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AlkynesAlkynes

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The triple bond consists of one σ and two πpbond

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Synthesis of Alkynes by Elimination ReactionsReactions

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Hydrogenation of Alkynes

Li dl ’ l l d i lk f Lindlar’s catalyst also produces cis-alkenes from alkynes

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Anti Addition of Hydrogen: Synthesis of trans-Alkenestrans Alkenes

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Geminal dihalides can also undergo consecutive dehydrohalogenation reactions to yield the alkyney g y y

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Th A idi f T i l AlkThe Acidity of Terminal Alkynes

Recall that acetylenic hydrogens have a pKa of about 25 and are Recall that acetylenic hydrogens have a pKa of about 25 and are much more acidic than most other C-H bonds

The relative acidity of acetylenic hydrogens in solution is

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NaOH

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Addition of Bromine and Chlorine to Alkynes

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Addition of Hydrogen Halides to Alkynes

Markovnikov

Anti MarkovnikovAnti-Markovnikov

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Oxidative Cleavage of Alkynes

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