seba
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Green oxidation of alcohols to symetrical esters with Oxone/NaCl
I've found out this cool reaction and tried it on ethanol.
It forms symetrical esters from primary alcohols and aldehydes out of benzylic alcohols.
I've used 10 mmol of ethanol, 10 mmol oxone, 1 mmol NaCl, 5 mL water. Stirred for about 5 h at RT. Smelled like EtOAc. Added more NaCl to separate
EtOAc out. A thin layer formed (after some time).
Original article:
Agnes Schulze , Georgia Pagona & Athanassios Giannis (2006) Oxone/Sodium Chloride:
A Simple and Efficient Catalytic System for the Oxidation of Alcohols to Symmetric Esters and Ketones,
Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
36:9, 1147-1156
To link to this article: http://dx.doi.org/10.1080/00397910500514030
[Edited on 21-3-2014 by seba]
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thesmug
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Cool! Do you have any pictures?
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Chemosynthesis
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Agreed: very cool!
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Etaoin Shrdlu
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I'm more interested in the possibilities for ketones personally, but this is awesome! Good find.
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seba
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Works for sec-alcohols (transformation into ketones) as well, although I haven't tried it yet.
The benzylic to aldehyde is also interesting. You can make from benzyl alcohol benzaldehyde very easily.
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AvBaeyer
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You may also find this interesting:
Facile Oxidation of Aldehydes to Acids and Esters with Oxone
Benjamin R. Travis, Meenakshi Sivakumar, G. Olatunji Hollist and Babak Borhan*
*Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, Email: borhan cem.msu.edu
B. R. Travis, M. Sivakumar, G. O. Hollist, B. Borhan,
Org. Lett., 2003, 5, 1031-1034.
DOI: 10.1021/ol0340078 (free Supporting Information)
Abstract
Highly efficient, mild, and simple protocols allow the oxidation of aldehydes to carboxylic acids and esters utilizing Oxone as the sole oxidant.
These reactions may prove to be valuable alternatives to traditional metal-mediated oxidations.
General Procedure for Oxidation of Aldehyde to Carboxylic Acid: The aldehyde (1 equiv)
was dissolved in DMF (0.1 M). Oxone (1 equiv) was added in one portion and stirred at RT for 3 h. The reactions were monitored by TLC and GC analysis.
1N HCl was used to dissolve the salts and EtOAc was added to extract the products. The organic extract was washed with 1N HCl (3x) and brine, dried
over Na2SO4, and the solvent was removed under reduced pressure to obtain the crude product. Products were purified by silica gel column
chromatography.
General Procedure for Oxidation of Aldehydes to Esters: The aldehyde (1 equiv) was
dissolved in the appropriate alcoholic solvent (0.1 M). Oxone (1 equiv) was added and stirred at RT for 18 h. The reaction was monitored by TLC and GC
analysis. 1N HCl was used to dissolve the salts and EtOAc was added to extract the products. The organic extract was washed with 1N HCl (3x) and
brine, dried over Na2SO4, and the solvent was removed under reduced pressure to obtain the crude product. Products were purified by silica gel column
chromatography.
AvB
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seba
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Yes I knew that reaction, but it didn't work for alcohols. That's why I went searching around about a possible modification.
I have also an idea about a kind of similar reaction, which I didn't yet find specifically mentioned in literature, which might work. I'll report
soon, but I must get a reagent first.
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smaerd
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Very nice. How was the yield if you don't mind sharing?
Warms my heart to see a repeatable green chem. reaction. Green chemistry publications are all too often over-looked but in general offer methods very
feasible to an at home scientist.
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S.C. Wack
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BTW JOC 25, 1901 (1960)
...The KHSO5-KHSO4-K2S04 mixture readily converts 2-propanol to acetone and ethanol to acetic acid (or to ethyl acetate if an excess of ethanol is
used)...
[procedure/method #] 5. Acetone. A 1-l. three necked flask was fitted with a total condensate, variable take-off distilling head, a mechanical stirrer
and an addition funnel. The flask was charged with the KHSO5-KHSO4-K2SO4 (50.0 g.) and 2-propanol (200 ml.). The stirrer was started and concentrated
sulfuric acid [amount unsaid here or in text] added at such a rate that the temperature of the reaction mixture was maintained at about 70C. A liquid,
b.p. 57-65C, was distilled from the reaction flask. This liquid was redistilled through an 18-inch, silver mirrored Vigreux column...The distilled
acetone obtained weighed 10.2 g. [100%]
Ethanol was treated similarly. No acetaldehyde distilled from the reaction flask, but ethyl acetate was recovered from the reaction mixture.
[conversion and yield 100% based on KHSO5]
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Polverone
Now celebrating 21 years of madness
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Thread Split
15-11-2014 at 12:51 |
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