Quiz - Alkynes - 2 | Alkynes

Organic Chemistry 2 - Quiz - Alkynes - 2


Which of the following reactions typically involves anti-Markovnikov addition of HBr to an alkyne?

Anti-Markovnikov addition of HBr to an alkyne is typically achieved by a radical process. This reaction provides a syn-addition of a hydrogen and a bromine radical to the alkyne, producing a vinyl bromide.


What is the resulting product when 3-hexyne undergoes partial hydrogenation using Lindlar's catalyst?

Partial hydrogenation of an alkyne using Lindlar's catalyst selectively produces the corresponding cis-alkene. Hence, 3-hexyne would be reduced to cis-3-hexene.


Which method is commonly used for the preparation of alkynes through the removal of two molecules of hydrogen halide from a vicinal or geminal dihalide?

Dehydrohalogenation using a strong base, such as potassium hydroxide or sodium amide, is a common method for preparing alkynes from vicinal or geminal dihalides by the removal of two molecules of hydrogen halide.


What is the IUPAC name for the smallest member of the alkyne series with a carbon-carbon triple bond end position?

Ethyne, also known as acetylene, is the smallest alkyne. It has the IUPAC name 'Ethyne' due to the presence of a carbon-carbon triple bond at the end position in a two-carbon chain.


What is the product of the electrophilic addition of one molecule of X2 to an alkyne?

When X2, such as Br2 or Cl2, is added to an alkyne, a vicinal dihalide is formed because the halogen atoms add to adjacent carbon atoms.


Which reagent is typically used for the oxidative cleavage of alkynes to give carboxylic acids?

Oxidative cleavage of alkynes with ozone typically produces carboxylic acids. The reagent attacks the triple bond, breaking it and ultimately forming the carboxylic acid functional groups.


The acidity of terminal alkynes is exploited in which reaction to form a carbon-carbon bond?

The Sonogashira coupling involves the reaction of a terminal alkyne, after deprotonation to form an acetylide anion, with an aryl or vinyl halide to form a new carbon-carbon bond.


In the reduction of an alkyne to an alkene, why is sodium in liquid ammonia used instead of hydrogen and a metal catalyst?

Sodium in liquid ammonia is used in the Birch reduction of alkynes to selectively obtain the trans-alkene, whereas hydrogen with a metal catalyst would typically fully reduce the alkyne to an alkane.


The electrophilic addition reaction of HX to an alkyne follows which mechanism?

The electrophilic addition reaction of HX to an alkyne proceeds through a two-step mechanism involving a carbocation intermediate.