vovan78
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Benzaldehydes to dichlorotoluenes
Does anybody know a mild synthesis for this:
ArC(O)H ------> ArCHCl2
Thanks.
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falconZ
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to try BCl3 (2 h reflux in hexane)
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Tetrahedron Letters
Volume 41, Issue 5 , 29 January 2000, Pages 579-581
Benzaldehyde (2.0 mmol, 0.21 g) is dissolved in hexane (10 mL) at room temperature in a dry flask maintained under a nitrogen atmosphere. Boron
trichloride (2.0 mmol, 2.0 mL of a 1.0 M solution in hexane) is added to the aldehyde solution at room temperature with the immediate formation of a
white precipitate. The reaction mixture is then refluxed for 2h. Water (5 mL) is added to the reaction mixture, the organic layer is separated and the
product isolated by column chromatography (hexanes, silica gel) to yield 0.29 g (90%) of the desired
product.
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vovan78
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Thank you falconZ
It's fine procedure, but I don't have BCl3 in my lab 
In yours article I've found this; it could be useful to someone else:
Generally, PCl5 is used to generate geminal dichlorides(2) Other methods include the use of PhCCl3/FeCl3 (3) SeO2/Me3SiCl (4) SOCl2/DMF (5) and
SOCl2/(Me2N)3PO (6) as chlorination
reagents. Recently, the oxophilic d-block metal chlorides were used to chlorinate aromatic aldehydes.(7)
Ref.
2. Armstrong, D. E.; Richardson, D. H. J. Chem. Soc. 1933, 496.
3. Filimonov, B. F.; Litvinenko, G. S.; Dvorko, G. F. Zh. Obshch. Khim. 1977, 47, 1670.
4. Lee, J. G.; Park, I. S.; Seo, J. W. Bull. Korean Chem. Soc. 1995, 16, 349.
5. Newman, M. S.; Sujeeth, P. K. J. Org. Chem. 1978, 43, 4367.<a
href="http://pubs.acs.org/cgi-bin/abstract.cgi/joceah/1978/43/i22/f-pdf/f_jo00416a027.pdf" class="link">PDF</a>
6. Khurana, J. M.; Mehta, S. Indian J. Chem., Sect. B 1988, 27b, 1128.
7. Firouzabadi, H.; Shiriny, F. Tetrahedron 1996, 52, 14929.
[Edited on 22-1-2007 by vovan78]
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