Sets forth the analytical tools needed to solve key problemsin organic chemistry With its acclaimed decision-based approach, Electron Flow inOrganic Chemistry enables readers to develop the essentialcritical thinking skills needed to analyze and solve problems inorganic chemistry, from the simple to complex. The author breaksdown common mechanistic organic processes into their basic units toexplain the core electron flow pathways that underlie theseprocesses. Moreover, the text stresses the use of analytical toolssuch as flow charts, correlation matrices, and energy surfaces toenable readers new to organic chemistry to grasp the fundamentalsat a much deeper level. This Second Edition of Electron Flow in OrganicChemistry has been thoroughly revised, reorganized, andstreamlined in response to feedback from both students andinstructors. Readers will find more flowcharts, correlationmatrices, and algorithms that illustrate key decision-makingprocesses step by step. There are new examples from the field ofbiochemistry, making the text more relevant to a broader range ofreaders in chemistry, biology, and medicine. This edition alsooffers three new chapters: Proton transfer and the principles of stability Important reaction archetypes Qualitative molecular orbital theory and pericyclicreactions The text's appendix features a variety of helpful tools,including a general bibliography, quick-reference charts andtables, pathway summaries, and a major decisions guide. With its emphasis on logical processes rather than memorizationto solve mechanistic problems, this text gives readers a solidfoundation to approach and solve any problem in organicchemistry.
Involved as it is with 95% of the periodic table, inorganicchemistry is one of the foundational subjects of scientific study.Inorganic catalysts are used in crucial industrial processes andthe field, to a significant extent, also forms the basis ofnanotechnology. Unfortunately, the subject is not a popular one forundergraduates. This book aims to take a step to change this stateof affairs by presenting a mechanistic, logical introduction to thesubject. Organic teaching places heavy emphasis on reaction mechanisms -"arrow-pushing" - and the authors of this book have found that amechanistic approach works just as well for elementary inorganicchemistry. As opposed to listening to formal lectures orlearning the material by heart, by teaching students to recognizecommon inorganic species as electrophiles and nucleophiles, coupledwith organic-style arrow-pushing, this book serves as a gentle andstimulating introduction to inorganic chemistry, providing studentswith the knowledge and opportunity to solve inorganic reactionmechanisms. • The first book to apply the arrow-pushing method toinorganic chemistry teaching • With the reaction mechanisms approach("arrow-pushing"), students will no longer have to rely onmemorization as a device for learning this subject, but willinstead have a logical foundation for this area of study • Teaches students to recognize common inorganic speciesas electrophiles and nucleophiles, coupled with organic-stylearrow-pushing • Provides a degree of integration with what studentslearn in organic chemistry, facilitating learning of thissubject • Serves as an invaluable companion to any introductoryinorganic chemistry textbook
Most reactions in organic chemistry do not proceed in a single step but rather take several steps to yield the desired product. In the course of these multi-step reaction sequences, short-lived intermediates can be generated that quickly convert into other intermediates, reactants, products or side products. As these intermediates are highly reactive, they cannot usually be isolated, but their existence and structure can be proved by theoretical and experimental methods. Using the information obtained, researchers can better understand the underlying reaction mechanism of a certain organic transformation and thus develop novel strategies for efficient organic synthesis. The chapters are clearly structured and are arranged according to the type of intermediate, providing information on the formation, characterization, stereochemistry, stability, and reactivity of the intermediates. Additionally, representative examples and a problem section with different levels of difficulty are included for self-testing the newly acquired knowledge. By providing a deeper understanding of the underlying concepts, this is a musthave reference for PhD and Master Students in organic chemistry, as well as a valuable source of information for chemists in academia and industry working in the field. It is also ideal as primary or supplementary reading for courses on organic chemistry, physical organic chemistry or analytical chemistry.
Get four times the study power with this specially priced set of MCAT review books! Set includes: - McGraw-Hill Education MCAT Biological and Biochemical Foundations of Living Systems 2015 - McGraw-Hill Education MCAT Behavioral and Social Sciences & Critical Analysis 2015 - McGraw-Hill Education MCAT Chemical and Physical Foundations of Biological Systems 2015 - McGraw-Hill Education MCAT 2 Full-length Practice Tests 2015 Each book has been fully revised for the brand-new test format scheduled to be introduced in 2015. With the review books, you get textbook-quality scientific diagrams, concise summaries of all the important concepts, and abundant practice questions. Then you can take the two full-length practice tests just like the real exam, with complete explanations for every question.
