JOURNAL OF CHEMICAL RESEARCH 2007 413
Table 1 Continued
Entry Substrate
Product
Time/min
40
B.P./°C)
Yielda
Obsd
Lit
1
5
60–62/15c
192–194c
82
NOH
NOH
O
O
1
6
35
48–50b
47–51b
85
a
b
c
Isolated yields; melting point of compounds; boiling point under reduced pressure at mm Hg.
All the products were compared with authentic sample and gave satisfactory IR, NMR and MS data
The purity of the products which have different boiling points to their literature values, were checked by GC and TLC. R value and
f
retention time was matched with authentic samples. On distillation of these compounds at atmospheric pressure, it was observed
that yields of the products were reduced by 8–15%.
oxidation of the regenerated aldehydes. The method showed
chemo-selectivity. The oxidative deoximation of benzoin
(3 min). Helium was used as the carrier gas at a constant flow rate
of 1.2 ml/min. The samples were analysed in the splitless mode at
injection temperature of 250°C, EI source temperature 230°C and
quadrupole analyser at 150°C.
(entry 8) and the unsaturated oxime (cinnamaldoxime, entry
7
) proceeded without affecting the hydroxyl group and double
bond respectively. In order to examine the chemo-selectivity
of the method further, two sets of experiments were performed
under similar reaction conditions. In the first set of experiments,
an equimolar mixture of benzophenone oxime and styrene
were allowed to react with CC-2. The benzophenone oxime
under went chemo-selective deoximation giving 85%
benzophenone without any observable oxidation of styrene.
Similarly in another experiment, an equimolor mixture of
benzophenone oxime and benzyl alcohol, were allowed to
react with CC-2 at room temperature. The benzophenone
oxime underwent chemoselective oxidative deoximation
giving (85%) benzophenone, whereas benzyl alcohol was
recovered almost quantitatively. It indicated non-competitive
oxidation of oximes in the presence of hydroxyl group as well
as with a double bond.
Typical experimental procedure
In a typical experimental procedure, a solution of benzophenone
oxime, 9.85 g (0.05 mol) in 50 ml acetonitrile was added slowly to
a suspension of CC-2, 12.2 g (0.025 mol) in 25 ml acetonitrile–H O
2
mixture (8:2) with stirring at room temperature. The progress of
the reaction was monitored by TLC. The completion of reaction
was also indicated by ceasing the precipitation of bis-(2,4,
6
-trichlorophenyl) urea. The reaction mixture was filtered by suction
and washed with acetonitrile (4 × 10 ml). The solvent was evaporated
and the residue was cooled under ice cold which gave crude solid
product followed by recrystallisation from diethyl ether to afford
pure crystals of benzophenone; yield: 7.74 g (85%), m.p. 47–48°C
(lit 46–48°C).
WethankDrR.Vijayaraghavan,Director,andProf.M.P.Kaushik,
Associate Director, DRDE, Gwalior, for their keen interest,
encouragement and fruitful discussion.
In conclusion, we describe a simple, mild, convenient and
chemo-selective method for the oxidative deoximation of
oximes by the use of CC-2. The hydroxyl and alkene groups
are not affected. Finally the dechlorinated product (4) can be
converted to (2) by rechlorination and could be reused several
times making it recyclable.
Received 21 April 2007; accepted 6 June 2007
Paper 07/4615 doi: 10.3184/030823407X218093
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PAPER: 07/4615