Information AboutPeriodinane |
| CATEGORIES ABOUT PERIODINANE | |
| periodinanes | |
|
The concept of hypervalent iodine was developed by J.J. Musher in 1969. In order to accommodate the excess of electrons in hypervalent compounds the 3-center-4-electron Bond was introduced in analogy with the 3-center-2-electron Bond observed in electron deficient compounds. One such bond exists in iodine(III) compounds and two such bonds reside in iodine(V) compounds. The first hypervalent iodine compound, dichloroiodobenzene (C6H5Cl2I) was prepared in 1886 by the German chemist C. Willgerodt by passing Chlorine gas through Iodobenzene in a cooled solution of Chloroform . :C6H5I + ICl3 → C6H5ICl2 + ICl λ3-iodanes such as diarylchloroiodanes have a Pseudotrigonal Bipyramidal geometry displaying Apicophilicity with a Phenyl group and a chlorine group at the apical positions and other phenyl group with two Lone Pair electrons in the equatorial positions. The λ5-iodanes such as the Dess-Martin Periodinane have Square Pyramidal geometries with 4 heteroatoms in basal positions and one apical phenyl group. Classical organic procedures exist for the preparation of iodosobenzene diacetate from Peracetic Acid and Acetic Acid . :C6H5I + CH3COOOH → C6H5I(OOCCH3)2 The acetate can be hydrolysed with water to iodoxybenzene or '''iodylbenzene''' C6H5O2I This compound was first prepared by Willgerodt by Disproportionation of iodosylbenzene under Steam Distillation to iodylbenzene and iodobenzene :2 PhIO → PhIO2 + PhI is a known Oxidizing Agent . Iodosobenzene diacetate can also be hydrolyzed to iodosylbenzene with Sodium Hydroxide which is actually a Polymer with the Molecular Formula (C6H5OI)n . Iodosylbenzene is used in Organic Oxidation s. Dess-Martin Periodinane (1983) is another powerful oxidant and an improvement of the IBX Acid already in existence in 1893. The IBX acid is prepared from 2-iodobenzoic acid and potassium Bromate and Sulfuric Acid and is insoluble in most solvents whereas the Dess-Martin reagent prepared from reaction of the IBX acid with Acetic Anhydride is very soluble. The oxidation mechanism ordinarily consists of a Ligand Exchange Reaction followed by a Reductive Elimination . REFERENCES |
|
|