Oximation of pentafluorobenzaldehyde ; pentafluorobenzaldoxime
SyntheticPage 169
DOI:
10.1039/SP169
Submitted Oct 31, 2001, published Nov 05, 2001
Chemicals Used
pentafluorobenzaldehyde,
water,
hydroxylamine hydrochloride,
sodium carbonate,
ethanol
Procedure
To hydroxylamine (15 g; 0.22 mol) in water (200 cm3) was added pentafluorobenzaldehyde (12 g; 0.061 mol) in ethanol (30 cm3). The mixture was stirred vigorously, and sodium carbonate (23 g) added portionwise. After stirring over night, the mixture was cooled to 0 oC and the solid filtered and recrystallised (DCM) to give product as white crystals (12.68 g; 98%)
Author's Comments
Literature procedure doesn't involve recrystallisation, and product is obtained fairly pure without it. The crystals are slightly yellow without recrystallisation.
The product is the syn isomer (see Pejkovic-Tadic et al. Helv. Chim. Acta, 1965, 48, 1157).
Other oximes were prepared by slightly different methods, and are reported separately.
The reaction was performed only once.
Data
1H nmr (CDCl3) 8.24 (1H, s), 9.09 (1H, s)
m.p. 131-133 oC (Lit 132-133 o C [Aroskar et al.])
Lead Reference
A. J. McCarroll and J. C. Walton, J. Chem. Soc. Perkin Trans. 2, 2000, 1868.
Other References
E. V. Aroskar, P. J. N. Brown, R. G. Plevey and R. Stephens, J. Chem. Soc. (C), 1968, 1569.
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Keywords: oxime, hydroxylamine hydrochloride, 169