Phenylhydroxylamine

Phenylhydroxylamine
IUPAC name N-phenylhydroxylamine
Other names beta-henylhydroxylamine; N-hydroxyaniline; phenylhydroxylamine; N-hydroxybenzeneamine; hydroxylaminobenzene
Identifiers
CAS number	100-65-2 Y
Jmol-3D images	Image 1
SMILES ONC1=CC=CC=C1
Properties
Molecular formula	C6H7NO
Molar mass	109.1274 g/mol
Appearance	yellow needles
Melting point	80-81 °C
Related compounds
Related compounds	hydroxylamine, nitrosobenzene
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Phenylhydroxylamine is the organic compound with the formula C₆H₅NHOH. It is an intermediate in the redox-related pair C₆H₅NH₂ and C₆H₅NO. Phenylhydroxylamine should not be confused with its isomer α-phenylhydroxylamine or O-phenylhydroxylamine, is C₆H₅ONH₂.

Preparation and derivatives

This compound can be prepared by the reduction of C₆H₅NO₂ with zinc in the presence of NH₄Cl followed by crystallization as yellowish needles from salt-saturated water.^[1][2] Alternatively, it can be prepared by transfer hydrogenation of C₆H₅NO₂ using hydrazine as an H₂ source over a rhodium catalyst.^[3] The product can be purified from contaminating NaCl by extraction into benzene followed by precipitation with petroleum ether. C₆H₅NHOH is unstable to heating, and in the presence of strong acids easily rearranges to 4-aminophenol. Oxidation of phenylhydroxylamine with dichromate is a useful method of preparation of nitrosobenzene.

The compound condenses with benzaldehyde to form diphenylnitrone, a well-known 1,3-dipole:^[4]

C₆H₅NHOH + C₆H₅CHO → C₆H₅N(O)=CHC₆H₅ + H₂O

References

1. ^ E. Bamberger “Ueber das Phenylhydroxylamin” Chemische Berichte, volume 27 1548-1557 (1894). E. Bamberger, "Ueber die Reduction der Nitroverbindungen" Chemische Berichte, volume 27 1347-1350 (1894) (first report).
2. ^ O. Kamm (1941), "Phenylhydroxylamine", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV1P0445 ; Coll. Vol. 1: 445 
3. ^ P. W. Oxley, B. M. Adger, M. J. Sasse, and M. A. Forth (1993), "N-Acetyl-N-Phenylhydroxylamine via Catalytic Transfer Hydrogenation of Nitrobenzene using Hydrazine and Rhodium on Carbon", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV8P0016 ; Coll. Vol. 16: 16 
4. ^ I. Brüning, R. Grashey, H. Hauck, R. Huisgen, H. Seidl (1973), "2,3,5-Triphenylisoxazolidine", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV5P1124 ; Coll. Vol. 5: 1124