SULFUR-CONTAINING CARBOXYLIC-ACIDS .5. SYNTHESIS AND STRUCTURE OF DIALKYL SULFIDES AND DIALKYL SULFOXIDES WITH VICINAL CARBOXYL OR ACYLAMINO GROUPS

Bifunctional sulfides and sulfoxides containing carboxy, carbamoyl, or acylamino groups in the beta-position are synthesized, and their IR s pectra were studied. An unusual decrease in the.frequencies of the car bonyl vibrations (by 20-34 cm-1) was found for thiodipropionic acid, i ts amides, and bis(beta-acylaminoethyl) sulfides by comparison with th e corresponding sulfoxides. The low-frequency shift of the CO band in these carbonylsulfides was not, as expected, associated with the intra molecular S...O coordination, since the x-ray structural investigation of thiodipropionic acid and bis(2-trifluoroacetylaminoethyl) sulfide did not show short intra- and intermolecular contacts involving the su lfur atom. Both structures contain intermolecular hydrogen bonds (C-O. ..HO or C=O...HN).