FIELD: chemistry.
SUBSTANCE: invention relates to monosubstituted phosphinic acid, method for thereof obtaining and to application of said acid as regulator in free-radical polymerisation. Monosubstituted phosphinic acid of formula 
(I), where X represents H+, alkali metal ion, alkali earth metal ion, ion of divalent or trivalent metal, ammonium ion, organic ammonium group or organic radical with molecular weight ≤200 g/mol, in particular Na+ or K+; where R1 represents H, alkyl group, preferably containing from 1 to 20 C atoms, alkylaryl group, preferably containing from 7 to 20 C atoms.
EFFECT: invention makes it possible to obtain regulators, which do not result in formation of poorly soluble salts, and, in addition, polymers, obtained with thereof application, are characterised by uniform degree of polymerisation, which has narrow distribution in sizes.
15 cl, 13 ex, 1 tbl
