Manufacturing Process
The starting product 2-ethyl-3-benzofuranyl p-hydroxyphenyl ketone
(benzaron) was prepared in 4 steps:
1. First step was a reaction of salicylic aldehyde with chloroacetone to produce
2-acetyl-1-benzofuran.
2. It was reduced by hydrazine hydrate in an alkaline medium by process of
Hyuang-Minlon, J.A.C.S., 1946, 68, 2487 to give 2-ethyl-1-benzofurane.
3. 2-Ethyl-3-(4-methoxybenzoyl)-1-benzofuran was obtained from 2-ethyl-1-
benzofuran and 4-methoxy-benzoylchloride in a presence of tin tetrachloride.
4. It was heated with pyridine hydrochloride at 200°-220°C to give 2-ethyl-3-
benzofuranyl p-hydroxyphenyl ketone (benzaron) as described in N.P.B.Hoi,
C.Beaudet; US Patent No. 3,012,042; Dec. 5, 1961.
Benzaron (1 part) was dissolved in a very slight excess of 3% caustic soda. To
this solution is gradually added a slight excess of iodine dissolved in a 25%
aqueous solution of potassium iodide. The resultant solution is acidified with a
20% solution of sodium bisulphite, centrifuged, washed with water and then
recrystallized in acetic acid to give of 2-ethyl-3-benzofuranyl 4-hydroxy-3,5-
diiodophenyl ketone. MP: 167°C.
