Phenylhydroxyl amine

The initial product, nitrosobenzene, is so easily reduced to p-phenylhydroxyl-amine that it has never been isolated in the free state, but its presence has been established by reaction in solution with hydroxylamine to 3deld a phenyldi-azonium salt, which couples readily with a a-naphthylamine to form the dyestuff phenyl-azo-a-naphthylamine (compare Section IV,77) ... 

Under the cataljdic influence of alkali, nitrosobenzene and p-phenylhydroxyl-amine react to yield azoxybenzene ... 

The single-step -duoroaruline [31-40-4] process based on duorodeoxygenation of nitrobenzene (via in situ generation of /V-phenylhydroxyl amine) in anhydrous hydrogen duoride (94—96) has not been commercialized primarily due to concurrent formation of aniline, as well as limited catalyst life. The potential attractiveness of this approach is evidenced by numerous patents (97—101). Concurrent interest has been shown in the two-step process based on /V-phenylhydroxylamine (HF-Bamberger reaction) (102—104). 

Experiment. — Nitrosophenylhydroxylamine.1 Phenylhydroxyl-amine (2-2 g.) is dissolved in 20 c.c. of N-hydrochloric acid and an aqueous solution of 1 -4 g. of sodium nitrite is rather quickly added with strong cooling in ice. White needles are at once precipitated. They are filtered with suction, washed with ice-cold water, and dried on porous plate. Melting point 59°. 

Redox equlibrium (Equation 11.4) between nitrosobenzene and phenylhydroxyl-amine is fully reversible on the time scales of polarography and preparative elec-... 

One other synthesis of a A3-oxadiazoline was obtained unintentionally. Hull and Farrand114 refluxed cyanamide and phenylhydroxyl-amine in acetone expecting to obtain the disubstituted hydroxylamine (23). Instead, the solvent acetone had condensed with the hypothetical... 

The yield of cupferron from a given weight of phenylhydroxyl-amine averages 85-go per cent of the theoretical amount. 

Reaction LXXIV. (a) Action of Mineral Acids on Phenylhydroxyl-amine. (B., 26, 1844, 2810 27, 1927 20, 3040.)—In the presence of mineral acids phenylhydroxylamine undergoes rearrangement to form p-arni nophenol. 

Gattermann subsequently proved that phenylhydroxyl-amine is the primary reduction product, and this was demonstrated by causing it to combine with benzaldehyde (which was present during reduction) as fast as formed, giving benzylidene-phenylhydroxylamine —... 

A withdrawal of oxygen and addition of hydrogen occurs simultaneously in the reduction of nitrobenzene to phenylhydroxyl-amine ... 

It is evident that the whole connection between experimental conditions and the obtainable reduction phase is regulated by the reaction velocities of the competing processes. The possibility of the formation of each reduction product is always present in the reduction of nitrobenzene only those products, however, can become the principal products which are so rapidly produced that the other possible processes cannot find time to take place to any appreciable extent. Thus only aniline will be principally produced if the intermediately occurring phenylhydroxylamine is not rearranged more quickly than the reduction takes place. Inversely, to obtain amidophenol, the rearrangement velocity must be so increased that the reduction velocity of phenylhydroxyl-amine will be trifling. 

A complication for the preparation of / -aminophenol (XIX) from phenylhydroxyl-amine, regardless of how the latter is prepared, is that XIX may act as a nucleophile in competition with water with the formation of 4,4 -diaminodiphenyloxide (XX) [119] the yield of XX increases with increasing concentrations of XIX. XX is carcinogenic and must be removed carefully from pharmaceutical preparations of XIX to A-acetyl-4-amino-phenol, paracetamol. 

N-Phenylhydroxylamine, mp 83.5-85°C, can be isolated at this stage in 75-85% yields if desired, but it should be borne in mind that N-phenyl hydroxyl amine is not very stable. The isolation can be carried out by adding an equal volume of methylene chloride to the tetrahydrofuran solution which is then dried over magnesium sulfate and concentrated to low volume under reduced pressure. Addition of a little petroleum ether precipitates N-phenylhydroxyl amine which is then filtered and washed with petroleum ether. 

N-Phenylhydroxyl amine Hydroxyl amine, N-phenyl- (8) Benzenamine, N-hydroxy- (9) (100-65-2)... 

The keten-imine PhCOCPh=C=NPh reacts with jV-phenylhydroxyl-amine to yield the isoxazole-imine (334), which spontaneously rearranges to the oxazole-imine (335) by way of an intermediate aziridine. ... 

Some reactive nitrones dimerize to isoxazolidines immediately on formation. Thus, a nitrone 16c, which is prepared from /V-phenylhydroxyl-amine and dimethyl acetylenedicarboxylate, dimerized to isoxazolidine (25).44 A-Phenylhydroxylamine and H-butyraldehyde gives a-(w-propyl)-A-phenylnitrone, which dimerizes in a similar manner.10 ... 

Reaction of phenylhydroxyl amine with benzene. The reaction of phenyl-hydroxylamine (1) with benzene catalyzed with this acid gives (2) and (3) as the major products. When the catalyst is trifluoroacetic acid, (4) becomes the... 

The electrochemical reduction of aromatic nitro compounds has been studied in much greater detail than have aliphatic nitro compounds. The products of reduction are highly dependent on the pH of the electrolyte. In acid solutions the process proceeds via the nitroso and phenylhydroxyl-amine compounds to the amine -... 

No vigorous, exothermic reaction is seen during the addition of acetyl chloride, but the additon should be slow because of the heterogeneous nature of the reaction and the need to destroy efficiently hydrogen chloride as it is formed. The product, like N-phenylhydroxyl amine, is sensitive to... 

Extractant C H qO NF N-(p-Trifluoromethyl)benzoyl-N-phenylhydroxyl amine. Distribution constant ... 

Extractant 426 CgHgO No N-Nitroso-N-phenylhydroxyl amine (cupferron), HA ... 

For example, a small wave due to trace of nitrobenzene, reducible at very positive potentials (at about —0-3 V) at the dropping mercury electrode, can be measured precisely in the presence of a thousandfold or even ten thousandfold excess of phenylhydroxyl-amine, reducible in acid solutions at above —1-0 V. 

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