An aldol condensation using ethanal and benzaldehyde also works if you add your ethanal into a refluxing mixture of benzaldehyde and sodium hydroxide solution. Although, cis/trans (E/Z) isomer mixtures are possible, the trans predominates as it is formed much more quickly. The yield, is not quite the 80%+ expected of most modern lab preparations, but the starting materials are cheap and the procedure is simple.
It will depend on your starting compound. Which initial substances do you means?
http://pubs.acs.org/doi/abs/10.1021/ja01594a065
Claude J. Schmidle , Patricia G. Barnett
J. Am. Chem. Soc., 1956, 78 (13), pp 3209–3210
Cinnamaldehyde is prepared in one step by the oxidation of cinnamyl alcohol using PCC [pyridinium chlorochromate (C5H5NH+ CrO3Cl-)] as the oxidizing agent in DCM (dichloromethane). The reaction system is subjected to reflux & stirring (using a magnetic bar) for about 20 minutes. The reaction is selective , i.e. the double bond is nearly not affected & it will not undergo further oxidation towards the carboxylic acid.
Convenient preparations of the desired aldehyde from the corresponding alcohol are described in the following references:
L-Proline: an efficient N,O-bidentate ligand for copper-catalyzed aerobic oxidation of primary and secondary benzylic alcohols at room temperature
Chem. Commun., 2013,49, 7908-7910
Efficient oxidation of arylmethylene compounds using nano-MnO2
Tetrahedron Letters
Volume 54, Issue 15, 10 April 2013, Pages 2010–2013
An aldol condensation using ethanal and benzaldehyde also works if you add your ethanal into a refluxing mixture of benzaldehyde and sodium hydroxide solution. Although, cis/trans (E/Z) isomer mixtures are possible, the trans predominates as it is formed much more quickly. The yield, is not quite the 80%+ expected of most modern lab preparations, but the starting materials are cheap and the procedure is simple.
An addition to method provided by Paul Carolan: u can use DBU instead NaOH. Yields are around 70%
Source:
Article One-Pot Synthesis of (R)-Baclofen via Aldol Condensation of ...
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