1,2-Naphthoquinone 4 sulfonate, ammonium

After the mixture has been cooled to o°, the ammonium i,2-naphthoquinone-4-sulfonate is collected on a 20-cm. Buchner funnel and as much of the mother liquor is removed as possible by pressing the cake with a porcelain spatula or glass stopper. The product is washed with three equal portions of a cold mixture of 150 cc. of saturated ammonium chloride solution and 100 cc. of water. The wash solution is removed as completely as possible and the product washed twice with 50-cc. portions of alcohol, followed by 300 cc. of ether in small portions (Note 5). The ammonium i,2-naphthoquinone-4-sulfonate is spread out in a thin layer and dried to constant weight at 35-40°. An orange, microcrystalline product of bright appearance is thus obtained. The yield is 350-365 g. (94-98 per cent of the theoretical amount). The ammonium salt is of good quality and is sufficiently pure for many purposes. No satisfactory method has been devised for its further purification, but it can be converted into a pure potassium salt as follows. 

If technical i-amino-2-naphthol-4-sulfonic acid is used, the yield of ammonium i,2-naphthoquinone-4-sulfonate is 313 g. (84 per cent) of a rust-colored product. If the technical material... 

Preparation. One method utilizes ammonium 1,2-naphthoquinone-4-sulfonate. One liter of methanol is cooled to 0° in a salt-ice bath during slow addition of 80 ml. of coned, sulfuric acid. The cooling bath is removed, 1 mole of the ammonium salt is added and stirred to an even paste, and the temperature is gradually raised to boiling, with separation of the ether (2), more methanol is added, and the mixture is o o O... 

White or gray needles, usually Contg 0.5 11.O May turn pink on exposure to light, especially when moist. Insol in water, alcohol, ether, benzene sol in hot sodium bisulfite soln sol in alkaline soln but such solns oxidize quickly on exposure to air yielding a brown substance which is sol in hot water giving a green soln. Controlled oxidation with HNOj yields ammonium 1,2-naphthoquinone-4-sulfonate, see Fieser, toe. eiz... 

The Fenton-type system, Fe(II)/Cu(n)/H202, produced phenol with a moderate selectivity [28b]. In the absence of Cu(II) or Fe(III), biphenyl was the main product. Quinones, in particular l,2-naphthoquinone-4-sulfonate, played a vital role in the Fe(III)-promoted hydroxylation of benzene with HjOj, giving moderate yields of phenol [70]. The addition of polyethyleneglycol to Fe(III)/ HjOj in aqueous acetonitrile enhanced the phenol yield and selectivity [71]. A heterophase reaction in the presence of surfactants (quaternary ammonium salts, crown ethers, and polymers) has led to a further improvement. Biphasic benzene hydroxylation in the system composed of aqueous H O, Fe SO modified with 2-pyrazinecarboxylic acid (Hpca) derivatives, and CF COOH produced phenol with a selectivity of 97% (based on benzene) at substrate conversion of 8.6% (Eq. 14.22)... 

---