(Chief Bee)
05-08-03 23:36
No 432203
(Rated as: excellent)
Jones oxidation of 1-o-tolyl-propan-2-ol; 1-o-tolyl-propan-2-one
SyntheticPage 171 (2001) (http://www.syntheticpages.org/browse.ph
Chemicals Used
Chromium trioxide (Lancaster) 1-o-tolyl-propan-2-ol Acetone (GPR) conc H2SO4 (BDH) water
Procedure
Chromium trioxide (12.8 g, 0.128 mol) was dissolved in 18 mL water (142 mL/molCrO3)in a beaker. The resulting solution was cooled to 0°C whereupon 11 mL conc H2SO4 (87 mL/mol CrO3) was added dropwise. The solution was diluted with 36 mL water (285 mL/mol Cr03) and cooled to 0°C. A solution of the alcohol (19.2 g, 0.128 mol) in acetone (80 mL) (600mL/mol CrO3) was cooled to 0°C and the Jones reagent added slowly, maintaining a temperature <20°C.
Stirring was continued for 3 h at 0°C. Sodium bisulfite was added in small portions until the brown colour of the chromic acid had disappeared from the upper layer. The top layer was decanted and the lower layer extracted with ether (2 x 200 mL). The extracts were combined and washed with NaCl solution, dried over MgSO4, filtered and concentrated in vacuo. The resulting brown oil was purified by chromatography on silica gel with petrol:ethyl acetate (10:1) as the eluent yielding the title compound as a yellow oil (14.2g, 75%).
Author's Comments
Although this reaction is very commonly used in synthesis, I found it difficult to find exact conditions when searching. The literature assumes that everyone knows how to make the reagent! Although I have only carried out this reaction once, I found it high yielding and easy to follow.
(Hive Bee)
05-09-03 00:18
No 432206
Although this reaction is very commonly used in synthesis, I found it difficult to find exact conditions when searching. The literature assumes that everyone knows how to make the reagent!
Indeed, your right. The preparation & reaction conditions for the Jones oxidant aren't even included in Vogel. Huh, funny, I learnt about this common oxidation in my first year chemistry course. Mabey the Jones oxidant isn't concidered as the preferable way to go anymore, ... because CrO3 is a suspected carcinogen
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(Daddy)
05-18-03 12:49
No 433908
after reading all those posts in the past years about people inadvertingly ending up with P2Pol when doing certain EASY to perform reactions, and then moaning about what to do with this unwanted byproduct (throwing it in the sink mostly), it should give some people something to rethink hard again.
Simple ways of converting easy to get P2Pols and MDP2Pols come to mind.
It can be done at kgmol scales too. Not much reactions on this important post, are you folks still hybernating?
LT/
WISDOMwillWIN