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Org. Synth. 1963, 43, 62
DOI: 10.15227/orgsyn.043.0062
IODOSOBENZENE DIACETATE
[Benzene, iodoso-, diacetate]
Submitted by J. G. Sharefkin and H. Saltzman1.
Checked by J. Diekmann and B. C. McKusick.
1. Procedure

Caution! Reactions and subsequent operations involving peracids and peroxy compounds should be run behind a safety shield. For relatively fast reactions, the rate of addition of the peroxy compound should be slow enough so that it reacts rapidly and no significant unreacted excess is allowed to build up. The reaction mixture should be stirred efficiently while the peroxy compound is being added, and cooling should generally be provided since many reactions of peroxy compounds are exothermic. New or unfamiliar reactions, particularly those run at elevated temperatures, should be run first on a small scale. Reaction products should never be recovered from the final reaction mixture by distillation until all residual active oxygen compounds (including unreacted peroxy compounds) have been destroyed. Decomposition of active oxygen compounds may be accomplished by the procedure described in Korach, M.; Nielsen, D. R.; Rideout, W. H. Org. Synth. 1962, 42, 50 (Org. Synth. 1973, Coll. Vol. 5, 414). [Note added January 2011].

Caution! Avoid inhaling the vapor of peracetic acid or allowing the liquid to come into contact with the skin. The reaction is best carried out in a hood (Note 1).
The apparatus consists of a 200-ml. beaker equipped with a magnetic stirrer or any other type suitable for stirring a small volume of liquid. The flask is charged with 20.4 g. (0.10 mole) of iodobenzene2 and is immersed in a water bath maintained at 30° (Note 2). Thirty-six grams (31 ml., 0.24 mole) of commercial 40% peracetic acid (Note 3) is added dropwise to the well-stirred iodobenzene over a period of 30–40 minutes. Stirring is continued for another 20 minutes at a bath temperature of 30°, during which time a homogeneous yellow solution is formed. Crystallization of iodosobenzene diacetate may begin during this period.
The beaker is chilled in an ice bath for 1 hour. The crystalline diacetate that separates is collected on a Büchner funnel and washed with three 20-ml. portions of cold water. After drying for 30 minutes on the funnel with suction, the diacetate is dried overnight in a vacuum desiccator containing calcium chloride (Note 4). The dried diacetate weighs 26.7–29.3 g. (83–91%) and melts at 158–159° with decomposition. The purity of the diacetate, determined by the titration method of Lucas, Kennedy, and Formo,3 is 97–98%, which is good enough for most purposes. The purity can be increased to 99–100% by a recrystallization from 5M acetic acid.
2. Notes
1. Rubber gloves should be worn when handling vessels containing peracetic acid, for traces of the liquid can cause severe irritation. Skin that has come into contact with peracetic acid should be washed immediately and treated with sodium bicarbonate. Details for the safe handling of peracetic acid are found in Bulletin 4 supplied by Buffalo Electrochemical Corp.
2. Appreciable amounts of iodoxybenzene are formed if the temperature of the bath is allowed to go above 30° or if the addition of peracetic acid is faster than indicated.
3. Satisfactory 40% peracetic acid is obtainable from Buffalo Electrochemical Corp., Food Machinery and Chemical Corp., Buffalo, New York. The specifications given by the manufacturer for its composition are: peracetic acid, 40%; hydrogen peroxide, 5%; acetic acid, 39%; sulfuric acid, 1%; water, 15%. Its density is 1.15 g. per ml.
A fresh sample of this 40% peracetic acid contains about 1.54 equivalents, or 0.77 mole, of peroxide per 100 ml. of solution, corresponding to 1.34 equivalents per 100 g. The concentration can be determined by treating the peroxide solution with potassium iodide and titrating the liberated iodine with standard sodium thiosulfate. The concentration of peroxide in peracetic acid decreases somewhat on long standing and should be checked before the peracetic acid is used. The yield of diacetate is lowered if the concentration of the peroxide is less than 1.0 equivalent per 100 g. of peracetic acid. The total amount of peroxide used should be 2.4 moles, or 4.8 equivalents, for each mole of iodobenzene.
4. The surface of the diacetate may become yellow during the drying, but this does not affect its usefulness for most purposes.
3. Discussion
Willgerodt4 prepared iodosobenzene diacetate by adding chlorine to iodobenzene and hydrolyzing the dichloride to iodosobenzene, which was then reacted with acetic acid. Pausacker5 used this method to synthesize a number of analogs but found it inferior to his modification of the method of Böeseken and Schneider6 in which iodobenzene is treated with 30% hydrogen peroxide and acetic anhydride. Arbusov7 obtained the diacetate in 79% yield by the action of a mixture of peracetic and acetic acids on iodobenzene. Quantitative yields of the diacetate have been claimed for the reaction of iodobenzene dichloride with lead tetraacetate in glacial acetic acid containing 10% acetic anhydride, followed by precipitation of the lead as the chloride.8
4. Merits of the Preparation
Iodosobenzene diacetate is best prepared by the action of peracetic acid and acetic acid on iodobenzene. The present procedure is superior to earlier ones5,6,7,8 because it uses inexpensive, commercially available peracetic acid, is faster, and gives higher yields. The procedure seems general for aryl iodides with electron-releasing substituents, for the submitters have obtained good yields of diacetates from o-, m- and p-iodotoluene, 2- and 4-iodo-m-xylene, 2-iodo-p-xylene, o-iodophenetole, and 4-iodobiphenyl.
Iodosobenzene diacetate is used as a reagent for the preparation of glycol diacetates from olefins,9 for the oxidation of aromatic amines to corresponding azo compounds,10 for the ring acetylation of N-arylacetamides,11 for oxidation of some phenols to phenyl ethers,12 and as a coupling agent in the preparation of iodonium salts.13 Its hydrolysis to iodosobenzene constitutes the best synthesis of that compound.14

