Reduction of esters to primary alcohols using LiAlH4

by James

Description: Addition of lithium aluminum hydride to esters leads to the formation of primary alcohols (after addition of acid)
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{ 2 comments… read them below or add one }

Cara Pimental January 31, 2014 at 6:05 pm

What about with the cyclic ester? I am wondering about the alkoxide intermediate. Is it two separate LAH molecules, one acting at each end?

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Mohammed Sharif April 11, 2014 at 9:10 am

It’s not 2 separate LAH, but rather 2 separate H+ in the acid workup. If you look at the mechanism, when bond D, the one on the “leaving” oxygen, breaks, the electrons go toward the oxygen. It’s not shown, but this just makes another oxygen anion. In the case of the cyclic ester, the mechanism is the same, but if you draw it out, you’ll see that the “leaving” oxygen is just stuck at the other end of the chain. In the acid workup, the H+ protonates both ends.

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