Organic Chemistry 4th Edition + Student Solution Manual and Study Guide

Book Preface

WHY I WROTE THIS BOOK

Students who perform poorly on organic chemistry exams often  report having invested countless hours studying. Why do many  students have difficulty preparing themselves for organic chemistry exams? Certainly, there are several contributing factors,  including inefficient study habits, but perhaps the most dominant factor is a fundamental disconnect between what students  learn in the lecture hall and the tasks expected of them during an exam. To illustrate the disconnect, consider the following  analogy.

Imagine that a prestigious university offers a course entitled  “Bike-Riding 101.” Throughout the course, physics and engineering professors explain many concepts and principles (for example,  how bicycles have been engineered to minimize air resistance).  Students invest significant time studying the information that was  presented, and on the last day of the course, the final exam consists of riding a bike for a distance of 100 feet. A few students may  have innate talents and can accomplish the task without falling.  But most students will fall several times, slowly making it to the  finish line, bruised and hurt; and many students will not be able  to ride for even one second without falling. Why? Because there is  a disconnect between what the students learned and what they were  expected to do for their exam.

Many years ago, I noticed that a similar disconnect exists in  traditional organic chemistry instruction. That is, learning organic  chemistry is much like bicycle riding; just as the students in the  bike-riding analogy were expected to ride a bike after attending lectures, it is often expected that organic chemistry students  will independently develop the necessary skills for solving problems. While a few students have innate talents and are able to  develop the necessary skills independently, most students require  guidance. This guidance was not consistently integrated within  existing textbooks, prompting me to write the first edition of my  textbook, Organic Chemistry. The main goal of my text was to  employ a skills-based approach to bridge the gap between theory  (concepts) and practice (problem-solving skills). The second and  third editions further supported this goal by introducing hundreds  of additional problems based on the chemical literature, thereby  exposing students to exciting real-world examples of chemical  research being conducted in real laboratories. The phenomenal  success of the first three editions has been extremely gratifying  because it provided strong evidence that my skills-based approach  is indeed effective at bridging the gap described above.

I firmly believe that the scientific discipline of organic chemistry is NOT merely a compilation of principles, but rather, it is  a disciplined method of thought and analysis. Students must certainly understand the concepts and principles, but more importantly, students must learn to think like organic chemists . . . that  is, they must learn to become proficient at approaching new situations methodically, based on a repertoire of skills. That is the true  essence of organic chemistry.

A SKILLS-BASED APPROACH

To address the disconnect in organic chemistry instruction, I have  developed a skills-based approach to instruction. The textbook  includes all of the concepts typically covered in an organic chemistry textbook, complete with conceptual checkpoints that promote  mastery of the concepts, but special emphasis is placed on skills development through SkillBuilders to support these concepts.

Each SkillBuilder contains three parts:

Learn the Skill: contains a solved problem that demonstrates a  particular skill.

Practice the Skill: includes numerous problems (similar to the  solved problem in Learn the Skill) that give students valuable opportunities to practice and master the skill.

Apply the Skill: contains one or more problems in which the  student must apply the skill to solve real-world problems (as  reported in the chemical literature). These problems include conceptual, cumulative, and applied problems that encourage students  to think outside of the box. Sometimes problems that foreshadow  concepts introduced in later chapters are also included.

At the end of each SkillBuilder, a Need More Practice? reference suggests end-of-chapter problems that students can work to  practice the skill. This emphasis upon skills development provides students  with a greater opportunity to develop proficiency in the key skills  necessary to succeed in organic chemistry. Certainly, not all necessary skills can be covered in a textbook. However, there are certain  skills that are fundamental to all other skills.

As an example, resonance structures are used repeatedly  throughout the course, and students must become masters of  resonance structures early in the course. Therefore, a significant  portion of Chapter 2 is devoted to pattern-recognition for drawing resonance structures. Rather than just providing a list of rules  and then a few follow-up problems, the skills-based approach provides students with a series of skills, each of which must be mastered in sequence. Each skill is reinforced with numerous practice  problems. The sequence of skills is designed to foster and develop  proficiency in drawing resonance structures.

The skills-based approach to organic chemistry instruction  is a unique approach. Certainly, other textbooks contain tips for  problem solving, but no other textbook consistently presents skills  development as the primary vehicle for instruction.

WHAT’S NEW IN THIS EDITION

Peer review played a very strong role in the development of the first,  second, and third editions of Organic Chemistry. For each edition,  the manuscript was reviewed by several hundred professors and several thousand students. In preparing the fourth edition, peer review has played an equally prominent role. We have received a tremendous amount of input from the market, including surveys, class tests,  diary reviews, and phone interviews. All of this input has been carefully culled and has been instrumental in identifying the focus of the fourth edition.

