| Ibx Acid |
Website Links For Acid |
Information AboutIbx Acid |
| CATEGORIES ABOUT 2-IODOXYBENZOIC ACID | |
| periodates | |
| organoiodides | |
| reagents for organic chemistry | |
|
REACTION MECHANISM to Formaldehyde a) ligand exchange reaction ( Activation Energy 9.1 Kcal / Mole , b) hypervalent twist 12.1 kcal/mole c) elimination 4.7 kcal/mole). Steric repulsion between protons in red]] The Reaction Mechanism for an oxidation of an Alcohol to an Aldehyde according the so-called hypervalent twisting mechanism involves a Ligand Exchange Reaction replacing the hydroxyl group by the alcohol followed by a twist and a Elimination Reaction . The twist is a requirement because the iodine to oxygen Double Bond is oriented out of plane with the Alkoxy group and the Concerted elimination would not be able to take place. This twist reaction is a rearrangement in which the oxygen atom is moved into a proper plane for a 5 membered cyclic Transition State in the elimination reaction and is calculated by Computational Chemistry to be the Rate-determining Step in the oxidation. The twist mechanism also explains why oxidation is faster for larger alcohols than for small alcohols. The twist is driven forward by the Steric Hindrance that exists between the Ortho hydrogen atom and the protons from the Alkoxy group and larger alkoxy groups create larger steric repulsion. The same computation predicts a much faster reacting IBX derivative with a 100 fold Reaction Rate when this ortho hydrogen atom is replaced by a Methyl group thus facilitating the twist until the elimination reaction takes prevalence as the rate determining step. SCOPE IBX is also available as Silica Gel or Polystyrene bound IBX. In many application IBX acid is replaced by Dess-Martin Periodinane which is more soluble in common organic solvents. A sample reaction is a IBX oxidation used in the Total Synthesis of Eicosanoid . to , THF , 4h, 94% Chemical Yield (Mohapatra, 2005)]] IBX exists as two Tautomer s one of which is the Carboxylic Acid . The Acidity of IBX which has been determined in water ( PKa 2.4) and DMSO (pKa 6.65) is known to affect organic reactions for instance acid-catalyzed Isomerization accompanying oxidations. EXTERNAL LINKS REFERENCES |
|
|