A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1941, 21, 103
DOI: 10.15227/orgsyn.021.0103
[Acetophenone, 2,4-dihydroxy-]
Submitted by S. R. Cooper
Checked by Nathan L. Drake, Harry D. Anspon, and Ralph Mozingo.
1. Procedure
One hundred and sixty-five grams (1.2 moles) of anhydrous zinc chloride (Note 1) is dissolved with the aid of heat in 165 g. (158 ml., 2.7 moles) of glacial acetic acid, which has been placed in a 1-l. beaker. To this hot mixture (about 140°), 110 g. (1 mole) of resorcinol is added with constant stirring. The solution is heated on a sand bath until it just begins to boil (about 152°). The flame is then removed and the reaction allowed to complete itself at a temperature not in excess of 159° (Note 2). After standing on the sand bath without further heating for 20 minutes, the solution is diluted with a mixture of 250 ml. of concentrated hydrochloric acid and 250 ml. of water. The dark red solution is placed in an ice bath and cooled at 5°. The resulting precipitate is collected on a filter and washed free from zinc salts with 1 l. of dilute (1:3) hydrochloric acid in 200-ml. portions. This orange-red product, after drying, weighs 104–110 g. and melts at 141–143°. It is distilled under reduced pressure (Note 3), and boils at 180–181° at 10 mm. (147–152° at 3–4 mm.). After most of the product has distilled, the temperature rises sharply, and the operation is discontinued when the temperature reaches 190°. The light-yellow distillate is removed from the receiver with hot ethanol and the ethanol is evaporated (Note 4). This product weighs 100–106 g. It is further purified as follows: the substance is dissolved in 1.8 l. of hot dilute (1:11) hydrochloric acid, filtered hot, and cooled to 5°. The crystals are removed by filtration, washed with two 200-ml. portions of ice water, and dried. The yield of tan-colored resacetophenone, melting at 142–144°, is 93–99 g. (61–65%).
2. Notes
1. Although finely ground zinc chloride dissolves more rapidly, lumps or sticks are satisfactory.
2. If the temperature rises much above the initial boiling point, the yield of red product increases at the expense of resacetophenone formation. The boiling point also may vary slightly.
3. Any convenient apparatus for distillation of a solid may be used.
4. It is convenient to remove most of the material by melting and pouring it out of the receiver. The remainder is removed with hot ethanol.
3. Discussion
Resacetophenone has been prepared by heating resorcinol with zinc chloride and acetic acid,1,2 with zinc chloride and acetic anhydride,2 with zinc chloride and acetyl chloride,3 with boron trifluoride and acetic anhydride,4 and with aluminum chloride and acetyl chloride.5 It has been prepared by the action of zinc chloride on resorcinol diacetate,2 by heating 4-methylumbelliferone with potassium hydroxide,6 by heating resacetophenone carbonic acid,7 and by the action of acetyl chloride on resorcinol.8

References and Notes
  1. Robinson and Shah, J. Chem. Soc., 1934, 1491.
  2. Nencki and Sieber, J. prakt. Chem., (2) 23, 147 (1881).
  3. Eijkman, Chem. Weekblad, 1, 453 (1904) [Chem. Zentr., 75, II, 1597 (1904)].
  4. Killelea and Lindwall, J. Am. Chem. Soc., 70, 428 (1948).
  5. Desai and Ekhlas, Proc. Indian Acad. Sci., 8A, 194 (1938).
  6. Pechmann and Duisberg, Ber., 16, 2119 (1883).
  7. Liebermann and Lindenbaum, Ber., 40, 3570 (1907).
  8. Cox, Rec. trav. chim., 50, 848 (1931).

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)


Acetophenone, 2,4-dihydroxy-

resacetophenone carbonic acid

ethanol (64-17-5)

hydrochloric acid (7647-01-0)

acetic acid (64-19-7)

acetic anhydride (108-24-7)

acetyl chloride (75-36-5)

aluminum chloride (3495-54-3)

potassium hydroxide (1310-58-3)

zinc chloride (7646-85-7)

resorcinol (108-46-3)

boron trifluoride (7637-07-2)

4-methylumbelliferone (90-33-5)

resorcinol diacetate (108-58-7)