Dess-Martin oxidation
The oxidation by hypervalent iodine reagents includes the Dess- Martin oxidation and the IBX oxidation. These are chemical reactions and describe the oxidation of primary or secondary alcohols by the oxidant, IBX (2- iodoxybenzoic acid ), or Dess- Martin periodinane.
- 2.1 mechanism
- 2.2 reaction conditions
IBX oxidation
The IBX - oxidation is used in organic chemistry to oxidize primary alcohols to aldehydes. 2- iodoxybenzoic, short IBX, is a heat and shock sensitive molecule. In addition, it can not be solved in many solvents.
Mechanism
The reaction proceeds in two steps. First, the alcohol to be oxidized nucleophilic attacks on the iodine atom of the IBX 1, wherein a water molecule is split off. Then follow the shown in the figure by arrows electron rearrangements. In this way, the binding of the former primary alcohol to iodine atom is broken, which is thus reduced. The alcohol used is thereby oxidized to the corresponding aldehyde 4.
Dess-Martin oxidation of
The Dess- Martin oxidation is a name reaction in organic chemistry and named after the American chemists Daniel Benjamin Dess and James Cullen Martin. The reaction is used for the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively. As oxidizing agent, the Dess- Martin periodinane is used. It is prepared by reacting IBX in DMSO with the help of acetic anhydride to the Dess- Martin periodinane.
Mechanism
The reaction proceeds similarly to the IBX oxidation. At the beginning of the iodine atom of compound 1 from the nucleophilic alcohol with elimination of a molecule of acetic acid ( AcOH ) is under attack. A α -H elimination of alcohol is then oxidized to release a further molecule of acid. The iodine atom is in this case reduced by the oxidation state V to III. It strives to include electrons and therefore acts as an electron sink. The result is a ketone 4
Especially the Dess- Martin oxidation is a very selective and mild oxidation, which is an alternative to the Swern oxidation, Jones oxidation, or Pfitzner - Moffatt oxidation, however, is one of the reactions that take place with a low atom economy.
Reaction conditions
Typically, the reaction is performed at room temperature in a solvent such as chloroform or dichloromethane may be performed using only 1.1 equivalents of periodinane reagent. The reaction time is about 0.5 hour to 2 hours, the mixture is worked up by means of basic hydrolysis. A newer variant uses as a solvent, the ionic liquid Butylmethylimidazoliumtetrafluoroborat ( BMIM BF4).