The Reduction of Polar C-X o Bonds

Summary Three methods to reduce a triple bond 

What product is formed when CH30CH2CH2C = CCH2CH(CH3)2 is treated with each reagent (a) H2 (excess), Pd-C (b) H2 (1 equiv), Lindlar catalyst (c) H2 (excess), Lindlar catalyst (d) Na, NH3  

Deuterium is introduced into a molecule by using reducing agents that contain D atoms instead of H atoms. Draw the products formed when 2-hexyne is treated with each reagent (eO D2, Pd-C  

A chiral alkyne A with molecular formula CsHio is reduced with H2 and Lindlar catalyst to B having the R configuration at its stereogenic center. What are the structures of A and B  

Reduction of these C-X a bonds is another example of nucleophilic substitution, in which LiAUTt serves as a source of a hydride nucleophile (IT). Because H is a strong nucleophile, the reaction follows an 8 2 mechanism, illustrated for the one-step reduction of an alkyl halide in Mechanism 12.3. 

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