Nitrobenzene, oxidation with

Consequently, the native and enzymatically liberated lignins from white Scots pine, oak, birch, maple, kiri1 wood and bagasse were oxidized with nitrobenzene in alkali. The method of Stone 113) was applied quantitatively in this study. The amount of each degradation product obtained from each of the lignins is listed in Table 12 110). 

To determine the reasons for this, DHP s were prepared from a mixture of [ring-2-3H] p-coumaryl alcohol and [or-14C] coniferyl alcohol in the presence of carbohydrates by the procedure described above (35). The LCC fraction so obtained was subjected to combustion, and the exact p-hydroxyphenylpropane guaiacylpropane ratio was determined from the activity of 3H20 and 14C02 released (Figure 2). A portion of the same LCC fraction was also oxidized with nitrobenzene and alkali, and the resulting liberated aromatic aldehydes were then analyzed by HPLC. Results are shown in Table V. 

Some results regarding the content of H, G, and S in different lignins and wood samples obtained using Py-GC [6] are shown in Figure 9.1.3. The same figure shows for comparison the results obtained using a common chemical method (oxidation with nitrobenzene) and FTIR. 

Condensation of 2-amino-l,8-naphthyridine-3-carboxamide 400 with aromatic aldehydes in glacial acetic acid affords 2-aryl-l,2,3,4-tetrahydropyrimido[4,5-Z>][l,8]naphthyridin-4-ones 401, whose oxidation with nitrobenzene in glacial acetic acid gives 2-arylpyrimido[4,5-Z>][l,8]naphthyridin-4(3//)-ones 402. Compounds 402 were also synthesized without isolation of naphthyridones intermediate 401 formed by condensation of amide 400 with aromatic aldehydes on refluxing in a mixture of nitrobenzene and glacial acetic acid (1987IJC(B)1194). 

In this reaction the intermediate adduct is oxidized with nitrobenzene the latter being transformed into nitroso compound and then is regenerated by air oxygen. Also benzamide is regenerated by ammonia. The total scheme for the amination process looks very simple and attractive (Scheme 16) [43, 89]. 

The mechanism of the oxidation with nitrobenzene in basic media is not certain. [144] It is interesting to note the similarity with the second indigo synthesis of Adolf von Baeyer cf. section 2.1.4). 

Taking advantage of the observation that phenol is formed from nitrobenzene and phenyllithium at low temperature, Wiriyachitra and Cava have succeeded in converting nuciferine into 3-hydroxynuciferine. The sequence involves bromination of the aporphine in a strongly acidic medium, reaction with -butyllithium to form the aromatic lithio compound, and finally oxidation with nitrobenzene. ... 

Tyrosine is the source of p-hydroxybenzaldehyde when milled wood lignin is oxidized with nitrobenzene. The loss of more than 20% of individual amino acids in the presence of milled wood lignin and a number of sugars and glucans was demonstrated. Numerous unidentified compounds were detected some may arise as reaction products among amino acids and sugars (e.g., 57). 

Diaminoanthraquinone is an important intermediate for vat dyes and disperse dyes, and is prepared by oxidizing leuco-l,4-diaminoanthraquinone with nitrobenzene in the presence of piperidine. An improved process has been reported (45). 

Hurley and Testa (Ref 17) exposed nitrobenzene in isopropyl alcohol, degassed and in air, to a mercury lamp at 3660A Products in the absence of air were acetone and phenyl-hydroxylamine (PHA). In air PHA was oxidized to nitro sob enzene which couples with PHA to form azoxybenzene. They hypothesized that the triplet molecule abstracted H-atoms from the solvent no effect was noted with ben zene as solvent. They also worked with nitrobenzene in isopropyl alcohol-water mixts containing HC1 with a mercury lamp at 3660A (Ref 18), and found that the quantum yields depended on pH and isopropyl alcohol content, but were independent of oxygen with acid present. Their conclusion was that the quantum yield consisted of two parts, H abstraction by the triplet, and protonation of the triplet... 

Sharp and Walker (36) have reported good linear plots of Mx - Mh for 3- and 4-substituted pyridines, pyridine-N-oxides and nitrobenzenes against the appropriate substituent constants. Charton (37) has reported correlations of dipole moments for substituted ethylenes and related compounds with eq. (1) using the oj, and Op constants. Best results were generally obtained with Op. 

