3. Acids and Bases

Predict the product that results from the following 'pushed electrons.'

(a)

Predict the product that results from the following 'pushed electrons.'

(c)

Predict the product that results from the following 'pushed electrons.'

(f)

Predict the product that results from the following 'pushed electrons.'

(i)

The following reaction steps are shown using conventional electron pushing. (a) Draw the second product whose formation would have been rationalized with this same arrow.

(c)

Why are NH₃ and CH₃NH₂ no longer nucleophiles when they are protonated?

In each case, circle the stronger nucleophile.

(d)

We show in Chapter 20 that α , β-unsaturated ketones are electrophilic at C₄. Rationalize this observation.

In each case, circle the stronger nucleophile.

(c)

Provide a reasonable arrow-pushing mechanism for the following Lewis acid–Lewis base reactions.

(a)

Provide an arrow-pushing mechanism for the following hypothetical base half-reactions.

(b)

BCl₃ has an empty p orbital, so it is a strong Lewis acid. Would you expect an amide to react with BCl₃ at nitrogen or oxygen?

In each case, circle the stronger nucleophile.

(b)

Based on the analysis you used in Assessment 17.3, which carbonyl would you expect to react most quickly with a nucleophile?

(c)

Classify the following nucleophiles as strong, weak, or intermediate. Would you expect each to add to a carbonyl directly or wait for a carbocation to form?

b)