Question 1

The reaction of tert-butyl bromide, (CH₃)₃CBr, with methanol in an inert solvent proceeds by an S_N1 mechanism to give tert-butyl methyl ether, (CH₃)₃COCH₃. What is the effect of doubling the concentration of methanol on the rate of the reaction? A)the rate remains the same B)the rate decreases by a factor of 2 C)the rate increases by a factor of 2 D)the rate increases by a factor of 4

Accepted Answer

The reaction proceeds via an SN1 mechanism, which involves a rate-determining step of forming a carbocation intermediate. The concentration of the nucleophile (methanol, in this case) does not affect the rate of this step, so doubling the concentration of methanol does not change the reaction rate.

Question 2

What is the equation for the rate of formation of 2-methoxypropane, CH₃CH(OCH₃)CH₃, from the reaction of 2-bromopropane (i-PrBr) with methanol? A)Rate = k [i-PrBr] B)Rate = k [i-PrBr]² C)Rate = k [CH₃OH] D)Rate = k [i-PrBr][CH₃OH]

Accepted Answer

A

Question 3

Which of the following reactions corresponds to a substitution?
A)propene $\rarr$ 1,2-dibromopropane
B)1-iodopropane $\rarr$ propene
C)propene $\rarr$ propane
D)1-iodopropane $\rarr$ 1-bromopropane

Accepted Answer

A substitution reaction is a reaction in which an atom or a group of atoms is replaced by another atom or group of atoms. In this case, the 1-iodopropane is undergoing substitution as the iodine is being replaced by a bromine atom in the product 1-bromopropane. Option A is an addition reaction, option B is an elimination reaction, and option C is also an addition reaction. Hence, option D is the only choice corresponding to a substitution reaction.

Question 4

What is the equation for the rate of formation of tert-butyl alcohol from the reaction of tert-butyl bromide (t-BuBr) with water by an S_N1 mechanism? A)Rate = k [t-BuBr] B)Rate = k [t-BuBr][H₂O] C)Rate = k [H₂O] D)Rate = k [t-BuBr]²

Accepted Answer

Since the mechanism is S_N1, it means that the rate-determining step involves only one reactant, which is t-BuBr in this case. Therefore, the rate equation is only dependent on the concentration of t-BuBr, giving us choice A. The other choices involve either the concentration of water or an unknown variable, which is not applicable in this case.

Question 5

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium azide, NaN₃? A)1-fluorohexane B)1-chlorohexane C)1-bromohexane D)1-iodohexane

Accepted Answer

1-iodohexane undergoes the fastest SN1 reaction with sodium azide due to iodine being the best leaving group among the options, facilitating the reaction more efficiently.

Question 6

Which of the following alkyl halides undergoes the fastest solvolysis reaction with formic acid, HCOOH?
A)tert-butyl fluoride
B)tert-butyl chloride
C)tert-butyl bromide
D)tert-butyl iodide

Accepted Answer

Tert-butyl iodide undergoes the fastest solvolysis reaction with formic acid due to the weaker C-I bond compared to C-Br, C-Cl, and C-F bonds, making it more susceptible to nucleophilic attack.

Question 7

Which of the following statements related to S_N1 reactions is not true? A)The S_N1 reaction can be described as a heterolytic bond cleavage followed by nucleophilic attack B)Carbocations are electrophilic C)The charged carbon atom of a carbocation has an unfilled valence shell D)Nucleophiles are Lewis acids

Accepted Answer

Nucleophiles are Lewis bases, as they donate a pair of electrons to form a covalent bond. Lewis acids are electron pair acceptors.

Question 8

Which of the following reactions corresponds to a substitution?
A)tert-butanol $\rarr$ tert-butyl chloride
B)tert-butanol $\rarr$ 2-methylpropene
C)3,3-dimethyl-2-butanol $\rarr$2,3-dimethyl-2-butene
D)cyclohexene $\rarr$1,2-dichlorocyclohexane

Accepted Answer

In reaction A, tert-butanol is converted to tert-butyl chloride, which involves replacing the hydroxyl group (-OH) with a chlorine atom (Cl), characteristic of a substitution reaction.

Question 9

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium methylthiolate, NaSMe? A)methyl iodide B)ethyl iodide C)2-bromopropane D)tert-butyl chloride

Accepted Answer

The rate of SN1 reactions is directly related to the stability of the carbocation intermediate that is formed. Methyl iodide undergoes the fastest reaction because it forms the most stable tertiary carbocation intermediate. Ethyl iodide is less stable than methyl iodide because it forms a less stable secondary carbocation intermediate. 2-bromopropane and tert-butyl chloride form even less stable primary and tertiary carbocation intermediates, respectively. Therefore, the answer is A) methyl iodide.