This new textbook is the successor to the volume "Side Reactions in Organic Synthesis - A Guide to Successful Synthesis Design" (2004), written by the same author. Whereas the predecessor mainly covered the limitations of aliphatic substitution reactions, this new volume focuses on the most important aromatic substitution reactions, both electrophilic and nucleophilic, such as amination reactions, halogenation reactions, Friedel-Crafts acylations, or transition metal-catalyzed arylation reactions. Each chapter not only describes the scope of a specific reaction type, but also reveals what cannot be achieved with this reaction, i.e. what type of side reactions are to be expected with certain starting materials or electrophiles/nucleophiles. With its unique approach, this is a must-have book for graduate students in organic chemistry and synthetic chemists both in academia and industry!
P R E F A C E xxv PHILOSOPHY From its first edition through this, its fourth, Organic Chemistry has been designed to meet the needs of the “mainstream,” two-semester, undergraduate organic chemistry course. It has evolved as those needs have changed, but its philosophy remains the same. The overarching theme is that organic chemistry is not only an interesting subject, but also a logical one. It is logical because its topics can be connected in a steady progression from simple to complex. Our approach has been to reveal the logic of organic chemistry by being selective in the topics we cover, as well as thorough and patient in developing them. Teaching at all levels is undergoing rapid change, especially in applying powerful tools that exploit the graphics capability of personal computers. Organic chemistry has always been the most graphical of the chemical sciences and is well positioned to benefit significantly from these tools. Consistent with our philosophy, this edition uses computer graphics to enhance the core material, to make it more visual, and more understandable, but in a way that increases neither the amount of material nor its level. ORGANIZATION The central message of chemistry is that the properties of a substance come from its structure. What is less obvious, but very powerful, is the corollary. Someone with training in chemistry can look at the structure of a substance and tell you a lot about its properties. Organic chemistry has always been, and continues to be, the branch of chemistry that best connects structure with properties. This text has a strong bias toward structure, and this edition benefits from the availability of versatile new tools to help us understand that structure. The text is organized to flow logically and step by step from structure to properties and back again. As the list of chapter titles reveals, the organization is according to functional groups—structural units within a molecule most responsible for a particular property— because that is the approach that permits most students to grasp the material most readily. Students retain the material best, however, if they understand how organic reactions take place. Thus, reaction mechanisms are stressed early and often, but within a functional group framework. A closer examination of the chapter titles reveals the close link between a functional group class (Chapter 20, Carboxylic Acid Derivatives) and a reaction type (Nucleophilic Acyl Substitution), for example. It is very satisfying to see students who entered the course believing they needed to memorize everything progress to the point of thinking and reasoning mechanistically. Some of the important stages in this approach are as follows: • The first mechanism the students encounter (Chapter 4) describes the conversion of alcohols to alkyl halides. Not only is this a useful functional-group transformation, but its first step proceeds by the simplest mechanism of all—proton transfer. The overall mechanism provides for an early reinforcement of acid-base chemistry and an early introduction to carbocations and nucleophilic substitution. • Chapter 5 continues the chemistry of alcohols and alkyl halides by showing how they can be used to prepare alkenes by elimination reactions. Here, the students see a second example of the formation of carbocation intermediates from alcohols, but in this case, the carbocation travels a different pathway to a different destination. • The alkenes prepared in Chapter 5 are studied again in Chapter 6, this time with an eye toward their own chemical reactivity. What the students learned about carbocations in Chapters 4 and 5 serves them well in understanding the mechanisms of the reactions of alkenes in Chapter 6. • Likewise, the mechanism of nucleophilic addition to the carbonyl group of aldehydes and ketones described in Chapter 17 sets the stage for aldol condensation in Chapter 18, esterification of carboxylic acids in Chapter 19, nucleophilic acyl substitution in Chapter 20, and ester condensation in Chapter 21. xxvi PREFACE THE SPARTAN INTEGRATION The third edition of this text broke new ground with its emphasis on molecular modeling, including the addition of more than 100 exercises of the model-building