Question

Total number of compounds with Chiral carbon atoms from following is ________.

$\text{CH}_3 - \text{CH}_2 - \text{CH(NO}_2\text{) - COOH} \\ \text{CH}_3 - \text{CH}_2 - \text{CHBr - CH}_2 - \text{CH}_3 \\ \text{CH}_3 - \text{CH(I) - CH}_2 - \text{NO}_2 \\ \text{CH}_3 - \text{CH}_2 - \text{CH(OH) - CH}_2\text{OH} \\$

Answer 1

Correct Answer: 5

To determine the number of compounds with chiral carbon atoms, we analyze each given compound for chirality. A carbon is chiral if it has four different substituents. We'll examine each compound for such carbons:

• $\text{CH}_3 - \text{CH}_2 - \text{CH(NO}_2\text{) - COOH}$
  The third carbon ($\text{CH}$) is attached to $-\text{CH}_3$, $-\text{CH}_2\text{COOH}$, $-\text{NO}_2$, and $-\text{H}$. This is a chiral center.
• $\text{CH}_3 - \text{CH}_2 - \text{CHBr - CH}_2 - \text{CH}_3$
  The third carbon ($\text{CHBr}$) is attached to $-\text{CH}_2\text{CH}_3$, $-\text{Br}$, $-\text{CH}_2\text{CH}_3$, and $-\text{H}$. It's symmetric, thus not chiral.
• $\text{CH}_3 - \text{CH(I) - CH}_2 - \text{NO}_2$
  The second carbon ($\text{CH(I)}$) is attached to $-\text{CH}_3$, $-\text{CH}_2\text{NO}_2$, $-\text{I}$, and $-\text{H}$. This is a chiral center.
• $\text{CH}_3 - \text{CH}_2 - \text{CH(OH) - CH}_2\text{OH}$
  The third carbon ($\text{CH(OH)}$) is attached to $-\text{CH}_2\text{OH}$, $-\text{OH}$, $-\text{CH}_2\text{CH}_3$, and $-\text{H}$. This is a chiral center.

The total number of compounds with chiral carbons is 5. 

Answer 2

To identify chiral carbons, examine carbon atoms with four different substituents, which render them asymmetric:

Step 1. CH₃–CH₂–CH(NO₂)–COOH: The second carbon is chiral due to four distinct substituents.
Step 2. CH₃–CH₂–CHBr–CH₂–CH₃: The third carbon is chiral, as it has four different substituents.
Step 3. CH₃–CH(I)–CH₂–NO₂: The second carbon is chiral due to its four different groups.
Step 4. CH₃–CH₂–CH(OH)–CH₂OH: The third carbon is chiral, as it has four distinct substituents.
Step 5. CH₃–CH–CH(I)–C₂H₅: The second carbon is chiral due to four different substituents.

Thus, there are five compounds containing chiral carbons.
The Correct answer is: 5