3 ml of methylene chloride, 0.036 ml of mercaptoacetic acid and 0.04 ml of pyridine were charged in a flask, and 384 mg of heneicosafluoro-n-decylphenyliodonium trifluoromethanesulfonate was added thereto while stirring at room temperature, followed by allowing the mixture to react for 30 minutes at room temperature. The reaction mixture was subjected to silica gel column chromatography, and pentane and then diethyl ether were passed through the column. The diethyl ether was then distilled of to obtain 240 mg (89% yield) of heneicosafluoro-n-decylthioacetic acid.
