Patent ID: 8501966

Claim:
A method for producing a methylene disulfonate compound represented by Formula (3) wherein R 1 and R 2 are independently a hydrogen atom or a C 1-4 alkyl group whose hydrogen atom may be substituted with a halogen atom; n is an integer from 1 to 4; and when n is an integer from 2 to 4, n R 1 s and n R 2 s may be the same or different; comprising reacting, in the presence of an acid and a dehydrating agent, a formaldehyde compound with at least one salt of alkanedisulfonic acid selected from the group consisting of alkali metal salts of alkanedisulfonic acid represented by Formula (1), wherein R 1 and R 2 are independently a hydrogen atom or a C 1-4 alkyl group whose hydrogen atom may be substituted with a halogen atom; n is an integer from 1 to 4; and when n is an integer from 2 to 4, n Ws and n R 2 s may be the same or different; and X is an alkali metal; and alkaline earth metal salts of alkanedisulfonic acid represented by Formula (2) wherein R 1 and R 2 are independently a hydrogen atom or a C 1-4 alkyl group whose hydrogen atom may be substituted with a halogen atom; n is an integer from 1 to 4; and when n is an integer from 2 to 4, n R 1 s and n R 2 s may be the same or different; and Y is an alkaline earth metal.