The percent of each enantiomer in the given solution has to be calculated. Concept introduction: The pair of Enantiomers has different configurations. Pair of enantiomers has different optical activity, which means if one will show levorotatory then the other will show dextrorotatory. The direction and magnitude of rotation of plane-polarized light by an optically compound is measured by using polarimeter . This rotation of polarized light is specific for a compound at specified temperature and wavelength, so it is called as Specific rotation of that compound. The specific rotation of enantiomers has equal magnitudes and opposite signs. Specific rotation of compound is calculated by, [ α ] λ T = α l ( d m ) × c ( g / 100 m L ) [ α ] λ T − s p e c i f i c r o t a t i o n ( a t T a n d λ ) α − o b s e r v e d r o t a t i o n c − c o n c e n t r a t i o n o f t h e s a m p l e l − l e n g t h o f t h e s a m p l e t u b e If the mixture contain unequal amount of enantiomers of a compound, then the amount of excess of enantiomer is called enantiomeric excess or optical purity. It is calculated by, enantiomeric excess = observed specific rotation specific rotation of the pure enantiomer ×100%

Question

On the next page is an LC separation of the parabens found in baby wash. Parabens are suspected in a link to breast cancer therefore an accurate way to quantitate them is desired. a. In the chromatogram, estimate k' for ethyl paraben. Clearly indicate what values you used for all the terms in your calculation. b. Is this a "good" value for a capacity factor? Explain. c. What is the resolution between n-Propyl paraben and n-Butyl paraben? Again, indicate clearly what values you used in your calculation. MAU | Methyl paraben 40 20 0 -2 Ethyl paraben n-Propyl paraben n-Butyl paraben App ID 22925 6 8 min

Answer 1

Question

Chapter 4, Problem 91P

Interpretation Introduction

Interpretation:

The percent of each enantiomer in the given solution has to be calculated.

Concept introduction:

The pair of Enantiomers has different configurations.

Pair of enantiomers has different optical activity, which means if one will show levorotatory then the other will show dextrorotatory.

The direction and magnitude of rotation of plane-polarized light by an optically compound is measured by using polarimeter.

This rotation of polarized light is specific for a compound at specified temperature and wavelength, so it is called as Specific rotation of that compound.

The specific rotation of enantiomers has equal magnitudes and opposite signs.

Specific rotation of compound is calculated by,

[α]λT=αl ( dm)×c (g/100mL) [α]λT−specific rotation (at T and λ)α−observed rotationc−concentration of the samplel−length of the sample tube

If the mixture contain unequal amount of enantiomers of a compound, then the amount of excess of enantiomer is called enantiomeric excess or optical purity. It is calculated by,

enantiomeric excess =observed specific rotationspecific rotation of the pure enantiomer×100%

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On the next page is an LC separation of the parabens found in baby wash. Parabens are suspected in a link to breast cancer therefore an accurate way to quantitate them is desired. a. In the chromatogram, estimate k' for ethyl paraben. Clearly indicate what values you used for all the terms in your calculation. b. Is this a "good" value for a capacity factor? Explain. c. What is the resolution between n-Propyl paraben and n-Butyl paraben? Again, indicate clearly what values you used in your calculation. MAU | Methyl paraben 40 20 0 -2 Ethyl paraben n-Propyl paraben n-Butyl paraben App ID 22925 6 8 min

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