Preparation of 4-methylpropiophenone 1
73g aluminium chloride
300mL dichloroethane
46mL propionyl chloride
54mL toluene
600mL iced water
200mL 5% NaOH solution
Magnesium sulfate
54mL (500mmol, 46g) toluene was added over 30 minutes to a solution of 73g (550mmol) anhydrous aluminium chloride and 46mL (525mmol, 49g)propionyl chloride in 200ml dichloroethane cooled via an external ice bath. The solution was allowed to stir for a further 1.5 hours at 20oC, and wasthen carefully added to 500mL stirred iced water. The lower dichloroethane layer was separated off, and the aqueous layer extracted with 2x50mLdichloroethane. The combined extracts were washed with 2x100mL 5% NaOH, 100ml water, and then dried over magnesium sulfate. The solvent wasremoved, and the ketone vacuum distilled at 123-126oC, to give 1-(4-methylphenyl)-propan-1-one as a colourless oil.Yield: 70.0g (95%)
Comments:
Wash with 3x100mL 5% NaOH instead of 2x100mL.DCM should be a better solvent, simply because it is easier to remove under vacuum.
4-methylpropiophenone to 2-bromo-4’-methylpropiophenone 1,2
38mL 4-methylpropiophenone
1mL 48% HBr
14mL bromine
125mL glacial acetic acid
650mL water
300mL dichloroethane
Magnesium sulfate
To a solution of 38mL (250mmol, 37g) 4-methylpropiphenone in 125mL glacial acetic acid was added 1mL 48% HBr followed by, over the course of anhour, 14mL (275mmol, 44g) elemental bromine. The reaction mixture, which changed to a nice pink colour during addition, was stirred for a further 1.5hours, then slowly poured into 500mL ice-cold water, with swirling after each careful addition. The cream-coloured precipitated product was taken up in200mL dichloroethane, and the aqueous layer extracted with 100mL dichloroethane. The combined extracts were washed with 2x250mL cold water,then dried over magnesium sulfate. The solvent was removed under vacuum, taking care to keep the temperature below 50oC, leaving a turquoise oil,2-bromo-(4’-methylphenyl)-propan-1-one, which solidified almost immediately on cooling, into sparkling waxy crystals.Yield: 57g (100%)
Comments:
Try and keep the temperature below 30oC when removing the solvent – coloured crystals indicate some decomposition (above were avery light colour, so only mild). DCM would be a better extraction solvent since it could be stripped off at a lower temperature, causing lessdecomposition.
нормально так мажет метильная мулька)) и выход хороший 
