Chapter 18, Problem 18.49EP

(a)

Interpretation Introduction

Interpretation: Whether the boiling point will be the same or different for the compounds $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ has to be predicted.

Concept introduction: Lactic acid is an organic compound with the formula ${\text{CH}}_{\text{3}}\text{CH}\left(\text{OH}\right)\text{COOH}$.  Lactic acid exists in two different forms which are $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$.  These two forms of lactic acid are enantiomers.

Answer to Problem 18.49EP

The boiling point for $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ is same.

Explanation of Solution

The most of the properties of $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ are same.  But the properties involving the interaction with the plane polarised light and other chiral molecules, like solubility in a chiral solvent will be different.  The boiling point of $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ will be same.

(b)

Interpretation Introduction

Interpretation: Whether the optical activity will be the same or different for the compounds $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ has to be predicted.

Concept introduction: Lactic acid is an organic compound with the formula ${\text{CH}}_{\text{3}}\text{CH}\left(\text{OH}\right)\text{COOH}$.  Lactic acid exists in two different forms which are $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$.  These two forms of lactic acid are enantiomers.

Answer to Problem 18.49EP

The optical activity for $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ is different.

Explanation of Solution

The most of the properties of $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ are same.  But the properties involving the interaction with the plane polarised light and other chiral molecules, like solubility in a chiral solvent will be different.

Hence, the optical activity for $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ is different.

(c)

Interpretation Introduction

Interpretation: Whether the reaction with ethanol will be the same or different for the compounds $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ has to be predicted.

Concept introduction: Lactic acid is an organic compound with the formula ${\text{CH}}_{\text{3}}\text{CH}\left(\text{OH}\right)\text{COOH}$.  Lactic acid exists in two different forms which are $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$.  These two forms of lactic acid are enantiomers.

Answer to Problem 18.49EP

The the reaction with ethanol for $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ is same.

Explanation of Solution

The most of the properties of $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ are same.  But the properties involving the interaction with the plane polarised light and other chiral molecules, like solubility in a chiral solvent will be different.  The reaction of $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ with ethanol will be similar.

Hence, the reaction with ethanol for $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ is same.

(d)

Interpretation Introduction

Interpretation: Whether the reaction with $(-)-\text{2,3}-\text{butanediol}$ will be the same or different for the compounds $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ has to be predicted.

Concept introduction: Lactic acid is an organic compound with the formula ${\text{CH}}_{\text{3}}\text{CH}\left(\text{OH}\right)\text{COOH}$.  Lactic acid exists in two different forms which are $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$.  These two forms of lactic acid are enantiomers.

Answer to Problem 18.49EP

The reaction with $(-)-\text{2,3}-\text{butanediol}$ for $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ is different.

Explanation of Solution

The two forms of lactic acid, $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ are enantiomers.  Therefore, most of the properties of $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ are same.  But the properties involving the interaction with the plane polarised light and other chiral molecules, like solubility in a chiral solvent will be different.  The reaction of $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ with $(-)-\text{2,3}-\text{butanediol}$ will be different.

Hence, the reaction with $(-)-\text{2,3}-\text{butanediol}$ for $\left(\text{+}\right)-\text{lactic}\text{acid}$ and $(-)-\text{lactic}\text{acid}$ is different.