Hydroxystilbamidin,Merrell National,US,1954
Preparation of 2-Nitro-4,4'-Dicyanostilbene: 10 grams of 2-nitro-ptolunitrileand 8.1 grams of 4-cyano-benzaldehyde were heated to 170° to
180°C, 1.2 and 0.6 cc of piperidine were added at quarter-hour intervals,
heating was continued for a further one and a quarter hours, the product
cooled, triturated with glacial acetic acid and filtered. The residue was
crystallized from glacial acetic acid as yellow needles, MP 290°C.
Preparation of 2-Amino-4,4'-Dicyanostilbene: 10.0 grams of 2-nitro-4,4'-
dicyanostilbene thus prepared were suspended in 200 cc of glacial acetic acid
and a hot solution of 50 grams of stannous chloride (SnCl2 · 2H2O) in 50 cc of
concentrated hydrochloric acid was quickly added. Rapid reaction occurred and
the boiling was continued for a further 4 minutes, the reaction mixture was
cooled, filtered, and the stannous chloride residue decomposed with 25%
aqueous caustic soda solution. The liberated amine crystallized from glacial
acetic acid as yellow needles, MP 232°C.
Preparation of 2-Hydroxy-4,4'-Dicyanostilbene: 10 grams of 2-amino-4,4'-
dicyanostilbene thus prepared were dissolved in 400 cc of boiling glacial acetic
acid and 200 cc of dilute sulfuric acid added; the solution was suddenly chilled
and diazotized over one and a half hours at 5° to 10°C with sodium nitrate
(3.0 grams/15 cc H2O). The diazonium salt solution was decomposed by boiling for 15 minutes with 600 cc of 55% aqueous sulfuric acid solution; the
solution was diluted, cooled and filtered. The residue crystallized from ethyl
alcohol as lemon yellow prismatic needles, MP 296°C
Preparation of 2-Hydroxy -4,4'-Diamidinostilbene Dihydrochloride: 10 grams of
2-hydroxy-4,4'-dicyanostilbene were suspended in 250 cc of absolute ethyl
alcohol and the mixture saturated with dry hydrogen chloride at 0°C. The
whole was left for eight days at room temperature. The imino-ether
hydrochloride formed was filtered off, washed with dry ether and dried in the
air for a short time. It was then added to 250 cc of 10% ethyl alcoholic
ammonia and the whole heated for 5 hours at 45°C. The 2-hydroxy-4,4'-
diamidinostilbene dihydrochloride which separated was crystallized from 10%
hydrochloric acid. It forms pale yellow needles, MP 357°C (decomposition).
Preparation of the Final Isethionate Product: The diisethionate may be
produced by treating a solution of the dihydrochloride with alkali carbonate,
separating and dissolving the resultant base in aqueous isethionic acid and
precipitating the diisethionate with acetone. The product may be purified by
dissolving in hot methyl alcohol containing a trace of water followed by
precipitation by the cautious addition of acetone. The diiseihionate has a MP of
286°C.
