Question

The Cimetidine has several nitrogen atom in its structure. Identify the most basic atom of given cimetidine derivative.

• A. I
• B. II
• C. III
• D. V

Answer 1

The correct option is D V

$\begin{array}{c}\text{amongst (I,II,III \& IV,V); (V,I,II \& III) are}\end{array}$

$\text{nitrogen atoms,}\therefore \text{as nitrogen is more}$

$\text{electronegative}\therefore \text{. more basic atom has to be (I),(II),(V)}$ $\text{or (III) as nitrogen also have lone pair}$

$\begin{array}{c}\text{and as in (I), (II), (III) the lone- pair is engaged}\\ \text{in conjugation therefore (V) is more basic as its lone-}\\ \text{pair is free.}\end{array}$