Question 10

The reaction of methyl iodide with sodium azide, NaN₃, proceeds by an S_N2 mechanism. What is the effect of doubling the concentration of NaN₃ on the rate of the reaction? A)the rate remains the same B)the rate decreases by a factor of 2 C)the rate increases by a factor of 2 D)the rate increases by a factor of 4

Accepted Answer

Doubling the concentration of the sodium azide will increase the frequency of collisions between the reactants, leading to an increase in the rate of the reaction. In an S_N2 mechanism, the rate-determining step involves only one reactant (methyl iodide in this case) and is independent of the concentration of the other reactant (sodium azide). Therefore, the rate will not be affected by doubling the concentration of methyl iodide.

Question 11

Which of the following alkyl halides undergoes the fastest solvolysis reaction with methanol, CH₃OH? A)methyl chloride B)ethyl chloride C)2-chloropropane D)tert-butyl chloride

Accepted Answer

Tert-butyl chloride undergoes the fastest solvolysis in methanol due to the formation of a highly stable tertiary carbocation intermediate, which significantly lowers the activation energy for the reaction.

Question 12

What is the equation for the rate of formation of 1-iodobutane from the reaction of 1-chlorobutane (BuCl) with NaI by an S_N2 mechanism? A)Rate = k [BuCl] B)Rate = k [BuCl][NaI] C)Rate = k [NaI] D)Rate = k [BuCl]²

Accepted Answer

The S_N2 mechanism suggests that the rate determining step involves both the BuCl and NaI molecules. Therefore, the rate of formation of 1-iodobutane would be proportional to the concentrations of both BuCl and NaI, leading to the rate equation of Rate = k [BuCl][NaI].

Question 13

Which of the following is the best set of conditions for the preparation of tert-butyl methyl ether? A)tert-butyl fluoride and NaOCH₃ in CH₃OH B)methanol and sodium tert-butoxide in tert-butanol C)fluoromethane and sodium tert-butoxide in tert-butanol D)tert-butyl bromide and CH₃OH

Accepted Answer

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

Question 14

Which of the following is best set of conditions for the preparation of tert-butanol?
A)tert-butyl fluoride in water
B)tert-butyl bromide in water
C)tert-butyl fluoride and NaOH in DMSO
D)tert-butyl bromide and NaOH in DMSO

Accepted Answer

The answer of Which of the following is best set...

Question 15

Which of the following alkyl halides undergoes the fastest solvolysis reaction with ethanol, CH₃CH₂OH? A)methyl fluoride B)ethyl bromide C)2-chloropropane D)tert-butyl bromide

Accepted Answer

The rate of solvolysis depends on the stability of the carbocation intermediate formed. The more stable the carbocation, the faster the reaction. In this case, tert-butyl bromide (D) forms a tertiary carbocation, which is more stable than the primary carbocation formed by methyl fluoride (A) or ethyl bromide (B), and the secondary carbocation formed by 2-chloropropane (C). Therefore, tert-butyl bromide undergoes the fastest solvolysis reaction with ethanol.

Question 16

The reaction of tert-butyl chloride, (CH₃)₃CCl, with water in an inert solvent gives tert-butyl alcohol, (CH₃)₃COH. What is the effect of doubling the concentration of water on the rate of the reaction? A)the rate remains the same B)the rate decreases by a factor of 2 C)the rate increases by a factor of 2 D)the rate increases by a factor of 4

Accepted Answer

The reaction of tert-butyl chloride with water to form tert-butyl alcohol is a unimolecular nucleophilic substitution reaction (SN1). The rate of an SN1 reaction is determined only by the concentration of the substrate (tert-butyl chloride in this case) and is independent of the concentration of the nucleophile (water). Therefore, doubling the concentration of water does not affect the rate of the reaction.

Question 17

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium cyanide, NaCN? A)methyl iodide B)ethyl iodide C)2-iodopropane D)tert-butyl iodide

Accepted Answer

The rate of SN1 reactions is dependent on the stability of the carbocation intermediate formed during the reaction. Methyl iodide will form the most stable carbocation due to its small size, which allows for a greater degree of hyperconjugation with adjacent C-H bonds, leading to more stabilization of the intermediate. Thus, methyl iodide will undergo the fastest reaction with NaCN. The other alkyl halides have larger and bulkier alkyl groups, which will hinder the formation and stabilization of the carbocation intermediate, leading to slower reaction rates.

