SULFINIC ACIDS AND RELATED COMPOUNDS. 15. CONVENIENT METHODS FOR ESTERIFYING SENSITIVE SULFINIC ACID SALTS¹

Abstract

In a study of conversions of sensitive sulfinate salts to esters, a trisulfide bissulfinate, [NaO₂S(CH₂)₄S]₂S (1), was esterified with trialkyloxonium fluorborates. This procedure (Method A) was better for ethylation than use of ROH-HC1/BF₃ (C₂H₅)₂O (Method B). but Method B was better for methylation. Disodium 3-sulfinopropanoate (7) was best dimethylated with CH₃OH/BF₃ · (C₂H₅)₂O without HCl (Method C). Method B or C gave satisfactory results with sodium p-toluenesulfinate (3), but ROH/BF₃ · (C₂H₅)₂O with the free acid was better than either (Method D). p-Tolylsulfonyldiazomethane did not esterify p-toluenesulfinic acid: only the sulfonate was isolated (10, 15–20% yield).