In chemistry, 3,3,4,4-tetramethyltetrahydrofuran or 3,3,4,4-tetramethyloxolane is a heterocyclic compound with the formula C8H16O, or (CH3)2((CH2)C2(CH2)O)(CH3)2. It can be seen as derivative of tetrahydrofuran (oxolane) with two methyl groups replacing two hydrogen atoms on each of the carbon atoms in the ring that are not adjacent to the oxygen. It can be seen also as a cyclic ether of 2,2,3,3-tetramethylbutane, an isomer of octane.