Naphthylamines, hydrogenation

Fluoronaphthalene [321-38-0] is prepared from 1-naphthylamine by the Balz-Schiemaim reaction in 52% yield or by diazotization in anhydrous hydrogen fluoride in 82% yield. Electrophilic substitution occurs at the 4-position, eg, nitration with fuming nitric acid in acetic acid gave 88% yield of l-fluoro-4-nitro-naphthalene [341 -92-4]. 

Naphthaleneamine. 1-Naphthylamine or a-naphth5iamine/7i5 -i2- can be made from 1-nitronaphthalene by reduction with iron—dilute HCl, or by catalytic hydrogenation it is purified by distillation and the content of 2-naphthylamine can be reduced as low as 8—10 ppm. Electroreduction of 1-nitronaphthalene to 1-naphthylamine using titania—titanium composite electrode has been described (43). Photoinduced reduction of 1-nitronaphthalene on semiconductor (eg, anatase) particles produces 1-naphthylamine in 77% yield (44). 1-Naphthylamine/7J4-J2-. can also be prepared by treating 1-naphthol with NH in the presence of a catalyst at elevated temperature. The sanitary working conditions are improved by gas-phase reaction at... 

A kinetic study of the desulphonation of 2-naphthylamine-l-sulphonic acid by hydrochloric, sulphuric and phosphoric acids showed the rate to be proportional to the concentration of hydrogen ions and the aromatic and a mechanism involving the formation of 1-naphthylsulphamic acid was proposed702. 

I, 4-benzoquinone.4 Other methods that have been employed include the oxidation of naphthalene with hydrogen peroxide,5 the oxidation of 1,4-naphthalenediamine 6 and naphthylamine sulfonic acid 7 and the oxidation of 4-amino-1-naphthol prepared by electrolytic reduction of 1-nitronaphthalene.8... 

A marginal hydrogenation of the benzenic ring of 1-naphthylamine leading to 5,6,7,8-tetrahydro-l-naphthylamine [72] was explained as due to a weaker adsorption of the benzene part than of the aniline part of the naphthylamine. However, this reaction was disregarded for the HDN of 1-naphthylamine, as the minor role it could play under the studied conditions. 

The oxidation of primary and secondary alcohols in the presence of 1-naphthylamine, 2-naphthylamine, or phenyl-1-naphthylamine is characterized by the high values of the inhibition coefficient / > 10 [1-7], Alkylperoxyl, a-ketoperoxyl radicals, and (3-hydroxyperoxyl radicals, like the peroxyl radicals derived from tertiary alcohols, appeared to be incapable of reducing the aminyl radicals formed from aromatic amines. For example, when the oxidation of tert-butanol is inhibited by 1-naphthylamine, the coefficient /is equal to 2, which coincides with the value found in the inhibited oxidation of alkanes [3], However, the addition of hydrogen peroxide to the tert-butanol getting oxidized helps to perform the cyclic chain termination mechanism (1-naphthylamine as the inhibitor, T = 393 K, cumyl peroxide as initiator, p02 = 98 kPa [8]). This is due to the participation of the formed hydroperoxyl radical in the chain termination ... 

Reduction of a nitro compound to the corresponding naphthylamine proceeds exactly as in the benzene series. A batch process using iron and hydrochloric acid is traditional but has been somewhat superseded by catalytic hydrogenation. 

Of the primary monoamines, some, such as. aniline, o-toluidine, xylidine, are colourless liquids. Others, such as p-toluidine, pseudo-cumidine and the naphthylamines, are solids. They can be distilled without decomposition and are volatile with steam. In water they are rather sparingly soluble—a 3 per cent solution of aniline can be made. The di- and polyamines are usually solids, not volatile in steam and much more soluble in water than the monoamines. The amines are basic in character, but, as a result of the negative nature of the phenyl-group, the aromatic amines are considerably weaker bases than are the aliphatic amines. Consequently aqueous solutions of the (stoicheio-metrically) neutral aniline salts are acid to litmus because of the hydrolysis which they undergo. For the same reason a small amount of the free base can be extracted with ether from an aqueous solution of an aniline salt. (Test with a solution of hydrogen chloride in ether or, after evaporation of the ether, by the reaction with bleaching powder.)... 

The napkthols are in many respects still more reactive than phenol. This is shown most distinctly by the fact that the naphthyl ethers can be obtained by the method used for the preparation of esters of carboxylic acids, namely, directly by the action of hydrogen chloride on the phenol in the presence of the alcohol. The naphthols, moreover, react readily with zinc-ammonium chloride and with ammonium sulphite and ammonia to yield naphthylamines. The second of these two methods is a general one. It was investigated by H. Bucherer. 

What about jr-electron donor substituents on nitrosoarenes other than dimethylamino Pedley gives us the enthalpies of formation for three hydroxy derivatives the isomeric 4-nitroso-l-naphthol, 2-nitroso-l-naphthol and l-nitroso-2-naphthol, species 45-47 respectively. Of the three species, only the first cannot have an intramolecular hydrogen bond. By analogy to nitrophenols75 — there being no thermochemical data for the more related and hence relevant nitronaphthols—we expect that species 46 would be less stable than 45. After all, gaseous 2-nitrophenol is ca 20 kJ mol 1 less stable than its 4-isomer. We recall from the discussion of the isomeric naphthylamines that 1- and 2-naphthol are of almost identical stability. This suggests that species 46 and 47 should be of comparable stability. Both expectations are sorely violated by the literature results the enthalpies of formation of species 45, 46 and 47 increase in the order —20.3 4.9, —5.4 6.2 and 36.1 4.7 kJmol-1 respectively. If there is experimental error, where does the error lie ... 

During radiolysis of polybutadiene and butadiene-styrene copolymers hydrogen and methane evolve.151-158 The incorporation of styrene as co-monomer strongly reduces the total gas yield.155-156 Small amounts of N-phenyl-b-naphthylamine greatly reduce the gas yield151 and, at the same time, reduce G(X) considerably. 

The direct replacement of the hydroxyl group in simple phenols by an amino or substituted amino group requires drastic conditions and the method is not suitable for laboratory preparations. With the polyhydric phenols, and more particularly with the naphthols, such replacements occur more readily. Thus 2-naphthol is converted into 2-naphthylamine by heating with ammoniacal ammonium sulphite solution at 150°C in an autoclave. The reaction (the Bucherer reaction) depends upon the addition of the hydrogen sulphite ion to the keto form of the naphthol and the subsequent reaction with ammonia. 

The hydrochloride of the ac.-tetrahydro-0-naphthylamine can be obtained readily by neutralizing a dry ether solution of the base with an ether solution of hydrogen chloride. It crystallizes from water in large plates which melt at 237°. 

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