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OsO 4 is expensive and highly toxic, making it an unappealing reagent to use in stoichiometric amounts. However, its reactions are made catalytic by adding reoxidants to reoxidise the Os(VI) by-product back to Os(VIII). Typical reagents include H 2 O 2 (Milas hydroxylation), N-methylmorpholine N-oxide (Upjohn dihydroxylation) and K 3 Fe(CN) 6 ...
Sharpless asymmetric dihydroxylation (also called the Sharpless bishydroxylation) is the chemical reaction of an alkene with osmium tetroxide in the presence of a chiral quinine ligand to form a vicinal diol.
Ruthenium-based reagents are rapid. [17] Typically, the ruthenium tetroxide is created in situ from ruthenium trichloride, and the oxidant NaIO 4. The turnover-limiting step of the reaction is the hydrolysis step; therefore, sulfuric acid is added to increase the rate of this step. [17] [18]
N-Methylmorpholine N-oxide (more correctly 4-methylmorpholine 4-oxide), NMO or NMMO is an organic compound.This heterocyclic amine oxide and morpholine derivative is used in organic chemistry as a co-oxidant and sacrificial catalyst in oxidation reactions for instance in osmium tetroxide oxidations and the Sharpless asymmetric dihydroxylation or oxidations with TPAP. [1]
This mixture became known as Lemieux reagent [8] [9] and has been used to determine the position of double bonds and for preparing carbonyl compounds. [10] Unlike the Lemieux–Johnson oxidation, which normally stops at the aldehyde, this older method could continue to give a mixture of aldehydes and carboxylic acids.
Prior to this method, use of stoichiometric amounts of the toxic and expensive reagent osmium tetroxide was often necessary. The Upjohn dihydroxylation is still often used for the formation of cis -vicinal diols; however, it can be slow and is prone to ketone byproduct formation.
Ruthenium tetroxide is the inorganic compound with the formula RuO 4.It is a yellow volatile solid that melts near room temperature. [3] It has the odor of ozone. [4] Samples are typically black due to impurities.
The Milas hydroxylation is an organic reaction converting an alkene to a vicinal diol, and was developed by Nicholas A. Milas in the 1930s. [1] [2] The cis-diol is formed by reaction of alkenes with hydrogen peroxide and either ultraviolet light or a catalytic osmium tetroxide, [3] vanadium pentoxide, or chromium trioxide.