(Diacetoxyiodo)benzene

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(Diacetoxyiodo)benzene
(diacetoxyiodo)benzene.svg
Names
Preferred IUPAC name
Phenyl-λ3-iodanediyl diacetate
Other names
Bis(acetoxy)(phenyl)iodane
Bis(acetato-O)phenyliodine
Bis(acetoxy)iodobenzene (BAIB)
(Diacetoxyiodo)benzene
I,I-Diacetatoiodobenzene
Iodobenzene diacetate
Iodosobenzene I,I-diacetate
Phenyliodine(III) diacetate (PIDA)
Phenyliodo diacetate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.019.826 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 221-808-1
PubChem CID
  • InChI=1S/C10H11IO4/c1-8(12)14-11(15-9(2)13)10-6-4-3-5-7-10/h3-7H,1-2H3
    Key: ZBIKORITPGTTGI-UHFFFAOYSA-N
  • CC(=O)OI(C1=CC=CC=C1)OC(=O)C
Properties
C10H11IO4
Molar mass 322.098 g·mol−1
Appearancewhite powder
Melting point 163–165 °C (325–329 °F; 436–438 K)
reacts
Solubility soluble in acetic acid, acetonitrile, dichloromethane
Structure [1] [2]
orthorhombic
Pnn2
a = 15.693(3) Å, b = 8.477(2) Å, c = 8.762(2) Å [2]
T-shaped molecular geometry
Related compounds
Related compounds
(Bis(trifluoroacetoxy)iodo)benzene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

(Diacetoxyiodo)benzene, also known as phenyliodine(III) diacetate (PIDA) is a hypervalent iodine chemical with the formula C
6
H
5
I(OCOCH
3
)
2
. It is used as an oxidizing agent in organic chemistry.

Contents

Preparation

This reagent was originally prepared by Conrad Willgerodt [3] by reacting iodobenzene with a mixture of acetic acid and peracetic acid: [4] [5]

C6H5I  + CH3CO3H  + CH3CO2H  C6H5I(O2CCH3)2 + H2O

PIDA can also be prepared from iodosobenzene and glacial acetic acid: [5]

C6H5IO  + 2  CH3CO2H  C6H5I(O2CCH3)2 + H2O

More recent preparations direct from iodine, acetic acid, and benzene have been reported, using either sodium perborate [6] or potassium peroxydisulfate [7] as the oxidizing agent: [8]

C6H6  + I2  + 2  CH3CO2H  + K2S2O8  C6H5I(O2CCH3)2 + KI  + H2SO4  + KHSO4

The PIDA molecule is termed hypervalent as its iodine atom (technically a hypervalent iodine) is in its +III oxidation state and has more than typical number of covalent bonds. [9] It adopts a T-shaped molecular geometry, with the phenyl group occupying one of the three equatorial positions of a trigonal bipyramid (lone pairs occupy the other two) and the axial positions occupied by oxygen atoms from the acetate groups. The "T" is distorted in that the phenyl-C to I to acetate-O bond angles are less than 90°. [1] A separate investigation of the crystal structure confirmed that it has orthorhombic crystals in space group Pnn2 and reported unit-cell dimensions in good agreement with the original paper. [1] [2] The bond lengths around the iodine atom were 2.08 Å to the phenyl carbon atom and equal 2.156 Å bonds to the acetate oxygen atoms. This second crystal structure determination explained the distortion in the geometry by noting the presence of two weaker intramolecular iodineoxygen interactions, resulting in an "overall geometry of each iodine [that] can be described as a pentagonal-planar arrangement of three strong and two weak secondary bonds." [2]

Unconventional reactions

One use of PIDA is in the preparation of similar reagents by substitution of the acetate groups. For example, it can be used to prepare (bis(trifluoroacetoxy)iodo)benzene (phenyliodine(III) bis(trifluoroacetate), PIFA) by heating in trifluoroacetic acid: [10] [8]

PIFA synthesis by exchange.png

PIFA can be used to carry out the Hofmann rearrangement under mildly acidic conditions, [11] rather than the strongly basic conditions traditionally used. [12] [13] The Hofmann decarbonylation of an N-protected asparagine has been demonstrated with PIDA, providing a route to β-amino-L-alanine derivatives. [14]

PIDA is also used in Suárez oxidation, where photolysis of hydroxy compounds in the presence of PIDA and iodine generates cyclic ethers. [15] [16] [17] This has been used in several total syntheses, such as the total synthesis of (−)-majucin, (−)-Jiadifenoxolane A, [18] and cephanolide A. [19]

Related Research Articles

<span class="mw-page-title-main">Aromatic compound</span> Compound containing rings with delocalized pi electrons

Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The word "aromatic" originates from the past grouping of molecules based on smell, before their general chemical properties were understood. The current definition of aromatic compounds does not have any relation with their smell.

The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877 to attach substituents to an aromatic ring. Friedel–Crafts reactions are of two main types: alkylation reactions and acylation reactions. Both proceed by electrophilic aromatic substitution.

The Hofmann rearrangement is the organic reaction of a primary amide to a primary amine with one less carbon atom. The reaction involves oxidation of the nitrogen followed by rearrangement of the carbonyl and nitrogen to give an isocyanate intermediate. The reaction can form a wide range of products, including alkyl and aryl amines.

In organic chemistry, an electrophilic aromatic halogenation is a type of electrophilic aromatic substitution. This organic reaction is typical of aromatic compounds and a very useful method for adding substituents to an aromatic system.

