Ebook Introduction to general, organic and biochemistry (9th edition) Part 1

(BQ) Part 1 book Introduction to general, organic and biochemistry has contents: Matter, energy, and measurement; chemical bonds, chemical reactions, solutions and colloids, reaction rates and chemical equilibrium, acids and bases, nuclear chemistry,...and other contents.

Period number Group number, U.S system Group number, IUPAC system 8A (18) Hydrogen H 1.0079 1A (1) 2A (2) Lithium Beryllium Uranium 92 METALS METALLOIDS U NONMETALS 238.0289 Helium Atomic number Symbol Atomic weight He 3A (13) 4A (14) 5A (15) 6A (16) 7A (17) 4.0026 Boron Carbon Nitrogen Oxygen Fluorine Neon 10 Li Be B C N O F Ne 6.941 9.0122 10.811 12.011 14.0067 15.9994 18.9984 20.1797 Sodium 11 Magnesium 12 Aluminum 13 Silicon 14 Phosphorus 15 Sulfur 16 Chlorine 17 Argon 18 Na Mg 22.9898 24.3050 3B (3) 4B (4) 5B (5) 6B (6) 7B (7) Potassium Calcium Scandium Titanium Vanadium Chromium Manganese 19 20 23 21 24 25 22 8B P S Cl Ar (10) 2B (12) Si (9) 1B (11) Al (8) 26.9815 28.0855 30.9738 32.066 35.4527 39.948 Iron 26 Cobalt 27 Nickel 28 Copper 29 Zinc 30 Gallium 31 Germanium 32 Arsenic 33 Selenium 34 Bromine 35 Krypton 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 39.0983 40.078 44.9559 47.867 50.9415 51.9961 54.9380 55.845 58.9332 58.6934 63.546 65.38 69.723 72.61 74.9216 78.96 79.904 83.80 Silver 47 Cadmium 48 Indium 49 Tin 50 Iodine 53 Xenon 54 Rubidium Strontium Yttrium 39 37 38 Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium 44 41 45 40 42 43 46 Antimony Tellurium 52 51 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 85.4678 87.62 88.9059 91.224 92.9064 95.96 (97.907) 101.07 102.9055 106.42 107.8682 112.411 114.818 118.710 121.760 127.60 126.9045 131.29 Osmium 76 Iridium 77 Platinum 78 Gold 79 Mercury 80 Thallium 81 Lead 82 Bismuth 83 Polonium 84 Astatine 85 Radon 86 Cesium 55 Barium Lanthanum Hafnium Tantalum Tungsten Rhenium 75 74 73 57 56 72 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 132.9054 137.327 138.9055 178.49 180.9488 183.84 186.207 190.2 192.22 195.084 196.9666 200.59 204.3833 207.2 208.9804 (208.98) (209.99) (222.02) Francium 87 Radium 88 Actinium Rutherfordium Dubnium Seaborgium Bohrium 105 89 104 106 107 — 112 — — 113 — — 114 — — 115 — — 116 — — 118 — Fr (223.02) Ra Ac (226.0254) (227.0278) Note: Atomic masses are 2007 IUPAC values (up to four decimal places) Numbers in parentheses are atomic masses or mass numbers of the most stable isotope of an element Hassium Meitnerium Darmstadtium Roentgenium 108 109 110 111 Rf Db Sg Bh Hs Mt Ds Rg Discovered Discovered Discovered Discovered Discovered Discovered (261.11) (262.11) (263.12) (262.12) (265) (266) (271) (272) 1996 2004 1999 2004 1999 2006 Erbium 68 Thulium 69 Lanthanides Actinides Cerium 58 Praseodymium Neodymium Promethium Samarium Europium Gadolinium 59 60 61 62 63 64 Terbium 65 Dysprosium Holmium 66 67 Ytterbium Lutetium 71 70 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 140.115 140.9076 144.24 (144.91) 150.36 151.965 157.25 158.9253 162.50 164.9303 167.26 168.9342 173.54 174.9668 Thorium 90 Protactinium Uranium Neptunium Plutonium Americium Curium 96 Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium 97 98 99 101 103 102 100 91 Th Pa 232.0381 231.0388 92 93 94 95 U Np Pu Am 238.0289 (237.0482) (244.664) (243.061) Cm Bk Cf Es Fm Md No Lr (247.07) (247.07) (251.08) (252.08) (257.10) (258.10) (259.10) (262.11) STANDARD ATOMIC WEIGHTS OF THE ELEMENTS 2007 Based on relative atomic mass of atom in its nuclear and electronic ground state.† Name Actinium* Aluminum Americium* Antimony Argon Arsenic Astatine* Barium Berkelium* Beryllium Bismuth Bohrium Boron Bromine Cadmium Cesium Calcium Californium* Carbon Cerium Chlorine Chromium Cobalt Copper Curium* Darmstadtium Dubnium Dysprosium Einsteinium* Erbium Europium Fermium* Fluorine Francium* Gadolinium Gallium Germanium Gold Hafnium Hassium Helium Holmium Hydrogen Indium Iodine Iridium Iron Krypton Lanthanum Lawrencium* Lead Lithium Lutetium Magnesium Manganese Meitnerium Symbol Atomic Number Atomic Weight Ac Al Am Sb Ar As At Ba Bk Be Bi Bh B Br Cd Cs Ca Cf C Ce Cl Cr Co Cu Cm Ds Db Dy Es Er Eu Fm F Fr Gd Ga Ge Au Hf Hs He Ho H In I Ir Fe Kr La Lr Pb Li Lu Mg Mn Mt 89 13 95 51 18 33 85 56 97 83 107 35 48 55 20 98 58 17 24 27 29 96 110 105 66 99 68 63 100 87 64 31 32 79 72 108 67 49 53 77 26 36 57 103 82 71 12 25 109 Mendelevium* Mercury Md Hg Molybdenum Mo 12, where 12C is a neutral Atomic Number Atomic Weight Nd Ne Np Ni Nb N No Os O Pd P Pt Pu Po K Pr Pm Pa Ra Rn Re Rh Rg Rb Ru Rf Sm Sc Sg Se Si Ag Na Sr S Ta Tc Te Tb Tl Th Tm Sn Ti W Uub Uuh Uuo Uup Uuq Uut U V Xe Yb Y 60 10 93 28 41 102 76 46 15 78 94 84 19 59 61 91 88 86 75 45 111 37 44 104 62 21 106 34 14 47 11 38 16 73 43 52 65 81 90 69 50 22 74 112 116 118 115 114 113 92 23 54 70 39 144.22(3) 20.1797(6) (237) 58.6934(4) 92.90638(2) 14.0067(2) (259) 190.23(3) 15.9994(3) 106.42(1) 30.973762(2) 195.084(9) (244) (209) 39.0983(1) 140.90765(2) (145) 231.03588(2) (226) (222) 186.207(1) 102.90550(2) (272) 85.4678(3) 101.07(2) (261) 150.36(2) 44.955912(6) (266) 78.96(3) 28.0855(3) 107.8682(2) 22.9896928(2) 87.62(1) 32.065(5) 180.9488(2) (98) 127.60(3) 158.92535(2) 204.3833(2) 232.03806(2) 168.93421(2) 118.710(7) 47.867(1) 183.84(1) (285) (292) (294) (228) (289) (284) 238.02891(3) 50.9415(1) 131.293(6) 173.54(5) 88.90585(2) Zn Zr 30 40 Name Symbol (227) 26.9815386(8) (243) 121.760(1) 39.948(1) 74.92160(2) (210) 137.327(7) (247) 9.012182(3) 208.98040(1) (264) 10.811(7) 79.904(1) 112.411(8) 132.9054519(2) 40.078(4) (251) 12.0107(8) 140.116(1) 35.453(2) 51.9961(6) 58.933195(5) 63.546(3) (247) (271) (262) 162.500(1) (252) 167.259(3) 151.964(1) (257) 18.9984032(5) (223) 157.25(3) 69.723(1) 72.64(1) 196.966569(4) 178.49(2) (277) 4.002602(2) 164.93032(2) 1.00794(7) 114.818(3) 126.90447(3) 192.217(3) 55.845(2) 83.798(2) 138.90547(7) (262) 207.2(1) 6.941(2) 174.9668(1) 24.3050(6) 54.938045(5) (268) Neodymium Neon Neptunium* Nickel Niobium Nitrogen Nobelium* Osmium Oxygen Palladium Phosphorus Platinum Plutonium* Polonium* Potassium Praseodymium Promethium* Protactinium* Radium* Radon* Rhenium Rhodium Roentgenium Rubidium Ruthenium Rutherfordium Samarium Scandium Seaborgium Selenium Silicon Silver Sodium Strontium Sulfur Tantalum Technetium* Tellurium Terbium Thallium Thorium* Thulium Tin Titanium Tungsten Ununbium Ununhexium Ununoctium Ununpentium Ununquadium Ununtrium Uranium* Vanadium Xenon Ytterbium Yttrium 101 80 (258) 200.59(2) Zinc Zirconium 42 95.96(2) †The atomic weights of many elements can vary depending on the origin