Abstract
Slow distillation of 5, 5, -dimethyl-Δ2-pyrazoline isomerizes it to 5, 5-dimethyl-Δ1-pyrazoline, and heating the latter with hydrazine hydrochloride reconverts it to the Δ2 isomer. This is the first experimental evidence that the Δ2 double bond in a pyrazoline can move to the Δ1 position, i. e., in a direction the reverse of that previously known. The 5, 5-dimethyl-Δ1 -pyrazoline described is the simplest Δ1 pyrazoline hitherto isolated.
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The authors heartily thank A. A. Petrov for making it possible to chart the PMR spectra, and V. B. Lebedev and V. S. Stopskom for obtaining and treating the spectrograms.
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Ioffe, B.V., Tsitovich, D.D. Isomerization of 5, 5-dimethylpyrazolines. preparation and properties of 5, 5-dimethyl-Δ1-pyrazoline and 3, 4-dimethyl-Δ2-pyrazoline. Chem Heterocycl Compd 1, 375–379 (1966). https://doi.org/10.1007/BF00473813
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DOI: https://doi.org/10.1007/BF00473813