3 2,5-Dinitrophenol

Other Names a-Dinitrophenol l-Hydroxy-2,4-dinitrobenzene 2,4-DNP 2,4-Dinitrophenol Aldifen DNP Dinitrophenol Dinofan Fenoxyl Carbon N NSC 1532 Nitrophen Nitrophene Phenol, a-dinitro- 

CA Index Name Phenol, 2,4-dinitro-CAS Registry Number 51-28-5 

Chemical/Dye Class Nitro Molecular Formula C5H4N2O5 Molecular Weight 184.11 pH Range 2.0. 7 

Solubility Sparingly soluble in water soluble in ethanol, benzene Melting Point 112-114°C 

Boiling Point (Calcd.) 312.1 27.0°C Pressure 760Torr Synthesis Synthetic methods -io 

In a 1 htre round-bottomed flask equipped with a reflux condenser place a solution of 62-6 g. of anhydroas sodium carbonate in 600 ml. of water and add 60 g. of commercial 2 4-dinitro-l-chlorobeiizene. Reflux the mixture for 24 hours or until the oil passes into solution. Acidify the yeUow solution with hydrochloric acid and, when cold, filter the crystalline dinitrophenol which has separated. Dry the product upon filter paper in the air. The yield is 46 g. If the m.p. differs appreciably from 114°, recrystallise from alcohol or from water. 

It is advisable to keep the picric acid in the moist condition (containing about 10 per cent, of water) in a bottle with a cork stopper. Small quantities may be 

Htfely stored whilst dry, but this is not recommended in the interest of Safety. Under no circumstances should glass stoppers be employed for potentially explosive substances, since on replacing the stopper some of the material may be ground between the stopper and the neck of the bottle and an explosion may result. 

In one chronic feeding study in rats DNOC did not cause an increased incidence of any type of tumor. DNOC was clastogenic, increasing the frequency of chromosomal aberrations both in vivo and in vitro. Conflicting results for mutagenicity have been obtained in bacterial assays.  

The 2003 ACGIH threshold limit valuetime-weighted average (TLV-TWA) for dinitro-o-cresol is 0.2mg/m with a notation for skin absorption. 

World Health Organization Environmental Health Criteria 220-Dinitro-ortho-cresol, 75pp. Geneva, 2000 

Bidstrup PL, Payne DJH Poisoning by dinitro-ort o-cresol, report of eight fatal cases occurring in Great Britain. Br Med J 2 16-19, 1951 

National Institute for Occupational Safety and Health Criteria for a Recommended Standard. .. Occupational Exposure to Dinitro-ortho-cresol. DHEW (NIOSH) Pub No 78-131, 147pp. Washington, DC, US Government Printing Office, 1978 

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Dinitrophenol may be readily prepared by taking advantage of the great reactivity of the chlorine atom in 2 4-dinitro-l-chlorobenzene ... 

RCH(OH)=CHCOR or -keto esters RCH(OH)=CHCOOR ) dissolve in dilute sodium hydroxide solution, i.e., contain an acidic group of sufficient strength to react with the alkah. Carboxyhc acids and sulphonic acids are soluble in dilute solutions of sodium bicarbonate some negatively-substituted phenols, for example, picric acid, 2 4 6-tribromo-phenol and 2 4-dinitrophenol, are strongly acidic and also dissolve in dilute sodium bicarbonate solution. 

Group III. Carboxylic and sulphonic acids (also sym.-tribromophenol, 2 4-dinitrophenol and picric acid) are also soluble in dilute sodium bicarbonate solution. 

The nitration of anisole in 40% aq. nitric acid in the presence of some nitrous acid yielded 2,4-dinitrophenol as the main product. In more concentrated solutions of nitric acid 0- and />-nitroanisoles were the main products, less than o-1 % of the weta-isomer being formed. " The isomeric ratios for nitration imder a variety of conditions are given later ( 5.3.4). 

Dinitrophenol (indicator) dissolve 0.1 g in a few mL alcohol, then dilute with water to 100 mL pH range colorless 2.6-4.0 yellow. 

