The development of materials for use in nonlinear optical (NLO) devices has become a vigorous area of research in the chemical community.1 Several chemical compositions have been proven to be effective NLO materials. Polymeric materials are very attractive because of their processability which will lead to facile device fabrication.2
H and D atoms were reacted with trans-butene-2 to produce vibrationally excited sec-butyl and sec-butyl-d1 radicals with a range of excess energies with respect to C–C rupture. Previous work [R. E. Harrington, B. S. Rabinovitch, and H. M. Frey, J. Chem. Phys. 33, 1271 (1960)] on butene-1 has also been extended. Observed rate constants for the unimolecular decomposition of these sec-butyl radicals relative to collisional stabilization were obtained as a function of pressure. Possible competing side reactions are discussed and evaluated. Butenyl radical formed by H abstraction from butene-2 tends to retain the geometric configuration of the original butene; also, the ratio of the pentenes formed by methyl coupling, illustrative of the two principal resonance structures, is (3-methyl-butene-1) / (total pentene-2)∼0.4. An expected energy isotope effect for D atoms, which give sec-butyl-d1 radicals having ∼1.9 kcal/mole more vibrational energy than the corresponding sec-butyl radical formed from H atoms, was seen. With butene-1 or butene-2 reactant, no evidence was found for H-atom migration in the excited sec-butyl radical formed. The disproportionation/recombination ratio of sec-butyl radicals was found from all systems to be 0.63.
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