type. This, the fourth edition, moves to the next level of modeling. Gwendolyn and Alan Shusterman’s 1997 Journal of Chemical Education article “Teaching Chemistry with Electron Density Models” described how models showing the results of molecular orbital calculations, especially electrostatic potential maps, could be used effectively in introductory courses. The software used to create the Shustermans’ models was Spartan, a product of Wavefunction, Inc. In a nutshell, the beauty of electrostatic potential maps is their ability to display the charge distribution in a molecule. At the most fundamental level, the forces that govern structure and properties in organic chemistry are the attractions between opposite charges and the repulsions between like charges. We were therefore optimistic that electrostatic potential maps held great promise for helping students make the connection between structure, especially electronic structure, and properties. Even at an early stage we realized that two main considerations had to guide our efforts. • An integrated approach was required. To be effective, Spartan models and the information they provide must be woven into, not added to, the book’s core. • The level of the coverage had to remain the same. Spartan is versatile. We used the same software package to develop this edition that is used in research laboratories worldwide. It was essential that we limit ourselves to only those features that clarified a particular point. Organic chemistry is challenging enough. We didn’t need to make it more difficult. If we were to err, it would therefore be better to err on the side of caution. A third consideration surfaced soon after the work began. • Student access to Spartan would be essential. Nothing could help students connect with molecular modeling better than owning the same software used to produce the text or, even better, software that allowed them not only to view models from the text, but also to make their own. All of this led to a fruitful and stimulating collaboration with Dr. Warren Hehre, a leading theoretical chemist and the founder, president, and CEO of Wavefunction, Inc. Warren was enthusiastic about the project and agreed to actively participate in it. He and Alan Shusterman produced a CD tailored specifically to NEW IN THIS EDITION ALL-NEW ILLUSTRATIONS All figures were redrawn to convey visual concepts clearly and forcefully. In addition, the author created a number of new images using the Spartan molecular modeling application. Now students can view electrostatic potential maps to see the charge distribution of a molecule in vivid color. These striking images afford the instructor a powerful means to lead students to a better understanding of organic molecules. FULL SPARTAN IMAGE INTEGRATION The Spartangenerated images are impressive in their own right, but for teaching purposes they are most effective when they are closely aligned with the text content. Because the author personally generated the images as he wrote this edition, the molecular models are fully integrated with text, and the educational value is maximized. Additionally, icons direct students to specific applications of either the SpartanView or SpartanBuild program, found on the accompanying CD-ROM. Appendix 3 provides a complete guide to the Learning By Modeling CD-ROM. ALL-NEW SPECTRA Chapter 13, Spectroscopy, was heavily revised, with rewritten sections on NMR and with all the NMR spectra generated on a high-field instrument. IMPROVED SUMMARIES The end-of-chapter summaries are recast into a more open, easier-to-read format, inspired by the popularity of the accompanying summary tables. NEW DESIGN This edition sports a new look, with an emphasis on neatness, clarity, and color carefully used to heighten interest and to create visual cues for important information. PREFACE xxvii accompany our text. We call it Learning By Modeling. It and Organic Chemistry truly complement each other. Many of the problems in Organic Chemistry have been written expressly for the model-building software SpartanBuild that forms one part of Learning By Modeling. Another tool, SpartanView, lets students inspect more than 250 already constructed models and animations, ranging in size from hydrogen to carboxypeptidase. We were careful to incorporate Spartan so it would be a true amplifier of the textbook, not just as a standalone tool that students might or might not use, depending on the involvement of their instructor. Thus, the content of the CD provides visual, three-dimensional reinforcement of the concepts covered on the printed page. The SpartanView icon invites students to view a molecule or animation as they are reading the text. Opportunities to use SpartanBuild are similarly correlated to the text with an icon directing students to further explore a concept or solve a modeling-based problem with the software. In addition to its role as the electronic backbone of the CD component and the integrated learning approach, the Spartan software makes a visible impact on the printed pages of this edition. I used Spartan on my own computer to create many