PURPOSE: To obtain a new compound which is useful as a starting material for synthesizing high-molecular weight derivatives, thus giving products of high refractive index, specific gravity, clarity or the like, which can be used as an optical material, particularly as a lens material.
CONSTITUTION: A compound of formula I {A is -(R1-X2)m-R2-[R1, R2 are alkylene, formula II (Ph is phenylene; K is 0 to 2); X2 is 0, S; m is 0 or more]; X1 is 0, S; Y is mercapto, OH, amino}, for example, 0,0'-bis(2-mercaptoethyl) dithiophosphoric acid. The compound of formula I is obtained, for example, by reaction of equimolar amounts of a compound of formula III and diphosphorus pentasulfide in a solvent of hexane or the like, when needed, in the presence of a catalyst such as tetra-n-butylammonium bromide, preferably at 40 to 50°C for 1.5 to 3 hours.
Shingo Matsuoka
Yoshin Nagasato
