Anthranilic acid

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Anthranilic acid
Skeletal formula Anthranilic acid molecule
Identifiers
CAS number 118-92-3 YesY
PubChem 227
ChemSpider 222 YesY
EC number 204-287-5
DrugBank DB04056
KEGG C00108 YesY
ChEBI CHEBI:30754 YesY
ChEMBL CHEMBL14173 YesY
RTECS number CB2450000
Jmol-3D images Image 1
Image 2
Properties
Molecular formula C7H7NO2
Molar mass 137.14 g mol−1
Appearance white or yellow solid
Odor odorless
Density 1.412 g/cm3
Melting point 146 to 148 °C (295 to 298 °F; 419 to 421 K)[1]
Boiling point 200 °C (392 °F; 473 K) (sublimes)
Solubility in water 0.572 g/100 mL (25 °C)
Solubility very soluble in chloroform, pyridine
soluble in ethanol, ether, ethyl ether
slightly soluble in trifluoroacetic acid, benzene
log P 1.21
Vapor pressure 0.1 Pa (52.6 °C)
Acidity (pKa) 2.14
Refractive index (nD) 1.578 (144 °C)
Thermochemistry
Std enthalpy of
formation
ΔfHo298
-380.4 KJ/mol
Hazards
MSDS External MSDS
R-phrases R36 R37
S-phrases S26 S39
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point > 150 °C (302 °F; 423 K)
Autoignition temperature > 530 °C (986 °F; 803 K)
LD50 1400 mg/kg (oral, rat)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Anthranilic acid (or o-amino-benzoic acid) is an aromatic acid with the formula C6H4(NH2)(CO2H). The molecule consists of a substituted benzene ring, hence is classed as aromatic, with two adjacent, or "ortho-" functional groups, a carboxylic acid and an amine. The compound is consequently amphoteric. In appearance, anthranilic acid is a white solid when pure, although commercial samples may appear yellow. It is sometimes referred to as vitamin L1 and has a sweetish taste.[2] The anion [C6H4(NH2)(CO2)]-, obtained by the deprotonation of anthranilic acid, is called anthranilate.

Structure[edit]

Although not usually referred to as such, it is an amino acid. Solid anthranilic acid consists of both the amino-carboxylic acid and the zwitterionic ammonium carboxylate forms.[3]

Production[edit]

Many routes to anthranilic acid have been described. Industrially it is produced from phthalic anhydride, beginning with amination:

C6H4(CO)2O + NH3 + NaOH → C6H4(C(O)NH2)CO2Na + H2O

The resulting sodium salt of phthalamic acid is decarbonylated via a Hofmann rearrangement of the amide group, induced by hypochlorite:[4]

C6H4(C(O)NH2)CO2Na + HOCl → C6H4NH2CO2H + NaCl + CO2

A related method involves treating phthalimide with sodium hypobromite in aqueous sodium hydroxide, followed by neutralization.[5] In the era when indigo dye was obtained from plants, it was degraded to give anthranilic acid.

Biosynthesis[edit]

anthranilate is the precursor to the amino acid tryptophan.

Anthranilic acid is biosynthesized from chorismic acid. It is the precursor to the amino acid tryptophan via the attachment of phosphoribosyl pyrophosphate to the amine group.

Uses[edit]

Industrially, anthranilic acid is an intermediate in the production of azo dyes and saccharin. It and its esters are used in preparing perfumes to imitate jasmine and orange, pharmaceuticals (loop diuretics e.g. furosemide) and UV-absorber as well as corrosion inhibitors for metals and mold inhibitors in soya sauce.

Anthranilic acid can be used in organic synthesis to generate benzyne.[6]

It is also a DEA List I Chemical because of its use in making the now-widely outlawed euphoric sedative drug methaqualone (Quaalude, Mandrax).[7]

It has been suggested that anthranilate esters could be efficient insect repellents, replacing DEET.

See also[edit]

References[edit]

  1. ^ IPCS
  2. ^ The Merck Index, 10th Ed. (1983), p.62., Rahway: Merck & Co.
  3. ^ C. J. Brown "The Crystal Structure of Anthranilic Acid" Proc. Royal Society of London A, 1968, vol. 302, pp. 185-199. doi:10.1098/rspa.1968.0003
  4. ^ Takao Maki, Kazuo Takeda "Benzoic Acid and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a03_555.
  5. ^ Vogel's Textbook of Practical Organic Chemistry, 4th Ed., (B. S. Furniss et al., Eds.) (1978), p.666, London: Longman.
  6. ^ Logullo, F. M.; Seitz, A. H.; Friedman, L. (1973), "Benzenediazonium-2-carboxy- and Biphenylene", Org. Synth. ; Coll. Vol. 5: 54 
  7. ^ Angelos SA, Meyers JA. The isolation and identification of precursors and reaction products in the clandestine manufacture of methaqualone and mecloqualone. Journal of Forensic Sciences 1985 Oct;30(4):1022-47. PMID 3840834