Organic Chemistry
Organic Chemistry
5th Edition
ISBN: 9780078021558
Author: Janice Gorzynski Smith Dr.
Publisher: McGraw-Hill Education
bartleby

Concept explainers

bartleby

Videos

Textbook Question
Book Icon
Chapter 7, Problem 7.58P

Consider the following S N 1 reaction.

Chapter 7, Problem 7.58P, Consider the following SN1 reaction.  a.Draw a mechanism for this reaction using curved arrows.

a. Draw a mechanism for this reaction using curved arrows.

b. Draw an energy diagram. Label the axes, the reactants, products, E a , and Δ H ο . Assume that the starting material and product are equal in energy.

c. Draw the structure of any transition states.

d. What is the rate equation for this reaction?

e. What happens to the reaction rate in each of the following instances? [1] The leaving group is changed from I to Cl ; [2] The solvent is changed from H 2 O to DMF; [3] The alkyl halide is changed from ( CH 3 ) 2 C ( I ) CH 2 CH 3 to ( CH 3 ) 2 CHCH ( I ) CH 3 ; [4] The concentration of H 2 O is increased by a factor of five; and [5] The concentrations of both the alkyl halide and H 2 O are increased by a factor of five.

Expert Solution
Check Mark
Interpretation Introduction

(a)

Interpretation: The mechanism of the given reaction is to be drawn by the use of curved arrows.

Concept introduction: The replacement or substitution of one functional group with another different functional group in any chemical reaction is termed as substitution reaction. The electron rich chemical species that contains negative charge or lone pair of electrons are known as a nucleophile. In a nucleophilic substitution reaction, nucleophile takes the position of leaving group by attacking the electron deficient carbon atom.

Answer to Problem 7.58P

The mechanism of the given reaction is shown in Figure 1.

Explanation of Solution

The structure of the given alkyl halide shows that carbon atom, on which bromine is present, is bonded to three other carbon atoms. Hence, the bromine atom is bonded to tertiary carbon atom and the given alkyl halide is 3°. The tertiary alkyl halide is most likely to undergo nucleophilic substitution reaction through SN1 mechanism.

In SN1 mechanism, the removal of halide leads to the formation of carbocation and the incoming nucleophile then attack on the electron deficient carbocation. The mechanism of the given reaction is shown in Figure 1.

Organic Chemistry, Chapter 7, Problem 7.58P , additional homework tip  1

Figure 1

Conclusion

The mechanism of the given reaction is shown in Figure 1.

Expert Solution
Check Mark
Interpretation Introduction

(b)

Interpretation: The energy diagram is to be drawn. The axes, reactants, products, Ea and ΔHο is to be labeled.

Concept introduction: The replacement or substitution of one functional group with another different functional group in any chemical reaction is termed as substitution reaction. The graphical representation of chemical reaction in which x-axis represents energy of the reaction and y-axis represents the reaction coordinate is called energy profile diagram.

Answer to Problem 7.58P

The energy diagram of the given reaction is shown in Figure 2.

Explanation of Solution

In SN1 mechanism, the removal of halide leads to the formation of carbocation and the incoming nucleophile then attack on the electron deficient carbon atom. In the given reaction, first the breakage of CI bond occurs and then the formation of CO bond takes place.

The energy of products is equal to the energy of reactants. Therefore, the energy diagram of the given reaction is,

Organic Chemistry, Chapter 7, Problem 7.58P , additional homework tip  2

Figure 2

The x-axes of the energy diagram represent the energy of reactants and products and y-axes represent the reaction coordinate.

Conclusion

The energy diagram of the given reaction is shown in Figure 2.

Expert Solution
Check Mark
Interpretation Introduction

(c)

Interpretation: The structure of the transition state is to be drawn.

Concept introduction: In SN1 mechanism, the removal of halide leads to the formation of carbocation and the incoming nucleophile then attack on the electron deficient carbon atom. Carbocation is the intermediate of reaction that proceeds through SN1 mechanism.

Answer to Problem 7.58P

The structure of the transition states is shown in Figure 3.

Explanation of Solution

In SN1 mechanism, the removal of halide leads to the formation of carbocation and the incoming nucleophile then attack on the electron deficient carbon atom. In the given reaction, first the breakage of CI bond occurs and then the formation of CO bond takes place. The intermediate of the given reaction is stable tertiary carbocation.

Therefore, the transition states of the given reaction are,

Organic Chemistry, Chapter 7, Problem 7.58P , additional homework tip  3

Figure 3

Conclusion

The structure of the transition states is shown in Figure 3.

