A 500mmol batch of 2,5-dimethoxybenzaldehyde was started yesterday. Procedure was exactly like the first one in this thread. Anhydrous conditions with sodium methoxide as the base.
Yield: 91,5g (94,2%) 2,5-dimethoxyphenylacetone as a yellow oil which becomes slightly orange over a couple of hours in contact with air.
This morning I decided to try a few different benzaldehydes just to see if they would give the corresponding phenylacetones as well. The reactions were not allowed to run full time.
100mmol 2-fluorobenzaldehyde 34% ketone
100mmol 4-fluorobenzaldehyde 38% ketone
100mmol 2,4-dimethoxybenzaldehyde 31% ketone
100mmol 3,4-ethylenedioxybenzaldehyde 42% ketone
Reaction conditions used were:
100mmol aldehyde, 2g aliquat 336, 120mmol NaOH as a 50% aq. soln. and 50ml toluene was stirred at 20 deg C. 105mmol methyl 2-chloropropionate added dropwise during 30 min while temp was kept at 20 deg C. Stirring was continued for 30 min then 150mmol NaOH in 50ml water was added and stirring continued for 1 hour. Phases separated and toulene phase extracted once with 50 ml water. The combined aqueous extracts was acidified to pH 3,5 with diluted HCl, heated to 45 deg C for 20 min, then extracted with 2x 30ml DCM. The combined DCM extractions was dried over MgSO4 and the solvent removed in a rotovap, leaving the ketone as a yellow oil.
I guess we have a winner.....