Vibrating_Lights (Hive Addict)
06-18-03 07:33
No 440821
      Methyleneation of Ketones?  Bookmark   

In this synth
../rhodium/chemistry /methylenation.html
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11.0 grams (0.1 mol) catechol is dissolved in 1000ml of 20% NaOH, and 3.2 grams (0.1 mol) of cetyltrimethylammonium bromide is added. The mixture is heated to 60C for 30 minutes and then allowed to cool to room temperature, whereupon 21.2 grams (0.25 mol) of dichloromethane is added with stirring. The mixture is then heated to 80C with a good reflux condenser for 5 hours, the solution saturated with NaCl and filtered. The solution is then extracted with 3x50 ml CH2Cl2, the pooled extracts washed with 50ml 20% NaOH to remove any phenolic materials, and then with 50 ml brine. The solution is dried over MgSO4, and the solvent removed under vacuum. Yield 90% of 1,3-benzodioxole.
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Could the Phenylacetone be methyleneated in this this manner without anything reacting with the carbonyl group.

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    Aurelius
(Active Asperger Archivist)
06-18-03 12:29
No 440863
      Yields  Bookmark   

Yields would probably suffer a little bit, but you could probably do it.

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    Lilienthal
(Moderator)
06-19-03 00:41
No 440973
      Ketones in the presence of base would ...  Bookmark   

Ketones in the presence of base would polymerize due to an aldol condensation. Protecting the ketone as an acetal might help.
 
 
 
 
    Aurelius
(Active Asperger Archivist)
06-19-03 11:37
No 441090
      Try the reaction  Bookmark   

on a small scale with and without protection to see which gives better overall yields.  If the NaOH is only 20% then I don't think that condensation will predominate.  It will happen, but is it to such a degree as to warrant the use of a protecting agent (adding and removing slightly lowers yields- unless we have a patent that shows quantitative addition and removal).

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    Vibrating_Lights
(Hive Addict)
06-19-03 14:14
No 441126
      Phlactamide  Bookmark   

would the phlactamide be suitable to make the rxn work??
VL_

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    Aurelius
(Active Asperger Archivist)
06-19-03 18:45
No 441178
      Amide as a protecting group?  Bookmark   

With low temperatures and quick reaction times you should be ok, but I think the amide might hydrolyze (basic conditions)

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