A term including monothioacetals having the structure R2C(OR')(SR') (subclass monothioketals, R ≠ H); and dithioacetals having the structureR2C(SR')2 (subclass dithioketals, R ≠ H, R' ≠ H), Ühendid struktuuriga R2C(OR')(SR') (monotioketaalid, R ≠ H) ja R2C(SR')2 (ditioketaalid, R ≠ H, R' ≠ H)