and treatment of the sample This is particularly true for Li; commercially available lithium-containing materials have Li atomic weights in the range of 6.939 and 6.996 The uncertainties in atomic weight values are given in parentheses following the last significant figure to which they are attributed 12C 65.38(2) 91.224(2) *Elements with no stable nuclide; the value given in parentheses is the atomic mass number of the isotope of longest known half-life However, three such elements (Th, Pa, and U) have a characteristic terrestial isotopic composition, and the atomic weight is tabulated for these http://www chem.qmw.ac.uk/iupac/AtWt/ Study smarter and improve your grade For General, Organic, and Biochemistry Developed at the University of Massachusetts, Amherst, and class tested by tens of thousands of chemistry students, OWL is a fully customizable and flexible web-based learning system OWL supports mastery learning and offers numerical, chemical and contextual parameterization to produce thousands of problems correlated to this text The OWL system also features a database of simulations, tutorials, and exercises, as well as end-of-chapter problems from the text With OWL, you get the most widely used online learning system available for chemistry with unsurpassed reliability and dedicated training and support Features { Interactive simulations of chemical systems are accompanied by guiding questions that lead you through an exploration of the simulation These concept-building tools guide you to your own discovery of chemical concepts and relationships { Interactive problem-solving tutors ask questions and then give feedback that helps you solve the problem { Explorations of animations, 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to purchase access to other helpful products from Cengage Learning I N T RO D U C T I O N TO General, Organic, and Biochemistry NINTH EDITION Frederick A Bettelheim William H Brown Beloit College Mary K Campbell Mount Holyoke College Shawn O Farrell Olympic Training Center Australia • Brazil • Japan • Korea • Mexico • Singapore • Spain • United Kingdom • United States Introduction to General, Organic, and Biochemistry, Ninth Edition Frederick A Bettelheim, William H Brown, Mary K Campbell, Shawn O Farrell Publisher: Mary Finch Senior Acquisitions Editor: Lisa Lockwood Senior Development Editor: Sandra Kiselica © 2010 Brooks/Cole, Cengage Learning ALL RIGHTS RESERVED No part of this work covered by the copyright herein may be reproduced, transmitted, stored or used in any form or by any means graphic, electronic, or mechanical, including but not limited to photocopying, recording, scanning, digitizing, taping, Web distribution, information networks, or information storage and retrieval systems, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without the prior written permission of the publisher Assistant Editor: Brandi Kirksey Editorial Assistant: Elizabeth Woods Media Editor: Lisa Weber Marketing Manager: Nicole Hamm Marketing Assistant: Elizabeth Wong Marketing Communications Manager: Linda Yip For product information and technology assistance, contact us at Cengage Learning Customer & Sales Support, 1-800-354-9706 For permission to use material from this text or product, submit all requests online at www.cengage.com/permissions Further permissions questions can be emailed to permissionrequest@cengage.com Content Project Manager, Editorial Production: Teresa L Trego Library of Congress Control Number: 2008939244 Creative Director: Rob Hugel ISBN-13: 978-0-495-39112-8 Art Director: John Walker ISBN-10: 0-495-39112-3 Print Buyer: Judy Inouye Permissions Editor: Mollika Basu Production Service: Pre-Press PMG Text Designer: Ellen Pettengell Brooks/Cole 10 Davis Drive Belmont, CA 94002-3098 USA Photo Researcher: Marcy Lunetta/Page to Page Copy Editor: Kevin Gleason Illustrator: Greg Gambino/2064 Designs OWL Producers: Stephen Battisti, Cindy Stein, David Hart (Center for Educational Software Development, University of Massachusetts, Amherst) Cengage Learning is a leading provider of customized learning solutions with office locations around the globe, including Singapore, the United Kingdom, Australia, Mexico, Brazil, and Japan Locate your local office at: international.cengage.com/region Cengage Learning products are represented in Canada by Nelson Education, Ltd Cover Designer: John Walker Cover Image: Lester Lefkowitz/CORBIS For your course and learning solutions, visit academic.cengage.com Compositor: Pre-Press PMG Purchase any of our products at your local college store or at our preferred online store www.ichapters.com Printed in Canada 12 10 09 08 To my lovely wife, Courtney — Between textbook revisions, a full-time job, and school, I have been little more than a ghost around the house, hiding in my study writing Courtney held the family together, taking care of our children and our home while maintaining her own writing schedule None of this would have been possible without her love, support, and tireless effort —SF To my grandchildren for the love and joy they bring to my life: Emily, Sophia, and Oscar; Amanda and Laura; Rachel; Gabrielle and Max —WB To Andrew, Christian, and Sasha — Thank you for the rewards of being your mom And to Bill, Mary, and Shawn — It is always a pleasure to work with you —SK Contents in Brief General Chemistry Chapter Matter, Energy, and Measurement Chapter Atoms 31 Chapter Chemical Bonds 68 Chapter Chemical Reactions 108 Chapter Gases, Liquids, and Solids 141 Chapter Solutions and Colloids 178 Chapter Reaction Rates and Chemical Equilibrium 210 Chapter Acids and Bases 240 Chapter Nuclear Chemistry 276 Organic Chemistry Chapter 10 Organic Chemistry 307 Chapter 11 Alkanes 323 Chapter 12 Alkenes and Alkynes 352 Chapter 13 Benzene and Its Derivatives 382 Chapter 14 Alcohols, Ethers, and Thiols 397 Chapter 15 Chirality: The Handedness of Molecules 420 Chapter 16 Amines 441 Chapter 17 Aldehydes and Ketones 457 Chapter 18 Carboxylic Acids 475 Chapter 19 Carboxylic Anhydrides, Esters, and Amides 498 iv Contents in Brief Biochemistry Chapter 20 Carbohydrates 517 Chapter 21 Lipids 546 Chapter 22 Proteins 578 Chapter 23 Enzymes 614 Chapter 24 Chemical Communicators: Neurotransmitters and Hormones 639 Chapter 25 Nucleotides, Nucleic Acids, and Heredity 665 Chapter 26 Gene Expression and Protein Synthesis 695 Chapter 27 Bioenergetics: How the Body Converts Food to Energy 726 Chapter 28 Specific Catabolic Pathways: Carbohydrate, Lipid, and Protein Metabolism 747 Chapter 29 Biosynthetic Pathways 772 Chapter 30 Nutrition 787 Chapter 31 Immunochemistry 809 Chapter 32 Body Fluids (Chapter 32 can be found on this book’s companion website, which is accessible from www.cengage.com/chemistry/bettelheim) ■ v Contents Chapter Matter, Energy, and Measurement 2D Strontium-90 45 2E The Use of Metals as Historical Landmarks 47 1.1 Why Do We Call Chemistry the Study of Matter? 