Question

In benzyne two external unshared electronic orbital :

• A. do not overlap to form a $\pi$ bond
• B. can overlap to form a complete $\pi$ bond
• C. poorly overlap to form a very weak bond
• D. contribute in benzene ring

Answer 1

The correct option is C poorly overlap to form a very weak bond

The strained triple bond of $Benzyne$ is a distorted triple bond among more $s{p}^2$-hybridized carbons. Thus, the aromatic $\pi$ system, which consists of the overlapping p orbitals of the six $s{p}^2$ ring carbons, should be largely intact. The two remaining electrons of the "triple bond" occupy the two $s{p}^2$ orbitals at the triple bond carbons that are not involved in any $\sigma$ bond. However, these $s{p}^2$ orbitals cannot form a real $\pi$ bond, as they are not parallel to one another. Thus, they cannot effectively overlap. Therefore, arynes' "triple bonds" are highly reactive.