Nitrobenzene

About: Nitrobenzene is a research topic. Over the lifetime, 5285 publications have been published within this topic receiving 83368 citations. The topic is also known as: essence of mirbane & nitrobenzol.

Structure of the Electrical Double Layer at the Interface between Nitrobenzene Solution of Tetrabutylammonium Tetraphenylborate and Aqueous Solution of Lithium Chloride

Abstract: Electrocapillary curves at the polarized interface between a nitrobenzene solution of tetrabutylammonium tetraphenylborate (TBATPB) and an aqueous solution of lithium chloride at various concentrations of TBATPB and LiCl have been measured by the drop time method using a dropping electrolyte solution electrode at 25 °C. The relative surface excesses of tetrabutylammonium and tetraphenylborate ions in the nitrobenzene phase and of lithium and chloride ions in the aqueous phase were well described by the Gouy-Chapman theory of diffuse layers for both sides of the interface. A model of the electrical double layer for the nitrobenzene–water interface is presented, in which an ion-free inner layer consisting of laminated monolayers of water and nitrobenzene is sandwiched by the two diffuse layers on each side of the interface. The potential difference across the inner layer, which was estimated to be ca. 20 mV at the potential of zero charge, was found to be dependent on the surface charge density and to be ne...

Electrochemical reactions of organic compounds in liquid ammonia. II. Nitrobenzene and nitrosobenzene

Abstract: The electrochemical behavior of nitrobenzene and nitrosobenzene in anhydrous liquid ammonia was investigated by cyclic voltammetry and controlled potential coulometry. In the absence of added protonating agents, nitrosobenzene and nitrobenzene are both reversibly reduced in two one-electron transfer steps to yield the stable radical anion and stable dianion species. In the presence of the weak acid isopropyl alcohol, the dianion of nitrosobenzene adds a single proton to form the anionic species, which can be reversibly oxidized back to parent compound. The dianion of nitrobenzene also adds a single proton and then rapidly decomposes with the loss of hydroxyl ion to neutral nitrosobenzene, which undergoes further reduction and protonation. The overall reduction process consists of the addition of a single electron to yield a stable radical anion followed by addition of three electrons and two protons to yield the protonated dianion of nitrosobenzene. I n the presence of strong acid (ammonium ion), nitrosobenzene is reduced in a single two-electron reduction process to yield phenylhydroxylamine. Nitrobenzene is reduced in two steps, involving the addition of one and three electrons, to yield the same final product, phenylhydroxylamine. Estimates of the equilibrium or rate constants for several of these reactions associated with the electrode reactions are given. The mechanism of the electrochemical reduction of nitrobenzene to phenylhydroxylamine and aniline has received considerable attention over the past 25 years.'-I4 Most of this work involved the use of aqueous solutions containing alcohol or an ether to aid in the dissolution of the relatively insoluble organic compound. Attempts a t elucidating the reduction mechanism were made by correlating changes in electrochemical behavior of the system with changes in pH, which was adjusted through the use of various buffer systems. Some studies have also been undertaken in nonaqueous solvent systems with addition of proton sources of varying proton-donating strength. In aqueous solution, nitrobenzene is reduced to phenylhydroxylamine in a single fourelectron reduction step a t all pH values. At pH values less than 4.7, nitrobenzene is assumed to be pre-protonated giving the species C ~ H S N O ~ H ~ ~ + , while analysis of the polarographic wave shows that the rate-determining step involves the addition of two electrons and a single p r o t ~ n . ~ . ~ The mechanism of reduction is given as: C6H5N02H22* + 2e+ H' C,H,NOH' + H?O (slow) C,H,NOH+ + 2e+ 2H' C,H,NH,OH+ (fast) The reduction product of the rate-determining step (C6HsNOH+) is reducible a t a less negative potential than the starting compound (CsHsNO*H2*+), which explains why this intermediate has never been detected during the course of an experiment. A second wave a t a more negative potential occurs in acid solution corresponding to reduction of the protonated phenylhydroxylamine species CbHsNHzOH+, to yield aniline in a single two-electron transfer step: Smith. Bard / Nitrohenzrne and Nitrosohenzene

Adsorption of nitrobenzene from aqueous solution by MCM-41.

Abstract: Adsorption of nitrobenzene onto mesoporous molecular sieves (MCM-41) from aqueous solution has been investigated systematically using batch experiments in this study. Results indicate that nitrobenzene adsorption is initially rapid and the adsorption process reaches a steady state after 1 min. The adsorption isotherms are well described by the Langmuir and the Freundlich models, the former being found to provide the better fit with the experimental data. The effects of temperature, pH, ionic strength, humic acid, and the presence of solvent on adsorption processes are also examined. According to the experimental results, the amount of nitrobenzene adsorbed decreases with an increase of temperature from 278 to 308 K, pH from 1.0 to 11.0, and ionic strength from 0.001 to 0.1 mol/L. However, the amount of nitrobenzene adsorbed onto MCM-41 does not show notable difference in the presence of humic acid. The presence of organic solvent results in a decrease in nitrobenzene adsorption. The desorption process shows a reversibility of nitrobenzene adsorption onto MCM-41. Thermodynamic parameters such as Gibbs free energy are calculated from the experimental data at different temperatures. Based on the results, it suggests that the adsorption is primarily brought about by hydrophobic interaction between nitrobenzene and MCM-41 surface.