Question 1

Which of the following statements about an S_N1 reaction mechanism is true?

Accepted Answer

The S_N1 reaction mechanism, which seems to be a typographical error and likely refers to an SN1 reaction mechanism, involves a step where the leaving group departs before the nucleophile attacks. The rate of this type of reaction increases as the leaving group's ability to leave improves, making option C correct.

Question 2

Which of the following is the most nucleophilic?

Accepted Answer

Nitrogen is more electronegative than sulfur, making the lone pair of electrons on the nitrogen atom more available for nucleophilic attack. Fluorine in choice D is highly electronegative, making it a poor nucleophile. The sulfur atoms in choices A and B are bonded to multiple carbon atoms, which decreases their nucleophilicity compared to the nitrogen atom in choice C.

Question 3

The reaction of bromoethane with sodium acetate affords the substitution product methyl acetate.What is the effect of doubling the concentration of sodium acetate on the rate of the reaction?

Accepted Answer

The concentration of sodium acetate is a reactant in the reaction, and increasing its concentration will increase the rate of the reaction according to the rate law. Doubling the concentration should result in an approximately doubling of the rate of the reaction. Therefore, the correct answer is (C) the rate increases by a factor of 2.

Question 4

The reaction of 1-bromobutane with sodium hydroxide affords the substitution product 1-butanol.What would happen to the rate of the reaction if the concentration of both 1-bromobutane and sodium hydroxide were doubled?

Accepted Answer

The reaction is bimolecular (SN2), so the rate is proportional to the concentration of both reactants. Doubling both concentrations increases the rate by a factor of 4.

Question 5

Rank the following carbocations in order of decreasing stability, putting the most stable first.

Accepted Answer

The answer of Rank the following carbocations in order of...

Question 6

Which of the following is not a characteristic of an S_N1 reaction?

Accepted Answer

The answer of Which of the following is not a...

Question 7

Rank the alkyl halides in order of decreasing S_N2 reactivity, putting the most reactive first.

Accepted Answer

The answer of Rank the alkyl halides in order of...

Question 8

What is the rate-determining step of an S_N1 reaction mechanism?

Accepted Answer

In an S_N1 reaction mechanism, the rate-determining step is the slowest step of the reaction. In this case, the slowest step is the breaking of the bond between the carbon and the leaving group to generate a carbocation. This is because the carbocation intermediate is highly unstable and reactive, and therefore takes a significant amount of time to form. The attack of the nucleophile on the carbocation to form the product is a relatively fast step compared to the formation of the carbocation.

Question 9

Rank the following in order of increasing nucleophilicity, putting the least nucleophilic first.

Accepted Answer

The answer of Rank the following in order of increasing...

Question 10

Which of the following statements about an S_N1 reaction mechanism is true?

Accepted Answer

The answer of Which of the following statements about an...

Question 11

Which of the following is a polar aprotic solvent?

Accepted Answer

The answer of Which of the following is a polar...

Question 12

The reaction of tert-butyl bromide, (CH₃)₃CBr, with ethanol affords the substitution product tert-butyl ethyl ether, (CH₃)₃COCH₂CH₃, in acidic conditions.What would happen to the rate of the reaction if the concentration of ethanol was doubled?

Accepted Answer

The answer of The reaction of tert-butyl bromide, (CH₃)₃CBr,...

Question 13

Which of the following anions is the most nucleophilic in polar aprotic solvents?

Accepted Answer

The answer of Which of the following anions is the...

Question 14

Which of the following statements about S_N2 reactions is true?

Accepted Answer

The statement "Displacement occurs with inversion of configuration" is true for S_N2 reactions.

Question 15

Which compound is most likely to follow second-order kinetics in a substitution reaction?

Accepted Answer

The answer of Which compound is most likely to follow...

Question 16

Rank the following in order of decreasing nucleophilicity, putting the most nucleophilic first.

Accepted Answer

In general, the nucleophilicity increases as the negative charge density increases and/or the steric hindrance decreases. In this case, III is the most nucleophilic because it has a negative charge on oxygen and the least steric hindrance. II is less nucleophilic because it has a negative charge on nitrogen, which is less electronegative than oxygen and thus less efficient at stabilizing the charge. IV is less nucleophilic than II because the lone pair on sulfur is less available for nucleophilic attack due to steric hindrance from the bulky tert-butyl groups. I is the least nucleophilic because it does not have a negative charge and only has a polarized C-O bond, which is not very reactive. Therefore, the correct order of decreasing nucleophilicity is III > II > IV > I, which is choice B.

Question 17

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium hydroxide?

Accepted Answer

1-Iodobutane undergoes the fastest SN1 reaction with sodium hydroxide because iodine is a better leaving group due to its larger size and lower bond strength compared to chlorine, fluorine, and bromine.

Question 18

Which of the following statements about the S_N2 mechanism for nucleophilic substitution reactions is true?

Accepted Answer

The S_N2 mechanism for nucleophilic substitution reactions involves one step and occurs with inversion of configuration. This is due to the fact that the nucleophile attacks the substrate from the opposite face of the leaving group, resulting in a complete inversion of stereochemistry. This mechanism is also known as the S[subscript]N2 reaction.