1.2 What Is the Scientific Method? 1.3 How Do Scientists Report Numbers? How To Determine the Number of Significant Figures in a Number 1.4 How Do We Make Measurements? 1.5 What Is a Handy Way to Convert from One Unit to Another? 12 How To Do Unit Conversions by the FactorLabel Method 13 1.6 What Are the States of Matter? 17 1.7 What Are Density and Specific Gravity? 18 1.8 How Do We Describe the Various Forms of Energy? 20 1.9 How Do We Describe Heat and the Ways in Which It Is Transferred? 21 Summary of Key Questions 26 Problems 26 What Do We Need to Know Before We Begin? 68 What Is the Octet Rule? 69 How Do We Name Anions and Cations? 71 What Are the Two Major Types of Chemical Bonds? 73 What Is an Ionic Bond? 75 How Do We Name Ionic Compounds? 77 What Is a Covalent Bond? 79 How To Draw Lewis Structures 82 3.8 How Do We Name Binary Covalent Compounds? 87 3.9 What Is Resonance? 89 How To Draw Curved Arrows and Push Electrons 90 3.10 How Do We Predict Bond Angles in Covalent Molecules? 92 3.11 How Do We Determine if a Molecule Is Polar? Chemical Connections 23 Chapter Atoms 31 2.1 2.2 2.3 2.4 2.5 2.6 2.7 What Is Matter Made Of? 31 How Do We Classify Matter? 32 What Are the Postulates of Dalton’s Atomic Theory? 35 What Are Atoms Made Of? 38 What Is the Periodic Table? 43 How Are the Electrons in an Atom Arranged? 49 How Are Electron Configuration and Position in the Periodic Table Related? 56 2.8 What Is a Periodic Property? 57 Summary of Key Questions 60 Problems 61 Chemical Connections 2A Elements Necessary for Human Life 33 2B Abundance of Elements Present in the Human Body and Earth’s Crust 37 2C Isotopic Abundance and Astrochemistry 43 vi 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Summary of Key Questions 98 Problems 100 Chemical Connections 1A Drug Dosage and Body Mass 11 1B Hypothermia and Hyperthermia 22 1C Cold Compresses, Waterbeds, and Lakes Chapter Chemical Bonds 68 3A Coral Chemistry and Broken Bones 73 3B Ionic Compounds in Medicine 80 3C Nitric Oxide: Air Pollutant and Biological Messenger 88 Chapter Chemical Reactions 108 4.1 What Is a Chemical Reaction? 4.2 What Are Formula Weights and Molecular Weights? 109 4.3 What Is a Mole and How Do We Use it to Calculate Mass Relationships? 110 4.4 How Do We Balance Chemical Equations? 114 How To Balance a Chemical Equation 114 4.5 How Do We Calculate Mass Relationships in Chemical Reactions? 118 108 96 13 Benzene and Its Derivatives Key Questions 13.1 What Is the Structure of Benzene? 13.2 How Do We Name Aromatic Compounds? 13.3 What Are the Characteristic Reactions of Benzene and Its Derivatives? © Eric Delmar/iStockphoto.com 13.4 What Are Phenols? Peppers of the Capsicum family (see Chemical Connections 13F) 13.1 What Is the Structure of Benzene? So far we have described three classes of hydrocarbons—alkanes, alkenes, and alkynes—called aliphatic hydrocarbons More than 150 years ago, organic chemists realized that yet another class of hydrocarbons exists, one whose properties are quite different from those of aliphatic hydrocarbons Because some of these new hydrocarbons have pleasant odors, they were called aromatic compounds Today we know that not all aromatic compounds share this characteristic Some have pleasant odors, but some Online homework for this chapter may be assigned in GOB OWL Aromatic compound Benzene or one of its derivatives 13.1 What Is the Structure of Benzene? have no odor at all, and others have downright unpleasant odors A more appropriate definition of an aromatic compound is any compound that has one or more benzene-like rings We use the term arene to describe aromatic hydrocarbons Just as a group derived by removal of an H from an alkane is called an alkyl group and given the symbol Ri, a group derived by removal of an H from an arene is called an aryl group and given the symbol Ar i Benzene, the simplest aromatic hydrocarbon, was discovered in 1825 by Michael Faraday (1791–1867) Its structure presented an immediate problem to chemists of the day Benzene has the molecular formula C6H6, and a compound with so few hydrogens for its six carbons (compare hexane, C6H14,and cyclohexane C6H12), chemists argued, should be unsaturated But benzene does not behave like an alkene (the only class of unsaturated hydrocarbons known at that time) Whereas 1-hexene, for example, reacts instantly with Br2 (Section 12.6C), benzene does not react at all with this reagent Nor does benzene react with HBr, H2O/H2SO4, or H2 /Pd—all reagents that normally add to carbon–carbon double bonds A Kekulé’s Structure of Benzene The first structure for benzene was proposed by Friedrich August Kekulé in 1872 and consisted of a six-membered ring with alternating single and double bonds, with one hydrogen bonded to each carbon ■ 383 Arene A compound containing one or more benzene-like rings Aryl group A group derived from an arene by removal of a H atom from an arene and given the symbol Ar i Ar i The symbol used for an aryl group Benzene is an important compound in both the chemical industry and the laboratory, but it must be handled carefully Not only is it poisonous if ingested in liquid form, but its vapor is also toxic and can be absorbed either by breathing or through the skin Long-term inhalation can cause liver damage and cancer H H H C C C C C C H H H A Kekul´e structure showing all atoms A Kekul´e structure as a line-angle drawing Although Kekulé’s proposal was consistent with many of the chemical properties of benzene, it was contested for years The major objection was its failure to account for the unusual chemical behavior of benzene If benzene contains three double bonds, Kekulé’s critics asked, why doesn’t it undergo reactions typical of alkenes? B Resonance Structure of Benzene The concept of resonance, developed by Linus Pauling in the 1930s, provided the first adequate description of the structure of benzene According to the theory of resonance, certain molecules and ions are best described by writing two or more Lewis structures and considering the real molecule or ion to be a resonance hybrid of these structures Each individual Lewis structure is called a contributing structure To show that the real molecule is a resonance hybrid of the two Lewis