Q: In the Claisen condensation, which of the following is required for the reaction to proceed?

An ester with an $$oldsymbol{ ext{α}}-$$hydrogen and a strong base such as $$NaOEt$$

Q: A student mixes acetone ($$CH_3COCH_3) $$with sodium hydroxide ($$NaOH) $$and heats the mixture. What is the major organic product?

Mesityl oxide (an $$oldsymbol{ ext{α,β}}-$$unsaturated ketone)

Q: Which of the following is a correct statement about the resonance stabilization in benzene?

Benzene's six $$oldsymbol{ ext{π}}$$ electrons are delocalized over all six carbon atoms.

Question 1

Which of the following statements best describes the stability of conjugated dienes compared to isolated dienes?

Accepted Answer

Conjugated dienes are more stable because delocalization of electrons lowers the overall energy.

Question 2

Which of the following compounds is aromatic according to Hückel's rule?

Accepted Answer

Benzene ($$C_6H_6)$$

Question 3

A student reacts benzene with bromine ($$Br_2) in $$the presence of iron(III) bromide ($$FeBr_3). $$What is the major product?

Accepted Answer

Bromobenzene

Question 4

Which of the following is the correct mechanism for the nitration of benzene?

Accepted Answer

Benzene reacts with $$HNO_3$$ and $$H_2SO_4 to $$generate the nitronium ion ($$NO_2$$^+$$), which then attacks the benzene ring.

Question 5

Which reagent would best convert a ketone to a secondary alcohol?

Accepted Answer

Sodium borohydride ($$NaBH_4)$$

Question 6

Aldehydes are generally more reactive than ketones toward nucleophilic addition. Which statement best explains this observation?

Accepted Answer

Aldehydes have less steric hindrance and a more positive carbonyl carbon than ketones.

Question 7

Which of the following is the correct product of the reaction between acetic anhydride and ethanol?

Accepted Answer

Ethyl acetate and acetic acid

Question 8

In the Claisen condensation, which of the following is required for the reaction to proceed?

Accepted Answer

An ester with an $$oldsymbol{	ext{α}}-$$hydrogen and a strong base such as $$NaOEt$$

Question 9

Which of the following statements about the aldol reaction is correct?

Accepted Answer

It involves the addition of an enolate ion to a carbonyl compound.

Question 10

A student mixes acetone ($$CH_3COCH_3) $$with sodium hydroxide ($$NaOH) $$and heats the mixture. What is the major organic product?

Accepted Answer

Mesityl oxide (an $$oldsymbol{	ext{α,β}}-$$unsaturated ketone)

Question 11

Which of the following best describes the effect of an electron-withdrawing group (such as $$NO_2) on $$the rate of electrophilic aromatic substitution?

Accepted Answer

It decreases the rate by destabilizing the intermediate carbocation.

Question 12

Which acid derivative is most reactive toward nucleophilic acyl substitution?

Accepted Answer

Acid chloride

Question 13

Which of the following is a correct statement about the resonance stabilization in benzene?

Accepted Answer

Benzene's six $$oldsymbol{	ext{π}}$$ electrons are delocalized over all six carbon atoms.

Question 14

A chemist wants to synthesize 4-bromobenzoic acid from benzene. Which sequence of reactions would be most efficient?

Accepted Answer

Bromination, then oxidation with $$KMnO_4$$

Question 15

Which of the following is the correct formula for the enolate ion formed from acetaldehyde ($$CH_3CHO) $$under basic conditions?

Accepted Answer

$$CH_2CHO^-$$

Question 16

Which of the following reactions is an example of redox chemistry involving a ketone?

Accepted Answer

Reduction of acetone ($$CH_3COCH_3) to $$isopropanol ($$CH_3CHOHCH_3) $$using $$NaBH_4$$

Question 17

Which of the following best explains why esters are less reactive than acid chlorides in nucleophilic acyl substitution?

Accepted Answer

Esters have a less electrophilic carbonyl carbon due to resonance donation from the alkoxy group.

Question 18

Which of the following is the major product when acetophenone ($$C_6H_5COCH_3) $$undergoes bromination at the $$oldsymbol{	ext{α}}-$$position using $$Br_2$$ and $$AcOH$$?

Accepted Answer

1-bromoacetophenone ($$C_6H_5COCH_2Br)$$

Question 19

A student performs an aldol condensation between benzaldehyde and acetone. What is the structure of the major product?

Accepted Answer

An $$oldsymbol{	ext{α,β}}-$$unsaturated ketone: $$C_6H_5CH=$$CHCOCH_3$$

Question 20

Which of the following statements about the Claisen condensation is correct?

Accepted Answer

It requires two esters, at least one with an $$oldsymbol{	ext{α}}-$$hydrogen, and produces a $$oldsymbol{eta}-$$keto ester.

Organic Chemistry II: Study Guide Overview (Conjugated Systems, Aromaticity, Carbonyl Chemistry, and More)

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