of the figures, providing students with numerous visual explorations of the concepts of charge distribution. BIOLOGICAL APPLICATIONS AND THEIR INTEGRATION Comprehensive coverage of the important classes of biomolecules (carbohydrates, lipids, amino acids, peptides, proteins, and nucleic acids) appears in Chapters 25–27. But biological applications are such an important part of organic chemistry that they deserve more attention throughout the course. We were especially alert to opportunities to introduce more biologically oriented material to complement that which had already grown significantly since the first edition. Some specific examples: • The new boxed essay “Methane and the Biosphere” in Chapter 2 combines elements of organic chemistry, biology, and environmental science to tell the story of where methane comes from and where it goes. • A new boxed essay, “An Enzyme-Catalyzed Nucleophilic Substitution of an Alkyl Halide,” in Chapter 8 makes a direct and simple connection between SN2 reactions and biochemistry. • Two new boxed essays, “How Sweet It Is!” in Chapter 25, and “Good Cholesterol? Bad Cholesterol? What’s the Difference?” in Chapter 26, cover topics of current interest from an organic chemist’s perspective. • The already-numerous examples of enzymecatalyzed organic reactions were supplemented by adding biological Baeyer-Villiger oxidations and fumaric acid dehydrogenation. Chapters 25–27 have benefited substantially from the Spartan connection. We replaced many of the artistrendered structural drawings of complex biomolecules from earlier editions with accurate models generated from imported crystallographic data. These include: • maltose, cellobiose, and cellulose in Chapter 25 • triacylglycerols in Chapter 26 • alanylglycine, leucine enkephalin, a pleated - sheet, an -helix, carboxypeptidase, myoglobin, DNA, and phenylalanine tRNA in Chapter 27 All of these are included on Learning By Modeling, where you can view them as wire, ball-and-spoke, tube, or space-filling models while rotating them in three dimensions. Both the text and Learning By Modeling include other structures of biological interest including: • a space-filling model of a micelle (Chapter 19) • electrostatic potential maps of the 20 common amino acids showing just how different the various side chains are (Chapter 27) SPECTROSCOPY Because it offers an integrated treatment of nuclear magnetic resonance (NMR), infrared (IR), and ultravioletvisible (UV-VIS) spectroscopy, and mass spectrometry (MS), Chapter 13 is the longest in the text. It is also the chapter that received the most attention in this edition. All of the sections dealing with NMR were extensively rewritten, all of the NMR spectra were newly recorded on a high-field instrument, and all of the text figures were produced directly from the electronic data files. Likewise, the IR and UV-VIS sections of Chapter 13 were revised and all of the IR spectra were recorded especially for this text. After being first presented in Chapter 13, spectroscopy is then integrated into the topics that follow it. The functional-group chapters, 15, 16, 17, 19, 20, 22, xxviii PREFACE and 24, all contain spectroscopy sections as well as examples and problems based on display spectra. INTEGRATION OF TOPICS Too often, in too many courses (and not just in organic chemistry), too many interesting topics never get covered because they are relegated to the end of the text as “special topic chapters” that, unfortunately, fall by the wayside as the end of the term approaches. We have, from the beginning and with each succeeding edition, looked for opportunities to integrate the most important of these “special” topics into the core material. I am pleased with the results. Typically, this integration is accomplished by breaking a topic into its component elements and linking each of those elements to one or more conceptually related core topics. There is, for example, no end-of-text chapter entitled “Heterocyclic Compounds.” Rather, heteroatoms are defined in Chapter 1 and nonaromatic heterocyclic compounds introduced in Chapter 3; heterocyclic aromatic compounds are included in Chapter 11, and their electrophilic and nucleophilic aromatic substitution reactions described in Chapters 12 and 23, respectively. Heterocyclic compounds appear in numerous ways throughout the text and the biological role of two classes of them—the purines and pyrimidines—features prominently in the discussion of nucleic acids in Chapter 27. The economic impact of synthetic polymers is too great to send them to the end of the book as a separate chapter or to group them with biopolymers. We regard polymers as a natural part of organic chemistry and pay attention to them throughout the text. The preparation of vinyl polymers is described in Chapter 6, polymer stereochemistry in Chapter 7, diene polymers in Chapter 10, Ziegler–Natta catalysis in Chapter 14, and condensation polymers in Chapter 20. INTEGRATING THE CHEMISTRY CURRICULUM I always thought that the general chemistry course would be improved if more organic chemists taught it, and have done just that myself for