structures, we position a double-headed arrow between them H H H C C C C H H C C H H H H C C C C C C H H H Alternative Lewis contributing structures for benzene Resonance hybrid A molecule best described as a composite of two or more Lewis structures 384 ■ Chapter 13 Benzene and Its Derivatives The two contributing structures for benzene are often called Kekulé structures A note about resonance hybrids Do not confuse resonance contributing structures with equilibration among different chemical species A molecule described as a resonance hybrid is not equilibrating among the electron configurations of the various contributing structures Rather, the molecule has only one structure, which is best described as a hybrid of its various contributing structures The colors of the color wheel provide a good analogy Purple is not a primary color; the primary colors of blue and red are mixed to make purple You can think of a molecule represented by a resonance hybrid as being purple Purple is not sometimes blue and sometimes red Purple is purple In the analogous way, a molecule described as a resonance hybrid is not sometimes one contributing structure and sometimes another; it is a single structure all the time The resonance hybrid has some of the characteristics of each Lewis contributing structure For example, the carbon–carbon bonds are neither single nor double but rather something intermediate between the two extremes It has been determined experimentally that the length of the carbon–carbon bond in benzene is not as long as a carbon–carbon single bond nor as short as a carbon–carbon double bond, but rather is midway between the two The closed loop of six electrons (two from the second bond of each double bond) characteristic of a benzene ring is sometimes called an aromatic sextet Wherever we find resonance, we find stability The real structure is generally more stable than any of the hypothetical Lewis contributing structures The benzene ring is greatly stabilized by resonance, which explains why it does not undergo the addition reactions typical of alkenes 13.2 How Do We Name Aromatic Compounds? A One Substituent Monosubstituted alkylbenzenes are named as derivatives of benzene— for example, ethylbenzene The IUPAC system retains certain common names for several of the simpler monosubstituted alkylbenzenes, including toluene and styrene CH2CH3 CH3 Ethylbenzene Toluene CH " CH2 Styrene The IUPAC system also retains common names for the following compounds: OH Phenol Phenyl group C6H5 i the aryl group derived by removing a hydrogen atom from benzene OCH3 Anisole NH2 Aniline O O C9H C OH Benzaldehyde Benzoic acid The substituent group derived by loss of an H from benzene is called a phenyl group, C6H5 i, the common symbol for which is Phi In molecules 13.2 How Do We Name Aromatic Compounds? ■ 385 containing other functional groups, phenyl groups are often named as substituents Phenyl group (C6H5 9; Ph 9) 1-Phenylcyclohexene 4-Phenyl-1-butene B Two Substituents When two substituents occur on a benzene ring, three isomers are possible We locate the substituents either by numbering the atoms of the ring or by using the locators ortho (o), meta (m), and para (p) The numbers 1,2- are equivalent to ortho (Greek: straight); 1,3- to meta (Greek: after); and 1,4- to para (Greek: beyond) 1 1,2- or ortho- 1,3- or meta 1,4- or para When one of the two substituents on the ring imparts a special name to the compound (for example, iCH3, iOH, iNH2, or iCOOH), we name the compound as a derivative of that parent molecule and assume that the substituent occupies ring position number The IUPAC system retains the common name xylene for the three isomeric dimethylbenzenes Where neither substituent imparts a special name, we locate the two substituents and list them in alphabetical order before the ending “benzene.” The carbon of the benzene ring with the substituent of lower alphabetical ranking is numbered Ci1 COOH NH2 CH3 CH2CH3 1 2 3 3 Cl CH3 Cl Br 4-Bromobenzoic acid ( p-Bromobenzoic acid) 3-Chloroaniline (m-Chloroaniline) 1,3-Dimethylbenzene (m-Xylene) 1-Chloro-4-ethylbenzene ( p-Chloroethylbenzene) C Three or More Substituents When three or more substituents are present on a benzene ring, specify their locations by numbers If one of the substituents imparts a special name, then name the molecule as a derivative of that parent molecule If none of the substituents imparts a special name, then locate the substituents, number them to give the smallest set of numbers, and list them in alphabetical order before the ending “benzene.” In the following examples, the first compound is a derivative of toluene and the second is a derivative of phenol Because no substituent in the third compound imparts a special name, list its three substituents in alphabetical order followed by the word “benzene.” p-Xylene is a starting material for the synthesis of poly(ethylene terephthalate) Consumer products derived from this polymer include Dacron polyester fibers and Mylar films (Section 19.6B) 386 ■ Chapter 13 Benzene and Its Derivatives CH3 OH 1 Br NO2 NO2 Br Br Br Cl 4-Chloro-2-nitrotoluene CH2CH3 2,4,6-Tribromophenol 2-Bromo-1-ethyl-4-nitrobenzene Example 13.1 Naming Aromatic Compounds Write names for these compounds COOH H3C NH2 I (a) (b) (c) Br Br Cl Strategy First check to see if one of the substituents on the benzene ring imparts a special name If one of them does, then name the compound as a derivative of that parent molecule Solution (a) The parent is toluene, and the compound is 3-iodotoluene or m-iodotoluene (b) The parent is benzoic acid, and the compound is 3,5-dibromobenzoic acid (c) The parent is aniline, and the compound is 4-chloroaniline or p-chloroaniline Problem 13.1 Write names for these compounds OH NH2 COOH Cl (a) (b) (c) NO2 Cl D Polynuclear Aromatic Hydrocarbons Polynuclear aromatic hydrocarbon A hydrocarbon containing two or more benzene rings, each of which shares two carbon atoms with another benzene ring Polynuclear aromatic hydrocarbons (PAHs) contain two or more benzene rings, with each pair of rings sharing two adjacent carbon atoms Naphthalene, anthracene, and phenanthrene, the most common PAHs, and substances derived from them are found in coal tar and high-boiling petroleum residues Naphthalene Anthracene Phenanthrene 13.3 What Are the Characteristic Reactions of Benzene and Its Derivatives? ■ 387 Chemical Connections 13A Carcinogenic Polynuclear Aromatics and Smoking A carcinogen is a compound that causes cancer The first carcinogens to be identified were a group of polynuclear