The presence of asymmetric centers in the given compounds has to be checked. Concept introduction: Stereoisomers are isomers which have different spatial arrangement in spite of same bond connectivity. Stereoisomers are due to the presence of stereo center. Asymmetric center is a stereo center which arises to hydrocarbons if the carbon is bonded to four different groups.

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 103P

(a)

Interpretation Introduction

Interpretation:

The presence of asymmetric centers in the given compounds has to be checked.

Concept introduction:

Stereoisomers are isomers which have different spatial arrangement in spite of same bond connectivity. Stereoisomers are due to the presence of stereo center.

Asymmetric center is a stereo center which arises to hydrocarbons if the carbon is bonded to four different groups.

(b)

Interpretation Introduction

Interpretation:

The chirality of the given compounds has to be checked.

Concept introduction:

Optical activity (chirality) of a molecule is the interaction between molecule and plane-polarized light.

Molecule having asymmetric center shows optical activity except mesocompounds.

If a compound having non-superimposable mirror image, then the compound is chiral.

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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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