Question 1

Which resonance effect explains why the carbonyl carbon of benzaldehyde is less electrophilic than that of acetaldehyde?

Accepted Answer

The phenyl ring donates electron density via resonance, delocalizing the positive charge on the carbonyl carbon.

Question 2

What is the correct IUPAC name for the compound with the structure $$\mathrm{PhCH_2CH(CH_3$)CH_2CH_2CHO}$$?

Accepted Answer

4-methyl-5-phenylpentanal

Question 3

Which of the following correctly ranks the compounds in order of increasing boiling point?

Accepted Answer

$$\mathrm{n}-$$butane \u003c diethyl ether \u003c 2-butanone \u003c 1-butanol

Question 4

Which reagent sequence would you use to selectively reduce an ester to an aldehyde?

Accepted Answer

1. DIBAL-H 2. $$\mathrm{H_2O}$$

Question 5

Which set of reagents will convert 1-hexyne into 2-hexanone?

Accepted Answer

Hg$$^{2+}$$, H$$_2SO$_4$$, H$$_2O$$

Question 6

What is the structure of the hydrate of cyclopentanone?

Accepted Answer

A cyclopentane ring with two hydroxyl groups on the same carbon.

Question 7

Which functional group is present in the cyclic structure of glucose?

Accepted Answer

hemiacetal

Question 8

When an aldehyde is reacted with HCN in the presence of KCN, what product is formed?

Accepted Answer

cyanohydrin

Question 9

Why do acetal-forming reactions using ethylene glycol have more favorable equilibrium constants than those using methanol?

Accepted Answer

They are more favorable on entropy grounds.

Question 10

Which reagent will react with acetals to regenerate the carbonyl compound?

Accepted Answer

$$\mathrm{H_3O^+}$$

Question 11

What is the IUPAC name for the compound $$\mathrm{CH_3CHBrCH_2COCH_2CHO}$$?

Accepted Answer

5-bromo-3-oxohexanal

Question 12

Which of the following best describes the product formed when benzaldehyde reacts with hydroxylamine in the presence of acid?

Accepted Answer

An oxime

Question 13

Which of the following is the correct IUPAC name for the compound shown below?

$$\mathrm{CH_3CH_2COCH_2CH_2CO_2H}$$

Accepted Answer

4-oxohexanoic acid

Question 14

Which of the following is a correct stepwise mechanism for the acid-catalyzed condensation of cyclohexanone with hydroxylamine?

Accepted Answer

Protonation of the carbonyl, nucleophilic attack by H$$_2N$$–OH, proton transfers, and loss of water to form the oxime.

Question 15

Which of the following is the correct structure for the semicarbazone derivative of 3-pentanone?

Accepted Answer

A structure with a C=N–NH–CO–NH$$_2$$ group attached to the central carbon of 3-pentanone.

Question 16

Which of the following best describes the product formed when a diol reacts with a ketone in the presence of acid?

Accepted Answer

A cyclic acetal

Question 17

Which of the following is the correct structure for the diethyl acetal of butanal?

Accepted Answer

$$\mathrm{CH_3CH_2CH_2CH(OCH_2CH_3)_2}$$

Organic Chemistry Practice Problems – Step-by-Step Guidance

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