aromatic hydrocarbons, all of which have at least four aromatic rings Among them is benzo[a]pyrene, one of the most carcinogenic of the aromatic hydrocarbons It forms whenever incomplete combustion of organic compounds occurs Benzo[a]pyrene is found, for example, in cigarette smoke, automobile exhaust, and charcoalbroiled meats Benzo[a]pyrene causes cancer in the following way Once it is absorbed or ingested, the body attempts to convert it into a more water-soluble compound that can be excreted easily By a series of enzyme-catalyzed reactions, benzo[a]pyrene is transformed into a diol (two iOH groups) epoxide (a three-membered ring, one atom of which is oxygen) This compound can bind to DNA by reacting with one of its amino groups, thereby altering the structure of DNA and producing a cancer-causing mutation enzymecatalyzed oxidation O HO OH A diol epoxide Benzo[a]pyrene At one time, naphthalene was used as mothballs and an insecticide in preserving woolens and furs, but its use decreased after the introduction of chlorinated hydrocarbons such as p-dichlorobenzene 13.3 What Are the Characteristic Reactions of Benzene and Its Derivatives? By far the most characteristic reaction of aromatic compounds is substitution at a ring carbon, which we give the name aromatic substitution Groups we can introduce directly on the ring include the halogens, the nitro iNO2 group, and the sulfonic acid iSO3H group A Halogenation As noted in Section 13.1, chlorine and bromine not react with benzene, in contrast to their instantaneous reaction with cyclohexene and other alkenes (Section 12.6C) In the presence of an iron catalyst, however, chlorine reacts rapidly with benzene to give chlorobenzene and HCl: H  Cl2 Benzene FeCl3 Cl  HCl Chlorobenzene Treatment of benzene with bromine in the presence of FeCl3 results in formation of bromobenzene and HBr B Nitration When we heat benzene or one of its derivatives with a mixture of concentrated nitric and sulfuric acids, a nitro iNO2 group replaces one of the hydrogen atoms bonded to the ring 388 ■ Chapter 13 Benzene and Its Derivatives Chemical Connections 13B Iodide Ion and Goiter One hundred years ago, goiter, an enlargement of the thyroid gland caused by iodine deficiency, was common in the central United States and central Canada This disease results from underproduction of thyroxine, a hormone synthesized in the thyroid gland Young mammals require this hormone for normal growth and development A deficiency of thyroxine during fetal development results in mental retardation Low levels of thyroxine in adults result in hypothyroidism, commonly called goiter, the symptoms of which are lethargy, obesity, and dry skin I HO I CH2CHCOO O I Iodine is an element that comes primarily from the sea Rich sources of it, therefore, are fish and other seafoods The iodine in our diets that doesn’t come from the sea most commonly is derived from food additives Most of the iodide ion in the North American diet comes from table salt fortified with sodium iodide, commonly referred to as iodized salt Another source is dairy products, which accumulate iodide because of the iodine-containing additives used in cattle feeds and the iodine-containing disinfectants used on milking machines and milk storage tanks I NH3 Thyroxine H  HNO3 H2SO4 NO2  H2O Nitrobenzene A particular value of nitration is that we can reduce the resulting iNO2 group to a primary amino group, iNH2, by catalytic reduction using hydrogen in the presence of a transition-metal catalyst In the following example, neither the benzene ring nor the carboxyl group is affected by these experimental conditions: O2N COOH  3H2 4-Nitrobenzoic acid ( p-Nitrobenzoic acid) Ni atm COOH  2H2O H2N 4-Aminobenzoic acid ( p-Aminobenzoic acid, PABA) Bacteria require p-aminobenzoic acid for the synthesis of folic acid (Section 30.4), which is in turn required for the synthesis of the heterocyclic aromatic amine bases of nucleic acids (Section 25.2) Whereas bacteria can synthesize folic acid from p-aminobenzoic acid, folic acid is a vitamin for humans and must be obtained through the diet C Sulfonation Heating an aromatic compound with concentrated sulfuric acid results in formation of an arenesulfonic acid, all of which are strong acids, comparable in strength to sulfuric acid H  H2SO4 SO3H  H2O Benzenesulfonic acid 13.4 What Are Phenols? ■ 389 Chemical Connections 13C The Nitro Group in Explosives Treatment of toluene with three moles of nitric acid in the presence of sulfuric acid as a catalyst results in nitration of toluene three times to form the explosive 2, 4, 6-trinitrotoluene, TNT The presence of these three nitro groups confers the explosive properties to TNT Similarly, the presence of three nitro groups leads to the explosive properties of nitroglycerin CH2O NO2 CH3 O2N In recent years several new explosives have been discovered, all of which contain multiple nitro groups Among them are RDX and PETN The plastic explosive Semtex, for example, is a mixture of RDX and PETN It was used in the destruction of Pan Am flight 103 over Lockerbie, Scotland, in December 1988 NO2 O2N OCH2CCH2O NO2 N CH2O NO2 Trinitroglycerin (Nitroglycerin) NO2 CH2O NO2 NO2 CHO NO2 O2 N 2,4,6-Trinitrotoluene (TNT) N N CH2O NO2 NO2 Cyclonite (RDX) Pentaerythritol tetranitrate (PETN) A major use of sulfonation is in the preparation of synthetic detergents, an important example of which is sodium 4-dodecybenzenesulfonate To prepare this type of detergent, a linear alkylbenzene such as dodecylbenzene is treated with concentrated sulfuric acid to give an alkylbenzenesulfonic acid The sulfonic acid is then neutralized with sodium hydroxide H2SO4 CH3(CH2)10CH2 NaOH Dodecylbenzene SO3Na CH3(CH2)10CH2 Sodium 4-dodecylbenzenesulfonate, SDS (an anionic detergent) Alkylbenzenesulfonate detergents were introduced in the late 1950s, and today they claim nearly 90% of the market once held by natural soaps Section 18.4 discusses the chemistry and cleansing action of soaps and detergents 13.4 What Are Phenols? Phenol A compound that contains an iOH group bonded to a benzene ring A Structure and Nomenclature OH OH OH OH Charles D Winters/Cengage Learning The functional group of a phenol is a hydroxyl group bonded to a benzene ring Substituted phenols are named either as derivatives of phenol or by common names OH OH OH CH3 OH Phenol 3-Methylphenol (m-Cresol) 1,2-Benzenediol (Catechol) 1,3-Benzenediol (Resorcinol) 1,4-Benzenediol (Hydroquinone) Phenol in crystalline form 390 ■ Chapter 13 Benzene and Its Derivatives Phenols are widely distributed in nature Phenol