2-Iodoxybenzoic acid

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"IBX" redirects here. For other uses, see IBX (disambiguation).
2-Iodoxybenzoic acid
Names
Preferred IUPAC name
1-Hydroxy-1λ5,2-benziodoxole-1,3-dione
Other names
1-Hydroxy-1λ3,2-benziodoxol-3(1H)-one 1-oxide
Identifiers
3D model (
JSmol
)
976364
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.157.592 Edit this at Wikidata
UNII
  • InChI=1S/C7H5IO4/c9-7-5-3-1-2-4-6(5)8(10,11)12-7/h1-4H,(H,10,11) checkY
    Key: CQMJEZQEVXQEJB-UHFFFAOYSA-N checkY
  • InChI=1/C7H5IO4/c9-7-5-3-1-2-4-6(5)8(10,11)12-7/h1-4H,(H,10,11)
    Key: CQMJEZQEVXQEJB-UHFFFAOYAL
  • O=C1OI(=O)(O)c2ccccc12
  • c1ccc2c(c1)C(=O)OI2(=O)O
Properties
C7H5IO4
Molar mass 280.02 g/mol
Melting point 233 °C (decomposes)
Hazards
GHS labelling:
GHS05: CorrosiveGHS07: Exclamation mark
Danger
H314, H315, H319, H335
P260, P261, P264, P271, P280, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P332+P313, P337+P313, P362, P363, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

2-Iodoxybenzoic acid (IBX) is an

oxone. One of the main drawbacks of IBX is its limited solubility; IBX is insoluble in many common organic solvents. IBX is an impact- and heat-sensitive explosive (>200°C).[2] Commercial IBX is stabilized by carboxylic acids such as benzoic acid and isophthalic acid
.

Preparation

IBX can be prepared in a single step by adding an excess of

2-iodobenzoic acid occurs at elevated temperatures, and therefore purification by recrystallization from water is not possible. Purity can be increased (≥99%) by shorting the reaction time to one hour at 70°C, at the cost of slightly reducing yield to 77%.[2]

IBX Preparation from 2-iodobenzoic acid and Oxone.

Reaction mechanism

The

methyl
group thus facilitating the twist until the elimination reaction takes prevalence as the rate determining step.

kJ
/mol), b) hypervalent twist 12.1 kcal/mol (51 kJ/mol), c) elimination 4.7 kcal/mol (20 kJ/mol)).

IBX exists as two

pKa 2.4) and DMSO (pKa 6.65)[4] is known to affect organic reactions, for instance acid-catalyzed isomerization
accompanying oxidations.

Scope

IBX is also available as silica gel or polystyrene bound IBX. In many applications, IBX is replaced by Dess–Martin periodinane which is more soluble in common organic solvents. A sample reaction is an IBX oxidation used in the total synthesis of eicosanoid:[5] More and Finney[6] and Van Arman[7] have demonstrated that common organic solvents are suitable for many IBX oxidations, despite its low solubility, and in fact may simplify product purification.

chemical yield
(Mohapatra, 2005)

In 2001,

K. C. Nicolaou and co-workers published a series of papers in the Journal of the American Chemical Society demonstrating, among other transformations, the use of IBX to oxidize primary and secondary benzylic carbons to aromatic aldehydes and ketones, respectively.[8]

Oxidative cleavage

IBX is notable for oxidizing vicinal diols (or glycols) to diketones without cleavage of the carbon-carbon bond,[9] but oxidative cleavage of glycols to two aldehydes or ketones can occur when modified conditions are used (elevated temperatures or trifluoroacetic acid solvent).[10]

Oxidative cleavage of vicinal diols

The reaction mechanism for this glycol cleavage is based on initial formation of an adduct between 10-I-4 IBX and DMSO to a 12-I-5 intermediate 3 in which DMSO acts as a leaving group for incoming alcohol 4 to intermediate 5. One equivalent of water is split off forming 12-I-5 spirobicyclic periodinane 6 setting the stage for fragmentation to 7. With hydroxyl alpha protons present, oxidation to the acyloin competes. Trifluoroacetic acid is found to facilitate the overall reaction.

Oxidative cleavage of vicinal diols: mechanism

α-Hydroxylations

Kirsch and co-workers were able to hydroxylate keto compounds with IBX in α-position under mild conditions.[11] This method could be extended to β-keto esters.[12]

Oxidation of β-hydroxyketones to β-diketones

Bartlett and Beaudry discovered that IBX is a valuable reagent for the transformation of β-hydroxyketones to β-diketones. IBX provides yields superior to both the Swern and Dess–Martin oxidation protocols.[13]

References

  1. ^ Boeckman, R. K. Jr.; Shao, P.; Mullins, J. J. (2000). "Dess–Martin periodinane: 1,1,1-Triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one" (PDF). Organic Syntheses. 77: 141; Collected Volumes, vol. 10, p. 696.
  2. ^
    doi:10.1021/jo9824596
    .
  3. PMID 16218584
    .
  4. PMID 16566050
    .
  5. hdl:2027/spo.5550190.0006.316
    .
  6. PMID 12182609
    .
  7. doi:10.1016/j.tetlet.2009.06.045
    .
  8. PMID 11878978
    .
  9. doi:10.1016/0040-4039(94)80038-3
    .
  10. PMID 17315062
    .
  11. PMID 16292876
    .
  12. PMID 19760735
    .
  13. PMID 22023037
    .
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