Expert Solution
Check Mark
Interpretation Introduction

(d)

Interpretation: The rate equation of the given reaction is to be predicted.

Concept introduction: The rate of SN1 reaction depends upon the concentration of reactant (alkyl halide, RX) only. The concentration of incoming nucleophile (Nu) has no effect on the rate of SN1 reaction.

The rate of SN1 reaction is expressed as,

Rate=k[RX]

Answer to Problem 7.58P

The rate equation of the given reaction is, Rate=k[(CH3)2C(I)CH2CH3].

Explanation of Solution

The rate of SN1 reaction depends upon the concentration of reactant (alkyl halide, RX) only. The concentration of incoming nucleophile (Nu) has no effect on the rate of SN1 reaction.

The rate of SN1 reaction is expressed as,

Rate=k[RX]

The alkyl halide of given reaction is (CH3)2C(I)CH2CH3 and the nucleophile is H2O.

Therefore, the rate equation of given reaction is,

Rate=k[(CH3)2C(I)CH2CH3]

Conclusion

The rate equation of the given reaction is, Rate=k[(CH3)2C(I)CH2CH3].

Expert Solution
Check Mark
Interpretation Introduction

(e)

Interpretation: The change that occurs to the reaction rate in given instances is to be stated.

Concept introduction: The rate of SN1 reaction depends upon the concentration of reactant (alkyl halide, RX) only. The concentration of incoming nucleophile (Nu) has no effect on the rate of SN1 reaction.

The rate of SN1 reaction is expressed as,

Rate=k[RX]

Answer to Problem 7.58P

The change that occurs to the reaction rate in given instances is,

[1] The rate of the reaction will decrease.

[2] The rate of the reaction will decrease.

[3] The rate of the reaction will decrease.

[4] The rate of the reaction remains unchanged.

[5] The rate of the reaction increases by five times.

Explanation of Solution

[1]

The tertiary halide undergoes nucleophilic substitution by SN1 mechanism in which carbocation is formed. The removal of halide leads to the formation of carbocation. Iodine is a good leaving group as compared to chlorine. The rate of SN1 reaction increases in the presence of good leaving group. Therefore, if the leaving group of the reaction is changed from I to Cl, the rate of the reaction will decrease.

[2]

The polar protic solvent favors SN1 reaction whereas polar aprotic solvent favors SN2 reaction. The mechanism of the given reaction is SN2. Water is a polar protic solvent whereas DMF is a polar aprotic solvent. Therefore, the rate of reaction will decrease if the solvent is changed from H2O to DMF.

[3]

The tertiary halide undergoes nucleophilic substitution by SN1 mechanism in which carbocation is formed. The removal of halide leads to the formation of carbocation. Iodine atom is bonded to tertiary carbon atom in (CH3)2C(I)CH2CH3 whereas in (CH3)2CHCH(I)CH3, it is bonded to secondary carbon atom. The order of increasing reactivity of alkyl halides toward SN1 reaction is 1°<2°<3°. Therefore, the rate of reaction will decrease if the alkyl halide is changed from (CH3)2C(I)CH2CH3 to (CH3)2CHCH(I)CH3.

[4]

The rate of SN1 reaction depends upon the concentration of reactant (alkyl halide, RX) only. The concentration of incoming nucleophile (Nu) has no effect on the rate of SN1 reaction.

The rate of SN1 reaction is expressed as,

Rate=k[RX]

According the given statement, the concentration of [H2O] is increased by a factor of five. Hence, the rate of the reaction is,

Rate=k[(CH3)2C(I)CH2CH3]

Therefore, the rate of the reaction remains unchanged when the concentration of [H2O] is increased by a factor of five.

[5]

The rate of SN1 reaction depends upon the concentration of reactant (alkyl halide, RX) only. The concentration of incoming nucleophile (Nu) has no effect on the rate of SN1 reaction.

The rate of SN1 reaction is expressed as,

Rate=k[RX]

According the given statement, the concentration of [H2O] and [RX] is increased by a factor of five. Hence, the rate of the reaction is,

Rate=k[5×(CH3)2C(I)CH2CH3]=5(k[(CH3)2C(I)CH2CH3])

Therefore, the rate of the reaction increases by five times when the concentration [H2O] and [RX] is increased by a factor of five.

Conclusion

The change that occurs to the reaction rate in given instances is,

[1] The rate of the reaction will decrease.

[2] The rate of the reaction will decrease.

[3] The rate of the reaction will decrease.

[4] The rate of the reaction remains unchanged.