itself and the isomeric cresols (o-, m-, and p-cresol) are found in coal tar Thymol and vanillin are important constituents of thyme and vanilla beans, respectively Urushiol is the main component of the irritating oil of poison ivy It can cause severe contact dermatitis in sensitive individuals O OH OH CH H3CO OH HO 2-Isopropyl-5methylphenol (Thymol) 4-Hydroxy-3-methoxybenzaldehyde (Vanillin) Urushiol Charles D Winters/Cengage Learning B Acidity of Phenols Poison ivy Phenols are weak acids, with pKa values of approximately 10 (Table 8.3) Most phenols are insoluble in water, but they react with strong bases, such as NaOH and KOH, to form water-soluble salts ONa  H2O OH  NaOH Phenol pKa  9.95 (stronger acid) Sodium hydroxide (stonger base) Sodium phenoxide (weaker base) Water pKa  15.7 (weaker acid) Most phenols are such weak acids that they not react with weak bases such as sodium bicarbonate; that is, they not dissolve in aqueous sodium bicarbonate C Phenols as Antioxidants An important reaction for living systems, foods, and other materials that contain carbon–carbon double bonds is autoxidation—that is, oxidation requiring oxygen and no other reactant If you open a bottle of cooking oil that has stood for a long time, you may notice a hiss of air entering the bottle This sound occurs because the consumption of oxygen by autoxidation of the oil creates a negative pressure inside the bottle Cooking oils contain esters of polyunsaturated fatty acids We will discuss the structure and chemistry of esters in Chapter 19 The important point here is that all vegetable oils contain fatty acids with long hydrocarbon chains, many of which have one or more carbon–carbon double bonds (see Problems 12.29 and 12.72 for the structures of four of these fatty acids) Autoxidation takes place adjacent to one or more of their double bonds O O9 H H CH2CH " CH CH ϩ O2 Section of a fatty acid hydrocarbon chain Light or heat CH2CH " CH CH A hydroperoxide Autoxidation is a radical-chain process that converts an RiH group to an RiOiOiH group, called a hydroperoxide This process begins when a hydrogen atom with one of its electrons (H·) is removed from a carbon adjacent to one of the double bonds in a hydrocarbon chain The carbon losing the H· has only seven electrons in its valence shell, one of which is unpaired An atom or molecule with an unpaired electron is called a radical 13.4 What Are Phenols? ■ 391 Chemical Connections 13D FD & C No (a.k.a Sunset Yellow) Did you ever wonder what gives gelatin desserts their red, green, orange, or yellow color? Or what gives margarines their yellow color? Or what gives maraschino cherries their red color? If you read the content labels, you will see code names such as FD & C Yellow No and FD & C Red No 40 At one time, the only colorants for foods were compounds obtained from plant or animal materials Beginning as early as the 1890s, however, chemists discovered a series of synthetic food dyes that offered several advantages over natural dyes, such as greater brightness, better stability, and lower cost Opinion remains divided on the safety of their use No synthetic food colorings are allowed, for example, in Norway and Sweden In the United States, the Food and Drug Administration (FDA) has certified seven synthetic dyes for use in foods, drugs, and cosmetics OCH3 HO HO N"N NaO3S (FD & C)—two yellows, two reds, two blues, and one green When these dyes are used alone or in combinations, they can approximate the color of almost any natural food Following are structural formulas for Allura Red (Red No 40) and Sunset Yellow (Yellow No 6) These and the other five food dyes certified in the United States have in common three or more benzene rings and two or more ionic groups, either the sodium salt of a carboxylic acid group, iCOO2Na , or the sodium salt of sulfonic acid group, iSO2 Na These ionic groups make the dyes soluble in water To return to our original questions, maraschino cherries are colored with FD & C Red No 40, and margarines are colored with FD & C Yellow No Gelatin desserts use either one or a combination of the seven certified food dyes to create their color N"N NaO3S H3C SO3Na SO3Na Allura Red (FD & C Red No 40) Sunset Yellow (FD & C Yellow No 6) Mechanism of Autoxidation Step 1: Chain Initiation—Formation of a Radical from a Nonradical Compound Removal of a hydrogen atom (H·) may be initiated by light or heat The product formed is a carbon radical; that is, it contains a carbon atom with one unpaired electron H CH2CH " CH CH9 light or heat Section of a fatty acid hydrocarbon chain CH2CH " CH CH9 A carbon radical Step 2a: Chain Propagation—Reaction of a Radical to Form a New Radical The carbon radical reacts with oxygen, itself a diradical, to form a hydroperoxy radical The new covalent bond of the hydroperoxy radical forms by the combination of one electron from the carbon radical and one electron from the oxygen diradical These two unpaired electrons combine to form a C9O single bond O O9 CH2CH " CH CH ϩ O O9 Oxygen is a diradical CH2CH " CH CH A hydroperoxy radical 392 ■ Chapter 13 Benzene and Its Derivatives Chemical Connections 13E Capsaicin, for Those Who Like It Hot Capsaicin, the pungent principle from the fruit of various species of peppers (Capsicum and Solanaceae), was isolated in 1876, and its structure was determined in 1919 Capsaicin contains both a phenol and a phenol ether O CH3O HO N C H The inflammatory properties of capsaicin are well known; the human tongue can detect as little as one drop in L of water We all know of the burning sensation in the mouth and sudden tearing in the eyes caused by a good dose of hot chili peppers For this reason, capsaicincontaining extracts from these flaming foods are used in sprays to ward off dogs or other animals that might nip at your heels while you are running or cycling Paradoxically, capsaicin is able to both cause and relieve pain Currently, two capsaicin-containing creams, Mioton and Zostrix, are prescribed to treat the burning pain associated with postherpetic neuralgia, a complication of the disease known as shingles They are also prescribed for diabetics to relieve persistent foot and leg pain Chuck Pefley/Stone/Getty Images Capsaicin (from various types of peppers) Red chilies being dried in the sun Step 2b: Chain Propagation—Reaction of a Radical to Form a New Radical The hydroperoxy radical removes a hydrogen atom (H·) from a new fatty acid hydrocarbon chain to complete the formation of a hydroperoxide and at the same time produce a new carbon radical O9O H CH2CH " CH CH9  CH2CH " CH CH Section of a new fatty acid hydrocarbon chain O9O9H CH2CH " CH CH9  CH2CH " CH CH A hydroperoxide A new carbon radical The most important point about the pair of chain propagation steps (Steps 2a and 2b) is that they form a continuous cycle of reactions, in the following way The new radical formed in Step 2b reacts with another molecule of O2 by Step 2a to give a new hydroperoxy radical This new hydroperoxy radical then reacts with a new hydrocarbon chain to repeat Step 2b, and so forth This cycle of propagation steps repeats over and over in a chain reaction Thus, once a radical is generated in Step 1, the cycle of propagation steps repeats many thousands of times and, in so doing, generates thousands of Summary of Key Questions ■ 393 hydroperoxide molecules The number of times the cycle of chain propagation steps repeats is called the chain length Hydroperoxides themselves are unstable and, under biological conditions, degrade to short-chain aldehydes and carboxylic acids with unpleasant “rancid” smells These odors may be familiar to you if you have ever smelled old cooking oil or aged foods that contain polyunsaturated fats or oils Similar formation of hydroperoxides in the low-density lipoproteins (Section 27.4) deposited on the walls of arteries leads to cardiovascular disease in humans In addition, many effects of aging are thought to result from the formation and subsequent degradation of hydroperoxides Fortunately, nature has developed a series of defenses against the formation of these and other destructive hydroperoxides, including the phenol vitamin E (Section 30.6) This compound is one of “nature’s scavengers.” It inserts itself into either Step 2a or 2b, donates an H· from its iOH group to the carbon radical, and converts the carbon radical back to its original hydrocarbon chain Because the vitamin E radical is stable, it breaks the cycle of chain propagation steps, thereby preventing further formation of destructive hydroperoxides While some hydroperoxides may form, their numbers are very small and they are easily decomposed to harmless materials by one of several possible enzyme-catalyzed reactions OH O OH H HO Vitamin E OCH3 Butylated hydroxytoluene (BHT) Butylated hydroxyanisole (BHA) Unfortunately, vitamin E is removed in the processing of many foods and food products To make up for this loss, phenols such as BHT and BHA are added to foods to “retard spoilage” (as they say on the packages) by autoxidation Likewise, similar compounds are added to other materials, such as plastics and rubber, to protect them against autoxidation Summary of Key Questions End-of-chapter problems identified in blue are assignable in GOB OWL Section 13.1 What Is the Structure of Benzene? Problem 13.8 • Benzene and its alkyl derivatives are classified as aromatic hydrocarbons or arenes • The first structure for benzene was proposed by Friederich August Kekulé in 1872 • The theory of resonance, developed by Linus Pauling in the 1930s, provided the first adequate structure for benzene Section 13.2 How Do We Name Aromatic Compounds? Problem 13.15 • Aromatic compounds are named according to the IUPAC system • The C6H5 i group is named phenyl • Two substituents on a benzene ring may be located by either numbering the atoms of the ring or by using the locators ortho (o), meta (m), and para ( p) • Polynuclear aromatic hydrocarbons contain two or more benzene rings, each sharing two adjacent carbon atoms with another ring Section 13.3 What Are the Characteristic Reactions of Benzene and Its Derivatives? Problem 13.20 • A characteristic reaction of aromatic compounds is aromatic substitution, in which another atom or group of atoms is substituted for a hydrogen atom of the aromatic ring • Typical aromatic substitution reactions are halogenation, nitration, and sulfonation 394 ■ Chapter 13 Benzene and Its Derivatives Section 13.4 What Are Phenols? • The functional group of a phenol is an iOH group bonded to a benzene ring • Phenol and its derivatives are weak acids, with pKa equal to approximately 10.0 • Vitamin E, a phenolic compound, is a natural antioxidant • Phenolic compounds such as BHT and BHA are synthetic antioxidants Summary of Key Reactions Halogenation (Section 13.3A) Treatment of an aromatic compound with Cl2 or Br2 in the presence of an FeCl3 catalyst substitutes a halogen for an H  Cl2 FeCl3 Cl  HCl Nitration (Section 13.3B) Heating an aromatic compound with a mixture of concentrated nitric and sulfuric acids substitutes a nitro group for an H  HNO3 H2SO4 heat Sulfonation (Section 13.3C) Heating an aromatic compound with concentrated sulfuric acid substitutes a sulfonic acid group for an H  H2SO4 heat SO3H  H2O Reaction of Phenols with Strong Bases (Section 13.4B) Phenols are weak acids and react with strong bases to form water-soluble salts NO2  H2O OH  NaOH ONa  H2O Problems ■ Indicates problems that are assignable in GOB OWL Blue numbered problems are applied Go to this book’s companion website at www.cengage com/chemistry/bettelheim for interactive versions of the How To tutorials and Active Figures, and to quiz yourself on this chapter Section 13.1 What Is the Structure of Benzene? 13.2 Answer true or false (a) Alkenes, alkynes, and arenes are unsaturated hydrocarbons (b) Aromatic compounds were so named because many of them have pleasant odors (c) According to the resonance model of bonding, benzene is best described as a hybrid of two equivalent contributing structures (d) Benzene is a planar molecule 13.3 What is the difference in structure between a saturated and an unsaturated compound? 13.4 Define aromatic compound 13.5 Why are alkenes, alkynes, and aromatic compounds said to be unsaturated? 13.6 Do aromatic rings have double bonds? Are they unsaturated? Explain ■ Problems assignable in GOB OWL 13.7 Can an aromatic compound be a saturated compound? 13.8 ■ Draw at least two structural formulas for each of the following (Several constitutional isomers are possible for each part.) (a) An alkene of six carbons (b) A cycloalkene of six carbons (c) An alkyne of six carbons (d) An aromatic hydrocarbon of eight carbons 13.9 Write a structural formula and the name for the simplest (a) alkane, (b) alkene, (c) alkyne, and (d) aromatic hydrocarbon 13.10 Account for the fact that the six-membered ring in benzene is planar but the six-membered ring in cyclohexane is not 13.11 The compound 1,4-dichlorobenzene ( p-dichlorobenzene) has a rigid geometry that does not allow free rotation Yet no cis-trans isomers exist for this structure Explain why it does not show cis-trans isomerism 13.12 One analogy often used to explain the concept of a resonance hybrid is to relate a rhinoceros to a unicorn and a dragon Explain the reasoning in this analogy and how it might relate to a resonance hybrid Problems Section 13.2 How Do We Name Aromatic Compounds? 