Preparation nitrophenols

Wang has prepared nitrophenol boronic acids 70 and 71, which show large UV shifts on addition of saccharides. These shifts have been attributed to a change in the balance of the phenolate to boronate equilibria in the presence of saccharides [136]. 

Wang has prepared nitrophenol boronic acids 184 and 185, which show large shifts in the UV on addition of saccharides. The changes have been attributed to a change in the balance of the phenolate to boronate equilibria in the presence of saccharides. The observed stability constants (Kohs) for 184 and 185 were 245 and 13.5 for D-fructose and 8.0 and 1.2 for D-glucose in 4% (v/v) methanol/water at pH 7.4 (phosphate bulfer). 

Prepared by reduction of 4-nitrophenol or 4-nitrosophenoi. Can be diazotized and used as a first component in azo-dyes. Chief outlet is for sulphur dyes in which it is fused with sodium polysulphides. L/sed as a photographic developer. 

Bright yellow needles m.p. 45 C, b.p. 2 4°C. Prepared together with 4-nitrophenol by careful nitration of phenol. Sodium sulphide reduces it to 2-aminophenol which is used in dyestuffs and photographic processes. 

Ditrophenol, -nitropbenol, C H NOj. Colourless needles m.p. 114 C. Prepared as 2-nitrophenol. Reduction with iron and hydrochloric acid gives 4-aminophenol. 

The preparation can be shortened by omitting this stage and extracting the black residue by boiling it first with the water already present in the flask. In this case the yield of p-nitrophenol is increased somewhat, but the product is usually verv dark in colour. 

Phenol may be nitrated with dilute nitric acid to 3deld a mixture of o- and nitrophenols the 3deld of p-nitrophenol is increased if a mixture of sodium nitiute and dilute sulphuric acid is employed. Upon steam distilling the mixture, the ortho isomer passes over in a substantially pure form the para isomer remains in the distillation flask, and can be readily isolated by extraction with hot 2 per cent, hydrochloric acid. The preparation of m-nitrophenol from wt-nitroaniline by means of the diazo reaction is described in Section IV,70. 

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. 

Although this reduction is more expensive than the Bnchamp reduction, it is used to manufacture aromatic amines which are too sensitive to be made by other methods. Such processes are used extensively where selectivity is required such as in the preparation of nitro amines from dinitro compounds, the reduction of nitrophenol and nitroanthraquinones, and the preparation of aminoazo compounds from the corresponding nitro derivatives. Amines are also formed under the conditions of the Zinin reduction from aromatic nitroso and azo compounds. 

Attempts to prepare 6-hydroxybenzofuroxan by demethylation of 5-methoxybenzofuroxan, by pyrolysis of 4-azido-3-nitrophenol, and by hypochlorite oxidation of 4-amino-3-nitrophenoD failed. This rather unstable compound was finally prepared by hydrolysis of 5-acetoxybenzofuroxan its tautomeric possibilities are numerous, but from the similarity of its ultraviolet spectrum to that of 5-methoxybenzofuroxan it was considered to be largely in the hydroxy form. It is a fairly strong acid, of pK 6.76 (cf. 5-hydroxybenzo-furazan, pK 7.28). 7-Hydroxy-4,6-dinitrobenzofuroxan has been reported as arising from oxidation and nitration of dinitrosoresorcinol monooxime (tetraoxocyclohexene trioxime). ... 

When completely cold, the nitrophenol is filtered, thoroughly pressed out, drained with suction, and washed with several portions of iced water, 450 cc. in all being used. It is spread on large sheets of filter paper and dried in a warm room. As thus prepared it has a yellowish brown appearance with darker particles intermixed. The yield is 170-180 g. (81-86 per cent of the theoretical amount) (Note 5). 

By using the same molecular proportions the following m-nitrophenols were prepared in equally good yields from the corresponding m-nitroanilincs 3-methoxy-5-nitrophenol and 3-nitro-4,6-xylenol. In the former case it is advisable to use slightly more ice in the diazotization and add the diazonium solution to a mixture of equal volumes of sulfuric acid and water. 

The effects of pH on electrokinetic velocities in micellar electrokinetic chromatography was studied by using sodium dodecyl sulfate solutions [179]. Micellar electrokinetic capillary chromatography with a sodium dodecyl sulfate pseudostationary phase has been used to determine the partition constants for nitrophenols, thiazolylazo dyes, and metal chelate compounds [180]. A similar technique was used to separate hydroquinone and some of its ether derivatives. This analysis is suitable for the determination of hydroquinone in skin-toning creams [181]. The ingredients of antipyretic analgesic preparations have also been determined by this technique [182], The addition of sodium dodecyl sulfate improves the peak shapes and resolution in chiral separations by micellar electrokinetic chromatography [183]. 

