What is OsO4 used for?
Osmium tetroxide is used in many industries. It’s used mainly as a staining agent for biological samples. Some examples of workers at risk of being exposed to osmium tetroxide include the following: Lab workers who use it as a staining agent in transmission electron microscopy.
What is a dihydroxylation reaction?
Dihydroxylation is an oxidative addition reaction, where two hydroxyl groups are added across a carbon–carbon double bond to form 1,2-diols or glycols. Dihydroxylation of alkenes can be carried out by two different stereochemical routes: anti dihydroxylation and syn dihydroxylation.
What is SYN dihydroxylation?
Reactions that add two hydroxyls to the same face of an alkene double bond as it’s converted to a single bond.
Is OsO4 a syn or anti?
The reaction with OsO4 is a concerted process that has a cyclic intermediate and no rearrangements. Vicinal syn dihydroxylation complements the epoxide-hydrolysis sequence which constitutes an anti dihydroxylation of an alkene. When an alkene reacts with osmium tetroxide, stereocenters can form in the glycol product.
What is NMO organic chemistry?
N-Methylmorpholine-N-oxide or NMO 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.
What is the name for OsO4?
Osmium tetroxide
Osmium tetroxide (also osmium(VIII) oxide) is the chemical compound with the formula OsO4.
What is anti dihydroxylation?
Anti dihydroxylation results in the anti-addition of two hydroxyl groups across an alkene. If this occurs on a cyclic diene as in cyclohexene below then anti-addition will result in a trans relationship between the two hydroxyl groups.
Is oso4 syn addition?
Addition Reactions of Alkenes To convert alkenes into cis-diols by syn dihydroxylation, they are reacted with a basic solution of potassium permanganate (KMnO4) or Osmium tetroxide (OsO4): Both reactions go through the formation of a cyclic intermediate which is formed by a syn addition to the double bond.
What is NMO and its role in oso4 oxidation?
NMO is also the cooxidant that enables the use of a catalytic amount of OsO4, because this reagent is able to reoxidize an Os(VI) species to an Os(VIII) species: The mechanism is simplified, for example in alkaline solutions, the catalyst is indeed hydrated. The key step is the cycloaddition of OsO4 to the olefin.
What does oso4 do in a reaction?
In organic synthesis OsO4 is widely used to oxidize alkenes to the vicinal diols, adding two hydroxyl groups at the same side (syn addition). See reaction and mechanism above. This reaction has been made both catalytic (Upjohn dihydroxylation) and asymmetric (Sharpless asymmetric dihydroxylation).
What causes exposure of OsO4 to human?
Acute/short-term: Osmium tetroxide is generally corrosive and can cause chemical burns to the skin, eyes, and respiratory tract. Acute inhalation exposure can lead to a burning sensation, tearing, cough, headache, wheezing, shortness of breath, pulmonary edema, and, ultimately, death at high concentrations.
What is an anti addition?
Anti addition: An addition reaction in which two substituents are added to opposite sides (or faces) of a double bond or triple bond. Electrophilic addition of Br2 to 1,2-dimethylcyclohexene is an anti addition reaction, resulting in trans-1,2-dibromocyclohexane. Related terms: Syn addition. Wikipedia entry.