5-Chloro-2-furaldehyde

Furfural (30 mmol) and ZnCl₂ (30 mmol) were dissolved in AcOH (30 mL) and stirred at room temperature. After 1 hour, a small amount of substrate (10 mmol) in acetic acid (5 mL) was added. The mixture was stirred at 70°C for 24 hours and diluted with Et₂O (100 mL), and washed successively with 0.1 N Na₂S₂O₃ (50 mL), 0.1 N NaHCO₃ (20 mL), and brine (20 mL).

The organic phase was dried (Na₂SO₄) to remove the solvent, yielding a crude product. This crude product was purified by column chromatography or vacuum distillation to obtain 5-CHLORO-2-FURALDEHYDE, in 10% yield.

White to yellow powder

5-Chloro-2-furaldehyde may be used as an internal standard during the analysis of furanic compounds by reversed-phase-high performance liquid chromatography–diode array detection (RP-HPLC–DAD) method.

(+)-1-Deoxynojirimycin hydrochloride interferes with normal processing of N-linked glycoproteins, producing reduced amounts of complex type oligosaccharides.

5-Chloro-2-furaldehyde is also known as 5-chlorofurfural. It reacts with aniline and aniline hydrochloride to form bis-(phenylamino) derivatives, without the furan ring cleavage. It also undergoes coupling with ethyl acetoacetate to form the corresponding ethyl bis-acetoacetate.

[1] Chemistry - A European Journal, 2016, vol. 22, # 1, p. 129 - 133
[2] Patent: WO2004/33440, 2004, A1. Location in patent: Page 238
[3] Patent: US2004/147559, 2004, A1. Location in patent: Page 121
[4] Patent: US2004/106794, 2004, A1. Location in patent: Page 122
[5] Patent: WO2005/66147, 2005, A1. Location in patent: Page/Page column 207