Simulation of photochemical processes and calculation of the quantum yields of isomerization reactions of substituted dienes

The possibility of construction of a semiempirical method for simulation of photochemical processes and calculation of the quantum yields of reactions has been studied. The practicability of the approach was exemplified with the photochemical transformations of some diene compounds into their cyclic isomers, namely, 2,4-dimethylpentadiene-1,3 → trimethylcyclobutene, 2,3-dimethylbutadiene-1,3 → dimethylcyclobutene, pentadiene-1,3 → 3-methylcyclobutene, cis-butadiene-1,3 → cyclobutene, and 2-methylbutadiene-1,3 → 1-methylcyclobutene. The calculated quantum yields of the reactions are in qualitative and quantitative agreement with experimental data.