rapidly and with high selectivity. These two processes can easily
offer a-monochlorinated acetophenones and b-ketoesters or
a,a-dichlorinated acetophenones and b-ketoesters with high
selectivity; and these two processes, that are greener than the
previous methods, using DCDMH are easy to scale up in
industry.
white solid 3g: 0.65 g (yield 93%). mp: 138–140 ◦C. A white
crystal was obtained by recrystallation from methanol. mp: 144–
145 ◦C (methanol).1H NMR (CDCl3, 500 MHz) d: 6.70 (s, 1H,
CHCl2), 7.52 (d, J= 8.5 Hz, 2H, ArH), 7.64 (d, J= 8.5 Hz,
2H, ArH), 7.72 (d, J= 8.5 Hz, 2H, ArH), 8.20 (d, J= 8.5 Hz,
2H, ArH). 13C NMR (CDCl3, 500 MHz) d: 67.9 (CHCl2), 123.2
(ArCBr), 127.3 (ArCH), 128.9 (ArCH), 129.3 (ArCH), 130.5
(ArCH), 132.3 (ArCH), 138.3 (ArCH), 146.0 (ArCH), 185.5
(CO). Element Analysis: found: C, 48.71%; H, 2.70%. Calculated
for C14H9BrCl2O (344.03): C, 48.83%; H, 2.62%.
Experimental
Typical procedure for preparation of a-chloroacetophenone (2a)
Silica gel (0.1 g) and DCDMH (1.48 g, 7.5 mmol) were added
into a mixture of 1a (1.2 g, 10 mmol) and methanol (10 ml)
in a flask equipped with a magnetic stirring bar. The solution
was heated at reflux for 1 hour and then was cooled to room
temperature. After the mixture was filtered, solvent was distilled
under reduced pressure and MTBE (20 ml) was added to the
residue. The MTBE layer was washed twice by water (20 ml)
and was dried over MgSO4. After that, the organic layer was
filtered and solvent was removed under reduced pressure. The
product was obtained as a white solid (1.5 g, 97% yield). mp:
51–52 ◦C (lit: 51–52 ◦C).15 1H NMR (CDCl3, 500 MHz): d 4.72
(s, 2H, CH2Cl), 7.51 (t, J= 7.8 Hz, 2H, ArH), 7.63 (t, J= 7.4 Hz,
1H, ArH), 7.96–7.98 (m, 2H, ArH).25
Acknowledgements
The authors thank Shanghai Foundation of Science and Tech-
nology for financial support (No. 073919106).
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1
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278 | Green Chem., 2009, 11, 275–278
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