfonyloxy group 4 nitrophenylsulfonyloxy group 4methoxyphenylsulfonyloxy group 2 nitrophenylsulfonyloxy group 3 nitrophenylsulfonyloxy group or 3 chlorophenylsulfonyloxy group dichlorophenyl piperazine salts used as starting material in the present invention may be presented by the formula iii examples of organic acid include oxalic acid maleic acid fumaric acid tartaric citric acid or benzoic acid examples of inorganic acid include hydrochloric acid hydrobromic acid sulfuric acid or phosphoric acid 1 2 3 dichlorophenyl piperazine hydrochloride is used as the preferred starting material in some particular embodiments the carbostyril compounds and dichlorophenyl piperazine or its salts used as starting material in the present invention are known compounds and may be obtained from the methods known in the literature including those as described in u s pat no 5 002 528 and u s patent application 2005 0215585 which are herein incorporated by reference.