[529-23-7] C₇H₇NO (MW 121)

InChI = 1S/C7H7NO/c8-7-4-2-1-3-6(7)5-9/h1-5H,8H2

InChIKey = FXWFZIRWWNPPOV-UHFFFAOYSA-N

(Friedländer synthon; quinoline synthesis; o-amino aldehyde)

Alternate Names: 2-formylaniline; 1-amino-2-formylbenzene.

Physical Data: mp 38–39 °C.

Solubility: sol ether, alcohol.

Preparative Methods: the reagent is best when freshly prepared. At one time it was commercially available but samples more than a few months old were found to be essentially useless due to oligomerization. The propensity of the reagent to self-react and the resulting oligomer structures have been extensively discussed.^1a A useful preparative method involves Iron(II) Sulfate reduction of 2-nitrobenzaldehyde.² The key to success is limiting the reaction time to 8–10 min and immediate, rapid steam distillation of the reaction product. The precursor is commercially available from a variety of sources and its preparation has also been reported.³ A supposedly simplified procedure has been suggested but it does not differ significantly from the earlier method.⁴

Purification: can be effected by steam distillation from saturated NaCl solution.

Handling, Storage, and Precautions: the reagent can be stored for periods of up to several months under an inert atmosphere at 0 °C in the dark. The mp is a good general indicator of purity and the NMR spectrum should show an aldehyde proton integrating 1∶4 against the aromatic protons. Use in a fume hood.