Thank you for registering.

One of our academic counsellors will contact you within 1 working day.

Please check your email for login details.
MY CART (5)

Use Coupon: CART20 and get 20% off on all online Study Material

ITEM
DETAILS
MRP
DISCOUNT
FINAL PRICE
Total Price: Rs.

There are no items in this cart.
Continue Shopping

why LiAlH4 has no effect on double and triple bonds?

why LiAlH4 has no effect on double and triple bonds?

Grade:

1 Answers

Suraj Prasad IIT Patna
askIITians Faculty 286 Points
5 years ago
Neither LiAlH4 nor NaBH4 are able to reduce an isolated C=C bond. But if you have an enal (a conjugated aldehyde) it can react (as an electrophile) either at the β-carbon or at the carbonyle group's carbon. According to the HSAB Principle the β-carbon is a "soft" center and would react preferably with "soft" nucleophiles while the carbonyle carbon is a "hard" center and prefers to react with "hard" nucleophiles. Now, NaBH4 is a rather soft nucleophile and thus it reacts with an enal at the β carbon. After this reaction the C=C bond is gone. But, if what is left behind is still a very reactive simple aldehyde that gets reduced to the alcohol by NaBH4 in a second step. LiAlH4 on the other hand is a rather hard nucleophile and thus reacts with an enal at the carbonyle carbon. After this reaction there is just an isolated double bond left that can't be reduced by LiAlH4 in a second step.

Think You Can Provide A Better Answer ?

Provide a better Answer & Earn Cool Goodies See our forum point policy

ASK QUESTION

Get your questions answered by the expert for free