<span class="mw-page-title-main">Periodinane</span>

Periodinanes also known as λ5-iodanes are organoiodine compounds with iodine in the +5 oxidation state. These compounds are described as hypervalent because the iodine center has more than 8 valence electrons.

<span class="mw-page-title-main">(Bis(trifluoroacetoxy)iodo)benzene</span> Chemical compound

(Bis iodo)benzene, C
6
H
5
I(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.

<span class="mw-page-title-main">Mercury(II) acetate</span> Chemical compound

Mercury(II) acetate is the chemical compound with the formula Hg(O2CCH3)2. Commonly abbreviated Hg(OAc)2, this compound is employed as a reagent to generate organomercury compounds from unsaturated organic precursors. It is a white water-soluble solid, but samples appear yellowish with time owing to decomposition.

<span class="mw-page-title-main">Iodobenzene</span> Chemical compound

Iodobenzene is an organoiodine compound consisting of a benzene ring substituted with one iodine atom. It is useful as a synthetic intermediate in organic chemistry. It is a volatile colorless liquid, although aged samples appear yellowish.

<span class="mw-page-title-main">Organomercury chemistry</span> Group of chemical compounds containing mercury

Organomercury chemistry refers to the study of organometallic compounds that contain mercury. Typically the Hg–C bond is stable toward air and moisture but sensitive to light. Important organomercury compounds are the methylmercury(II) cation, CH3Hg+; ethylmercury(II) cation, C2H5Hg+; dimethylmercury, (CH3)2Hg, diethylmercury and merbromin ("Mercurochrome"). Thiomersal is used as a preservative for vaccines and intravenous drugs.

<span class="mw-page-title-main">Lead(IV) acetate</span> Organometallic compound (Pb(C2H3O2)4)

Lead(IV) acetate or lead tetraacetate is an organometallic compound with chemical formula Pb(C2H3O2)4. It is a colorless solid that is soluble in nonpolar, organic solvents, indicating that it is not a salt. It is degraded by moisture and is typically stored with additional acetic acid. The compound is used in organic synthesis.

<span class="mw-page-title-main">Iodosobenzene</span> Chemical compound

Iodosobenzene or iodosylbenzene is an organoiodine compound with the empirical formula C6H5IO. This colourless solid compound is used as an oxo transfer reagent in research laboratories examining organic and coordination chemistry.

<span class="mw-page-title-main">Phenylmagnesium bromide</span> Chemical compound

Phenylmagnesium bromide, with the simplified formula C
6
H
5
MgBr
, is a magnesium-containing organometallic compound. It is commercially available as a solution in diethyl ether or tetrahydrofuran (THF). Phenylmagnesium bromide is a Grignard reagent. It is often used as a synthetic equivalent for the phenyl "Ph" synthon.

The Hofmann–Löffler reaction (also referred to as Hofmann–Löffler–Freytag reaction, Löffler–Freytag reaction, Löffler–Hofmann reaction, as well as Löffler's method) is an organic reaction in which a cyclic amine 2 (pyrrolidine or, in some cases, piperidine) is generated by thermal or photochemical decomposition of N-halogenated amine 1 in the presence of a strong acid (concentrated sulfuric acid or concentrated CF3CO2H). The Hofmann–Löffler–Freytag reaction proceeds via an intramolecular hydrogen atom transfer to a nitrogen-centered radical and is an example of a remote intramolecular free radical C–H functionalization.

Organoiodine chemistry is the study of the synthesis and properties of organoiodine compounds, or organoiodides, organic compounds that contain one or more carbon–iodine bonds. They occur widely in organic chemistry, but are relatively rare in nature. The thyroxine hormones are organoiodine compounds that are required for health and the reason for government-mandated iodization of salt.

Unlike its lighter congeners, the halogen iodine forms a number of stable organic compounds, in which iodine exhibits higher formal oxidation states than -1 or coordination number exceeding 1. These are the hypervalent organoiodines, often called iodanes after the IUPAC rule used to name them.

Iodobenzene dichloride (PhICl2) is a complex of iodobenzene with chlorine. As a reagent for organic chemistry, it is used as an oxidant and chlorinating agent.

Carbonyl oxidation with hypervalent iodine reagents involves the functionalization of the α position of carbonyl compounds through the intermediacy of a hypervalent iodine(III) enolate species. This electrophilic intermediate may be attacked by a variety of nucleophiles or undergo rearrangement or elimination.

Phenol oxidation with hypervalent iodine reagents leads to the formation of quinone-type products or iodonium ylides, depending on the structure of the phenol. Trapping of either product is possible with a suitable reagent, and this method is often employed in tandem with a second process.

<span class="mw-page-title-main">Trifluoroperacetic acid</span> Chemical compound

Trifluoroperacetic acid is an organofluorine compound, the peroxy acid analog of trifluoroacetic acid, with the condensed structural formula CF
3
COOOH
. It is a strong oxidizing agent for organic oxidation reactions, such as in Baeyer–Villiger oxidations of ketones. It is the most reactive of the organic peroxy acids, allowing it to successfully oxidise relatively unreactive alkenes to epoxides where other peroxy acids are ineffective. It can also oxidise the chalcogens in some functional groups, such as by transforming selenoethers to selones. It is a potentially explosive material and is not commercially available, but it can be quickly prepared as needed. Its use as a laboratory reagent was pioneered and developed by William D. Emmons.

In organometallic chemistry, metal–halogen exchange is a fundamental reaction that converts an organic halide into an organometallic product. The reaction commonly involves the use of electropositive metals and organochlorides, bromides, and iodides. Particularly well-developed is the use of metal–halogen exchange for the preparation of organolithium compounds.

References

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