23dimethylbutane23diol

23dimethylbutane23diol is the informal rendering of the compound with the IUPAC name 2,3-dimethylbutane-2,3-diol, commonly known as pinacol. It is a vicinal diol in which both central carbons (C2 and C3) are tertiary and bear hydroxyl groups as well as two methyl substituents. The molecule is symmetric, with a C2–C3 bond connecting two identical tertiary units, giving it a plane of symmetry and making it achiral.

Chemical formula and structure

The formula is C6H14O2. The structure features two adjacent carbon atoms each bonded to an OH group and two methyl groups, plus the connecting bond between the two central carbons. This arrangement yields a compact, highly polar molecule capable of extensive hydrogen bonding.

Properties and behavior

As a small, polar diol, pinacol exhibits significant hydrogen-bonding potential. Its physical state at ambient conditions can vary, but as a representative vicinal diol, it serves as a useful model compound in studies of diol chemistry and related rearrangements. Its symmetry and lack of chirality differentiate it from many other vicinal diols.

Reactions and applications

The compound is best known for its role in the pinacol rearrangement. Under acidic conditions, pinacol undergoes a rearrangement in which a methyl (or other substituent) migrates to generate a carbonyl-containing product, typically pinacolone (3,3-dimethyl-2-butanone). This transformation is a classic example used to illustrate carbocation rearrangements and the chemistry of vicinal diols. Pinacol serves as a standard substrate in teaching and research on rearrangement mechanisms and as a precursor to other carbonyl-containing compounds.

See also: pinacol rearrangement; pinacolone.