3. Acids and Bases

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

(b)

Which pair of compounds represents the two major organic products expected from the reaction of 2-bromobutane with sodium ethoxide (${\mathrm{NaO}}_{\mathrm{Et}}$) in ethanol via an E2 mechanism?

In a reaction mechanism, the tail of a curved arrow should be placed at which of the following locations to correctly indicate electron movement?

Given a reaction profile with two energy maxima and one energy minimum between them, which statement correctly identifies the intermediate(s) in the reaction pathway?

In the context of reaction mechanisms, which pattern of curved arrow pushing best describes the second step of a typical S$N_1$ reaction?

Which of the following best describes the role of acid in the Fischer esterification mechanism?

In the context of reaction mechanisms, what is the primary purpose of using curved arrows in the first step of a mechanism?

Which of the following best describes the products formed when a reaction mechanism is depicted using fishhook notation?

Show an arrow-pushing mechanism that forms the product on the right from the reactant at left. Here, three arrows are necessary in each reaction.

(a)

Which is the most likely mechanism for the reaction of $t_{3}Cl$ (tert-butyl chloride) with aqueous ${\mathrm{Na}}_O$ to form tert-butyl alcohol?

Given the following synthetic sequence: 1-bromopropane is treated with aqueous ${\mathrm{Na}}_{\mathrm{OH}}$ followed by acidification, predict the major organic product.

Which of the following best describes the mechanism for the conversion of $R_{\mathrm{Br}}$ (an alkyl bromide) to $R_{\mathrm{OH}}$ (an alcohol) using aqueous ${\mathrm{Na}}_{\mathrm{OH}}$ under reflux conditions?

Would you expect the following species to be electrophiles or nucleophiles? Some may be both. Explain your answer.

(e)

For each of the reactions in Problem 15, indicate which reactant is the nucleophile and which is the electrophile.

a.

b.

Which of the following best describes the mechanism of a $\mathrm{Diels}-\mathrm{Alder}$ reaction, a classic example of a pericyclic reaction?