Thermal Unimolecular Elimination of Water from tert-Butyl Alcohol: Deuterium Kinetic Isotope Effects, Transition Structure, Reaction Path, and Mechanism

Thermal decomposition of (CH 3 ) 2 C(OH)CD 3 in a static reactor and in a shock tube reactor led to intramolecular symmetry-corrected k H / k D kinetic isotope effects for eliminations of HOH and HOD of 1.80 ± 0.08 at 436 to 481 °C and 1.54 ± 0.12 at 813 to 883 °C. Calculations with B3LYP/6-31G* theory defined the transition structure for the 1,2-elimination reaction, the internal reaction coordinate path, and k H / k D predictions. The reaction takes place through a four-centered transition structure approached through very different progressions of bond length changes along the reaction coordinate.