PPT-Introduction to aromatic compounds

D r Zamir G Khan Assistant Professor H R Patel Institute of Pharmaceutical Education and Research Shirpur Dist Dhule MS 425405 Copyright Mr Z G Khan 2 If benzene is 135cyclohexatriene as . 15-8. Benzene undergoes substitution reactions with electrophiles.. Electrophiles attack benzene by substituting for a hydrogen atom, not addition to the ring.. Under the conditions of this type of reaction, ordinary non-aromatic conjugated polyenes would polymerize rapidly.. Dr. . Sheppard. CHEM . 2412. Summer 2015. Klein (2. nd. ed. .) . sections. : 18.1, 18.2, 18.8, 18.3, 18.4, 18.5. Aromatic Compounds. Originally distinguished because of smell. Then noticed trends in reactivity. Most common reactions for aromatics involve replacement of ring . hydrogens. by other atoms or groups . (substitution reactions). Mechanism of Electrophilic Aromatic Substitution Reactions. Electrophile. Conjugation and Aromaticity. Which resonance form contributes more? .  . A B C D. A = C > B E. B > A = C. Conjugation and Aromaticity. Do you expect a difference in bond lengths?.  . a. yes b. no. Orbitals. Natural gas?. Fig. 11.1. Aliphatic Hydrocarbon Structure Comparison. Bonding and Geometry. of Two-Carbon Molecules . 11.1 Structure and Physical. . Properties. 15-5. Molecules containing several fused benzene rings are called . polycyclic benzenoid. or . polycyclic aromatic hydrocarbons. (. PAHs. ).. Common names are used for these systems, since there is no simple naming system for them.. Session Objectives. Introduction nitro compounds. Nomenclature. Structure and physical properties. Preparation of nitro compounds. Chemical reactions. Cyanides and isocyanides. . General method of preparation. Leon. María. Elena. Larissa. Vanillin. Information. History of benzene. Ring structure. Functional groups. Hückel’s. rule. Vanillin. History of benzene. The . empirical formula for benzene had been long known, but its highly unsaturated structure was a challenge to determine. . Bitter almonds are the source of the aromatic compound benzaldehyde. Sources of . Benzene. Benzene. , C. 6. H. 6. , is the . parent hydrocarbon . of the . especially stable . compounds known . as . 1435-1436. 2014-2015. Learning Objectives. . Understand the. . resonance description of structure of benzene. Understand the hybridization in benzene. Understand the relation between the stability of benzene and resonance energy. Organic Chemistry. Second Edition. David Klein. Copyright © 2015 John Wiley & Sons, Inc. All rights reserved.. Klein, Organic Chemistry 2e . 18.1 Introduction to Aromatic Compounds. Aromatic. compounds or . MICHAEL FARADAY (1791-1867). first person to isolate and identify benzene. early benzene uses:. - . decaffeinate . coffee. - antiknock additive . in gasoline. - solvent in chem rxns. now we know benzene is a carcinogen!. Arenium Ion Mechanism . Some Aromatic Electrophilic Substitution Reactions Viz. Nitration, Sulphonation, Halogenation, Friedel- Crafts Reaction. Orientation & Reactivity in Mono Substituted Benzene. Dr. Geeta Singh. Assistant Professor. Department of Chemistry. D.D.U. Gorakhpur University, Gorakhpur. Introduction. Key . terms.. General reaction for aromatic electrophilic substitution.. Common reactions of AES..