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Alkyl halides are reduced by zinc and dil. $\ce{HCl}$ into alkanes $$\ce{ CH3Cl + H2 ->[Zn][dil\text{.} HCl]CH4 + HCl}$$

What I don't understand is the underlying mechanism behind this reaction, is it free radical or nucleophilic substitution. If it is the latter, then why isn't $\ce{CH3-CH3}$ a product? I would appreciate if someone could explain the entire mechanism behind this reaction.

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  • $\begingroup$ I was taught the reactants are alkyl halide and nascent hydrogen, along with zinc in a copper couple and acidic medium. Just an observation though. $\endgroup$ – Gaurang Tandon Feb 7 '18 at 7:50
  • $\begingroup$ Related: chemistry.stackexchange.com/q/66124/31775 $\endgroup$ – Apoorv Potnis Feb 7 '18 at 8:16
  • $\begingroup$ It's neither. If I had to guess, I would propose oxidative addition of zinc to form $\ce{R-Zn-Cl}$ as an intermediate, followed by hydrogenolysis. $\endgroup$ – Zhe Feb 7 '18 at 13:37

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