Concertedness in the Thermolysis of Some 1-Pyrazolines
1974 ◽
Vol 52
(17)
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pp. 3134-3139
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A mixture of cis- and trans-3,5-divinyl-1-pyrazoline was synthesized and isolated at 0° by the cycloaddition of vinyldiazomethane to butadiene. The kinetics of the thermolysis in diphenyl ether at 35–65° were studied by measuring the rate of nitrogen evolution. The cis isomer gave log (k1/s−1) = (12.28 ± 0.9 ) − (22.8 ± 0.4 )/θ where θ = 2.303RT in kcal mol−1, for the trans isomer log(k2/s−1) = (13.9 ± 0.9 ) − (25.7 ± 0.4 )/θ was obtained. These data when compared with those of 1-pyrazoline and 3-vinyl-1-pyrazoline lead to the conclusion that both carbon–nitrogen bonds are being broken in the rate determining step. Thus the alkyl-1-pyrazolines are concerted whereas the azoalkanes are not.
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2013 ◽
Vol 645
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pp. 60-63
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1984 ◽
Vol 39
(11-12)
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pp. 1057-1062
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