Accession Number : AD0698432

Title :   RADIATION-INDUCED DIMERIZATION OF 1,3-CYCLOHEXADIENE. SOLVENT EFFECTS AND THE FORMATION OF THE DIELS-ALDER DIMERS BY A CATIONIC CHAIN MECHANISM,

Corporate Author : ALBERTA UNIV EDMONTON DEPT OF CHEMISTRY

Personal Author(s) : Schutte,R. ; Freeman,G. R.

Report Date : 30 OCT 1968

Pagination or Media Count : 6

Abstract : The radiation-induced dimerization of 1,3-cyclohexadiene occurred by two simultaneous mechanisms: mechanism 1 produced mainly the endo and exo Diels-Alder products of 1,4,1',2' addition; mechanism 2 produced mainly the cis-anti-cis and cis-syn-cis isomeric products of 1,2,1',2' addition. Both mechanisms were sensitized by the aprotic solvents benzene, n-hexane, cyclohexane, and di-n-propyl ether, and were inhibited by the protic solvent ethanol. Mechanism 1 involved a cationic chain reaction in benzene, and probably also in the other aprotic solvents. In all the aprotic solvents the yield of the Diels-Alder products went through a maximum as the 1,3-cyclohexadiene (CHD) concentration was increased. There was no evidence of a chain in mechanism 2 and the yields of the corresponding dimers were relatively small. It appears that triplet-state CHD molecules were the immediate precursors of the dimers from mechanism 2, and that roughly half of the triplet CHD molecules resulted directly or indirectly from neutralization reactions. (Author)

Descriptors :   (*RADIATION CHEMISTRY, *POLYMERIZATION), (*DIENES, RADIATION CHEMISTRIES), CYCLOALKENES, DIENE SYNTHESIS, ADDITION REACTIONS, MOLECULAR ISOMERISM, MOLECULAR ORBITALS

Subject Categories : Radiation and Nuclear Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE