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1、 2011 Pearson Education, Inc.Organic Chemistry 6th EditionPaula Yurkanis BruiceChapter 1Electronic Structure and BondingAcids and Bases 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. Carbon-containing compounds were once considered “organ compounds” available only from living organism
2、s. The synthesis of the simple organic 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.相关知识 2011 Pearson Education
3、, Inc. Carbon neither gives up nor accepts electrons because it is in the 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 organi
4、sms. Why Carbon? 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Why Study Organic Chemistry? Since 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, Orga
5、nic Chemistry is a required course for studying Pharmacy, Medicine, and Dentistry. Admission into these professional programs is highly dependent on your performance in Organic Chemistry. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Examples of Organic Compounds Used as DrugsMethotre
6、xate, Anticancer Drug5-Fluorouracil, Colon Cancer DrugTamiflu, Influenza DrugAZT, HIV Drug5相关知识 2011 Pearson Education, Inc.Examples of Organic Compounds Used as DrugsHaldol, AntipsychoticElavil, AntidepressantProzac, AntidepressantViagra, TreatsErectile Dysfunction6相关知识 2011 Pearson Education, Inc.
7、The 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 its nucleus Mass number: the sum of the protons and neutrons of an atom Isotopes have the same atomic number but different mas
8、s 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.相关知识 2011 Pearson Education, Inc.The Distribution of Electrons in an Atom Quantum mechanics uses the mathematical equation
9、 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 likely to be found. The atomic orbital closer to the nucleus has the lowest energy. Degenera
10、te orbitals have the same energy. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.The ground-state electronic configuration describes the orbitalsoccupied by the atoms electrons with the lowest energy 2011 Pearson Education,
11、Inc.相关知识 2011 Pearson Education, Inc. 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 degener
12、ated orbitals before pairing up in the same orbitalThe following principles determine which orbitals electrons occupy: 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Lewiss theory: an atom will give up, accept, or share electrons inorder to achieve a filled outer shell or an outer shel
13、l that containseight electrons 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Ionic Bonds Are Formed by the Transfer of ElectronsAttractive forces between opposite charges are called electrostatic attractions 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Covalent Bonds A
14、re Formed by Sharing Electrons 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. Equal sharing of electrons: nonpolar covalent bond (e.g., H2) Sharing of electrons between atoms of different electronegativities: polar covalent
15、 bond (e.g., HF) 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.A polar covalent bond has a slight positive charge on one end and a slight negative charge on the other 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education,
16、 Inc.A 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.相关知识 2011 Pearson Education, Inc.Electrostatic Potential Maps 2011 Pearson
17、 Education, Inc.相关知识 2011 Pearson Education, Inc.Lewis StructureFormal charge = number of valence electrons (number of lone pair electrons +1/2 number of bonding electrons) 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Nitrogen has five valence electronsCarbon has four valence electro
18、nsHydrogen has one valence electron and halogen hasseven 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Important Bond NumbersNeutralCationicAnionic 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Non-Octet SpeciesSulfuric AcidPeriodic AcidPhosphoric Acid In the 3rd and 4t
19、h rows, expansion beyond the octet to 10 and 12 electrons is possible. Reactive species without an octet such as radicals, carbocations, carbenes, and electropositive atoms (boron, beryllium).Nitric Oxide Radical,Mammalian Signaling AgentRadicalCarbocationCarbeneBorane24相关知识 2011 Pearson Education,
20、Inc. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.The s OrbitalsAn orbital tells us the volume of space around the nucleuswhere an electron is most likely to be found 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.The p Orbitals 2011 Pearson Education, Inc.相关知识 2011 Pea
21、rson Education, Inc.Molecular 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.相关知识 2011 Pearson Education, Inc.
22、 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.In-phase overlap forms a bonding MO; out-of-phase overlap forms an antibonding MO: 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Sigma bond (s s) is formed by end-on overlap of two p orbitals:A s bond is stronger than a p b
23、ond 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Pi bond (p p) is formed by sideways overlap of two parallel p orbitals: 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Bonding in Methane 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Hybridization of One s
24、 and Three p Orbitals 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.The orbitals used in bond formation determine the bond angles Tetrahedral bond angle: 109.5 Electron pairs spread themselves into space as far from each other as possible 2011 Pearson Education, Inc.相关知识 2011 Pearson
25、Education, Inc.The Bonds in Ethane 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Hybrid Orbitals of Ethane 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Bonding in Ethene: A Double Bond 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Bonding in Ethyne: A Tr
26、iple Bond 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Bonding in the Methyl Cation 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Bonding in the Methyl Radical 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Bonding in the Methyl Anion 2011 Pearson Educati
27、on, Inc.相关知识 2011 Pearson Education, Inc.Bonding in Water 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Bonding in Ammonia and in the Ammonium Ion 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Bonding in Hydrogen Halides 2011 Pearson Education, Inc.相关知识 2011 Pearson Edu
28、cation, Inc.Summary 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 angle 2011 Pearson Education, Inc.相关知识 2011
29、 Pearson Education, Inc.The 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.相关知识 2011 Pearson Education, Inc.BrnstedLowry Acids and Bases Acid donates a proton Base acce
30、pts a proton Strong reacts to give weak The weaker the base, the stronger is its conjugate acid Stable bases are weak bases 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. An Acid/Base EquilibriumKa: The acid dissociation constant.The stronger the acid, the larger its Ka value and the
31、smaller its pKa value. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.The Most Common Organic Acids Are Carboxylic Acids 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Protonated alcohols and protonated carboxy
32、lic acids arevery strong acids 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.An amine can behave as an acid or as a base 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Strong Acids / Bases React to Form Weak A
33、cids / Bases 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.The 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 2011 Pearson Education, Inc.相关知识 201
34、1 Pearson Education, Inc.The stability of a base is affected by its size and its electronegativity 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. When atoms are very different in size, the stronger acid will have its proton
35、 attached to the largest atom size overrides electronegativity 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. When atoms are similar in size, the stronger acid will have its proton attached to the more electronegative atom 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.S
36、ubstituents Affect the Strength of an Acid 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. Inductive electron withdrawal increases the acidity of a conjugate acid 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Acetic acid is more acidic than ethanolThe delocalized electro
37、ns in acetic acid are shared by more than two atoms, thereby stabilizing the conjugated base 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.A Summary of the Factors That Determine Acid Strength1. Size: As the atom attached to the hydrogen increases in size, the strength of the acid inc
38、reases2. Electronegativity 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.3. Hybridization4. Inductive effect 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.5. Electron delocalization 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc. Lewis acid: non-proton-don
39、ating acid; will accept two electrons Lewis base: electron pair donorsLewis Acids and Bases 2011 Pearson Education, Inc.相关知识 2011 Pearson Education, Inc.Basicity and Drug Design: Methotrexate, Substituting Nitrogen for Oxygen68相关知识 2011 Pearson Education, Inc.Acidity 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:69相关知识