Peroxyoxalate chemiluminescence is the most efficient nonenzymatic chemiluminescent reaction known. Quantum efficiencies as high as 22—27% have been reported for oxalate esters prepared from 2,4,6-trichlorophenol, 2,4-dinitrophenol, and 3-trif1uoromethy1-4-nitropheno1 (6,76,77) with the duorescers mbrene [517-51-1] (78,79) or 5,12-bis(phenylethynyl)naphthacene [18826-29-4] (79). For most reactions, however, a quantum efficiency of 4% or less is more common with many in the range of lO " to 10 ein/mol (80). The inefficiency in the chemiexcitation process undoubtedly arises from the transfer of energy of the activated peroxyoxalate to the duorescer. The inefficiency in the CIEEL sequence derives from multiple side reactions available to the reactive intermediates in competition with the excited state producing back-electron transfer process. 

Amino-4-nitropheno1 is produced commercially by the partial reduction of 2,4-dinitrophenol This reduction may be achieved electrolyticaHy using vanadium (159) or chemically with polysulftde, sodium hydrosulftde, or hydrazine and copper (160). Alternatively, 2-acetamidophenol or 2-methylbenzoxazole may be nitrated in sulfuric acid to yield a mixture of 4- and 5-nitro derivatives that are then separated and hydrolyzed with sodium hydroxide (161). 

Polysulfide Melt. Cl Sulfur Black 1 [1326-82-5] (Cl 53185), derived from 2,4-dinitrophenol, is the most important dye in this group which also includes the indophenol-type intermediates. The latter are appHed in the stable leuco form. The derived dyes are usually confined to violet, blue, and green shades. Other members of this group are intermediates capable of forming quinoneimine (10) or phenazone stmctures (11) that produce red-brown or Bordeaux shades ... 

Sulfur dyes are used for dyeing ceUulosic fibers. They are insoluble in water and are reduced to the water-soluble leuco form for appHcation to the substrate by using sodium sulfide solution. The sulfur dye proper is then formed within the fiber pores by atmospheric oxidation (5). Sulfur dyes constitute an important class of dye for producing cost-effective tertiary shades, especially black, on ceUulosic fibers. One of the most important dyes is Cl Sulfur Black 1 [1326-82-5] (Cl 53185), prepared by heating 2,4-dinitrophenol with sodium polysulfide. 

Another example of the analogy between pyrazole and chlorine is provided by the alkaline cleavage of l-(2,4-dinitrophenyl)pyrazoles. As occurs with l-chloro-2,4-dinitrobenzene, the phenyl substituent bond is broken with concomitant formation of 2,4-dinitrophenol and chlorine or pyrazole anions, respectively (66AHC(6)347). Heterocyclization of iV-arylpyrazoles involving a nitrene has already been discussed (Section 4.04.2.1.8(i)). Another example, related to the Pschorr reaction, is the photochemical cyclization of (515) to (516) (80CJC1880). An unusual transfer of chlorine to the side-chain of a pyrazole derivative was observed when the amine (517 X = H, Y = NH2) was diazotized in hydrochloric acid and subsequently treated with copper powder (72TL3637). The product (517 X = Cl, Y = H) was isolated. 

A kinetic method for the determination of 2,4-dinitrophenol is proposed. The method is based on the inhibiting effect of 2,4-dinib ophenol on the Mn(II) catalysis of the oxidation of malachite green with potassium periodate. The reaction was followed spectrophotometrically at 615 nm. The optimal experimental conditions for the determination of 2,4-dinitrophenol were established under the optimal reaction conditions ... 

A linear dependence was established between tga and the concenb ation of 2,4-dinitrophenol ... 

The method was applied for the determination of 2,4-dinitrophenol in urine. The reproducibility was very good. The results obtained by the proposed method also agreed well with the values obtained by standard methods. 

The sulfhydiyl group in cysteine can be selectively protected in the presence of the amino group by reaction with 2,4-dinitrophenol at pH 5-6. ... 

Dinitrophenol [51-28-5] M 184.1, m 114 , pK 4.12. Crystd from benzene, EtOH, EtOH/water or water acidified with dil HCl, then recrystd from CCI4. Dried in an oven and stored in a vac desiccator over CaS04. 

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