Endo et al. [96] prepared AuPt, AuPd, and PtPd bimetallic nanoparticles with 2 nm in particle size in order to investigate catalytic activity for reduction of p-nitrophenol in water. The binary features of the nanoparticles were characterized by UV-Vis spectroscopic measurements. 

Similar observation was recorded for the GME and FGME catalyzed reduction of 4-nitrophenol (4NP) [46]. The GME and FGME nanoparticles are prepared in the... 

Still another method was reported by Schrader 12) (Equation 31). Compounds prepared by the general method of reaction of the chloro esters with the nitrophenol, either in the presence of base or by using a salt of the phenol, are shown in Formula 32. 

Diethyl chlorophosphate can also be prepared from ethyl alcohol and phosphoryl chloride in the presence of base, but the method shown is reported to give better yields. The intermediate diethyl chlorophosphate has been condensed with nitrophenol in a manner similar to that used for parathion (Equation 39). 

Because phenol is cheaper than nitrophenol, it might cost less to condense phenol with this chloro intermediate, followed by nitration with nitric acid. This method of preparing the oxygen analog can be used as shown in Equation 40. Still another method of preparation is shown in Equation 41. 

Schrader prepared the ester (38) in 60% yield by reaction of sodium p-nitrophenate with diethyl chlorophosphate, using xylene as solvent for the reaction. He made it, but in lower yields, from p-nitrophenol and diethyl chlorophosphate, using, respectively, pyridine and sodium cyanide as acceptors for hydrogen chloride. Schrader also prepared it in 96% yield by nitrating diethyl phenyl phosphate at 0° C. or below. Under the conditions he used, Schrader claims that the nitro group is directed to the para position. No yield is given for the diethyl phenyl phosphate, which he presumably made from sodium phenate and diethyl chlorophosphate. Diethyl chlorophosphate may be prepared in high yield (30) from diethyl phosphite and chlorine. 

Use of PEG-phenylcarbonate derivatives for preparation of urethane-linked PEG-proteins was reported (75). The main drawback of this approach lies in the toxicity of hydrophobic phenol residues (p-nitrophenol or 2,4,5-trichlorophenol) and their affinity to proteins. 

Other electrophilic substitution reactions on aromatic and heteroaromatic systems are summarized in Scheme 6.143. Friedel-Crafts alkylation of N,N-dimethyl-aniline with squaric acid dichloride was accomplished by heating the two components in dichloromethane at 120 °C in the absence of a Lewis acid catalyst to provide a 23% yield of the 2-aryl-l-chlorocydobut-l-ene-3,4-dione product (Scheme 6.143 a) [281]. Hydrolysis of the monochloride provided a 2-aryl-l-hydroxycyclobut-l-ene-3,4-dione, an inhibitor of protein tyrosine phosphatases [281], Formylation of 4-chloro-3-nitrophenol with hexamethylenetetramine and trifluoroacetic acid (TFA) at 115 °C for 5 h furnished the corresponding benzaldehyde in 43% yield, which was further manipulated into a benzofuran derivative (Scheme 6.143b) [282]. 4-Chloro-5-bromo-pyrazolopyrimidine is an important intermediate in the synthesis of pyrazolopyrimi-dine derivatives showing activity against multiple kinase subfamilies (see also Scheme 6.20) and can be rapidly prepared from 4-chloropyrazolopyrimidine and N-bromosuccinimide (NBS) by microwave irradiation in acetonitrile (Scheme... 

Of the substituted phenol ethers the amino-derivatives of anisole (anisidine) and phenetole (pkenetidine) may be mentioned. They are prepared from the nitrophenols by alkylation and subsequent reduction of the nitro-group. 

In actual practice, />-nitrophenylphosphate is present in large excesses, and the reaction is carried out at 38°C for 30 minutes. The resulting amount of / -nitrophenolatc ion is estimated by the help of an usual standard curve employing known concentrations of /j-nitrophenolatc prepared from/>-nitrophenol. 

Fig. 3.128. Effect of solvent strength on the chromatograms of a standard solution prepared by dissolving /1-CD ([/1-CD] = 9.5 mM) and the commercially available dediazoniation products 4-nitrophenol ([PNBOH] = 2.00X104 M), nitrobenzene ([NBH] = 1.98X10-4 M and 4-chloro-nitrobenhenzene ([PNBC1] = 1.99X10 4 M). (a) Mobile phase MeOH-water (75 25, v/v), (b) ACN-water (75 25, v/v). Reprinted with permission from C. Bravo-Diaz et al. [177].

---