New Features in the Fourth Edition

• Treatment of synthesis was strengthened throughout the text,  with a greater focus on retrosynthetic strategies. The coverage  of synthesis and retrosynthesis in Chapter 7 has been expanded  (with additional examples and more problems in SkillBuilder  7.8); and in Chapter 8, alkenes are considered both as synthetic targets and possible starting materials. In Chapter 9, the  coverage of synthesis with alkynide ions has been expanded,  with a focus on retrosynthesis. Indeed, the coverage of retrosynthesishas been expanded similarly in each chapter, gradually developing a scaffold of advanced synthetic skills.
• The introduction of bond-line drawings has been moved from  Chapter 2 to Chapter 1. This enables the use of bond-line  drawings when covering the material in Chapter 1.
• SkillBuilder 2.1 (converting between condensed structures  and bond-line structures) has been rewritten to show students how to interpret the condensed structures of aldehydes  (RCHO) and carboxylic acids (RCO2H).
• In Chapter 3 (acids and bases), a new section covers the relative acidity of cationic acids (with a new SkillBuilder), as well  as the relative basicity of their uncharged conjugate bases. This  new section (Section 3.5) covers the relative acidity of ammonium ions and the relative basicity of amines.
• In Chapter 6, the section describing nucleophilic centers and  electrophilic centers has been entirely rewritten. The previous treatment (3e) would suggest that methyl chloride is a  nucleophile, because of the lone pairs on the chlorine atom.
Furthermore, the previous treatment (3e) would suggest that  methanol is an electrophile, because the carbon atom is connected directly to an electron-withdrawing element. Both of  these conclusions are false, so this section was rewritten so that students don’t arrive at these false conclusions.
• Section 7.2 (nomenclature of alkyl halides) has been revised  to introduce the prefix “n” in alkyl substituents (for example,  n-butyl or n-propyl). This terminology is revisited again in  Section 12.1 (nomenclature of alcohols) as well as throughout  the text, where appropriate.
• In Chapter 7, when reagents are covered, a discussion has been  included to explicitly show that NaOEt/EtOH represents NaOEt dissolved in EtOH as the solvent. This was not obvious to students, and it is now explicitly shown.
• Sodium hydride is not an appropriate base for performing an  E2 reaction. A quick literature search shows no such examples.  NaH has been removed from Chapter 7.
• Chapter 7 (substitution and elimination) has been reorganized in the following ways.
• Nomenclature of alkenes has been moved out of Chapter 7  and into Chapter 8 (addition reactions of alkenes).
• Biological methylating agents have been moved into a BioLinks  box (rather than being a numbered section of the chapter).
• Kinetic isotope effects have been moved into a Special Topic  box (rather than being a numbered section of the chapter).
• Solvent effects have been moved to the end of the chapter.
• In Chapter 9, the coverage of dissolving metal reductions has  been revised to show that terminal alkynes cannot be reduced  by this method (only internal alkynes can be reduced with a  dissolving metal reduction). To reduce a terminal alkyne, it is  best to perform hydrogenation with a poisoned catalyst.
• In Chapter 15 (NMR spectroscopy), the discussion of complex  splitting has been revised to reflect the reality that J values are  generally similar (~7 Hz), so a triplet of quartets or a quartet  of triplets would be extremely rare. A sextet will be much more  common when a signal arises from protons that have three  neighbors on one side and two neighbors on the other side (for  example, the protons on C2 in 1-bromopropane). The entire  discussion of complex splitting has been revised accordingly.
• In the previous edition (3e), throughout Chapter 21 (alpha  carbon chemistry), after enolates were first introduced, enolates were then represented throughout the chapter by showing  the minor contributor to the resonance hybrid (the resonance  structure with a negative charge on C, rather than O). While  this simplified the mechanisms for students, it is more accurate  to show the major contributor. Throughout Chapter 21, all  instances of enolates (in all mechanisms) have been modified  to show the major contributor to the resonance hybrid (with  a negative charge on O), rather than the minor contributor.
• The end of each chapter has been enhanced with additional  multiple-choice questions that mimic the style of questions  on standardized exams, including the ACS, DAT, and PCAT  exams. The previous edition (3e) had approximately 3 such  questions at the end of each chapter. The new edition (4e)  now has between 7 and 10 such questions per chapter.
• Many students have requested that an answer key (for selected  problems) be included at the end of the text. This much-desired  feature has been provided in the fourth edition. The end of the  book now has a section with answers to selected problems.