Optically pure product

[drill-and-fill]

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I just finished DAT qVAULT orgo test #2 and there is one question that I can't seem to wrap my head around... The question asks, Which of the following reactions will give an optically pure product? And the answer is 2-chloro pentane reacting with NaCN... Can someone explain to me why this is the case?

 

[drill-and-fill]

Does optically pure product refer to a product that only has ONE chiral center...?

 

[ktran17]

read the question wrong =P.. sorry

was reviewing my notes for chad at the same time and was on the optically inactive section XD

 

[ah7391]

No that's wrong.

Optically pure means it only has one enantiomer. Since this reaction undergoes sn2 -CN is a typical substitution nucleophile for sn2 chemistry then it forms the inverse product only. All the product will have one chiral center.

Basically you wont have a racemic mixture at all (when both enantiomers are in solution like sn1 chemistry does)

 

[drill-and-fill]

But when you react 2-chloro pentane with NaCN, dont you get 2-methyl-1-pentamine, which has a chiral center at carbon #2?

 

[ah7391]

Does optically pure product refer to a product that only has ONE chiral center...?

And optically INACTIVE is when the product is achiral (or meso, watch out for those!)

 

[drill-and-fill]

I thought so... Thanks ah7391

 

[ah7391]

Np! Thank chad!