[5] The rate of the reaction increases by five times.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
Don't used Ai solution
Don't used Ai solution
Please correct answer and don't used hand raiting

Chapter 7 Solutions

Organic Chemistry

Ch. 7 - Prob. 7.11PCh. 7 - Does the equilibrium favor the reactants or...Ch. 7 - Prob. 7.13PCh. 7 - Classify each solvent as protic or aprotic. a. b....Ch. 7 - Prob. 7.15PCh. 7 - Prob. 7.16PCh. 7 - Prob. 7.17PCh. 7 - Prob. 7.18PCh. 7 - Prob. 7.19PCh. 7 - Draw the product of each SN2 reaction and indicate...Ch. 7 - Prob. 7.21PCh. 7 - Prob. 7.22PCh. 7 - What happens to the rate of an SN1 reaction under...Ch. 7 - Draw the products of each SN1 reaction and...Ch. 7 - Classify each carbocation as 1,2, or 3. a. b. c....Ch. 7 - Prob. 7.26PCh. 7 - Prob. 7.27PCh. 7 - Prob. 7.28PCh. 7 - Prob. 7.29PCh. 7 - Problem 7.30 For each alkyl halide and...Ch. 7 - Prob. 7.31PCh. 7 - Prob. 7.32PCh. 7 - Prob. 7.33PCh. 7 - Prob. 7.34PCh. 7 - Prob. 7.35PCh. 7 - Prob. 7.36PCh. 7 - Prob. 7.37PCh. 7 - Prob. 7.38PCh. 7 - Prob. 7.39PCh. 7 - Give the IUPAC name for each compound, including...Ch. 7 - Draw the products formed when each alkyl halide is...Ch. 7 - Give the IUPAC name for each compound. a. c. e. b....Ch. 7 - Prob. 7.43PCh. 7 - Draw the eight constitutional isomers having the...Ch. 7 - Which compound in each pair has the higher boiling...Ch. 7 - Draw the products of each nucleophilic...Ch. 7 - Prob. 7.47PCh. 7 - Rank the species in each group in order of...Ch. 7 - Which of the following nucleophilic substitution...Ch. 7 - Rank the species in each group in order of...Ch. 7 - Prob. 7.51PCh. 7 - Prob. 7.52PCh. 7 - 7.53 Consider the following reaction. Draw a...Ch. 7 - Prob. 7.54PCh. 7 - Draw the products of each SN2 reaction and...Ch. 7 - Prob. 7.56PCh. 7 - Prob. 7.57PCh. 7 - Consider the following SN1 reaction. a.Draw a...Ch. 7 - 7.59 Pick the reactant or solvent in each part...Ch. 7 - Draw the products of each SN1 reaction and...Ch. 7 - Prob. 7.61PCh. 7 - Prob. 7.62PCh. 7 - Prob. 7.63PCh. 7 - Fluticasone, the chapter-opening molecule, can be...Ch. 7 - Prob. 7.65PCh. 7 - 7.66 Diphenhydramine, the antihistamine in...Ch. 7 - Draw a stepwise, detailed mechanism for the...Ch. 7 - When a single compound contains both a nucleophile...Ch. 7 - Prob. 7.69PCh. 7 - Prob. 7.70PCh. 7 - Draw a stepwise, detailed mechanism f or the...Ch. 7 - Prob. 7.72PCh. 7 - Fill in the appropriate reagent or starting...Ch. 7 - Devise a synthesis of each compound from an alkyl...Ch. 7 - Suppose you have compounds A-D at y our disposal....Ch. 7 - Muscalure, the sex pheromone of the common...Ch. 7 - Prob. 7.77PCh. 7 - Prob. 7.78PCh. 7 - Draw a stepwise mechanism for the following...Ch. 7 - 7.80 As we will learn in Chapter 9, an epoxide is...Ch. 7 - Prob. 7.81PCh. 7 - In some nucleophilic substitutions under SN1...
Knowledge Booster
Background pattern image
Chemistry
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
Organic Chemistry: A Guided Inquiry
Chemistry
ISBN:9780618974122
Author:Andrei Straumanis
Publisher:Cengage Learning
Chapter 4 Alkanes and Cycloalkanes Lesson 2; Author: Linda Hanson;https://www.youtube.com/watch?v=AL_CM_Btef4;License: Standard YouTube License, CC-BY
Chapter 4 Alkanes and Cycloalkanes Lesson 1; Author: Linda Hanson;https://www.youtube.com/watch?v=PPIa6EHJMJw;License: Standard Youtube License