Howdy!
From my recent experience, propiophenone is hard to find. So is propionyl chloride but propionic acid is no problem. TFSE said I can use propionic acid and polyphosphoric acid and to look up PIHKAL, so I did. This is what I found first;
#71 DOPR
There was added a solution of 74 g 2,5-dimethoxypropiophenone (from the reaction of propionic acid and p-dimethoxybenzene in the presence of polyphosphoric acid, see under DOAM for an effective general procedure) in 140 g EtOH.
Next I found this;
#61 DOAM
A solution of 110 g p-dimethoxybenzene and 102 g valeric acid in 168 g polyphosphoric acid was heated on the steam bath for 3 h, giving a deep red homogeneous solution. This was poured into 1 L H2O with good stirring. The strongly acidic, cloudy suspension was extracted with 3x200 mL CH2Cl2, the extracts pooled, washed with 4x150 mL 5% NaOH, and finally once with dilute HCl. The solvent was removed under vacuum, and the residual amber oil cooled overnight at 0 °C. Some 30 g of crystalline, unreacted dimethoxybenzene were removed by filtration, and the 85 g of residual oil distilled at the water pump. Another 15 g of di-methoxybenzene came over as an early cut, but the fraction boil-ing at 184-192 °C (mostly 188-192 °C) weighed 53.0 g and was reasonably pure 2,5-dimethoxyamylophenone.
Does this mean that I can use an equal mole amount of propionic acid instead of valeric acid?
Thanks,
FF
