Benzene and Alkyl Benzene - Result Question 25
29. Which of the following molecules, in pure form, is/are unstable at room temperature?
(2012)
Show Answer
Answer:
Correct Answer: 29. (b, c)
Solution:
According to Huckel rule, the compounds which have $4 n(n=0,1,2,3 \ldots)$ delocalised $\pi$-electrons in a close-loop are anti-aromatic and characteristically unstable. Compound $B$ satisfy the criteria of anti-aromaticity as :
<img src=“https://temp-public-img-folder.s3.amazonaws.com/sathee.prutor.images/sathee_image/cropped_2024_01_16_b4fdca9f34924034e8d8g-420_jpg_height_97_width_416_top_left_y_864_top_left_x_1422.jpg"width="400"> Compound $C$ is anti-aromatic in its resonance form :
Compound $A$ has $4 \pi$-electrons which are also delocalised but do not constitute close loop, hence non-aromatic.
Compound $D$ is aromatic, characteristically stable.
Order of stability: Aromatic $>$ Non-aromatic $>$ Anti-aromatic
BETA