References and Notes
  1. Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York.
  2. H. J. Lucas and E. R. Kennedy, Org. Syntheses, Coll. Vol. 2, 351 (1943).
  3. H. J. Lucas, E. R. Kennedy, and M. W. Formo, Org. Syntheses, Coll. Vol. 3, 483 (1955).
  4. C. Willgerodt, Ber., 25, 3495 (1892).
  5. K. H. Pausacker, J. Chem. Soc., 107 (1953).
  6. J. Böeseken and G. C. C. C. Schneider, J. Prakt. Chem., 131, 285 (1931).
  7. B. A. Arbusov, J. Prakt. Chem., 131, 351 (1931).
  8. R. Neu, Ber., 72B, 1505 (1939).
  9. R. Criegee and H. Beucker, Ann. 541, 218 (1939).
  10. K. H. Pausacker, J. Chem. Soc., 1989 (1953).
  11. G. B. Barlin and N. V. Riggs, J. Chem. Soc., 3125 (1954).
  12. K. H. Pausacker and A. R. Fox, J. Chem. Soc., 295 (1957).
  13. F. M. Beringer, R. A. Falk, M. Karniol, I. Lillien, G. Masullo, M. Mausner, and E. Sommer, J. Am. Chem. Soc., 81, 342 (1959).
  14. H. Saltzman and J. G. Sharefkin, this volume, p. 658.

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

o-, m- and p-iodotoluene

2- and 4-iodo-m-xylene

sulfuric acid (7664-93-9)

acetic acid (64-19-7)

acetic anhydride (108-24-7)

sodium bicarbonate (144-55-8)

potassium iodide (7681-11-0)

sodium thiosulfate (7772-98-7)

iodine (7553-56-2)

chlorine (7782-50-5)

hydrogen peroxide,
peroxide (7722-84-1)

Iodobenzene (591-50-4)

iodobenzene dichloride (2401-21-0)

peracetic acid (79-21-0)

Iodosobenzene (536-80-1)

Iodoxybenzene (696-33-3)

Iodosobenzene diacetate,
Benzene, iodoso-, diacetate (3240-34-4)

4-iodobiphenyl (1591-31-7)

2-Iodo-p-xylene (1122-42-5)

o-iodophenetole (614-73-3)

lead tetraacetate (546-67-8)