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Standard XII

Chemistry

Elimination Reaction

Elimination r...

Question

Elimination reactions of cis- and trans-1-Bromo-2-methylcyclohexanes with $N a O E t$ in $E t O H$ can give the same or different main product, 1-methylcyclohexene (1) or 3-methylcyclohexene (2). Which of (a)-(d) indicates the main products?

1 from the cis and 2 from the trans substrate

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2 from the cis and 1 from the trans substrate

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2 both from the cis and the trans substrate

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1 both from the cis and the trans substrate

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Solution

The correct option is A 1 from the cis and 2 from the trans substrate
The substituents present at 1 and 2 positions of a chair cyclohexane take an axial and an equatorial position in cis form, but both equatorial positions or both axial positions in the trans form. Hence, the axial $B r$ has an adjacent axial hydrogen at $C 2$ and $(C 6)$ in cis form but only at C6 in trans. Therefore, the former can give the more substituted 1 but the latter cannot.

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Elimination reactions of cis- and trans-1-Bromo-2-methylcyclohexanes with NaOEt in EtOH can give the same or different main product, 1-methylcyclohexene (1) or 3-methylcyclohexene (2). Which of (a)-(d) indicates the main products?

Elimination reactions of cis- and trans-1-Bromo-2-methylcyclohexanes with $N a O E t$ in $E t O H$ can give the same or different main product, 1-methylcyclohexene (1) or 3-methylcyclohexene (2). Which of (a)-(d) indicates the main products?