Amines are derivatives of ammonia and are classified as `1^@, 2^@ , and 3^@` Primary and secondary (but not teritary amines) form intermolecular hydrogen bonds and thus they boil at higher temperature than expected.Like ammonia, all amines are basic, although they differ in their basic nature.As amines are considered as derivatives of ammonia, quatemary ammonium salts are considered as derivatives of ammonium salts.Only the quatemary ammonium salts can show optical activity.
Methylethylpropyl amine is optically inactive because

Options

A. It is not tetrahedral
B. Its molecules are superimposable on their mirror image
C. The enantiomers are rapidly interconverted into each other
D. the nitrogen is `sp^2` hybridized

Explanation

To determine why methyl ethyl propyl amine is optically inactive, we can follow these steps:

### Step 1: Identify the Structure of Methyl Ethyl Propyl Amine
Methyl ethyl propyl amine is a tertiary amine with the following structure:
- It has three alkyl groups attached to the nitrogen atom: a methyl group (CH3), an ethyl group (C2H5), and a propyl group (C3H7).

### Step 2: Understand Chirality
For a molecule to be optically active, it must have a chiral center, which is typically a carbon atom bonded to four different substituents. In the case of amines, the nitrogen atom can also be a chiral center if it is bonded to three different groups.

### Step 3: Analyze the Nitrogen Atom
In methyl ethyl propyl amine, the nitrogen atom is bonded to three different alkyl groups. However, the presence of these groups does not guarantee optical activity.

### Step 4: Consider Nitrogen Inversion
Tertiary amines like methyl ethyl propyl amine undergo a phenomenon known as "nitrogen inversion." This means that the nitrogen can rapidly interconvert between different spatial arrangements of the attached groups.

### Step 5: Conclusion on Optical Activity
Due to nitrogen inversion, the molecule does not exist as a stable chiral form. Instead, it exists as a racemic mixture, where the enantiomers interconvert rapidly, making it optically inactive.

### Final Answer
Methyl ethyl propyl amine is optically inactive because it undergoes rapid nitrogen inversion, preventing it from existing as a stable chiral compound.

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