MindMap Gallery Alkynes reaction
Detailed summary of olefin reactions in organic chemistry, with pictures and text, highlighting the key points! It’s full of useful information, friends in need should quickly collect it!
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This infographic, created using EdrawMax, highlights the rich cultural heritage and outstanding contributions of African Americans. It covers key areas such as STEM innovations, literature and thought, global influence of music and arts, and historical preservation. The document showcases influential figures and institutions that have played pivotal roles in shaping science, medicine, literature, and public memory, underscoring the integral role of African American contributions to society.
This infographic, created using EdrawMax, outlines the pivotal moments in African American history from 1619 to the present. It highlights significant events such as emancipation, key civil rights legislation, and notable achievements that have shaped the social and political landscape. The timeline serves as a visual representation of the struggle for equality and justice, emphasizing the resilience and contributions of African Americans throughout history.
This infographic, designed with EdrawMax, presents a detailed timeline of the evolution of voting rights and citizenship in the U.S. from 1870 to the present. It highlights key legislative milestones, court decisions, and societal changes that have expanded or challenged voting access. The timeline underscores the ongoing struggle for equality and the continuous efforts to secure voting rights for all citizens, reflecting the dynamic nature of democracy in America.
This infographic, created using EdrawMax, highlights the rich cultural heritage and outstanding contributions of African Americans. It covers key areas such as STEM innovations, literature and thought, global influence of music and arts, and historical preservation. The document showcases influential figures and institutions that have played pivotal roles in shaping science, medicine, literature, and public memory, underscoring the integral role of African American contributions to society.
Alkynes reaction
structure
smallest cyclic alkyne
Acidic
Attacked by alkali to form acetylide ion
Only strong bases can extract H from alkynes
preparation
Dehydrohalogenation of chlorinated hydrocarbons
Add too much strong base
mechanism
Both ortho-dihalogen and gedi-halogen can be used
reduction
hydrogenation
poisoned catalyst
Only alkenes are obtained without further reduction
Dissolving Metal Reduction
Metal sodium in liquid ammonia (−33°C)
Sodium metal produces free electrons
form trans alkenes
Because the trans structure electron repulsion is small
mechanism
Summarize
Hydrohalogenation
Markovnikov addition
mechanism
termolecular
anti-Markovnikov addition
For terminal alkynes
Radical addition only occurs with HBr (not with HCl or HI)
mechanism
Similar to olefin radical addition
Summarize
Hydration
Acid-Catalyzed Hydration of Alkynes
The reaction rate of alkynes is significantly lower than that of alkenes
Adding mercuric sulfate (HgSO4) significantly speeds up the reaction rate
The resulting enol is isomerized into ketone
Keto-enol tautomerization is an equilibrium process that is catalyzed by even trace amounts of acid (or base)
heterogeneous mechanism
After two proton transfers
Enol cannot be isolated because isomerization cannot be prevented
Hydroboration-Oxidation
Base-Catalyzed Tautomerization
aldehyde is formed
anti-Markovnikov addition
Enol is initially formed, but Cannot be separated and rapidly isomerizes to form aldehydes
After two proton transfers, but in the reverse order of acid catalysis
The first proton transfer gives enolate ion
Alkynes contain two π bonds. To avoid hydroboration of both π bonds, Add some sterically hindered hydroboration reagents to prevent further hydroboration
Regiochemistry of Alkyne Hydration
acid catalyzed formation of ketones
Base catalyzed formation of aldehydes
Halogenation
excess
equivalent
major antiaddition
Ozonolysis
oxidative cleavage to produce carboxylic acids
terminal alkyne
Alkylation of Terminal Alkynes
Deprotonation under strong base
alkylation is useful
subtopic
synthesis strategy