Y»-nitrophenol

For phenols, the number of chlorines replaced depends in part on the acidity of the phenol. Under mild conditions, phenol or y -nitrophenol displaces only one chlorine from TiCl, whereas -chlorophenol, (9-nitrophenol, -nitrophenol, picric acid, or 2-naphthol gives (ArO)2TiCl2. If the mixtures are heated sufficiently, eg, in refluxing phenol, all four chlorines can be displaced (49—52). 

Enantio- and diastereoselective syntheses of a variety of heterocycles were accomplished by combining the ruthenium-catalyzed Alder-ene reaction with a palladium-catalyzed asymmetric allylic alkylation (AAA) (Scheme 7). For the AAA, y>-nitrophenol was found to function as a suitable leaving group and yet was stable to the Alder-ene conditions. Extensive solvent studies were performed to determine the best conditions for the one-pot procedure. 

Holmes et al. (1998) performed two enzymatic reactions, the lipase-catalyzed hydrolysis of y>-nitrophenol butyrate and lipoxygenase-catalyzed peroxidation of linoleic acid, in w/c microemulsions stabilized by a fluorinated two-chained sulfosuccinate surfactant (di-HCF4). The activity of both enzymes in the w/c microemulsion environment was found to be essentially equivalent to that in a water/heptane microemulsion stabilized by Aerosol OT, a surfactant with the same headgroup as di-HCF4. The buffer 2-(A-morpholino)ethanesulfonic acid (MES) was used to fix the pH in the range 5-6. 

Nitromersol/777-j5 , y (4) and mercurophen [52486-78-9] (5) are prepared by the same mercuration reaction as phenyhnercuric acetate, only 4-nitro-(9-cresol and o-nitrophenol are used, respectively, iastead of benzene. The second step is reaction with sodium hydroxide to form the anhydride or sodium salt, respectively. 

The nitrophenols are widely used in industry. For the determination of nitrophenols (NP) elassie ehemieal methods sueh as titration, as well as potentiometry, voltametry, speetrophotometry and ehromatography ai e used. Existing methods are poorly seleetive and don t allow to determinat of nitrophenols in solution without their preliminai y separation. 

The procedure of simultaneous extracting-spectrophotometric determination of nitrophenols in wastewater is proposed on the example of the analysis of mixtures of mono-, di-, and trinitrophenols. The procedure consists of extraction concentrating in an acid medium, and sequential back-extractions under various pH. Such procedures give possibility for isolation o-, m-, p-nitrophenols, a-, P-, y-dinitrophenols and trinitrophenol in separate groups. Simultaneous determination is carried out by summary light-absorption of nitrophenol-ions. The error of determination concentrations on maximum contaminant level in natural waters doesn t exceed 10%. The peculiarities of application of the sequential extractions under fixed pH were studied on the example of mixture of simplest phenols (phenol, o-, m-, />-cresols). The procedure of their determination is based on the extraction to carbon tetrachloride, subsequent back-extraction and spectrophotometric measurement of interaction products with diazo-p-nitroaniline. 

In this solvent the reaction is catalyzed by small amounts of trimethyl-amine and especially pyridine (cf. 9). The same effect occurs in the reaction of iV -methylaniline with 2-iV -methylanilino-4,6-dichloro-s-triazine. In benzene solution, the amine hydrochloride is so insoluble that the reaction could be followed by recovery. of the salt. However, this precluded study mider Bitter and Zollinger s conditions of catalysis by strong mineral acids in the sense of Banks (acid-base pre-equilibrium in solution). Instead, a new catalytic effect was revealed when the influence of organic acids was tested. This was assumed to depend on the bifunctional character of these catalysts, which act as both a proton donor and an acceptor in the transition state. In striking agreement with this conclusion, a-pyridone is very reactive and o-nitrophenol is not. Furthermore, since neither y-pyridone nor -nitrophenol are active, the structure of the catalyst must meet the conformational requirements for a cyclic transition state. Probably a concerted process involving structure 10 in the rate-determining step... 

Kitagawa W, N Kimura, Y Kamagata (2004) A novel p-nitrophenol degradation gene cluster from a Grampositive hact c mm Rhodococcus opacus SAOIOI. J Bacteriol 186 4894-4902. 

In a specific example in the same paper [17], one polymer contained triphenyl-methane fragments and the other o-nitrophenol moieties (A and B, respectively, in Scheme 5.1). The triphenylmethane residues were reacted with an alkyllithium and converted to surface-confined trityllithium species. This derivatized polymer was then mixed with an excess of the second polymer and the combination was used in the stoichiometric benzoylation of y-butryrolactonc (Scheme 5.2) or of phenylace-tonitrile (Scheme 5.3). The procedure was also demonstrated successfully using solid sodium hydride instead of the lithiated polymer. 

Compounds in order of increasing pKa values (in parentheses) Amoxicillin (2.4), Eosin Y (2.7), Lissamine Green ( 3), Erythrosine (3.6), Rose Bengal (3.9), 4-nitrophenol (7.15), 2-nitrophenol (7.22), 3-nitrophenol (8.36), 4-tert-butylphenol (10.16) 4-isoproplphenol (10.19). Erom [47] used with permission... 

It was later shown by Laurence and coworkers that there are significant systematic differences between P values of solvents obtained with indicators with an oxygen donor atom and those with a nitrogen donor atom (Nicolet and Laurence 1986). These authors recommended the use of a single indicator, preferably 4-nitrophenol relative to 4-nitroanisole or else 4-nitroaniline relative to 4-nitro-N,N-di/rae%>/aniline (rather than 4-nitro-N,N-die// y/aniline used by Kamlet and Taft 1976), to establish a basicity scale. The main point of difference is with respect to solvents that do not have an oxygen donor atom, such as amines, pyridines, and sulfides. In order to save the P scale, Kamlet and Taft proposed a family-dependent covalency parameter, equal to -0.20 for P=0 bases, 0.00 for C=0, S=0, and N=0 bases, 0.20 for -O-bases, 0.60 for pyridines, and 1.00 for amines, for use in linear free energy relationships (Kamlet etal. 1985). 

Machida M, Morita Y, Hayashi M, et al. 1982. Pharmacokinetic evidence for the occurrence of extrahepatic conjugative metabolism of p-nitrophenol in rats. Biochem Pharmacol 31 787-791. 

Enhancement of nitrophenol formation has also been observed upon irradiation of phenol, nitrite and two Mn(III,IV) (hydr)oxides, /3-Mn()2 and y-MnOOH [97], which show some photocatalytic activity [98]. Finally, interaction can take place between nitrate and nitrite (reactions 1, 2, 20), which also results in enhanced nitrophenol formation [85]. 

Bo, L., Quan, X., Chen, S., Zhao, H., and Zhao, Y. 2006. Degradation of p-nitrophenol in aqueous solution by microwave assisted oxidation process through a granular activated carbon fixed bed. Water Research, 40 3061-68. 

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