tert-Butylglycolic acid

In the title compound, C6H12O3, which has a sterically demanding tert-butyl group attached to a hydroxy-acetic acid residue, centrosymmetric hydrogen-bonded dimers are formed; the hydr-oxy OH group functions as the donor and the double-bonded O atom of the carboxyl group functions as the acceptor. The dimer engages in inter-dimer bonding through four shorter hydrogen bonds involving two donors (the carboxyl OH) and two acceptors (the hydroxyl O atom). A three-dimensional system of hydrogen bonds is established that has channels for the hydro-phobic butyl groups along (0, 0, z) and ( , , z). There are two independent mol-ecules in the asymmetric unit. © International Union of Crystallography 2007.