ORGANIC CHEMISTRY

Hints for Passing Organic Chemistry PREFACE Do you want to pass your course in organic chemistry? Here is my best advice, based on over thirty-five years of observing students learning organic chemistry: or Hint #1: Do the problems. It seems straightforward, but humans, including students, try to take the easy way out until they discover there is no shortcut. Unless you have a measured IQ above 200 and comfortably cruise in the top 1% of your class, do the problems. Usually your teacher (professor teaching assistant) will recommend certain ones; try to do all those recommended. If you do half of them, you will be half-prepared at test time. (Do you want your surgeon coming to your appendectomy having practiced only half the procedure?) And when you do the problems, keep this Solutions Manual CLOSED. Avoid looking at my answer before you write your answer-your trying and struggling with the problem is the most valuable part of the problem. Discovery is a major part of learning. Remember that the primary goal of doing these problems is not just getting the right answer, but understanding the material well enough to get right answers to the questions you haven't seen yet. Hint #2: Keep up. Getting behind in your work in a course that moves as quickly as this one is the Kiss of Death. For most students, organic chemistry is the most rigorous intellectual challenge they have faced so far in their studies. Some are taken by surprise at the diligence it requires. Don't think that you can study all of the material in the couple of days before the exam-well, you can, but you won't get a passing grade. Study organic chemistry like a foreign language: try to do some every day so that the freshly trained neurons stay sharp. Hint #3: Get help when you need it. Use your teacher's office hours when you have difficulty. Many schools have tutoring centers (in which organic chemistry is a popular offering). Here's a secret: absolutely the best way to cement this material in your brain is to get together with a few of your fellow students and make up problems for each other, then correct and discuss them. When you write the problems, you will gain great insight into what this is all about. Hint #3.5: When you write answers to problem, write them. Use the old-fashioned method of a writing implement on paper. Keep a notebook with your work. Show your instructor; he/she will be impressed. Purpose of This Solutions Manual So what is the point of this Solutions Manual? First, I can't do your studying for you. Second, since I am not leaning over your shoulder as you write your answers, I can't give you direct feedback on what you write and think-the print medium is limited in its usefulness. What I can do for you is: 1) provide correct answers: the publishers, Professor Wade, Professor Palandoken (my reviewer), and I have gone to great lengths to assure that what I have written is correct, for we all understand how it can shake a student's confidence to discover that the answer book flubbed up; 2) provide a considerable degree of rigor: beyond the fundamental requirement of correctness, I have tried to flesh out these answers, being complete but succinct; 3) provide insight into how to solve a problem and into where the sticky intellectual points are. Insight is the toughest to accomplish, but over the years, I have come to understand where students have trouble, so I have tried to anticipate your questions and to add enough detail so that the concept, as well as the answer, is clear. It is difficult for students to understand or acknowledge that their teachers are human (some are more human than others). Since I am human (despite what my students might report), I can and do make mistakes. If there are mistakes in this book, they are my sole responsibility, and I am sorry. If you find one, PLEASE let me know so that it can be corrected in future printings. Nip it in the bud. What's New in This edition? Better answers! Part of my goal in this edition has been to add more explanatory material to clarify how to arrive at the answer. In many problems, the possibility of more than one answer to a problem has been noted. Concept maps have been added at appropriate places to demonstrate the logic of particular concepts. Better graphics! The print medium is very limited in its ability to convey three-dimensional structural information, aproblem that has plagued organic chemists for over a century. Appendix 2 on Acidity has been revised, and Appendix 3 has been added as a suggestion students on how to organize reaction summaries to make studying more effective. Too much to hope for. Better jokes? Y Copyright© 2013 Pearson Education, Inc. to Students: Add your own notes on symbols and abbreviations. X Copyright © 2013 Pearson Education, Inc. 1-1 CHAPTER 1--INTRODUCTION AND REVIEW (a) Nitrogen has atomic number 7, so all nitrogen atoms have 7 protons. The mass number is the total number of neutrons and protons; therefore, 13N has 6 neutrons, 14N has 7 neutrons, 15N has 8 neutrons, 16N has 9 neutrons, and 17N has 10 neutrons. (b) Na 1s22s22p63s1 Mg 1s22s22p63s2 Al 1s22s22p93s23p1 Si 1s22s22p"3s²3px3p, P 1s22s22p63s23px13p,13p S 1s22s22p03s23p23p13p C1 1s22s22p63s23px23p23p! Ar 1s22s22p3s23p23p23p2 1-2 Lines between atom symbols represent covalent bonds between those atoms. Nonbonding electrons are indicated with dots. H H H + (a) H-N-H (b) H-O-H (c) H-O-H (d) H-C C C HH H H H H H H H H H H H H H (e) H-C-N-C-H (f) H C C- C-C H- (g) H -C - C C Ci: H H H H H H H H H H H (i) H-B-H (j) F-B-F: H :0: H H :F: (h) H-C - C C-H H H H The compounds in (i) and (j) are unusual in that boron does not have an octet of electrons-normal for boron because it has only three valence electrons. 