1. Given that ( R )-alpha-methylbenzylamine has a specific rotation of +30.5 o a

Question

1. Given that (R)-alpha-methylbenzylamine has a specific rotation of +30.5o and (S)-alpha-methylbenzylamine has a specific rotation of -30.5o, what is the optical purity of a mixture whose specific rotation was found to be +20.1o?

a) 30%

b) 70%

c) 66%

d) 54%

e) 80%

2. Eight grams of racemic alpha-methylbenzylamine was resolved into enantiomers by crystallization of its diastereomeric salts of L-(+)-tartaric acid, followed by neutralization. The isolated (S)-(-)-enantiomer was distilled in vacuum to give 1.5 g of pure amine. Calculate the yield of (S)-(-)-alpha-methylbenzylamine.

a) 19%

b) 25%

c) 38%

d) 55%

e) 63%

3. Which of the following acids can potentially be used for optical resolution of alpha-methylbenzylamine?

a) A

b) A and B

c) A and C

d) A B and C

e) All 4 acids

4. Assign the absolute configuration of the following molecules (left to right):

a) S, S, R, R

b) S, R, R, R

c) S, S, R, S

d) S, S, S, S

e) S, R, R, S

1. Given that (R)-alpha-methylbenzylamine has a specific rotation of +30.5degree and (S)-alpha-methylbenzylamine has a specific rotation of -30.5 degree, what is the optical purity of a mixture whose specific rotation was found to be +20.1degree? a) 30% b) 70% c) 66% d) 54% e) 80% 2. Eight grams of racemic alpha-methylbenzylamine was resolved into enantiomers by crystallization of its diastereomeric salts of L-(+)-tartaric acid, followed by neutralization. The isolated (S)-(-)-enantiomer was distilled in vacuum to give 1.5 g of pure amine. Calculate the yield of (S)-(-)-alpha-methylbenzylamine. a) 19% b) 25% c) 38% d) 55% e) 63% 3. Which of the following acids can potentially be used for optical resolution of alpha-methylbenzylamine? a) S, S, R, R b) S, R, R, R c) S, S, R, S d) S, S, S, S e) S, R, R, S a) A b) A and B c) A and C d) A B and C e) All 4 acids 4. Assign the absolute configuration of the following molecules (left to right):

Explanation / Answer

1. C (66%)

2. C (38%)

3. B (A and B)

4. C (S,S,R,S)

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