Question 19

Which of the following carbocations is the most stable?

Accepted Answer

Carbocation II is the most stable because it is a tertiary carbocation, meaning it has three alkyl groups attached to the positively charged carbon. This increases the electron density around the carbon, making it less likely to attract electrons and form a bond with a nucleophile. Carbocation I is a secondary carbocation, while carbocations III and IV are primary carbocations, making them less stable than carbocation II.

Question 20

Which of the following rate laws describes the kinetics of an S_N1 reaction?

Accepted Answer

The S_N1 reaction is a unimolecular substitution reaction where the rate-determining step involves only one molecule - the alkyl halide. Therefore, the rate law would only depend on the concentration of the alkyl halide, which is described by choice A.

Quiz 7: Alkyl Halides and Nucleophilic Substitution

Which of the following statements about an S_N1 reaction mechanism is true?

Which of the following is the most nucleophilic?

The reaction of bromoethane with sodium acetate affords the substitution product methyl acetate.What is the effect of doubling the concentration of sodium acetate on the rate of the reaction?

The reaction of 1-bromobutane with sodium hydroxide affords the substitution product 1-butanol.What would happen to the rate of the reaction if the concentration of both 1-bromobutane and sodium hydroxide were doubled?

Rank the following carbocations in order of decreasing stability, putting the most stable first.

Which of the following is not a characteristic of an S_N1 reaction?

Rank the alkyl halides in order of decreasing S_N2 reactivity, putting the most reactive first.

What is the rate-determining step of an S_N1 reaction mechanism?

Rank the following in order of increasing nucleophilicity, putting the least nucleophilic first.

Which of the following statements about an S_N1 reaction mechanism is true?

Which of the following is a polar aprotic solvent?

The reaction of tert-butyl bromide, (CH₃) ₃CBr, with ethanol affords the substitution product tert-butyl ethyl ether, (CH₃) ₃COCH₂CH₃, in acidic conditions.What would happen to the rate of the reaction if the concentration of ethanol was doubled?

Which of the following anions is the most nucleophilic in polar aprotic solvents?

Which of the following statements about S_N2 reactions is true?

Which compound is most likely to follow second-order kinetics in a substitution reaction?

Rank the following in order of decreasing nucleophilicity, putting the most nucleophilic first.

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium hydroxide?

Which of the following statements about the S_N2 mechanism for nucleophilic substitution reactions is true?

Which of the following carbocations is the most stable?

Which of the following rate laws describes the kinetics of an S_N1 reaction?

Quiz 7: Alkyl Halides and Nucleophilic Substitution

Which of the following statements about an SN1 reaction mechanism is true?

Which of the following is the most nucleophilic?

The reaction of bromoethane with sodium acetate affords the substitution product methyl acetate.What is the effect of doubling the concentration of sodium acetate on the rate of the reaction?

The reaction of 1-bromobutane with sodium hydroxide affords the substitution product 1-butanol.What would happen to the rate of the reaction if the concentration of both 1-bromobutane and sodium hydroxide were doubled?

Rank the following carbocations in order of decreasing stability, putting the most stable first.

Which of the following is not a characteristic of an SN1 reaction?

Rank the alkyl halides in order of decreasing SN2 reactivity, putting the most reactive first.

What is the rate-determining step of an SN1 reaction mechanism?

Rank the following in order of increasing nucleophilicity, putting the least nucleophilic first.

Which of the following statements about an SN1 reaction mechanism is true?

Which of the following is a polar aprotic solvent?

The reaction of tert-butyl bromide, (CH3) 3CBr, with ethanol affords the substitution product tert-butyl ethyl ether, (CH3) 3COCH2CH3, in acidic conditions.What would happen to the rate of the reaction if the concentration of ethanol was doubled?

Which of the following anions is the most nucleophilic in polar aprotic solvents?

Which of the following statements about SN2 reactions is true?

Which compound is most likely to follow second-order kinetics in a substitution reaction?

Rank the following in order of decreasing nucleophilicity, putting the most nucleophilic first.

Which of the following alkyl halides undergoes the fastest SN2 reaction with sodium hydroxide?

Which of the following statements about the SN2 mechanism for nucleophilic substitution reactions is true?

Which of the following carbocations is the most stable?

Which of the following rate laws describes the kinetics of an SN1 reaction?

Which of the following statements about an S_N1 reaction mechanism is true?

Which of the following is not a characteristic of an S_N1 reaction?

Rank the alkyl halides in order of decreasing S_N2 reactivity, putting the most reactive first.

What is the rate-determining step of an S_N1 reaction mechanism?

Which of the following statements about an S_N1 reaction mechanism is true?

The reaction of tert-butyl bromide, (CH₃) ₃CBr, with ethanol affords the substitution product tert-butyl ethyl ether, (CH₃) ₃COCH₂CH₃, in acidic conditions.What would happen to the rate of the reaction if the concentration of ethanol was doubled?

Which of the following statements about S_N2 reactions is true?

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium hydroxide?

Which of the following statements about the S_N2 mechanism for nucleophilic substitution reactions is true?

Which of the following rate laws describes the kinetics of an S_N1 reaction?