Manufacturing Process
3-Bromo-N-ethylcinnamamide:
I). A solution of trans-3-bromocinnamoyl chloride (12.3 g) in anhydrous
toluene (150 ml) was added slowly with stirring to a solution of ethylamine
(10 g) in dry ether (100 ml) at room temperature. The reaction mixture was
heated at reflux for 1 hour, and the solvent and excess amine were then
removed under reduced pressure. The residue was triturated with water,
filtered, and recrystallized from ethanol-water to give trans-3-bromo-Nethylcinnamamide, m.p. 89-90°C, as a white crystalline material. NMR and IR
spectra as well as elemental analysis were consistent with the assigned
II). trans-m-Bromocinnamic acid (14.8 g), ethanol (173 ml) and concentrated
sulfuric acid (0.4 ml) were combined and heated at reflux for 15 hours. About
150 ml of the ethanol was distilled off, and the remaining solution was poured
into ice/water (140 ml). The cold mixture was made strongly alkaline with
40% sodium hydroxide and extracted with methylene chloride (4x60 ml). The
combined methylene chloride extract was dried over anhydrous potassium
carbonate. The potassium carbonate was removed by filtration and the solvent
stripped off under reduced pressure. trans-ethyl-3-Bromocinnamate, was
obtained as a partially solidified oil. (IR spectrum was consistent with this
compound).
trans-Ethyl-3-bromocinnamate (8.4 g), ethylamine (6.7 g), methanol (18 ml)
and 4A molecular sieves (1 g) were combined and heated at reflux for ? hour.
The mixture was cooled to about 45°C and sodium methylate (0.6 g) added.
The mixture was then heated at reflux 1? hour and then cooled. It was
acidified with concentrated hydrochloric acid (12 ml). The sieves were
removed by filtration. Ice water was added to the filtrate to precipitate trans
3-bromo-N-ethylcinnamamide, m.p. 89-90°C (after recrystallization from
ethanol/water)
