Organic Chemistry

1. Organic Chemistry Jin Hongwei College of Chemical Engineering and Materials Science jhwei828@zjut.edu.cn

2. Chapter One Introduction • What is Organic Chemistry? • What is Organic Compound? • The Development of Organic Chemistry as a Science. • The Properties of Organic Compounds. • The Structural Theory of Organic Chemistry. • Structural Formulas of Organic Molecular and their Representations. • Homolysis and Heterolysis of Covalent Bonds. • Definition of Acids and Bases. • Classification of Organic Compounds.

3. Organic Chemistry • Organic Chemistryis the chemistry of the compounds of carbon. • The compounds of carbon are central to life on this planet. • Every living organism is made of organic chemicals; • the proteins that make up our hair, skin, and muscles; • the DNA that controls our genetic heritages; • the foods that nourish us and the clothes that keep us warm; • the medicines that heal us are all organic chemicals. BACK

4. Organic Compounds • Organic compounds------the compounds that contain carbon and hydrogen, and their derivatives. • 有机化合物-------碳氢化合物及其衍生物。 • 有 机 化 学-------研究碳氢化合物及其衍生物的化学。 BACK

5. The Development of Organic Chemistry as a Science(1) • As a science organic chemistry is less than 200 years old. • During the 1780s scientists began to distinguish between organic compounds and inorganic compounds. • Organic compounds were defined as compounds thatcould be obtained from living organisms. • Inorganic compounds were those that came from nonliving sources. • Along with this distinction, a belief called “vitalism” (“vital force” theory) grew.

6. The Development of Organic Chemistry as a Science(2) • The first step in the decline of the vital force theory occurred in 1828, when Friederich Wohler synthesized urea from inorganic starting materials. • Wohler was trying to make ammonium cyanate (NH4OCN) from silver cyanate (AgOCN) and ammonium chloride(NH4Cl). What he expected is described by the following equation. • AgOCN(aq) + NH4Cl(aq) = AgCl(s) + NH4OCN(aq)

7. The Development of Organic Chemistry as a Science(3) • The product he isolated from this reaction had none of the properties of cyanate compounds. It was a white, crystalline material that was identical to urea, H2NCONH2, which could be isolated from urine. Ammonium cyanate Urea 　　异腈酸铵　　　　　　　　　　　 尿素 BACK

8. The Properties of Organic Compounds

9. The Structural Theory of Organic Chemistry • Between 1858 and 1861, August Kekule, Archibald Scott Couper, and Alexander Butlerov, working independently, • laid the basis for the most fundamental theories in chemistry:The Structural Theory. • Two central premises are fundamental: A.The atoms in organic compounds can form a fixed number of bonds. (在有机化合物中的原子通常有固定的价态） • 1. Carbon is tetravalent; （碳原子总是四价的） • 2. Oxygen atoms are divalent; （氧原子通常是两价的） • 3. Hydrogen and halogen atomsare monovalent.(???)

10. The Structural Theory of Organic Chemistry B. A carbon atom can use one or more of its valences to form bonds to other carbon atom . (碳原子之间可以互相形成单键或多键） • Carbon-carbon bonds Single bond Double bond Triple bond BACK

11. Structural Formulas of Organic Molecular and their Representation • Organic chemists use a variety of ways to write structural formulas. The most common types of representations are • Dash formula, Condensed formulaandBond-line formula. Dash formula Condensed formula Bond-line formula 短线式 缩简式 键线式 BACK

12. Heterolysis and Homolysis of Covalent Bonds(1) • Reactions of organic compounds always involve the making and breaking of covalent bonds. • A covalent bond may break intotwofundamentally different ways. A.The bond may break so that one fragment takes away both electrons of the bond, leaving the other fragment with an empty orbital. This kind of cleavage, calledheterolysis（异裂）, produces charges fragments or ions. (cation and anion)（碳正离子和碳负离子） Anion Cation 负离子　　正离子

13. Heterolysis and Homolysis of Covalent Bonds(2) • B. The other possibility is that the bond breaks so that each fragment takes away one of the electrons of the bonds. • This process, calledhomolysis（均裂）, produces fragments with unpaired electrons called free radicals（自由基）. Free Redical 自由基 BACK

14. Definition of Acids and Bases(1) • The Bronsted-Lowry Definition: • A Bronsted-Lowry acid is a substance that donates a hydrogen ion (H+); a Bronsted-Lowry base is a substance that accepts H+. • In a general sense, Acid Base Conjugate Conjugate Base Acid

15. Definition of Acids and Bases(2) • The Lewis Definition: • A Lewis acid is a substance that accepts an electron pair; and a Lewis base is a substance that donates an electron pair. Lewis Base Lewis Acid For example:AlCl3 BF3 ZnCl2 CH3NH2 CH3OCH3 BACK

16. Classification of Organic Compounds • The structural features that make it possible to classify compounds by reactivity are calledfunctional groups. • Afunctional groupis the part of molecule where most of its chemical reactions occur, and is the part that effectively determines the compound’s chemical properties and many of its physical propertiesas well. • 官能团------是决定有机物理化性质的原子或原子团。 BACK

17. Specific words for you in this chapter • derivatives 衍生物 synthesize 合成 isolate 分离isomerism 同分异构现象 stability 稳定性 polarity 极性solubility 溶解性 side-reaction 副反应 bond 键 • tetravalent 四价态 valence 价态 formula 表达式 • orbital 轨道 heterolysis 异裂 homolysis 均裂 • cation 碳正离子 anion 碳负离子 free radical 自由基 • acid 酸 base 碱 conjugate 共轭 • orbital 轨道 functional group官能团