Question

Which statements are true for SN2 reactions of haloalkanes? (a) Both the haloalkane and the nucleophile are involved in the transition state. (b) The reaction proceeds with inversion of configuration at the substitution center. (c) The reaction proceeds with retention of optical activity. (d) The order of reactivity is 3° > 2° > 1° > methyl. (e) The nucleophile must have an unshared pair of electrons and bear a negative charge. (f) The greater the nucleophilicity of the nucleophile, the greater is the rate of reaction.

Answer 1

Answer:-

Statement (a) : "Both the haloalkane and the nucleophile are involved in the transition state" is True.

SN2 reactions follow second order kinetics. That is, the rate determining step involves both the concentrations of haloalkane and nucleophile.

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Statement (b), "The reaction proceeds with inversion of configuration at the substitution center is True.

In SN2 reactions, nucleophile attacks from the backside of the leaving group and thus, inversion of configuration occurs.

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Statement (c), "The reaction proceeds with retention of optical activity" is False.

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Statement (d), "The order of reactivity is 3°>2°>1°> methyl " is False.

The correct order of reactivity for SN2 reactions is : methyl > 1°> 2° > 3°.

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Statement (e), "The nucleophile must have an unshared pair of electrons and bear a negative charge" is True.

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Statement (f), "The greater the nucleophility of the nucleophile, the greater is the rate of the reaction" is True.

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