3-Methylthiophene is an organosulfur compound with the formula CH3C4H3S. It is a colorless, flammable liquid. It can be produced by sulfidation of 2-methylsuccinate.[1] Like its isomer 2-methylthiophene, its commercial synthesis involvess vapor-phase dehydrogenation of suitable precursors. 3-Methylthiophene is a precursor to the drug thenyldiamine and the pesticide morantel.[2]