7P - Organic Chemistry (Mcmurry)

Question

Question: Identify the most acidic Hydrogens in each of the following molecules:

 

(a) CH₃CH₂CHO

 

(b) (CH₃)₃CCOCH₃

 

(c) CH₃CO₂H

 

(d) Benzamide

(e) CH₃CH₂CH₂CN 

(f) CH₃CON(CH₃)₂

Step-by-Step Solution

Answer

Step 1: Structure of C H 3 C H 2 C H O

The structure of is like

Step 2: Number of most acidic Hydrogens

The number of most acidic Hydrogens in  $C{H}_{3}C{H}_{2}CHO$ is two.

 

Step 3: Explanation of the most acidic Hydrogens of CH 3 CH 2 CHO

In $C{H}_{3}C{H}_{2}CHO$, there are two most acidic Hydrogens as they all are present on a carbon to the electron withdrawing carbonyl group.

Step 4: (b) Structure of (CH 3 ) 3 CCOCH 3

The structure of (CH₃)₃CCOCH₃ is as shown below:

Step 5: Number of most acidic Hydrogens

The no of most acidic Hydrogens in  ${\left(C{H}_3\right)}_{3}CCOC{H}_3$  is three.

Step 6: Explanation of the most acidic Hydrogens of (CH 3 ) 3 CCOCH 3

In (CH₃)₃CCOCH₃, there are two most acidic Hydrogens as they all are present on a carbon to the electron withdrawing carbonyl group.

Step 7: (c) Structure of CH 3 CO 2 H

The structure of CH₃CO₂H is like

Step 8: Explanation of the most acidic Hydrogens of CH 3 CO 2 H

In CH₃CO₂H, there are four acidic Hydrogens. The carboxylic hydrogen is most acidic as it stabilizes by resonance. The methyl Hydrogens are also acidic but in lesser amount than that of the carboxylic hydrogens as they all are present on a carbon to the electron withdrawing carbonyl group.

 

 

Hence, CH₃CO₂H has one most acidic Hydrogen.

Step 9: (d) Structure of Benzamide

The structure of Benzamide is like

 

Step 10: Explanation of the most acidic Hydrogens of Benzamide

In Benzamide, there are two most acidic Hydrogens as they all are present on an electronegative nitrogen atom which is attached to the electron withdrawing carbonyl group and benzene ring.

Step 11: (e) Structure of CH 3 CH 2 CH 2 CN

The structure of CH₃CH₂CH₂CN is like

 

The number of most acidic Hydrogens in CH₃CH₂CH₂CN is 2.

Step 12: Explanation of the most acidic Hydrogens of CH 3 CH 2 CH 2 CN

In CH₃CH₂CH₂CN, there are two most acidic Hydrogens as they all are present on a carbon to the electron withdrawing nitrile group.

 

 

Hence, CH₃CH₂CH₂CN has two most acidic Hydrogens.

Step 13: (f) Structure of CH 3 CON(CH 3 ) 2

The structure of CH₃CON(CH₃)₂ is like

The number of most acidic Hydrogens in CH₃CON(CH₃)₂ is three.

 

Step 14: Explanation of the most acidic Hydrogens of CH 3 CON(CH 3 ) 2

In CH₃CON(CH₃)₂, there are three most acidic Hydrogens as they all are present on a carbon to the electron withdrawing carbonyl group which is also attached to the electronegative nitrogen atom.

 

Hence, CH₃CON(CH₃)₂ has three most acidic Hydrogens.