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In organic chemistry, alkynylation is an addition reaction in which a terminal alkyne (−C≡CH) is added to a carbonyl group (C=O) to form an α-alkynyl alcohol (R 2 C(−OH)−C≡C−R). [1] [2] When the acetylide is formed from acetylene (HC≡CH), the reaction gives an α-ethynyl alcohol. This process is often referred to as ethynylation.
Hydroboration–oxidation reaction is a two-step hydration reaction that converts an alkene into an alcohol. [1] The process results in the syn addition of a hydrogen and a hydroxyl group where the double bond had been. Hydroboration–oxidation is an anti-Markovnikov reaction, with the hydroxyl group attaching to the less-substituted carbon.
Propargyl alcohol, or 2-propyn-1-ol, is an organic compound with the formula C 3 H 4 O. It is the simplest stable alcohol containing an alkyne functional group. [ 3 ] Propargyl alcohol is a colorless viscous liquid that is miscible with water and most polar organic solvents.
When the carbonyl is an aldehyde (R"=H), a rearrangement can occur to generate enone, although the secondary propargylic alcohol can be isolated in some cases. [2] When this rearrangement is catalyzed by an acid, it is called Meyer–Schuster rearrangement. When the base is sodium metal the reaction is called Nef synthesis.
For example, using an alkyne instead of an alkene yields an enol, which tautomerizes into a ketone. Using an alcohol instead of water yields an ether (see also Hofmann-Sand reaction). In both cases, Markovnikov's rule is observed. Other applications of oxymercuration
A 3D model of ethyne (), the simplest alkyneIn organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. [1] The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula C n H 2n−2.
Meyer-Schuster Rearrangement. The reaction mechanism [5] begins with the protonation of the alcohol which leaves in an E1 reaction to form the allene from the alkyne.Attack of a water molecule on the carbocation and deprotonation is followed by tautomerization to give the α,β-unsaturated carbonyl compound.
For instance, the hydration of an alkene to an alcohol is reversed by dehydration. There are two main types of polar addition reactions: electrophilic addition and nucleophilic addition. Two non-polar addition reactions exist as well, called free-radical addition and cycloadditions.