A study of thermal Diels-Alder reaction of ethene with cyclohexa-1,3-diene by using AM1 method

UHF/AM1 molecular orbital method has been employed to study the thermal Diels-Alder reaction of ethene with cyclohexa-1,3-diene, The results showed that this reaction is exothermal, and it has two competitive routes; the activation energy of the concerted process is 112.667 kJ/mol, and that of the rate-determining step of the biradical pathway is 78.406 kJ/mol, the biradical process has lower activation energy than the concerted one.