19005-93-7

Indole-2-carboxaldehyde is a useful starter in indole and natural product chemistry.

Tetrahedron, 36, p. 2505, 1980 DOI: 10.1016/0040-4020(80)80230-4

Recrystallise the indole from aqueous MeOH (m 141-142o), Et2O (m 138o) or sublime it in vacuo (m 138o).The N,N-dimethylhydrazone [127280-17-5] has m 105-106o (from hexane/*C6H6). The thiosemicarbazone has m 229o (dec) (from 50% aqueous EtOH) [Doyle et al. J Chem Soc 2854 1956]. The 2,4-dinitrophenylhydrazone has m 315-320o (dec) (from pyridine/MeOH). [Suzuki et al. Chem Pharm Bull Jpn 39 2170 1991, Beilstein 21 III/IV 3754.]