the past nine years. I now see that just as general chemistry can benefit from the perspective that an organic chemist brings to it, so can the teaching and learning of organic chemistry be improved by making the transition from general chemistry to organic smoother. Usually this is more a matter of style and terminology than content—an incremental rather than a radical change. I started making such changes in the third edition and continue here. I liked, for example, writing the new boxed essay “Laws, Theories, and the Scientific Method” and placing it in Chapter 6. The scientific method is one thing that everyone who takes a college-level chemistry course should be familiar with, but most aren’t. It normally appears in Chapter 1 of general chemistry texts, before the students have enough factual knowledge to really understand it, and it’s rarely mentioned again. By the time our organic chemistry students get to “Laws, Theories, and the Scientific Method,” however, we have told them about the experimental observations that led to Markovnikov’s law, and how our understanding has progressed to the level of a broadly accepted theory based on carbocation stability. It makes a nice story. Let’s use it. FEWER TOPICS EQUALS MORE HELP By being selective in the topics we cover, we can include more material designed to help the student learn. Solved sample problems: In addition to a generous number of end-of-chapter problems, the text includes more than 450 problems within the chapters themselves. Of these in-chapter problems approximately one-third are multipart exercises that contain a detailed solution to part (a) outlining the reasoning behind the answer. Summary tables: Annotated summary tables have been a staple of Organic Chemistry ever since the first edition and have increased in number to more than 50. Well received by students and faculty alike, they remain one of the text’s strengths. End-of-chapter summaries: Our experience with the summary tables prompted us to recast the narrative part of the end-of-chapter summaries into a more open, easier-to-read format. SUPPLEMENTS For the Student Study Guide and Solutions Manual by Francis A. Carey and Robert C. Atkins. This valuable supplement provides solutions to all problems in the text. More than simply providing answers, most solutions guide the student with the reasoning behind each problem. In addition, each chapter of the Study Guide and Solutions Manual concludes with a Self-Test designed to assess the student’s mastery of the material. Online Learning Center At www.mhhe.com/carey, this comprehensive, exclusive Web site provides a wealth of electronic resources for PREFACE xxix instructors and students alike. Content includes tutorials, problem-solving strategies, and assessment exercises for every chapter in the text. Learning By Modeling CD-ROM In collaboration with Wavefunction, we have created a cross-function CD-ROM that contains an electronic model-building kit and a rich collection of animations and molecular models that reveal the interplay between electronic structure and reactivity in organic chemistry. Packaged free with the text, Learning By Modeling has two components: SpartanBuild, a user-friendly electronic toolbox that lets you build, examine, and evaluate literally thousands of molecular models; and SpartanView, an application with which you can view and examine more than 250 molecular models and animations discussed in the text. In the textbook, icons point the way to where you can use these state-of-the-art molecular modeling applications to expand your understanding and sharpen your conceptual skills. This edition of the text contains numerous problems that take advantage of these applications. Appendix 3 provides a complete guide to using the CD. For the Instructor Overhead Transparencies. These full-color transparencies of illustrations from the text include reproductions of spectra, orbital diagrams, key tables, computergenerated molecular models, and step-by-step reaction mechanisms. Test Bank. This collection of 1000 multiplechoice questions, prepared by Professor Bruce Osterby of the University of Wisconsin–LaCrosse, is available to adopters in print, Macintosh, or Windows format. Visual Resource Library. This invaluable lecture aid provides the instructor with all the images from the textbook on a CD-ROM. The PowerPoint format enables easy customization and formatting of the images into the lecture. The Online Learning Center, described in the previous section, has special features for instructors, including quiz capabilities. Please contact your McGraw-Hill representative for additional information concerning these supplements. A C K N O W L E D G M E N T S xxxi You may have noticed that this preface is almost entirely “we” and “our,” not “I” and “my.” That is because Organic Chemistry is, and always has been, a team effort. From the first edition to this one, the editorial and production staffs at WCB/McGraw-Hill have been committed to creating an accurate, interesting, studentoriented text. Special thanks go to Kent Peterson, Terry Stanton, and Peggy Selle for their