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(CH 3 ) 3 C-Br reacts at the same rate with Br - and H 2 O in substitution react

ID: 918679 • Letter: #

Question

(CH3)3C-Br reacts at the same rate with Br- and H2O in substitution reactions even though Br- is a more reactive nucleophile. Why?

Select one:

A. (CH3)3C-Br reacts by SN1 mechanism whose rate is independent of nucleophile reactivity.

B. H2O is proportionately more reactive as a nucleophile when a t-butyl substituent is present.

C. The t-butyl group sterically hinders nucleophiles, making different nucleophiles appear to react at the same rate.

D. The t-butyl carbocation is so reactive, the measurable rate of it's reaction with different nucleophiles is imperceptible.

AND

Which of the following is NOT true regarding an SN1 mechanism?

Select one:

A. The nucleophile always bonds to the electrophilic carbon from the side opposite the leaving group.

B. The reaction involves the formation of a carbocation.

C. Generally the observed rate law is: rate = k(substrate)

D. Stereochemically, as the final product forms, there is a mix of retention and inversion of the configuration of the carbon to which the nucleophile attaches, often with a small excess of inversion.

Explanation / Answer

(CH3)3C-Br reacts at the same rate with Br- and H2O in substitution reactions even though Br- is a more reactive nucleophile. Why?

Select one:

A. (CH3)3C-Br reacts by SN1 mechanism whose rate is independent of nucleophile reactivity.

Which of the following is NOT true regarding an SN1 mechanism?

A. The nucleophile always bonds to the electrophilic carbon from the side opposite the leaving group.