[118-92-3] · C7H7NO2 · Anthranilic Acid · (MW 137.14)
Physical Data: mp 144-148 °C; d 1.412 g cm-3.
Solubility: sol EtOH, AcOEt; partially sol water; insol petroleum ether.
Form Supplied in: yellow powder; widely available.
Anthranilic acid can be diazotized to benzenediazonium-2-carboxylate, which is a very useful benzyne precursor. This transformation is usually accomplished under aprotic conditions with Isopentyl Nitrite (caution: isopentyl nitrite is a heart stimulant) (eq 1).1
Anthranilic acid reacts with Phosgene (eq 2)2 or Ethyl 4-Chloroacetoacetate3 to afford isatoic anhydride.2
Benzoxazines have been obtained by treatment of a mixture of anthranilic acid and a substituted benzoic acid with Phosphorus Oxychloride (eq 3).4
Reaction of anthranilic acid with methazonic acid under acid conditions, followed by treatment with sodium acetate/acetic anhydride, leads, in moderate yield, to 3-nitroquinol-4-one (eq 4).5
Acridones can be obtained, by means of the Niementowski modification of the Friedländer synthesis, by heating a mixture of anthranilic acid and a ketone (eq 5).6
Condensation with formanilide yields a benzo-1,3-diazine (eq 6).7
The following interesting reaction between anthranilic acid and a cyclopropylphosphonium salt has also been reported (eq 7).8
Luis Castedo & Enrique Guitián
CSIC & University of Santiago, Spain