This invention provides a salt that is produced by [(R)-[(1S)-2-methyl-1- (1-keto-propoxy)propoxy](4-benzene butyl) oxygen phosphino]acetic acid and 10,11-di-H Cinchonidine, its structure is shown by formula(1). This invention also provides preparation of using this salt to optically split racemoid which consists of [(R)-[(1S)-2-methyl-1-(1-keto-propoxy)propoxy](4-benzene butyl) oxygen phosphino] acetic acid and [(S)-[(1R)-2-methyl-1-(1-keto-propoxy) propoxy](4- benzene butyl) oxygen phosphino] acetic acid. Compared with present resolution preparation, the yield and optical purity of resolution is obviously raised, it needs not recryst many times to depurate, and dosis of resolution agent is reduced. |