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Org. Synth. 1962, 42, 26
DOI: 10.15227/orgsyn.042.0026
3-BROMOPHTHALIDE
[1(3H)-Isobenzofuranone, 3-bromo-]
Submitted by I. A. Koten and Robert J. Sauer1.
Checked by R. C. Juola, Marjorie C. Caserio, and John D. Roberts.
1. Procedure
Ten grams (0.075 mole) of phthalide (Note 1), 13.3 g. (0.075 mole) of N-bromosuccinimide (Note 1), and 200 ml. of dry carbon tetrachloride (Note 1) are refluxed for 30 minutes in a 500-ml. flask carrying a reflux condenser equipped with a drying tube containing Drierite. The reaction mixture is exposed to the light of an ordinary 100-watt unfrosted light bulb placed 6–8 in. from the flask. The end of the reaction is indicated by the disappearance of N-bromosuccinimide from the bottom of the flask and accumulation of succinimide at the top of the reaction mixture. The succinimide is removed by filtration and the filtrate concentrated under atmospheric pressure to 15–20 ml. Cooling of this concentrate followed by filtration gives 12–13 g. (75–81%) of crude 3-bromophthalide, m.p. 74–80°. The crude material, when recrystallized from cyclohexane, gives colorless plates, m.p. 78–80° (Note 2),(Note 3),(Note 4).
2. Notes
1. The phthalide used was obtained from Aldrich Chemical Co. It was also prepared by the method of Gardner and Naylor, Org. Syntheses Coll. Vol. 2, 526 (1943). The N-bromosuccinimide was obtained from Arapahoe Chemicals, Inc.
The carbon tetrachloride used is dried over Drierite and filtered or distilled.
2. About 150 ml. of cyclohexane is necessary to recrystallize 12–13 g. of product, and the temperature of the solvent should be kept below 70° to avoid oiling of undissolved material. The recovery is 11–12 g.
3. When pure 3-bromophthalide is allowed to stand, its melting point is depressed, owing apparently to some decomposition. It may, therefore, be desirable to prepare the compound in smaller quantities than specified here. A sample of 3-bromophthalide, prepared by using 20 g. of phthalide and 26.6 g. of N-bromosuccinimide, amounted to 29.8 g. (93.4%) of crude product. Hydrolysis of the crude material2 gave phthalaldehydic acid, m.p. 96–98°.
4. Since one of the checkers developed a serious allergy to 3-bromophthalide, suitable precautions should be taken to avoid its inhalation and contact with the skin.
3. Discussion
3-Bromophthalide has previously been prepared by direct bromination of phthalide over a period of 10–13 hours in yields of 82–83%.2 The procedure above, a modification of the Wohl-Ziegler method, appears to be preferable since it may be completed in 3–4 hours, is applicable to the preparation of small samples, and gives comparable yields.

References and Notes
  1. Department of Chemistry, North Central College, Naperville, Ill. This work was supported by a grant from Research Corporation of New York City.
  2. R. L. Shriner and F. J. Wolf, Org. Syntheses, Coll. Vol. 3, 737 (1955).

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

Drierite

carbon tetrachloride (56-23-5)

cyclohexane (110-82-7)

Succinimide (123-56-8)

Phthalaldehydic acid (119-67-5)

Phthalide (87-41-2)

N-bromosuccinimide (128-08-5)

3-BROMOPHTHALIDE,
1(3H)-Isobenzofuranone, 3-bromo- (6940-49-4)