Studies in the polarographic and coulometric behaviour of aromatic nitro compounds—III. nitrosobenzene in ethanol, acetone and dioxan
✍ Scribed by S.K. Vijayalakshamma; R.S. Subrahmanya
- Publisher
- Elsevier Science
- Year
- 1972
- Tongue
- English
- Weight
- 550 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0013-4686
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✦ Synopsis
A-et-The green nltrosobenzene monomer is reduced polarographically to phenylhydroxylamlne in the pH range 4-9. Though this reduction is known to be a two-electron process, coulometry invariably gives a lower value of n because of the reaction of unreacted nitrosobenzene and the phenylhydroxylamlne formed. The green monomer is attacked by mercury in acid medium. In alkaline medium, the green monomer undergoes a change that follows first-order kinetics with respect to nitrosobenzene. The rate of the transformation depends on the solvent. It decreases in the order acetone > ethanol > dioxan. R&um&Le nitrobenzi%e vert monom&e est reduit polarographiquement en pht5nylhydroxylamlne dam l'intervalle de pH 4-9. 3icn que cctte rkduction soit censQ un processus g deux Qectrons, la coulometrie indique invariablement une valeur plus faible de n. ;1 cause de la r&action du nitrobenzene inah& et de la ph&ylhydroxylam.ine form&. Le monom&re vert est attaque par le mercure en milieu acide. En milieu alcalin, il 6prouve un changement ob&sant & une cinbtique du premier ordre par rapport au nitrobetine. La vitesse de cette transformation d+end du solvant; elle augmente dans l'ordre a&one > 6thanol > dioxane. Zusammenfassung-Das @lne Nitrosobenzol-Monomere wird im pH-Bereich zwischen 4 und 9 polarographisch zu Phenylhydroxylamin reduziert. Obwohl bekannt ist, dass bei dieser Realction zwei Elektronen iibertragen werden, findet man mit coulometrischen Messungen einen niedrigeren wert fiir n, weil Produkt und Ausgangsstoff miteinender reagieren. Das griine Monomere wird in saurer L&mg durch Quecksilber angegriffen. In alkalischem Medium unterliegt es elner VerZmderung, welche einer Kiuetik erster Ordnung in Bezug auf das Nitrosobenzol folgt. Die Gelschwiudigkeit dieser Umwandlung h&n@ vom LBsungsmittel ab. Sie nimmt in dieser Reihenfolge ah: Aceton > Aethanol > Dioxan. The details of the experimental procedure have already been described.* The values of m of the dme were l-175 and 1.243 mg/s and t values were 4 and 4-l s a drop in 1 N KCl. The experiments were conducted at 30" & O-1°C.
Nitrosobenzene was prepared by the standard method* and purified by steam distillation and recrystallization from ethanol.
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