organosulfur compound thioacetal http://purl.obolibrary.org/obo/CHEBI_59792 The sulfur analogue of 'acetal'. The term includes monothioacetals having the structure R2C(OR')(SR') (subclass monothioketals, R =/= H); and dithioacetals having the structure R2C(SR')2 (subclass dithioketals, R =/= H, R' =/= H). thioacetals