Organic Chemistry : Using Lithium Aluminum Hydride

Study concepts, example questions & explanations for Organic Chemistry

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Example Questions

Example Question #1 : Using Lithium Aluminum Hydride

Which of the following can be reduced when mixed with ?

Possible Answers:

Correct answer:

Explanation:

 is a very powerful reducing agent that works to reduce almost any carbonyl compound.  is an amide and the only carbonyl compound given of the answer choices.

Example Question #7 : Organic Reducing Agents

Img 0637

What reagents are needed to satisfy the given reaction?

Possible Answers:

Correct answer:

Explanation:

Img 0639

This problem requires that we convert our ketone group into a chlorine. However, this cannot be done directly, and requires multiple steps.

We begin by reducing the ketone with  to form an alcoxide. The alcoxide undergoes workup (the process whereby a negatively charged oxygen gains a proton) via , depicted above as simply "". We now have a secondary alcohol. From here, we can simply use the reagent  to convert the alcohol into the desired chlorine.

Example Question #2 : Using Lithium Aluminum Hydride

What is the product of the given reaction? 

Screen shot 2015 11 13 at 3.38.24 pm

Screen shot 2015 11 13 at 3.39.24 pm

Possible Answers:

I

II

V

IV

III

Correct answer:

IV

Explanation:

First step: esterification

Second step: lithium aluminum hydride reduction

Third step: neutralization to form primary alcohol

Fourth step: SN2 reaction to form final chlorinated product

Example Question #2 : Using Lithium Aluminum Hydride

What is the result of the following reaction?

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Possible Answers:

All of the above

Correct answer:

Explanation:

Lithium Aluminum Hydride is a potent reducing agent; it has the ability to turn esters and aldehydes into primary alcohols, and ketones into secondary alcohols. The starting material is an aldehyde, so the correct answer is thus a primary alcohol ONLY.

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