Tri-chloro acetic acid (1,1,1-), a colorless solid, is a compound formed by the substitution of methyl chloride methyl acetate, the chemical formula is ccl3cooh. The acidity of chloroacetic acid is stronger than that of acetic acid, which is affected by the electron-absorbing effect of chlorine. It is produced by the reaction of acetic acid and chlorine in the catalysis of iodine, and the chloral hydrate can be oxidized to obtain the tri-chloro acetic acid. Chloroacetic acid is mainly used for organic synthesis, medicine, pesticides and chemical reagents for the preparation of intermediates, also used as polymers (such as protein, DNA, RNA) precipitation agent. Chloroacetic acid was reduced to two chloroacetic acid, which has potential carcinogenic effect.