2-Thiopheneglyoxylic acid → 2-Hydroxyimino(thien-2-yl)acetic acid

Beteiligte Stoffe

Reaktionsschritte

A cooled solution of hydroxylamine hydrochloride (0.884 g) and sodium bicarbonate (1.08 g) in water (20 ml.) was added to a cooled (0°) solution of thien-2-yl-glyoxylic acid (2.0 g) and sodium bicarbonate (1.08 g) in water (20 ml.). After two days at 20° the solution was extracted with ether, cooled and acidified with concentrated hydrochloric acid. The resulting white solid was filtered off (0.564 g) and the filtrate was then thoroughly extracted with ether. The combined extracts were washed with brine, dried and concentrated. The solid residue was triturated with benzene to give the oxime (syn-isomer) (1.05 g; 51%), m.p. 132°, λmax. (ethanol) 284 nm (ε 9,500), λmax. (Nujol) 2590 and 1706 (CO2H) and 1655 cm-1 (C=N), τ (DMSO-d6), -2.5 to -0.5 (broad multiplet; N--OH and COOH), 2.36 (multiplet; thienyl C-5 H) and 2.82 (multiplet; thienyl C-3 H and C-4 H).

Herkunft & Nachweise