Question 18

The reaction of 1-bromopropane with sodium iodide gives 1-iodopropane. What is the effect of doubling the concentration of NaI on the rate of the reaction?
A)the rate remains the same
B)the rate decreases by a factor of 2
C)the rate increases by a factor of 2
D)the rate increases by a factor of 4

Accepted Answer

The reaction is a nucleophilic substitution reaction, where NaI acts as a nucleophile attacking the 1-bromopropane. Doubling the concentration of NaI will increase the concentration of the nucleophile, thus increasing the rate of the reaction. According to the rate law, the rate of an SN2 reaction is proportional to the concentration of both the substrate (1-bromopropane) and the nucleophile (NaI). Therefore, increasing the concentration of NaI by a factor of 2 will increase the rate of the reaction by a factor of 2.

Question 19

Which of the following statements related to S_N1 reactions is not true? A)The heterolysis of a bond between atoms which do not bear formal charges always produces a cation and an anion B)The charged carbon atom of a carbocation has a complete octet of valence shell electrons C)Carbocations are Lewis acids D)Nucleophiles seek centers of low electron density

Accepted Answer

The charged carbon atom of a carbocation does not have a complete octet of valence shell electrons. It only has six electrons in its outermost shell, making it an electron-deficient species.

Question 20

What is the equation for the rate of formation of 2-methoxypropane, (CH₃CH(OCH₃)CH₃, from the reaction of 2-bromopropane (i-PrBr) with sodium methoxide (NaOCH₃)? A)Rate = k [i-PrBr] B)Rate = k [i-PrBr]² C)Rate = k [NaOCH₃] D)Rate = k [i-PrBr][NaOCH₃]

Accepted Answer

The rate of formation of 2-methoxypropane is dependent on the concentrations of both i-PrBr and NaOCH₃, therefore the correct option is D, which includes both reactant concentrations in the rate equation. Option A is incorrect because it only includes the concentration of i-PrBr. Option B is incorrect because it includes an incorrect format for the concentration of i-PrBr. Option C is incorrect because it only includes the concentration of NaOCH₃.

Quiz 9: Nucleophilic Substitution and Beta-Elimination

The reaction of tert-butyl bromide, (CH₃) ₃CBr, with methanol in an inert solvent proceeds by an S_N1 mechanism to give tert-butyl methyl ether, (CH₃) ₃COCH₃. What is the effect of doubling the concentration of methanol on the rate of the reaction?

What is the equation for the rate of formation of 2-methoxypropane, CH₃CH(OCH₃) CH₃, from the reaction of 2-bromopropane (i-PrBr) with methanol?

Which of the following reactions corresponds to a substitution?

What is the equation for the rate of formation of tert-butyl alcohol from the reaction of tert-butyl bromide (t-BuBr) with water by an S_N1 mechanism?

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium azide, NaN₃?

Which of the following alkyl halides undergoes the fastest solvolysis reaction with formic acid, HCOOH?

Which of the following statements related to S_N1 reactions is not true?

Which of the following reactions corresponds to a substitution?

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium methylthiolate, NaSMe?

The reaction of methyl iodide with sodium azide, NaN₃, proceeds by an S_N2 mechanism. What is the effect of doubling the concentration of NaN₃ on the rate of the reaction?

Which of the following alkyl halides undergoes the fastest solvolysis reaction with methanol, CH₃OH?

What is the equation for the rate of formation of 1-iodobutane from the reaction of 1-chlorobutane (BuCl) with NaI by an S_N2 mechanism?

Which of the following is the best set of conditions for the preparation of tert-butyl methyl ether?

Which of the following is best set of conditions for the preparation of tert-butanol?

Which of the following alkyl halides undergoes the fastest solvolysis reaction with ethanol, CH₃CH₂OH?

The reaction of tert-butyl chloride, (CH₃) ₃CCl, with water in an inert solvent gives tert-butyl alcohol, (CH₃) ₃COH. What is the effect of doubling the concentration of water on the rate of the reaction?

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium cyanide, NaCN?

The reaction of 1-bromopropane with sodium iodide gives 1-iodopropane. What is the effect of doubling the concentration of NaI on the rate of the reaction?

Which of the following statements related to S_N1 reactions is not true?

