Russian Journal of Applied Chemistry, Vol. 75, No. 3, 2002, pp. 511 512. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 3,
2002, pp. 522 523.
Original Russian Text Copyright
2002 by Osadchenko, Tomilov.
BRIEF
COMMUNICATIONS
Phase-Transfer Catalysis in Synthesis of Oximes
I. M. Osadchenko and A. P. Tomilov
State Research Institute of Organic Chemistry and Technology, Moscow, Russia
Received September 25, 2001
Abstract Perfluorinated higher carboxylic acids were tested as phase-transfer catalysts in synthesis of
oximes.
The known synthetic routes to oximes are based
on reaction of a carbonyl compound with an aqueous
solution of a hydroxylamine salt [1 3] in the presence
of inorganic compounds, e.g., of NaOH:
a desiccator over CaCl to constant weight; 100 g of
acetophenone oxime was obtained, mp 57 C (pub-
lished data [2, 3]: 57 58 C); yield 70%.
2
(b) The reaction was performed similarly to pro-
cedure (a) but in the presence of 0.61 g (1.7 mmol) of
perfluoroenanthic acid with addition of a 20% NaOH
solution at 60 70 C; the mixture was heated at this
temperature for 3.5 h. Yield of acetophenone oxime
131.6 g (98%).
RCR + NH2OH HX + NaOH
O
RCR + H2O + NaX,
NOH
where R = Alk; R = Alk, H, Ar, Ht; X is an inorganic
anion.
(c) The reaction was performed similarly to pro-
cedure (a) but in the presence of 0.61 g (2.3 mmol) of
perfluorovaleric acid; time of heating at 60 70 C 3 h.
Yield of acetophenone oxime 132.3 g (99%).
Because carbonyl compounds, as a rule, are poorly
soluble in water, the reaction is usually performed in
aqueous alcohol. However, the reaction is slow (5
8 h) and does not go to completion even in the pres-
ence of excess hydroxylamine salt. The yield of the
oxime based on the taken carbonyl compound usually
does not exceed 80%.
5-Methyl-3-hexanone oxime. A reaction vessel
[the same as in procedure (a)] was charged with 57 g
(0.8 mol) of 5-methyl-3-hexanone, 39 g (0.56 mol) of
hydroxylamine hydrochloride, 100 ml of water, and
0.6 g (1.65 mmol) of perfluoroenanthic acid; 100 ml
of 25% aqueous NaOH was added, keeping the tem-
perature below 35 C, after which the mixture was
heated to 67 68 C and kept at this temperature for
3 h. After cooling, the upper layer was separated,
washed with three 20-ml portions of cold water, and
distilled in a vacuum (10 12 mm Hg). A fraction
boiling at 85 95 C was collected. Yield of 5-methyl-
To promote the reaction, various phase-transfer
catalysts were tested without using an organic solvent.
We found that the most effective phase-transfer cata-
lysts for oximation are higher perfluorinated car-
boxylic acids exhibiting a high surface activity. Addi-
tion of these compounds (0.07 0.10 wt %) appreciab-
ly shortens the reaction time and allows preparation of
oximes in high, sometimes almost quantitative yields.
This can be illustrated by several examples.
20
3-hexanone oxime 49.7 g (71%); n 1.4424 (pub-
D
20
Acetophenone oxime. (a) A 1-l reaction vessel
equipped with a thermometer, a reflux condenser,
a stirrer, and a dropping funnel was charged with
a solution of 76.5 g (1.1 mol) of hydroxylamine hy-
drochloride in 200 ml of water and 120 g (1.0 mol) of
acetophenone, and a 20% solution of 44 g (1.1 mol)
of NaOH was added dropwise with stirring at 36 C
until pH 7 8 was attained. The mixture was heated at
60 70 C for 5 h and then cooled to 0 3 C. The re-
sulting crystalline precipitate was filtered off, washed
with several portions of ice-cold water, and dried in
lished data [4]: n 1.4436).
D
Salicylaldoxime. Similarly to procedure (a), a
500-ml reactor was charged with 26 g (0.21 mol) of
salicylaldehyde, 16 g (0.21 mol) of hydroxylamine
hydrochloride, 40 ml of water, and 0.2 g (0.55 mol) of
perfluoroenanthic acid; a solution of 9 g (0.225 mol)
of NaOH in 30 ml of water was slowly added, after
which the mixture was heated to 65 70 C and kept at
this temperature for 3 h. After cooling to 5 10 C, the
mixture was worked up similarly to procedure (a).
1070-4272/02/7503-0511$27.00 2002 MAIK Nauka/Interperiodica
Osadchenko
