Abstract
Electrosynthesis of 4-chloro-substituted derivatives of pyrazole and its alkyl derivatives is carried out via the chlorination of original pyrazoles on a Pt anode in aqueous NaCl solutions under conditions of galvanostatic diaphragm electrolysis. The efficiency of this process is shown to depend on the structure of starting pyrazoles, particularly, the donor-acceptor properties of substituents, the position of the latter in the pyrazole ring, and the concomitant contribution of side reactions. Thus the yield of 4-chlorosubstituted products at the chlorination of pyrazole, 3,5-dimethylpyrazole, 1,5-dimethylpyrazole, and 3-nitropyrazole is 68, 92, 53, and 79%, respectively. By the example of 1,5-dimethylpyrazole, the possibility of electrochemical chlorination to the side chain of pyrazoles was demonstrated.
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Original Russian Text © B.V. Lyalin, V.A. Petrosyan, B.I. Ugrak, 2008, published in Elektrokhimiya, 2008, vol. 44, No. 12, pp. 1418–1425.
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Lyalin, B.V., Petrosyan, V.A. & Ugrak, B.I. Electrosynthesis of 4-chloro derivatives of pyrazole and alkylpyrazoles. Russ J Electrochem 44, 1320–1326 (2008). https://doi.org/10.1134/S1023193508120021
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DOI: https://doi.org/10.1134/S1023193508120021