1、 2011 Pearson Education,Inc.1Organic Chemistry 6th EditionPaula Yurkanis BruiceChapter 1Electronic Structure and BondingAcids and Bases 2011 Pearson Education,Inc.2 Carbon-containing compounds were once considered“organ compounds”available only from living organisms.The synthesis of the simple organ
2、ic compound urea in 1828 showed that organic compounds can be prepared in the laboratory from non-living material.Today,organic natural products are routinely synthesized in the laboratory.Organic Chemistry 2011 Pearson Education,Inc.3 Carbon neither gives up nor accepts electrons because it is in t
3、he center of the second periodic row.Consequently,carbon forms bonds with other carbons and other atoms by sharing electrons.The capacity of carbon to form bonds in this fashion makes it the building block of all living organisms.Why Carbon?2011 Pearson Education,Inc.4Why Study Organic Chemistry?Sin
4、ce carbon is the building block of all living organisms,a knowledge of Organic Chemistry is a prerequisite to understanding Biochemistry,Medicinal Chemistry,and Pharmacology.Indeed,Organic Chemistry is a required course for studying Pharmacy,Medicine,and Dentistry.Admission into these professional p
5、rograms is highly dependent on your performance in Organic Chemistry.2011 Pearson Education,Inc.5Examples of Organic Compounds Used as DrugsMethotrexate,Anticancer Drug5-Fluorouracil,Colon Cancer DrugTamiflu,Influenza DrugAZT,HIV Drug 2011 Pearson Education,Inc.6Examples of Organic Compounds Used as
6、 DrugsHaldol,AntipsychoticElavil,AntidepressantProzac,AntidepressantViagra,TreatsErectile Dysfunction 2011 Pearson Education,Inc.7The Structure of an Atom An atom consists of electrons,positively charged protons,and neutral neutrons.Electrons form chemical bonds.Atomic number:numbers of protons in i
7、ts nucleus Mass number:the sum of the protons and neutrons of an atom Isotopes have the same atomic number but different mass numbers.The atomic weight:the average weighted mass of its atoms Molecular weight:the sum of the atomic weights of all the atoms in the molecule 2011 Pearson Education,Inc.8T
8、he Distribution of Electrons in an Atom Quantum mechanics uses the mathematical equation of wave motions to characterize the motion of an electron around a nucleus.Wave functions or orbitals tell us the energy of the electron and the volume of space around the nucleus where an electron is most likel
9、y to be found.The atomic orbital closer to the nucleus has the lowest energy.Degenerate orbitals have the same energy.2011 Pearson Education,Inc.9 2011 Pearson Education,Inc.10The ground-state electronic configuration describes the orbitalsoccupied by the atoms electrons with the lowest energy 2011
10、Pearson Education,Inc.11 The Aufbau principle:an electron always goes to the available orbital with the lowest energy The Pauli exclusion principle:only two electrons can occupy one atomic orbital and the two electrons have opposite spin Hunds rule:electrons will occupy empty degenerated orbitals be
11、fore pairing up in the same orbitalThe following principles determine which orbitals electrons occupy:2011 Pearson Education,Inc.12Lewiss theory:an atom will give up,accept,or share electrons inorder to achieve a filled outer shell or an outer shell that containseight electrons 2011 Pearson Educatio
12、n,Inc.13Ionic Bonds Are Formed by the Transfer of ElectronsAttractive forces between opposite charges are called electrostatic attractions 2011 Pearson Education,Inc.14Covalent Bonds Are Formed by Sharing Electrons 2011 Pearson Education,Inc.15 2011 Pearson Education,Inc.16 Equal sharing of electron
13、s:nonpolar covalent bond (e.g.,H2)Sharing of electrons between atoms of different electronegativities:polar covalent bond(e.g.,HF)2011 Pearson Education,Inc.17A polar covalent bond has a slight positive charge on one end and a slight negative charge on the other 2011 Pearson Education,Inc.18 2011 Pe
14、arson Education,Inc.19A Polar Bond Has a Dipole Moment A polar bond has a negative end and a positive end dipole moment(D)=m=e x d(e):magnitude of the charge on the atom(d):distance between the two charges 2011 Pearson Education,Inc.20Electrostatic Potential Maps 2011 Pearson Education,Inc.21Lewis S
15、tructureFormal charge=number of valence electrons(number of lone pair electrons+1/2 number of bonding electrons)2011 Pearson Education,Inc.22Nitrogen has five valence electronsCarbon has four valence electronsHydrogen has one valence electron and halogen hasseven 2011 Pearson Education,Inc.23Importa
16、nt Bond NumbersNeutralCationicAnionic 2011 Pearson Education,Inc.24Non-Octet SpeciesSulfuric AcidPeriodic AcidPhosphoric Acid In the 3rd and 4th rows,expansion beyond the octet to 10 and 12 electrons is possible.Reactive species without an octet such as radicals,carbocations,carbenes,and electroposi
