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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 21, Number 6
JKCSEZ 21(6)
December 20, 1977 

Reaction Conditions and Mechanism of Electrolytic Reduction of Nitrobenzene

니트로벤젠의 전해환원 반응 조건과 메카니즘
Jung-Kyoon Chon, Woon-Kie Paik

천정균, 백운기
에탄올-물 혼합용매에서 납전극을 사용하여 니트로벤젠(ΦNO2)과 그 유도체의 전해 환원반응을 조사하였다. 산성용액에서는 퍼텐셜에 따라 ΦNHOH 및 ΦNH2가 생성되었으며 니트로벤젠(ΦNO)은 중간체가 아닌것으로 보였다. 염기성 용액에서는 ΦNO가 생성되며 더 낮은 퍼텐셜에서 환원시키면 ΦN=NΦ 등 짝지어진 화합물이 생성됨을 확인하였다. 사용한 전해질 용액에서 ΦNO와 ΦNHOH 사이에 화학적인 짝지음 반응(coupling reaction)은 일어나지 않았다. 각각의 반응에 대해 전류-전압관계와 pH 의존도 및 반응물질에대한 반응 차수로부터 반응 메카니즘을 도출하였다. ΦNO가 생성되는 반응은 치환기가 있을 때도 같은 메카니즘을 따르는 것으로 보인다.

Electrochemical reduction of nitrobenzene (ΦNO2) and its derivatives on Pb electrode was studied by means of galvanostatic measurements and coulometric electrolysis in ethanol-water solvent. In acidic solutions phenylhydroxyl amine and aniline ethanol-water solvent. In acidic solutions phenylhydroxyl amine and aniline were produced while nitrosobenzene and coupled products such as azo-and hydrazobenzene were produced in basic solutions. Nitrosobenzene (ΦNO) was not found to be an intermediate in the reduction reactions of ΦNO2 in acidic solutions. No direct coupling between ΦNO and ΦNHOH was observed to occur in the electrolyte solutions used. Mechanisms of the production of phenylhydroxylamine and nitrosobenzene are deduced from Tafel slope, pH dependence and reaction order with respect to nitrobenzene. Mechanism for the reduction of substituted nitrobenzenes seems to be identical to that of nitrobenzene.

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