ch. 14 questions

The IR spectrum of a compound containing a carbonyl group will contain a strong peak at around which wavenumber?

1700 cm-1

An acetal is produced by reaction of an aldehyde or ketone with __ equivalents of a(n) __

2, alcohol

Which of the following options correctly relate the physical properties of aldehydes and ketones to their structural features? Select all that apply.

Aldehydes and ketones are polar; they therefore exhibit dipole-dipole interactions between their molecules. The strength of the dispersion forces between the molecules of such compounds generally increases as molecular size increases. Aldehydes and ketones can form hydrogen bonds to H2O; shorter chain aldehydes and ketones are therefore water soluble.

Aldehydes and ketones have higher boiling points than alkanes of the same molecular mass. Which of the following options correctly describes this observation?

Aldehydes and ketones exhibit dipole-dipole interactions, which are stronger than the dispersion forces of alkanes.

Which of the following are good nucleophiles for addition to aldehydes or ketones? Select all that apply.

Hydride reagents such as NaBH4 Alcohols under acidic conditions The cyanide ion, -CN

Which of the following options correctly describe the reaction of aldehydes and ketones with reducing agents such as NaBH4 and LiAlH4? Select all that apply.

Hydride reduction occurs via the two-step nucleophilic addition mechanism, in which protonation occurs as the final step. This reaction produces an alcohol with no change in the carbon skeleton of the starting material. An aldehyde produces a primary alcohol in this type of reaction.

Which of the following reactions can be used to synthesize an aldehyde as the reaction product? Select all that apply.

Hydroboration-oxidation of a terminal alkyne Oxidation of a primary alcohol with PCC. Reduction of esters using DIBAL-H

Which of the following options correctly describe the general two-step mechanism for addition of a strong nucleophile to an aldehyde or ketone? Select all that apply.

In step 1, the sp2 hybridized carbonyl C becomes sp3 hybridized. In step 2, the negatively charged carbonyl O is protonated. In step 1, the nucleophile attacks the carbonyl group.

Which of the following options correctly describe the hydrolysis of imines and enamines? Select all that apply.

In the enamine a C-N bond is replaced by a C=O group. This process occurs in the presence of dilute aqueous acid.

Which of the following options correctly describe the mechanism of a Wittig reaction? Select all that apply.

Nucleophilic attack by the ylide at the carbonyl C occurs at the same time as the carbonyl O attacks the P of the ylide. Step 2 involves elimination of Ph3P=O and two new π bonds are formed at the same time.

Carbohydrates are molecules that contain multiple _____ groups and one _____ functional group.

OH, carbonyl

Which of the following options correctly describe the mechanism of imine formation? Select all that apply.

One reaction intermediate is a resonance-stabilized iminium ion. Several steps of this mechanism involve proton-transfer processes. Elimination of H2O produces an iminium ion.

Which of the following steps are required (not necessarily in order) to generate a Wittig reagent? Select all that apply.

Reaction of an alkyl halide with Ph3P Reaction of a phosphonium salt with a strong base

Which of the following options correctly describe the reactivity of the C=O carbon atom in aldehydes and ketones? (Select all that apply.)

Since the carbonyl C atom is relatively uncrowded, reactions at this site often involve nucleophilic addition reactions. This carbon atom is electrophilic due to the polarization of the C=O bond.

Which of the following options correctly describe the nature of the carbonyl carbon atom? (Select all that apply.)

The carbonyl carbon atom has less electron density than the carbonyl oxygen atom. This carbon atom is an electrophilic center.

Which of the following options correctly describe the reaction of an aldehyde or ketone with the cyanide ion? Select all that apply.

The cyanide ion is a strong nucleophile that reacts readily with the carbonyl group. The product of this reaction is a cyanohydrin. This reaction results in C-C bond formation.

Which of the following options correctly describe the hydrolysis of an acetal? Select all that apply.

The mechanism of acetal hydrolysis is the reverse of the mechanism for acetal formation. A ketone may result from acetal hydrolysis. Hydrolysis produces a carbonyl compound and two equivalents of an alcohol.

Which of the following options correctly describe steps in the mechanism for acid-catalyzed nucleophilic addition to an aldehyde or ketone? Select all that apply.

The reaction intermediate formed after Step 2 has an sp3 hybridized C atom attached to O. Nucleophilic attack occurs after protonation. The reaction begins with protonation of the carbonyl oxygen.

Which of the following options correctly describe the reaction of a secondary amine with a ketone or aldehyde? Select all that apply.

The reaction product has a C=C double bond. The product of this reaction is an enamine. This reaction is a reversible equilibrium.

Which of the following options correctly describe the reaction of a carbonyl compound with H2O in the presence of either acid or base catalyst? Select all that apply.

The reaction readily reverses to produce the parent carbonyl compound. The product is called a hydrate. H and OH add across the C-O π bond.

The reaction intermediate formed after Step 2 has an sp3 hybridized C atom attached to O. Nucleophilic attack occurs after protonation. The reaction begins with protonation of the carbonyl oxygen.

Weak nucleophiles require protonation before nucleophilic attack can occur. The reaction of all types of nucleophiles result in addition of the nucleophile and H across the C=O double bond.

Which of the following options correctly identify the mechanism for nucleophilic addition to aldehydes and ketones under different reaction conditions? Select all that apply.

Weak nucleophiles require protonation before nucleophilic attack can occur. The reaction of all types of nucleophiles result in addition of the nucleophile and H across the C=O double bond.

When a primary amine reacts with an aldehyde or a ketone, the net result is that _____.

a C=O group is replaced by C=NR

Which of the following could be produced by hydrolysis of an imine or an enamine? Select all that apply.

aldehyde amine ketone

In the Wittig reaction a(n) ______ is produced by reaction of an aldehyde/ketone with a Wittig reagent.

alkene

Carbohydrates such as glucose, which contains both an aldehyde group and several hydroxy groups, can undergo an intramolecular cyclization to form a cyclic ______.

hemiacetal

Reaction of a carbonyl compound with H2O results in the addition of H and OH across the C=O π bond, resulting in a product that has 2 OH groups on the former C=O carbon. This structure is called a(n) _____. Select all that apply.

hydrate gem-diol

In a compound that contains both an aldehyde and a hydroxyl group, the _____ group can attack the _____ to form a cyclic hemiacetal.

hydroxyl, carbonyl C atom

A Wittig reagent ______. Select all that apply.

is a source of nucleophilic carbon is an organophosphorus reagent contains a C-P bond and results in the formation of a new C-C bond.

Since O is _____ electronegative than C, the C=O is polarized and the C has _____ electron density than the O.

more, less

Which of the following terms correctly describe both the hydride (H-) ion and organometallic reagents such as Grignard reagents and organolithium reagents? (Select all that apply.)

nucleophiles, bases

Hydrates are formed when aldehydes/ketones are reacted with H2O. Under acidic conditions, the first step of the mechanism is ______. Under basic conditions, the first step of the mechanism is ______.

protonation of the carbonyl; addition of the nucleophile to the carbonyl

Alkyl groups are electron _____ and will _____ the stability of a carbonyl group but will _____ the stability of the corresponding carbonyl hydrate (gem-diol).

releasing, increase, decrease

Amines are classified as 1o, 2o, or 3o based on ______.

the number of alkyl groups directly attached to the N atom