Theoretical Investigation of the NO(3) Radical Addition to Double Bonds of Limonene

The addition reactions of NO(3) to limonene have been investigated using ab initio methods. Six different possibilities for NO(3) addition to the double bonds, which correspond to the two C–C double bonds (endocyclic or exocyclic) have been considered. The negative activation energies for the addition of NO(3) to limonene are calculated and the energies of NO(3)-limonene radical adducts are found to be 14.55 to 20.17 kcal mol-1 more stable than the separated NO(3) and limonene at the CCSD(T)/6–31G(d) + CF level. The results also indicate that the endocyclic addition reaction is more energetically favorable than the exocyclic one.