Experimental determination of the heat of hydrogenation of phenylcyclobutadiene.
The heat of hydrogenation of phenylcyclobutadiene (DeltaH degrees (hyd) = 57.4 +/- 4.9 kcal mol(-1)) was determined via a thermodynamic cycle by carrying out gas-phase measurements on 1-phenylcyclobuten-3-yl cation. This leads to an antiaromatic destabilization energy of 27 +/- 5 kcal mol(-1), a difference of 9.6 +/- 4.9 kcal mol(-1) for the first and second C-H bond dissociation energies of 1-phenylcyclobutene, and an estimate of 96 +/- 5 kcal mol(-1) for the heat of formation of cyclobutadiene. These results are compared to G3, G3(MP2), and B3LYP computations and represent the first experimental measurements of the energy of a monocyclic cyclobutadiene.
Fattahi
Alireza
A
Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Lis
Lev
L
Kass
Steven R
SR
D003503:Cyclobutanes / Q000138:chemical synthesis* / Q000528:radiation effects*; D006358:Hot Temperature; D006865:Hydrogenation; D015394:Molecular Structure; D013816:Thermodynamics
D003503:Cyclobutanes; C505507:phenylcyclobutadiene