Cyanide and thiocyanate anions in aqueous solution can be determined as cyanogen bromide after reaction with bromine [686]. The thiocyanate anion can be quantitatively determined in the presence of cyanide by adding an excess of formaldehyde solution to the sample, which converts the cyanide ion to the unreactive cyanohydrin. The detection limits for the cyanide and thiocyanate anions were less than 0.01 ppm with an electron-capture detector. Iodine in acid solution reacts with acetone to form monoiodoacetone, which can be detected at high sensitivity with an electron-capture detector [687]. The reaction is specific for iodine, iodide being determined after oxidation with iodate. The nitrate anion can be determined in aqueous solution after conversion to nitrobenzene by reaction with benzene in the presence of sulfuric acid [688,689]. The detection limit for the nitrate anion was less than 0.1 ppm. The nitrite anion can be determined after oxidation to nitrate with potassium permanganate. Nitrite can be determined directly by alkylation with an alkaline solution of pentafluorobenzyl bromide [690]. The yield of derivative was about 80t.with a detection limit of 0.46 ng in 0.1 ml of aqueous sample. Pentafluorobenzyl p-toluenesulfonate has been used to derivatize carboxylate and phenolate anions and to simultaneously derivatize bromide, iodide, cyanide, thiocyanate, nitrite, nitrate and sulfide in a two-phase system using tetrapentylammonium cWoride as a phase transfer catalyst [691]. Detection limits wer Hi the ppm range. 

The traditional unpredictably violent nature of the Skraup reaction (preparation of quinoline and derivatives by treating anilines with glycerol, sulfuric acid and an oxidant, usually nitrobenzene) is attributed to lack of stirring and adequate temperature control in many published descriptions [1], A reaction on 450 1 scale, in which sulfuric acid was added to a stirred mixture of aniline, glycerol, nitrobenzene, ferrous sulfate and water, went out of control soon after the addition. A 150 mm rupture disk blew out first, followed by the manhole cover of the vessel. The violent reaction was attributed to doubling the scale of the reaction, an unusually high ambient temperature (reaction contents at 32°C) and the accidental addition of excess acid. Experiment showed that a critical temperature of 120°C was attained immediately on addition of excess acid under these conditions [2],... 

Mixtures with nitrobenzene were formerly used as liquid high explosives, with addition of carbon disulfide to lower the freezing point, but high sensitivity to mechanical stimulus was disadvantageous [1], Dining the recovery of acids from nitration of toluene, mixtures of the oxide with nitrotoluene or dinitrotoluene may... 

Leopold, B. Oxidation of Wood from Picea abies (L) Karst, with Nitrobenzene... 

The hydroquinone 65 is cyclized in an organic solvent at 230 to 270°C to yield 6,13-dihydroxy-quinacridone 66. Oxidation with suitable agents (such as nitrobenzene, chromic acid, nitric acid) provides the linear trans-quinacridone quinone (62) ... 

The three-phase electrode with a thin-film configuration (Fig. 4.2) has been mainly used in combination with nitrobenzene as an organic solvent and lutetium bis(tetra-i-butylphthalocyaninato) complexes as a redoxprobe (LBPC) [21,23]. Figure 4.5 depicts a typical voltammogram recorded with this redox probe in contact with 0.1 mol/L aqueous solution of KNO3. LBPC can be both oxidized and re-... 

Anilines could be oxidized to nitrobenzenes by Howe and Hiatt with molybdenum or vanadium catalysts in the presence of TBHP, while azoxybenzenes were produced by Kosswig with titanium catalysts (Scheme 151). 

It is apparent from Table IV that with nitrobenzene as the oxidation catalyst the ionization-limited rate was not reached even at a nitrobenzene concentration of 2.7M (0.02M fluorene, 0.02M potassium terf-butoxide). The rate of oxidation at the low nitrobenzene concentrations is first-order in nitrobenzene, fluorene, and base. This is consistent with an oxidation rate determined by Reaction 12 and involving an equilibrium concentration of the fluorene anions. 

Dulitz Explosive (1886). Mixtures of K chlorate (or other oxidizer) with various quantities of gel prepd by treating NC with nitrobenzene. Eg 10 parts of K chlorate 1 part gel... 

Azoxybenzene has been prepared by reduction of nitrobenzene with alcoholic potassium hydroxide,1 with sodium amalgam,2 with hydrogen in the presence of lead oxide,3 with methyl alcohol and sodium hydroxide,4 with sodium methylate and methyl alcohol,5 and by electrolytic reduction 6 by oxidation of azobenzene with chromic anhydride 7 by treatment of /9-phenylhydroxylamine with alkaline potassium permanganate,8 with nitrobenzene,9 with mineral adds,10 and with mercury acetamide,11 and by oxidation of aniline with hydrogen peroxide,12 and with acid permanganate solution in the presence of formaldehyde.13 The procedure described above is a slight modification of one described in the literature.14... 

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