Phenylarsonic acid

Phenylarsonic acid is the chemical compound with the formula C₆H₅AsO(OH)₂, commonly abbreviated PhAsO₃H₂. This colourless solid is an organic derivative of arsenic acid, AsO(OH)₃, where one OH group has been replaced by a phenyl group. The compound is a buffering agent and a precursor to other organoarsenic compounds, some of which are used in animal nutrition, e.g. 4-hydroxy-3-nitrobenzenearsonic acid.

Phenylarsonic acid

Stereo structural formula of phenylarsonic acid
Names
Preferred IUPAC name Phenylarsonic acid
Other names Benzenearsonic acid
Identifiers
CAS Number	98-05-5^Y
3D model (JSmol)	Interactive image
Abbreviations	PAA
Beilstein Reference	2935741
ChEBI	CHEBI:29851
ChEMBL	ChEMBL364571
ChemSpider	7087^Y
ECHA InfoCard	100.002.393
EC Number	202-631-9
Gmelin Reference	131185
MeSH	Benzenearsonic+acid
PubChem CID	7365
RTECS number	CY3150000
UNII	57F9KU116M^Y
UN number	1557
CompTox Dashboard (EPA)	DTXSID6059158
InChI InChI=1S/C6H7AsO3/c8-7(9,10)6-4-2-1-3-5-6/h1-5H,(H2,8,9,10)^Y Key: LVKZSFMYNWRPJX-UHFFFAOYSA-N^Y
SMILES O[As](O)(=O)C1=CC=CC=C1
Properties
Chemical formula	C6H7AsO3
Molar mass	202.041 g·mol^−1
Appearance	Colourless solid
Density	1.76 g cm^−3
Melting point	154 to 158 °C (309 to 316 °F; 427 to 431 K)
Solubility in water	low
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Toxic
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation and structure

PhAsO₃H₂ can be prepared in several routes, but a common one entails treatment of phenyl diazonium salts with sodium arsenite (prepared from arsenious acid and base) in the presence of a copper(II) catalyst.^[1]

C
₆H
₅N⁺
₂ + NaAsO₃H₂ → C₆H₅AsO₃H₂ + Na⁺ + N₂

Related derivatives are prepared similarly.^[2] It was first prepared by Michaelis and Loenser.^[3][4][5] X-ray crystallography indicates that the molecules are connected by hydrogen-bonds consistent with short distance of 2.5 Å separating the oxygen atoms. The arsenic center is tetrahedral.^[6]

Related phenylarsonic acids

Several derivatives of phenylarsonic acid have been used as additives for animal feeds. These include 4-hydroxy-3-nitrobenzenearsonic acid (3-NHPAA, or Roxarsone), p-arsanilic acid (p-ASA), 4-nitrophenylarsonic acid (4-NPAA), and p-ureidophenylarsonic acid (p-UPAA).

References

1. Bullard, R. H.; Dickey, J. B. "Phenylarsonic Acid" Organic Syntheses, Collected Volume 2, pages 494 (1943). http://www.orgsyn.org/orgsyn/pdfs/CV2P0494.pdf
2. Ruddy, A. W.; Starkey, E. B. "p-Nitrophenylarsonic Acid" Organic Syntheses, Collected Volume 3, pp. 665 (1955). (PDF). Archived from the original (PDF) on 2007-09-30. Retrieved 2007-04-19.{{cite web}}: CS1 maint: archived copy as title (link)
3. A. Michaelis; H. Loesner (1877). "Ueber nitrirte Phenylarsenverbindungen". Berichte der Deutschen Chemischen Gesellschaft. 27: 263–272. doi:10.1002/cber.18940270151.
4. A. Michaelis (1875). "Ueber aromatische Arsenverbindungen". Berichte der Deutschen Chemischen Gesellschaft. 8 (2): 1316–1317. doi:10.1002/cber.187500802125.
5. A. Michaelis; W. La Coste; A. Michaelis (1880). "Ueber die Verbindungen der Elemente der Stickstoffgruppe mit den Radicalen der aromatischen Reihe. Dritte Abhandlung: Ueber aromatische Arsenverbindungen". Annalen der Chemie. 201 (2–3): 184–261. doi:10.1002/jlac.18802010204.
6. Struchkov, Yu. T. "Crystal and molecular structure of phenylarsonic acid" Russian Chemical Bulletin 1960, Volume 9, 1829-1833. doi:10.1007/BF00907739