1-3 (a) :N=N: (b) H-CN: (d) 0=C=0 H :0: (e) H--C-CN-H (f) H-C-0-H (g) H-C=C-C: (h) H-N=N-H H H H HH H (i) H-C=C-CH ( H-C=C=C-H (k) H-CEC-C-H H H H H H 1-4 There are no unshared electron pairs in parts (i), (j), and (k). (a) ONEN (b) H-CN (c) H-Q-N=O (d) C H 0 (e) H-C-C=N-H (f) H-C-O-H (g) H-C=C-CI0 (h) H-N=N-Н H H H H 1 Copyright© 2013 Pearson Education, Inc. 1-5 The symbols "8+" and "8-" indicate bond polarity by showing partial charge. (In the arrow symbolísm, the arrow should point to the partial negative charge.) &+ 8- 8+ 8 (a) C-CI (b) C-0 (c) 8+ 8- C-N 8+ 8 8- 8+ (d) C-S (e) C-В 8+ 8 8+ 8 (f) N-CI (g) N-O (h) 8- 8+ N-S 8 8+ 8+ 8 (i) N-B G) B-CI 1-6 Non-zero formal charges are shown beside the atoms, circled for clarity. H H H H H C H H (a) H-C-O-H (b) H-N- H :Cl; (c) H-C - N -C-H Cl 1+ H H H H H C In (b) and (c), the chlorine is present as chloride ion. There is no covalent bond between chloride and other atoms in the formula. H H H H H Θ.. + Θ (d) Na :0-C-H (e) H-C-H (f) H-C H (g) Na H-B H H H H H H H H H (h) Na H- B-CN: (i) H-C 0 C H (j) HOD-NH H H H H F R F1 H Π H F C H Ð .. (k) K 0 C CC-H (1) H-C=0- HAs shown in (d),(g), (h), and (k), alkali metals like sodium and potassium form only ionic bonds, never covalent bonds. H C H H H H 1-7 Resonance forms in which all atoms have full octets are the most significant contributors. In resonance forms, ALL ATOMS KEEP THEIR POSITIONS-ONLY ELECTRONS ARE SHOWN IN DIFFERENT POSITIONS. (In this Solutions Manual, braces {} are commonly used to denote resonance forms.) Θ. (a) :0 C - :0: Θ.. (b) :0 - N Θ. (c) :0- 本 :0 C Θ.. ⑆0 + Θ Θ Ο= C-0: م :0: O=N-: O=N-O: 2 ect of this scope is ever done alone. These are team efforts, and several people who have assisted and facilitated in one fashion or another deserve my thanks. Professor L. G. Wade, Jr., your textbook author, is a remarkable person. He has gone to extraordinary lengths to make the textbook as clear, organized, informative, and insightful as possible. He has solicited and followed many suggestions on his text, and his comments on my solutions have been perceptive and valuable. We agreed early on that our primary goal is to help the students learn a fascinating and challenging subject, and all of our efforts have been directed toward that goal. I have appreciated our collaboration. My friend and colleague, Dr. Hasan Palandoken, has reviewed the entire manuscript for accuracy and style. His extraordinary diligence, attention to detail, and chemical wisdom have made this a better manual. Hasan stands on the shoulders of previous reviewers who scoured earlier editions for errors: Dr. Kristen Meisenheimer, Jessica Gilman Ernakovich, Dr. Eric Kantorowski, and Dr. Dan Mattern. Mr. Richard King of Pasadena, Texas, Editorial Adviser, has offered numerous suggestions on how to clarify murky explanations. I am grateful to them all. The people at Pearson have made this project possible. Good books would not exist without their dedication, professionalism, and experience. Among the many people who contributed are: Lee Englander, who originally connected me with this project; Jeanne Zalesky, Executive Editor in Chemistry; Jennifer Hart, Senior Project Editor in Chemistry; and Coleen McDonald, Assistant Editor in Chemistry. The entire manuscript was produced using ChemDraw®, the remarkable software for drawing chemical structures developed by CambridgeSoft Corp., Cambridge, MА. Finally, I appreciate my friends who supported me throughout this project, most notably my wife and friend of over forty-six years, Judy Lang. The students are too numerous to list, but it is for them that all this happens. Jan William Simek, Professor Emeritus Department of Chemistry and Biochemistry Cal Poly State University San Luis Obispo, CA 93407 Email: DEDICATION To my inspirational chemistry teachers: Joe Plaskas, who made the batter; Kurt Kaufman, who baked the cake; Carl Djerassi, who put on the icing; and to my parents: Ervin J. and Imilda B. Simek, who had the original concept. vi Copyright© 2013 Pearson Education, Inc. SYMBOLS AND ABBREVIATIONS Below is a list of symbols and abbreviations used in this Solutions Manual, consistent with those used in the textbook by Wade; see the inside front cover of the text. (Do not expect all of these to make sense to you now. You will learn them throughout your study of organic chemistry.) BONDS ARROWS a single bond a double bond a triple bond a bond in three dimensions, coming out of the paper toward the reader a bond in three dimensions, going behind the paper away from the reader a stretched bond, in the process of forming or breaking in a reaction, shows direction from reactants to products signifies equilibrium (not to be confused with resonance) signifies resonance (not to be confused with equilibrium) shows direction of electron movement: the arrowhead with one barb shows movement of one electron; the arrowhead with two barbs shows movement of a pair of electrons shows polarity of a bond or molecule, the arrowhead signifying the more negative end of the dipole SUBSTITUENT GROUPS Me a methyl group, CH3 Et an ethyl group, CH2CH3 Pr a propyl group, a three-carbon group (two possible arrangements) Bu a butyl group, a four-carbon group (four possible arrangements) R the general abbreviation for an alkyl group (or any substituent group bonded at carbon) Ph a phenyl group, the name of a benzene ring as a substituent, represented: Or Ar the general abbreviation for an aromatic group continued on next page