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All 6 posts | Subject: Methyleneation of Ketones? | Please login to post | Down | |||||
Vibrating_Lights (Hive Addict) 06-18-03 14:33 No 440821 |
Methyleneation of Ketones? | |||||||
In this synth https://www.rhodium.ws/chemistry/methylenation.html ------- 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 60°C 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 80°C 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. ------ Could the Phenylacetone be methyleneated in this this manner without anything reacting with the carbonyl group. Start thinking more like a chemist and less like a criminal |
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Aurelius (Active Asperger Archivist) 06-18-03 19:29 No 440863 |
Yields | |||||||
Yields would probably suffer a little bit, but you could probably do it. Act quickly or not at all. |
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Lilienthal (Moderator) 06-19-03 07:41 No 440973 |
Ketones in the presence of base would ... | |||||||
Ketones in the presence of base would polymerize due to an aldol condensation. Protecting the ketone as an acetal might help. |
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Aurelius (Active Asperger Archivist) 06-19-03 18:37 No 441090 |
Try the reaction | |||||||
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). Act quickly or not at all. |
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Vibrating_Lights (Hive Addict) 06-19-03 21:14 No 441126 |
Phlactamide | |||||||
would the phlactamide be suitable to make the rxn work?? VL_ Start thinking more like a chemist and less like a criminal |
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Aurelius (Active Asperger Archivist) 06-20-03 01:45 No 441178 |
Amide as a protecting group? | |||||||
With low temperatures and quick reaction times you should be ok, but I think the amide might hydrolyze (basic conditions) Act quickly or not at all. |
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