Chapter 8 Multiple Choice Questions

. Which of the following has the largest equilibrium constant for the formation of a cyanohydrin?

. Which of the following has the largest equilibrium constant for hydration?

. Which of the following has the smallest equilibrium constant for hydration?

. Which is normally the main product when a mixture of aldehyde RCHO and an excess of alcohol R'OH is treated with an acid catalyst?

. Which is normally the main product when a mixture of aldehyde RCHO and an excess of alcohol R'OH is treated with a base catalyst?

. Which of (a)-(d) is least likely as an intermediate or product in the following reaction?

. Which of the following reactions does not give the compound indicated as a main product?

. Which of the following statements is wrong?

The yield of cyanohydrin is low when an aldehyde is simply added to an aqueous solution of NaCN.

The yield of cyanohydrin increases when an appropriate amount of acid is added to an aqueous solution of an aldehyde and NaCN.

Formation of cyanohydrin of aldehyde is accelerated by acid catalysis.

Formation of cyanohydrin of aldehyde is increased by increasing the concentration of cyanide ion.

. Which of the following statements is wrong?

Hydrolysis of an acetal is catalysed by acids.

Hydrolysis of an acetal is catalysed by bases.

Oximes are stabilized by conjugation between the C=N and OH groups.

Enamines are formed between secondary amines and the carbonyl group of aldehydes and ketones.

. Which aldehyde has the largest equilibrium constant for the formation of a cyanohydrin?

. Which aldehyde has the smallest equilibrium constant for the formation of a cyanohydrin?

. Which ketone has the largest equilibrium constant for hydration?

. Which combination of an aldehyde and an alcohol most readily forms a hemiacetal with base catalysis?

. Which of the following most readily forms a cyclic hemiacetal with acid catalysis?

. Which stage of the following reaction scheme for acetal formation does not correctly show the flow of electrons?

Stage (a)

Stage (b)

Stage (c)

Stage (d)

. Which of (a)-(d) is least likely as an intermediate or a product in the following reaction?

. Which of the following reactions indicates a correct result of the main process?

. Each of the following diagrams (1)-(4) indicates the flow of electrons in a possible main step in the formation of an imine from an aldehyde and an amine in aqueous solution. Which combination of two steps is the most probable in a mechanism of the overall reaction?

(1) and (3)

(1) and (4)

(2) and (3)

(2) and (4)

. Which of the following statements is wrong?

Hydration of an aldehyde is reversible either in acidic or basic solutions.

Hydration of simple ketones is not generally favourable.

Equilibrium in the hydration of aldehydes generally favours formation of the hydrate.

Oxygen isotope exchange occurs when a ketone is dissolved in water labelled with ¹⁸O in the presence of a catalytic amount of acid or base.

Quiz Content