A mixture of
118 g. (1 mole) of succinic acid,
188 g. (2 moles) of phenol, and
138 g. (83 ml., 0.9 mole) of phosphorus oxychloride (Note
1) is placed in a
2-l. round-bottomed flask fitted with an
efficient reflux condenser capped with a
calcium chloride tube (Note
2) and (Note
3). The mixture is heated on a
steam bath in a
hood (Note
3) for 1.25 hours,
500 ml. of benzene is added, and the refluxing is continued for an additional hour. The hot
benzene solution is decanted from the red syrupy residue of
phosphoric acid and filtered by gravity into a
1-l. Erlenmeyer flask. The syrupy residue is extracted with two
100-ml. portions of hot benzene, which are also filtered into the Erlenmeyer flask. The combined
benzene solutions are concentrated to a volume of about 600 ml. (Note
4), and the pale yellow solution is allowed to cool, whereupon the
diphenyl succinate separates as colorless crystals. It is filtered with suction on a
Büchner funnel, washed with three
50-ml. portions of ether, and dried on a porous plate at 40°. The yield of
diphenyl succinate, m.p.
120–121°, is
167–181 g. (
62–67%) (Note
5).