17、tive atoms(boron,beryllium).Nitric Oxide Radical,Mammalian Signaling AgentRadicalCarbocationCarbeneBorane 2011 Pearson Education,Inc.25 2011 Pearson Education,Inc.26The s OrbitalsAn orbital tells us the volume of space around the nucleuswhere an electron is most likely to be found 2011 Pearson Educa
18、tion,Inc.27The p Orbitals 2011 Pearson Education,Inc.28Molecular Orbitals Molecular orbitals belong to the whole molecule.s s bond:formed by overlapping of two s orbitals.Bond strength/bond dissociation:energy required to break a bond or energy released to form a bond.2011 Pearson Education,Inc.29 2
19、011 Pearson Education,Inc.30In-phase overlap forms a bonding MO;out-of-phase overlap forms an antibonding MO:2011 Pearson Education,Inc.31Sigma bond(s s)is formed by end-on overlap of two p orbitals:A s bond is stronger than a p bond 2011 Pearson Education,Inc.32Pi bond(p p)is formed by sideways ove
20、rlap of two parallel p orbitals:2011 Pearson Education,Inc.33Bonding in Methane 2011 Pearson Education,Inc.34Hybridization of One s and Three p Orbitals 2011 Pearson Education,Inc.35The orbitals used in bond formation determine the bond angles Tetrahedral bond angle:109.5 Electron pairs spread thems
21、elves into space as far from each other as possible 2011 Pearson Education,Inc.36The Bonds in Ethane 2011 Pearson Education,Inc.37Hybrid Orbitals of Ethane 2011 Pearson Education,Inc.38Bonding in Ethene:A Double Bond 2011 Pearson Education,Inc.39Bonding in Ethyne:A Triple Bond 2011 Pearson Education
22、,Inc.40Bonding in the Methyl Cation 2011 Pearson Education,Inc.41Bonding in the Methyl Radical 2011 Pearson Education,Inc.42Bonding in the Methyl Anion 2011 Pearson Education,Inc.43Bonding in Water 2011 Pearson Education,Inc.44Bonding in Ammonia and in the Ammonium Ion 2011 Pearson Education,Inc.45B
23、onding in Hydrogen Halides 2011 Pearson Education,Inc.46Summary The shorter the bond,the stronger it is The greater the electron density in the region of orbital overlap,the stronger is the bond The more s character,the shorter and stronger is the bond The more s character,the larger is the bond ang
24、le 2011 Pearson Education,Inc.47The vector sum of the magnitude and the direction of the individual bond dipole determines the overall dipole moment of a molecule Molecular Dipole Moment 2011 Pearson Education,Inc.48BrnstedLowry Acids and Bases Acid donates a proton Base accepts a proton Strong reac
25、ts to give weak The weaker the base,the stronger is its conjugate acid Stable bases are weak bases 2011 Pearson Education,Inc.49 An Acid/Base EquilibriumKa:The acid dissociation constant.The stronger the acid,the larger its Ka value and the smaller its pKa value.Ka=H3O+A-H2OAHLogKa=pKa 2011 Pearson
26、Education,Inc.50The Most Common Organic Acids Are Carboxylic Acids 2011 Pearson Education,Inc.51 2011 Pearson Education,Inc.52Protonated alcohols and protonated carboxylic acids arevery strong acids 2011 Pearson Education,Inc.53An amine can behave as an acid or as a base 2011 Pearson Education,Inc.5
27、4 2011 Pearson Education,Inc.55Strong Acids/Bases React to Form Weak Acids/Bases 2011 Pearson Education,Inc.56The Structure of an Acid Affects Its Acidity The weaker the base,the stronger is its conjugate acid Stable bases are weak bases The more stable the base,the stronger is its conjugate acid 20
28、11 Pearson Education,Inc.57The stability of a base is affected by its size and its electronegativity 2011 Pearson Education,Inc.58 2011 Pearson Education,Inc.59 When atoms are very different in size,the stronger acid will have its proton attached to the largest atom size overrides electronegativity
29、2011 Pearson Education,Inc.60 When atoms are similar in size,the stronger acid will have its proton attached to the more electronegative atom 2011 Pearson Education,Inc.61Substituents Affect the Strength of an Acid 2011 Pearson Education,Inc.62 Inductive electron withdrawal increases the acidity of
30、a conjugate acid 2011 Pearson Education,Inc.63Acetic acid is more acidic than ethanolThe delocalized electrons in acetic acid are shared by more than two atoms,thereby stabilizing the conjugated base 2011 Pearson Education,Inc.64A Summary of the Factors That Determine Acid Strength1.Size:As the atom
31、 attached to the hydrogen increases in size,the strength of the acid increases2.Electronegativity 2011 Pearson Education,Inc.653.Hybridization4.Inductive effect 2011 Pearson Education,Inc.665.Electron delocalization 2011 Pearson Education,Inc.67 Lewis acid:non-proton-donating acid;will accept two el
32、ectrons Lewis base:electron pair donorsLewis Acids and Bases 2011 Pearson Education,Inc.68Basicity and Drug Design:Methotrexate,Substituting Nitrogen for Oxygen 2011 Pearson Education,Inc.69Acidity and Cosmetics:Skin Peel Agents Skin Peels:Remove old skin with an acid to expose new young-looking skin.The stronger the acid,the deeper the peel.Examples of skin peel agents:Deep Peel Agent:Mild Peel Agents:
