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5 Summary of Organic Nomenclature -- Part 18
The triple bond of an alkyne is the same as the alkene double bond.
The product is vinyl halide.
The product has an orientation predicted by the rule.
A second molecule of HX can be added with the same orientation as the first.
The reaction of pent-1-yne with HBr gives the Markovnikov product.
The acetylenic carbon atoms are replaced with a mixture of products in an internal alkyne.
The mechanism is similar to hydrogen addition to alkenes.
Attack by ion completes the reaction.
When 2 moles of hydrogen halide add to an alkyne, the second mole usually adds with the same orientation as the first.
This consistent orientation leads to a geminal dihalide.
2, 2-dibromopentane is given by a double Markovnikov addition of HBr to pent-1-yne.
In the anti-Markovnikov sense, a free-radical chain reaction that adds HBr across the double bond of an alkene takes place.
There is a similar reaction with alkynes.
In the presence of peroxides, propose a mechanism for the reaction of pent-1-yne with HBr.
The reagent is a mixture of mercuric sulfate and sulfuric acid.
The hydration of alkynes is similar to the hydration of alkenes.
The products are not alcoholics.
The vinyl alcohol can't be isolated because it quickly rearranges to a ketone after hydration of an alkyne.
A vinyl cation is created when mercuric ion is added to water.
involve the formation of an enol is a type of rapid equilibrium.
There are ways to more detail in Chapter 22.
A C " O double bond is more stable than a C " C, so it's usually used for therapeutic pur double bond.
Several investigators have placed bulky substituents around the double bond to make stable enols.
The tautomerism takes place when a proton is added to the old position.
Under acidic conditions, the proton adds at its new position on the carbon atom, and then is removed from its old position in the hydroxy group.
The mercuric-catalyzed hydration of but-1-yne gives but-1-en-2-ol as an intermediate.
The intermediate equilibrates to its stable butan-2-one in the acidic solution.
The product is a mixture of two ketones when it reacts with mercuric sulfate.
Use mechanisms to show how these products are formed.
Water is added to the double bonds of alkenes with anti-Markovnikov orientation.
A similar reaction takes place with alkynes, except that a dialkylborane must be used to prevent Borane from being added to the triple bond.
Di(secondary isoamyl)borane only adds to the triple bond once.
Anti-Markovnikov addition of water across the triple bond results in a vinyl alco hol.
The more stable form of this enol isketo.
The product of a terminal alkyne is an aldehyde.
This sequence can be used to convert terminal alkynes to aldehydes.
The tautomerism works by a different mecha nism than it does in acid.
The OH group's protons are removed from their old position in the base and replaced with carbon.
The protons were added on carbon and then removed from the hydroxy group in acid.
Under basic conditions, the old position of the protons in the enol is removed and replaced with a new position on the carbon atom of the ketone or aldehyde.
Adding it to a new position.
The vinylborane with boron is given on the less highly substituted carbon.
Oxidation of this intermediate gives an enol.
ketones are produced by the hydroboration-oxidation of internal alkynes.
A single pure product is obtained when hydroboration-oxidation is applied.
Show the intermediates in the structure of the product.
Two products are obtained when hydroboration-oxidation is applied.
Show how a mixture of products should be expected.
Give the product expected from (1) HgSO4>H2SO4@catalyzed hydration and (2) hydroboration-oxidation.
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