(Bis(trifluoroacetoxy)iodo)benzene

(Bis(trifluoroacetoxy)iodo)benzene, C
6H
5I(OCOCF
3)
2, is a hypervalent iodine compound used as a reagent in organic chemistry. It can be used to carry out the Hofmann rearrangement under acidic conditions.[1]

(Bis(trifluoroacetoxy)iodo)benzene
Names
IUPAC name
phenyl{bis[(trifluoroacetyl)oxy]}-λ3-iodane
Other names
Phenyliodine bis(trifluoroacetate); PIFA
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.018.462
EC Number
  • 220-308-0
UNII
Properties
C10H5F6IO4
Molar mass 430.041 g·mol−1
Hazards
GHS pictograms
GHS Signal word Warning
H315, H319, H335
P261, P264, P271, P280, P302+352, P304+340, P305+351+338, P312, P321, P332+313, P337+313, P362, P403+233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Preparation

The syntheses of all aryl hypervalent iodine compounds start from iodobenzene. The compound can be prepared by reaction of iodobenzene with a mixture of trifluoroperacetic acid and trifluoroacetic acid in a method analogous to the synthesis of (diacetoxyiodo)benzene:[1]

It can also be prepared by dissolving diacetoxyiodobenzene (a commercially-available compound) with heating in trifluoroacetic acid:[2]

Uses

It also brings around the conversion of a hydrazone to a diazo compound, for example in the diazo-thioketone coupling. It also converts thioacetals to their parent carbonyl compounds.

Hofmann rearrangement

The Hofmann rearrangement is a decarbonylation reaction whereby an amide is converted to an amine by way of an isocyanate intermediate. It is usually carried out under strongly basic conditions.[3][4]

The reaction can also be carried out under mildly acidic conditions by way of the same intermediate using a hypervalent iodine compound in aqueous solution.[1] An example published in Organic Syntheses is the conversion of cyclobutanecarboxamide, easily synthesized from cyclobutylcarboxylic acid, to cyclobutylamine.[2] The primary amine is initially present as its trifluoroacetate salt, which can be converted to the hydrochloride salt to facilitate product purification.[1][2]

References
  1. Aubé, Jeffrey; Fehl, Charlie; Liu, Ruzhang; McLeod, Michael C.; Motiwala, Hashim F. (1993). "6.15 Hofmann, Curtius, Schmidt, Lossen, and Related Reactions". Heteroatom Manipulations. Comprehensive Organic Synthesis II. 6. pp. 598–635. doi:10.1016/B978-0-08-097742-3.00623-6. ISBN 9780080977430.
  2. Almond, M. R.; Stimmel, J. B.; Thompson, E. A.; Loudon, G. M. (1988). "Hofmann Rearrangement Under Mildly Acidic Conditions Using [I,I-Bis(Trifluoroacetoxy)]Iodobenzene: Cyclobutylamine Hydrochloride from Cyclobutanecarboxamide". Organic Syntheses. 66: 132. doi:10.15227/orgsyn.066.0132.; Collective Volume, 8, p. 132
  3. Wallis, Everett S.; Lane, John F. (1946). "The Hofmann Reaction". Organic Reactions. 3 (7): 267–306. doi:10.1002/0471264180.or003.07.
  4. Surrey, Alexander R. (1961). "Hofmann Reaction". Name Reactions in Organic Chemistry (2nd ed.). Academic Press. pp. 134–136. ISBN 9781483258683.
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