13.13 Answer true or false (a) A phenyl group has the molecular formula C6H5, and is represented by the symbol Phi (b) Para substituents occupy adjacent carbons on a benzene ring (c) 4-Bromobenzoic acid can be separated into cis and trans isomers (d) Naphthalene is a planar molecule (e) Benzene, naphthalene, and anthracene are polynuclear aromatic hydrocarbons (PAHs) (f) Benzo[a]pyrene causes cancer by binding to DNA and producing a cancer-causing mutation 13.14 Name these compounds NO2 CH3 (a) (b) Br Cl Br (c) C6H5CH2CH2CH2Cl (d) C6H5CCH2CH3 CH3 OH NH2 NO2 (e) C6H5 (f) CH3 H C6H5 C"C (g) H Cl (h) C6H5 Cl 13.15 ■ Draw structural formulas for these compounds (a) 1-Bromo-2-chloro-4-ethylbenzene (b) 4-Bromo-1,2-dimethylbenzene (c) 2,4,6-Trinitrotoluene (d) 4-Phenyl-1-pentene (e) p-Cresol (f) 2,4-Dichlorophenol 13.16 We say that naphthalene, anthracene, phenanthrene, and benzo[a]pyrene are polynuclear aromatic hydrocarbons In this context, what does “polynuclear” mean? What does “aromatic” mean? What does “hydrocarbon” mean? Section 13.3 What Are the Characteristic Reactions of Benzene and Its Derivatives? 13.17 Suppose you have unlabeled bottles of benzene and cyclohexene What chemical reaction could you use ■ Problems assignable in GOB OWL ■ 395 to tell which bottle contains which chemical? Explain what you would do, what you would expect to see, and how you would explain your observations 13.18 Three products with the molecular formula C6H4BrCl form when bromobenzene is treated with chlorine, Cl2, in the presence of FeCl3 as a catalyst Name and draw a structural formula for each product 13.19 The reaction of bromine with toluene in the presence of FeCl3 gives a mixture of three products, all with the molecular formula C7H7Br Name and draw a structural formula for each product 13.20 ■ What reagents and/or catalysts are necessary to carry out each conversion? (a) Benzene to nitrobenzene (b) 1,4-dichlorobenzene to 2-bromo-1,4-dichlorobenzene (c) Benzene to aniline 13.21 What reagents and/or catalysts are necessary to carry out each conversion? Each conversion requires two steps (a) Benzene to 3-nitrobenzenesulfonic acid (b) Benzene to 1-bromo-4-chlorobenzene 13.22 Aromatic substitution can be done on naphthalene Treatment of naphthalene with concentrated H2SO4 gives two (and only two) different sulfonic acids Draw a structural formula for each Section 13.4 What Are Phenols? 13.23 Answer true or false (a) Phenols and alcohols have in common the presence of an iOH group (b) Phenols are weak acids and react with strong bases to give water-soluble salts (c) The pKa of phenol is smaller than that of acetic acid (d) Autoxidation converts an RiH group to an RiOH (hydroxyl) group (e) A carbon radical has only seven electrons in the valence shell of one of its carbons and this carbon bears a positive charge (f ) A characteristic of a chain initiation step is conversion of a nonradical to a radical (g) Autoxidation is a radical-chain process (h) A characteristic of the chain propagation step is reaction of a radical and a molecule to form a new radical and a new molecule (i) Vitamin E and other natural antioxidants function by interrupting the cycle of chain propagation steps that occurs in autoxidation 13.24 Both phenol and cyclohexanol are only slightly soluble in water Account for the fact that phenol dissolves in aqueous sodium hydroxide but cyclohexanol does not 13.25 Define autoxidation 13.26 Autoxidation is described as a radical-chain reaction What is meant by the term “radical” in this context? By the term “chain”? By the term “chain length”? 13.27 How does vitamin E function as an antioxidant? 396 ■ Chapter 13 Benzene and Its Derivatives 13.28 What structural features are common to vitamin E, BHT, and BHA (the three antioxidants presented in Section 13.4C)? Chemical Connections 13.38 ■ Draw structural formulas for these compounds (a) 1-Phenylcyclopropanol (b) Styrene (c) m-Bromophenol (d) 4-Nitrobenzoic acid (e) Isobutylbenzene (f) m-Xylene 13.29 (Chemical Connections 13A) What is a carcinogen? What kind of carcinogen is found in cigarette smoke? 13.39 2,6-Di-tert-butyl-4-methylphenol (BHT, Section 13.4C) is an antioxidant added to processed foods to “retard spoilage.” How does BHT accomplish this goal? 13.30 (Chemical Connections 13B) In the absence of iodine in the diet, goiter develops Explain why goiter is a regional disease 13.40 Write the structural formula for the product of each reaction 13.31 (Chemical Connections 13C) Calculate the molecular weight of each explosive in this Chemical Connection In which explosive the nitro groups contribute the largest percentage of molecular weight?  HNO3 (a) CH3 13.32 (Chemical Connections 13D) What are the differences in structure between Allura Red and Sunset Yellow? 13.33 (Chemical Connections 13D) Which features of Allura Red and Sunset Yellow make them water-soluble?  Br2 (b) 13.34 (Chemical Connections 13D) What color would you get if you mixed Allura Red and Sunset Yellow? (Hint: Remember the color wheel.) 13.35 (Chemical Connections 13E) From what types of plants is capsaicin isolated? 13.36 (Chemical Connections 13E) How many cis-trans isomers are possible for capsaicin? Is the structural formula shown in this Chemical Connection the cis isomer or the trans isomer? Additional Problems 13.37 The structure for naphthalene given in Section 13.2D is only one of three possible resonance structures Draw the other two ■ Problems assignable in GOB OWL H2SO4 FeCl3 CH3 Br  H2SO4 (c) Br 13.41 ■ Styrene reacts with bromine to give a compound with the molecular formula C8H8Br2 Draw a structural formula for this compound ... Y 60 10 93 28 41 102 76 46 15 78 94 84 19 59 61 91 88 86 75 45 11 1 37 44 10 4 62 21 106 34 14 47 11 38 16 73 43 52 65 81 90 69 50 22 74 11 2 11 6 11 8 11 5 11 4 11 3 92 23 54 70 39 14 4.22(3) 20 .17 97(6)... ( 210 ) 13 7.327(7) (247) 9. 012 182(3) 208.98040 (1) (264) 10 . 811 (7) 79.904 (1) 11 2. 411 (8) 13 2.9054 519 (2) 40.078(4) (2 51) 12 . 010 7(8) 14 0 .11 6 (1) 35.453(2) 51. 99 61( 6) 58.93 319 5(5) 63.546(3) (247) (2 71) ... Fluorine Neon 10 Li Be B C N O F Ne 6.9 41 9. 012 2 10 . 811 12 . 011 14 .0067 15 .9994 18 .9984 20 .17 97 Sodium 11 Magnesium 12 Aluminum 13 Silicon 14 Phosphorus 15 Sulfur 16 Chlorine 17 Argon 18 Na Mg 22.9898