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13 Cards in this Set
- Front
- Back
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Aromatic basic facts |
stable, low reactivity, low H:C, fragrant not fatlike |
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Nomenclature (1/) Mono-substituted compounds |
Benzene is parent name, substituent is a prefix |
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Nomenclature (2/) Mono-substituted compounds |
Common names of some mono subs |
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Nomenclature (3/) Di-substituted compounds |
Ortho, meta, para used for placement of second substituent Common name used as base if applicable and given 1 for naming positions |
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Nomenclature (4/) Di-substituted compounds |
Xylene- di-methyl Always numbered to give lowest overall numbers to substituents. Alphabetically listed, not size or number |
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Nomenclature (5/) Hydrocarbon |
saturated chain- named by larger unit unsaturated chain- chain takes parent name |
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Nomenclature (6/) Hydrocarbon |
Phenyl- C6H5 (Ph-) as substituent Benzyl- phenyl methyl (Bn) |
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Reactions of benzene |
NO addition, oxidation, hydration Slow addition at high temperature and pressure Substitution observed over addition though highly unsaturated |
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Stability of benzene |
Resonance energy = 152 kJ mol^-1 Due to stabilization of benzene vs 1,3,5-cyclohexatriene Resonance structure (<>) 2+ Lewis structures written for a molecule that differ ONLY in position of electrons, none of the structures are in complete accord with chemical and physical properties; delocalization of electrons |
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Stability of benzene |
Bond Lengths (Angstroms): (C-C 1.47 C=C 1.34) Benzene 1.39 Bond Angle (C-A)- 120 degrees All C sp2 hybridized |
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Hückel's Rule |
4n+2 pi electrons yields aromaticity if planar -closed shell of delocalized electrons, substantial resonance energies 4n electrons yields anti-aromatic molecule |
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Aromaticity of annulenes |
1. Bridge removes interference of H's and regains aromaticity in plane 2. All cis pi bonds but angle strain if planar 3. Trans pi bond |
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H-NMR Spectroscopy |
single signal at 7.27 shielding from NMR field gives lower frequency |
