Manufacturing Process
Phenylmalonic acid (27 g) was mixed with dry ether (80 ml) and treated with
thionyl chloride (17.85 g, 10.9 ml) and dimethylformamide (4 drops). The
mixture was refluxed for 3 hours on a hot water bath. The solvent was
evaporated under reduced pressure and the residue dissolved in fresh dry
ether (80 ml). Phenol (14.1 g) was added all at once and the mixture refluxed
for 2 hours. The reaction was cooled to room temperature, washed with water
(25 ml) and extracted with saturated sodium bicarbonate solution until the
extracts were alkaline. The combined aqueous extracts were washed with
ether (100 ml) and acidified with 5 N HCl. The precipitated oil was extracted
with methylene chloride. The combined organic extracts were washed
thoroughly with water (6x120 ml) dried over anhydrous magnesium sulphate
and evaporated. The solid residue was crystallised from benzene to give
monophenyl phenylmalonate, a colourless crystalline solid 30.2 g (78.7 %) MP
115-117°C. This product (5.12 g, 0.02 m) was mixed with thionyl chloride (20
ml) and heated in a water bath at 75°C for 1 hour. The excess thionyl chloride
was evaporated under reduced pressure. The residue was mixed with dry
benzene (10 ml) and again evaporated to dryness to remove residual thionyl
chloride. The final residue was dissolved in dry acetone (100 ml) and added,
with stirring, to a solution of 6-aminophenicillanic acid (4.32) in water (100
ml), 1 N sodium hydroxide (20 ml), 1 N sodium bicarbonate solution (30 ml)
and acetone (50 ml) cooled to 12°C. The reaction mixture was stirred for 2
hours. The resulting mixture was stirred at room temperature for 2 hours. The
resulting solution was extracted with ether (3x60 ml) and the extracts
discarded. The aqueous layer was covered with ether (60 ml) and acidified
with 1 N HCl to pH 2. The ether layer was separated and the aqueous layer
extracted with ether (2x60 ml). The combine ether extracts were washed with
water (20 ml) and extracted with 1 N sodium bicarbonate solution to pH 7.
The neutral aqueous extract was evaporated under reduced temperature and
pressure. The residue was dried over phosphorous pentoxide in vacuo to give
6.7 (70.4%) of penicillin salt as an amorphous solid. The solid, when dissolved
in ethanol (50 ml) at room temperature gave on standing 30 min the penicillin
salt as a colorless crystalline solid 5.23 g (78.1 %).
