Given below are two statements: Statement I: Hyper conjugation is permanent effect. Statement II : Hyper conjugation in ethyl cation $(\mathrm{CH}_{3}-\stackrel{+}{\mathrm{C}} \mathrm{H}_{2})$ involves the overlapping of $\mathrm{Csp}^{2}-\mathrm{H}_{1 \mathrm{~s}}$ bond with empty 2 p orbital of other carbon. Choose the correct option:

(B) Statement I is correct but Statement II is false.

(A) Statement I is incorrect but Statement II is true.

(C) Both Statement I and Statement II are false.

(D) Both Statement I and Statement II are true.

JEE Main · 2021 · 27 Jul 2021 · Shift 2 · General Organic Chemistry

Given below are two statements:
Statement I: Hyper conjugation is permanent effect.
Statement II : Hyper conjugation in ethyl cation

(CH_{3} - C + H_{2})

involves the overlapping of

Csp^{2} - H_{1 s}

bond with empty 2 p orbital of other carbon.
Choose the correct option:

(A)Statement I is incorrect but Statement II is true.
(B)Statement I is correct but Statement II is false.✓ Correct
(C)Both Statement I and Statement II are false.
(D)Both Statement I and Statement II are true.

Answer: (B)

Solution

Hyperconjugation is the delocalisation of

σ

electrons of a

C - H

bond into an adjacent empty or

π

orbital, and it operates in the ground state of the molecule without any attacking reagent, so it is a permanent effect. In the ethyl cation the electron-deficient carbon is

s p^{2}

hybridised and holds the empty

2 p

orbital, while the

C - H

bonds that donate into it belong to the

s p^{3}

hybridised methyl carbon. The overlap is therefore between a

C s p^{3} - H 1 s

bond and the empty

2 p

orbital, not a

C s p^{2} - H 1 s

bond as written. Statement I is correct and Statement II is false.

JEE Main · 2021 · 27 Jul 2021 · Shift 2 · Single correct option

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JEE Main · 2021 · 27 Jul 2021 · Shift 2 · General Organic Chemistry

Solution

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