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Chapter 15. Organic Chemistry. Organic Chemistry. “Organic chemistry …is enough to drive one mad. It gives me the impression of a primeval forest, full of the most remarkable things, a monstrous and boundless thicket, with no way of escape, into which one may well dread to enter.”
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Chapter 15 Organic Chemistry
Organic Chemistry • “Organic chemistry …is enough to drive one mad. It gives me the impression of a primeval forest, full of the most remarkable things, a monstrous and boundless thicket, with no way of escape, into which one may well dread to enter.” • -Friedrich Wöhler
Which of these are “organic”? • CH3CH2CH2OH • NaCN • CH3COOH • CH3(CH2)16COOH • HCCH • CaCO3 • CH3CH=CH2 What is special about carbon?
Carbon • 1. Electron configuration, electonegativity, and covalent bonding • 2. Bond properties, catenation, and molecular shape • 3. Molecular stability
Hydrocarbons • “Aliphatic” • Alkanes Alkenes Alkynes • “Aromatic” H H H H H H C C C C H C C H H H H H
Single, double, and triple bonds H H C H H C C H H C C H H H H CH4 C2H4 C2H2
Alkanes, CnH2n+2 • “Saturated” C9H20
Ethane C2H6 CH3CH3 Structures & Rotation Staggered Eclipsed
Conformations • Different spatial arrangements generated by rotation around a single bond
Naming • 1. Longest C-C chain: root name • 2.Suffix: compound type • 3. Prefix for rings: “cyclo” • 4. Branches: root + “yl” • alphabetical • numbered
Alkane examples © Mc-Graw-Hill Companies, Inc. All rights reserved.
Physical Properties • Straight: lower melting points, higher boiling points • Branched: higher melting points, lower boiling points
Alkenes, CnH2n - sp2 • “Unsaturated”
Light energy temporarily excites bond electrons Bond breaks - allows rotation
Alkynes, CnH2n-2 - sp • “Unsaturated”
Aromatic - Benzene derivatives • Delocalized (conjugated) electron cloud
Free-Radical Substitution Reactions • Alkanes:
Important Reactions 1 - Substitution • C bonded to same number of atoms | R— C — X | :Y | R— C — Y | :X
Important Reactions 2 - Addition • Two s bonds from one s bond and one p bond R— C — C — R X—Y X Y | | R— C — C — R | |
Important Reactions 3 - Elimination • Elimination of small, stable molecule + entropy X Y | | R— C — C — R | | R— C — C — R X—Y
Oxidation-reduction | R— C —H | • Oxidation: • More bonds to O • Less bonds to H • Reduction: • Less bonds to O • More bonds to H | R— C — OH | O R— C H O R— C OH
Functional Groups with Single Bonds • Alcohols & Ethers • Haloalkanes • Amines d+ d- d+ d- R—O —H R—O —R d+ d- R—X:X = halogen d+ d- R— N — |
Alcohol Reactions • Elimination • Elimination of H2O in acid • Dehydration to C=C • Elimination of 2 H w/ strong ox.agent • Oxidation to C=O • Substitution • Single bonded products • “Reactive” C bonded to electronegative atom
Haloalkane Reactions • Elimination of HX in very strong base • C=C product • Substitution in base • Single bonded products —OH, —OR, —CN, —SH, —NH2, … • “Reactive” C bonded to electronegative atom