What is the equation for the rate of formation of 2-methoxypropane, (CH₃CH(OCH₃) CH₃, from the reaction of 2-bromopropane (i-PrBr) with sodium methoxide (NaOCH₃) ?

Quiz 9: Nucleophilic Substitution and Beta-Elimination

The reaction of tert-butyl bromide, (CH3) 3CBr, with methanol in an inert solvent proceeds by an SN1 mechanism to give tert-butyl methyl ether, (CH3) 3COCH3. What is the effect of doubling the concentration of methanol on the rate of the reaction?

What is the equation for the rate of formation of 2-methoxypropane, CH3CH(OCH3) CH3, from the reaction of 2-bromopropane (i-PrBr) with methanol?

Which of the following reactions corresponds to a substitution?

What is the equation for the rate of formation of tert-butyl alcohol from the reaction of tert-butyl bromide (t-BuBr) with water by an SN1 mechanism?

Which of the following alkyl halides undergoes the fastest SN2 reaction with sodium azide, NaN3?

Which of the following alkyl halides undergoes the fastest solvolysis reaction with formic acid, HCOOH?

Which of the following statements related to SN1 reactions is not true?

Which of the following reactions corresponds to a substitution?

Which of the following alkyl halides undergoes the fastest SN2 reaction with sodium methylthiolate, NaSMe?

The reaction of methyl iodide with sodium azide, NaN3, proceeds by an SN2 mechanism. What is the effect of doubling the concentration of NaN3 on the rate of the reaction?

Which of the following alkyl halides undergoes the fastest solvolysis reaction with methanol, CH3OH?

What is the equation for the rate of formation of 1-iodobutane from the reaction of 1-chlorobutane (BuCl) with NaI by an SN2 mechanism?

Which of the following is the best set of conditions for the preparation of tert-butyl methyl ether?

Which of the following is best set of conditions for the preparation of tert-butanol?

Which of the following alkyl halides undergoes the fastest solvolysis reaction with ethanol, CH3CH2OH?

The reaction of tert-butyl chloride, (CH3) 3CCl, with water in an inert solvent gives tert-butyl alcohol, (CH3) 3COH. What is the effect of doubling the concentration of water on the rate of the reaction?

Which of the following alkyl halides undergoes the fastest SN2 reaction with sodium cyanide, NaCN?

The reaction of 1-bromopropane with sodium iodide gives 1-iodopropane. What is the effect of doubling the concentration of NaI on the rate of the reaction?

Which of the following statements related to SN1 reactions is not true?

What is the equation for the rate of formation of 2-methoxypropane, (CH3CH(OCH3) CH3, from the reaction of 2-bromopropane (i-PrBr) with sodium methoxide (NaOCH3) ?

The reaction of tert-butyl bromide, (CH₃) ₃CBr, with methanol in an inert solvent proceeds by an S_N1 mechanism to give tert-butyl methyl ether, (CH₃) ₃COCH₃. What is the effect of doubling the concentration of methanol on the rate of the reaction?

What is the equation for the rate of formation of 2-methoxypropane, CH₃CH(OCH₃) CH₃, from the reaction of 2-bromopropane (i-PrBr) with methanol?

What is the equation for the rate of formation of tert-butyl alcohol from the reaction of tert-butyl bromide (t-BuBr) with water by an S_N1 mechanism?

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium azide, NaN₃?

Which of the following statements related to S_N1 reactions is not true?

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium methylthiolate, NaSMe?

The reaction of methyl iodide with sodium azide, NaN₃, proceeds by an S_N2 mechanism. What is the effect of doubling the concentration of NaN₃ on the rate of the reaction?

Which of the following alkyl halides undergoes the fastest solvolysis reaction with methanol, CH₃OH?

What is the equation for the rate of formation of 1-iodobutane from the reaction of 1-chlorobutane (BuCl) with NaI by an S_N2 mechanism?

Which of the following alkyl halides undergoes the fastest solvolysis reaction with ethanol, CH₃CH₂OH?

The reaction of tert-butyl chloride, (CH₃) ₃CCl, with water in an inert solvent gives tert-butyl alcohol, (CH₃) ₃COH. What is the effect of doubling the concentration of water on the rate of the reaction?

Which of the following alkyl halides undergoes the fastest S_N2 reaction with sodium cyanide, NaCN?

Which of the following statements related to S_N1 reactions is not true?

What is the equation for the rate of formation of 2-methoxypropane, (CH₃CH(OCH₃) CH₃, from the reaction of 2-bromopropane (i-PrBr) with sodium methoxide (NaOCH₃) ?