Hydroquinones nitric acid

EXPLOSION and FIRE CONCERNS noncombustible solid, but contact with water may release heat sufficient to ignite combustible materials NFPA rating Health 3, Flammability 0, Reactivity 1 can ignite or react violently with acetic acid, acetaldehyde, acetic anhydride, acrolein, acrylonitrile, allyl chloride, aluminum, chlorine trifluoride, chloroform and methanol, chlorohydrin, chlorosulfonic acid, 1,2-dichloroethylene, glyoxal, hydrogen chloride, hydrogen fluoride, hydroquinone, nitric acid, sulfuric acid, nitroethane, nitropropane, nitromethane, tetra-hydrofuran, water, zinc, and others reacts to form explosive products with ammonia and silver... 

When hydroquinone comes into contact with nitric acid, it combusts spontaneously within a millisecond. 

Dichloro-5,6-dicyano-l,4-benzoquinone is readily regenerated in good yield from the hydroquinone by oxidation with nitric acid.4... 

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) ... 

In an aqueous solution, 4-nitrophenol (100 pM) reacted with Fenton s reagent (35 pM). After 15 min into the reaction, the following products were identified 1,2,4-trihydrottybenzene, hydroquinone, hydroxy-p-benzoquinone, p-benzoquinone, and 4-nitrocatechol. After 3.5 h, 90% of the 4-nitrophenol was destroyed. After 7 h, no aromatic oxidation products were detected. The pH of the solution decreased due to the formation of nitric acid (Lipczynska-Kochany, 1991). In a dilute aqueous solution at pH 6.0, 4-nitrophenol reacted with excess hypochlorous acid forming 2,6-dichlorobenzoquinone, 2,6-dichloro-4-nitrophenol, and 2,3,4,6-tetrachlorophenol at yields of 20, 1, and 0.3%, respectively (Smith et al., 1976). 

Regeneration from DDHQ3 (1, 215 7, 96-97). Oxidation of a stirred suspension of the hydroquinone in water with nitric acid at 20-25° provides the quinone in 88% yield. 

The TS-l catalyzed hydroxylation of phenol to a 1 1 mixture of catechol and hydroquinone has already been commercialized by Enichem. Another reaction of considerable commercial importance is the above mentioned ammoximation of cyclohexanone to cyclohexanone oxime66, an intermediate in the manufacture of caprolactam. It could form an attractive alternative to the established process that involves a circuitous route via oxidation of ammonia to nitric acid followed by reduction of the latter to hydroxylamine (figure 4). 

Thanks to the easy removal of the precipitated DDQ hydroquinone after a DDQ oxidation, it is very practical to recover the pricey DDQ by oxidizing the corresponding hydroquinone with nitric acid.109... 

Escherichia coli (see Draths and Frost, 1994). Hydroquinone is a very practical intermediate in the manufacture of polymeric materials—almost 2 billion kg of adipic acid are produced from it and used annually in the manufacture of nylon 66. Most commercial syntheses of adipic acid utilize benzene as the starting material, derived from the benzene/toluene/xylene (BTX) fraction of petroleum refining. Benzene is hydrogenated over a metal catalyst to form cyclohexane, which is then oxidized over another catalyst that produces both cyclohexanone and cyclohexanol. See Figure 12.6. These molecules are catalytically oxidized in the presence of nitric acid to form adipic acid. 

DMSO (Wako Pure Chemicals Inc.) was distilled twice from 4A molecular sieves(Wako) under reduced pressure. Dicyanobis(l,10-phenanthroline)iron(II) [Fe(CN)2(phen)2] was synthesized by mixing 0.03 mol of phen and 0.01 mol of ammonium iron(II) sulfate hexahydrate in 400 cm3 of water, followed by the addition of KCN (0.15 mol). The resulting crude crystals were then dissolved in 30 cm3 of concentrated sulfuric acid followed by the addition of ldm3 of water. Dicyanobis(l,10-phenanthroline)iron(III) nitrate was obtained by the oxidation of corresponding iron(II) complex with concentrated nitric acid. The perchlorate salt was obtained by the addition of sodium perchlorate to the nitrate solution. Analytical grade hydroquinone, catechol, and L-ascorbic acid (Wako) were used without further purification. 

The cyclic voltammograms of all the carbons carrying preadsorbed silver, recorded in dilute nitric acid solution (Fig. 51), exhibit a Ag"/Ag" couple (cathodic wave < +0.4 V and an anodic response in the +0.40-0.60 V potential range), as well as the electroactive quinone/hydroquinone-like surface system ( p, s +0.50 V p.a2 = +0.90 V). The presence of distinctly shaped anodic silver oxidation peaks indicates the partial solution of sorbed (deposited) metal. An almost sixfold higher anodic peak for D—Ox carbon confirms the partially ionic form of the adsorbed silver. 

Moreno-Castilla and coworkers [139,140] did clarify the relationship between carbon surface chemistry and chromium removal. Table 3 summarizes some of the key results. Upon oxidation of carbon M in nitric acid (sample MO), the surface has become much more hydrophilic and more acidic, and the uptakes increased despite a decrease in total surface area. The enhancement in Cr(III) uptake was attributed to electrostatic attraction between the cations and the negatively charged surface. The enhancement in Cr(VI) uptake (at both levels of salt concentration) was attributed to its partial reduction on the surface of carbon MO (perhaps due to the presence of phenolic or hydroquinone groups), which is favored by the lower pH. The increase in uptake on carbon MO with increasing NaCl concentration is consistent with this explanation, from a straightforward analysis of the Debye-Hvickel and Nemst equations the decrease in uptake on carbon M was attributed to the competition of specifically adsorbed Cl and CrOj- ions on the positively charged surface. 

Ansell found that some 1,4-benzoquinones, particularly tri- and tetrasubstituted ones, can be prepared in high yield by oxidation of the hydroquinones with coned, nitric acid in ether at low temperature. A solution or suspension of 1 g. of the hydro-quinone in ether is stirred at a temperature between 0 and —20°, and coned, nitric... 

Manganese dioxide like other oxidants is effective for oxidative conversion of o- and p-hydroquinones into o- and p-benzoquinones, respectively. However, when nnstable benzoquinones snch as 664 and 665 are prodnced, the yields are not satisfactory. The synthesis of these qninones conld be performed snccessfully by oxidation of the corresponding hydroqninones 200 and 666 with MnOi impregnated with nitric acid in CH2CI2 in 68 and 86% yields, respectively (Scheme 128) °. Selection of the solvent nsed is qnite important generally, methylene chloride is preferred over benzene. 

Ceric compounds are reduced to cerous very easily by such reagents as hydrogen peroxide in acid solution, sulfur dioxide, hydrochloric acid, oxalic acid, stannous chloride, ferrous sulfate, etc. The transformation of ceric oxide to a cerous salt requires the presence of the desired acid and a reducing agent, since CeC>2 is difficultly soluble in mineral acids. It may be accomplished by (1) nitric acid and hydrogen peroxide (2) hydroquinone and hydrochloric or sulfuric acids (3) hydrochloric acid and an alkali iodide. 

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