professionalism, skill, and cooperative spirit. Linda Davoli not only copy edited the manuscript but offered valuable advice about style and presentation. GTS Graphics had the critical job of converting the copy-edited manuscript to a real book. Our contact there was Heather Stratton; her enthusiasm for the project provided us an unusual amount of freedom to fine-tune the text. I have already mentioned the vital role played by Warren Hehre and Alan Shusterman in integrating Spartan into this edition. I am grateful for their generosity in giving their time, knowledge, and support to this project. I also thank Dr. Michal Sabat of the University of Virginia for his assistance in my own modeling efforts. All of the NMR and IR spectra in this edition were recorded at the Department of Chemistry of James Madison University by two undergraduate students, Jeffrey Cross and Karin Hamburger, under the guidance of Thomas Gallaher. We are indebted to them for their help. Again, as in the three previous editions, Dr. Robert C. Atkins has been indispensable. Bob is the driving force behind the Study Guide and Solutions Manual that accompanies this text. He is much more than that, though. He reads and critiques every page of the manuscript and every page of two rounds of proofs. I trust his judgment completely when he suggests how to simplify a point or make it clearer. Most of all, he is a great friend. This text has benefited from the comments offered by a large number of teachers of organic chemistry who reviewed it at various stages of its development. I appreciate their help. They include Reviewers for the Fourth Edition Jennifer Adamski, Old Dominion University Jeffrey B. Arterburn, New Mexico State University Steven Bachrach, Trinity University Jared A. Butcher, Jr., Ohio University Barry Carpenter, Cornell University Pasquale R. Di Raddo, Ferris State University Jill Discordia, Le Moyne College William A. Donaldson, Marquette University Mark Forman, St. Joseph’s University Warren Giering, Boston University Benjamin Gross, University of Tennessee–Chattanooga R. J. Hargrove, Mercer University E. Alexander Hill, University of Wisconsin–Milwaukee Shawn Hitchcock, Illinois State University L. A. Hull, Union College Colleen Kelley, Northern Arizona University Brenda Kesler, San Jose State University C. A. Kingsbury, University of Nebraska–Lincoln Francis M. Klein, Creighton University Paul M. Lahti, University of Massachusetts–Amherst Rita S. Majerle, South Dakota State University Michael Millam, Phoenix College Tyra Montgomery, University of Houston–Downtown Richard Narske, Augustana University Michael A. Nichols, John Carroll University Bruce E. Norcross, SUNY–Binghamton Charles A. Panetta, University of Mississippi Michael J. Panigot, Arkansas State University Joe Pavelites, William Woods College Ty Redd, Southern Utah University Charles Rose, University of Nevada Suzanne Ruder, Virginia Commonwealth University Christine M. Russell, College of DuPage Dennis A. Sardella, Boston College Janice G. Smith, Mt. Holyoke College Tami I. Spector, University of San Francisco Ken Turnbull, Wright State University Clifford M. Utermoehlen, USAF Academy Curt Wentrup, University of Queensland S. D. Worley, Auburn University Reviewers for the Third Edition Edward Alexander, San Diego Mesa College Ronald Baumgarten, University of Illinois–Chicago Barry Carpenter, Cornell University John Cochran, Colgate University xxxii ACKNOWLEDGMENTS I. G. Csizmadia, University of Toronto Lorrain Dang, City College of San Francisco Graham Darling, McGill University Debra Dilner, U.S. Naval Academy Charles Dougherty, Lehman College, CUNY Fillmore Freeman, University of California–Irvine Charles Garner, Baylor University Rainer Glaser, University of Missouri–Columbia Ron Gratz, Mary Washington College Scott Gronert, San Francisco State University Daniel Harvey, University of California–San Diego John Henderson, Jackson Community College Stephen Hixson, University of Massachusetts–Amherst C. A. Kingsbury, University of Nebraska–Lincoln Nicholas Leventis, University of Missouri–Rolla Kwang-Ting Liu, National Taiwan University Peter Livant, Auburn University J. E. Mulvaney, University of Arizona Marco Pagnotta, Barnard College Michael Rathke, Michigan State University Charles Rose, University of Nevada–Reno Ronald Roth, George Mason University Martin Saltzman, Providence College Patricia Thorstenson, University of the District of Columbia Marcus Tius, University of Hawaii at Manoa Victoria Ukachukwu, Rutgers University Thomas Waddell, University of Tennessee–Chattanooga George Wahl, Jr., North Carolina State University John Wasacz, Manhattan College Finally, I thank my family for their love, help, and encouragement. The “big five” remain the same: my wife Jill, our sons Andy, Bob, and Bill, and daughter-inlaw Tasneem. They have been joined by the “little two,” our grandchildren Riyad and Ava. Comments, suggestions, and questions are welcome. Previous editions produced a large number of e-mail messages from students. I found them very helpful and invite you to contact me at: [email protected] Francis A. Carey