TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (claimed): Carboxylic acid bromo difluoro ethyl ester of formula (III) is reacted with sulfonating agent in presence of amine, to obtain 2-(alkyl carbonyloxy)-1,1-difluoro ethane-sulfonic-acid salt (I). Preferred Process: The salt is then reacted with oxidizing agent. The 2-(alkyl carbonyloxy)-1,1-difluoro ethane-sulfonic-acid salt is subjected to onium salt exchange process by attaching to onium salt of formula: Q+X-, to obtain 2-(alkyl carbonyloxy)-1,1-difluoro ethane-sulfonic acid onium salt of formula (IV). Then, the 2-(alkyl carbonyloxy)-1,1-difluoro ethane-sulfonic-acid salt is saponification process, to obtain 2-hydroxy-1,1-difluoro ethane sulfonic acid salt of formula (V) which is reacted with carboxylic acid derivative of formula: R'-C(=O)-X'or compound of formula (VI). Then, the product is esterified, to obtain 2-(alkyl carbonyloxy)-1,1-difluoro ethane-sulfonic-acid salt of formula (VII) which is subjected to onium exchange process by monovalent onium salt, to obtain 2-(alkyl carbonyloxy)-1,1-difluoro ethane-sulfonic acid onium salt of formula (VIII). The organic solvent extracts the crude 2-(alkyl carbonyloxy)-1,1-difluoroethane sulfonic acid ammonium salt. The layer containing organic solvent is washed and purified with thio-sulfuric acid metal aqueous solution are sulfuric-acid metal salt aqueous solution.Q+=sulfonium cation of formula (a), (b) or iodonium cation (c);R1-R3=(un)substituted 1-10C linear or branched alkyl, alkenyl, oxoalkyl, (un)substituted 6-18C aryl, aralkyl or aryl oxoalkyl which bonds and forms ring with sulfur;R4=(un)substituted 1-20C linear, branched or cyclic alkyl, alkenyl, or (un)substituted 6-14C aryl;M+=counter cation;X'=halogen or hydroxyl;R'=1-10C linear or branched alkyl, 3-20C alicyclic organic group, 3-20C alicyclic organic group or linear alkylene group in which two or more hydrogen on carbon is substituted by oxygen and forms keto group and 3-20C monocyclic or polycyclic lactone or 6-20C aryl in which one or more hydrogen on lactone and aryl is substituted by fluorine, hydroxyl, hydroxy carbonyl or 1-6C linear, branched or cyclic alkoxy in which hydrogen atom on alkyl is substituted by 2-acryloloxy group or 2-meth acryloyl oxy;m=1-5;n=0 or 1;andq=0-5.Preferred Component: The sulfonating agent is chosen from sodium dithionite and potassium dithionite. The amine is chosen from trimethyl amine, isopropyl diamine and triethyl amine. The transition metal catalyst is disodium tungstic acid. The reaction with sulfonating agent is performed in mixed solvent of organic solvent and water. Preferred Definitions:    A+=ammonium ion of formula: G2-NH+(-G1)(-G3);and    G1-G3=H, 1-6C alkyl, 1-6C alkoxy alkyl, 3-12C cycloalkyl, optionally substituted (phenyl, 7-12C aralkyl or naphthyl, heteroatom having optionally substituted two or more 2-10C heteroaromatic group).    SPECIFIC COMPOUNDS - Two specific 2-(alkyl carbonyloxy)-1,1-difluoro ethane-sulfonic-acid salt compounds such as triethyl ammonium 2-(1-adamantane)carbonyloxy-1,1-difluoroethane sulfonate and triethyl ammonium-1,1-difluoro-2-(pivaloyl oxy)ethane sulfonate are claimed.    EXAMPLE - 1-Adamantane carboxyl chloride, tetrahydrofuran, 2-bromo-2,2-difluoroethanol and triethyl amine were mixed, to obtain 1-adamantane-carboxylic acid-2'-bromo-2',2'-difluoro ethyl. The obtained product was mixed with triethyl ammonium-2-(1-adamantane)carbonyloxy-1,1-difluoroethane sulfonate and subjected to onium exchange process. Then, triphenyl sulfonium bromide was dripped into the mixture for 2 hours and filtered, to obtain triphenyl sulfonium-2-(1-adamantane)carbonyloxy-1,1-difluoro ethane sulfonate.