PPT-Aromatic compounds

Dr Sheppard CHEM 2412 Summer 2015 Klein 2 nd ed sections 181 182 188 183 184 185 Aromatic Compounds Originally distinguished because of smell Then noticed trends in reactivity. 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.. (. Benzene. ). 140 pm. 140 pm. 140 pm. 140 pm. 140 pm. 140 pm. All C—C bond distances = 140 pm. Benzene. empirical formula. = CH. 140 pm. 140 pm. 140 pm. 140 pm. 140 pm. 140 pm. . 146 pm. 134 pm. 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. page 1 Aromatic Compounds Historically, benzene and its first derivatives had pleasant aromas, and were called aromatic compounds. Structure of Benzene Kekul Bitter almonds are the source of the aromatic compound benzaldehyde. Sources of Benzene. Some Facts About Benzene. Reacts mainly by substitution. Friedrich August Kekule’. The Orbital Model for Benzene. 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.. 22.1 Hydrocarbons. Organic Chemistry. includes almost all carbon compounds. Not limited to compounds found in living cells. Hydrocarbon: organic compound made of only hydrogen and carbon atoms. hydrocarbons. 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 . 240 . Chem. 1. The expressing . aromatic compounds . came to mean . benzene. . and derivatives of benzene. .. . Structure of Benzene: Resonance Description. C. 6. H. 6. It contains a six-membered ring and three additional degrees of unsaturation.. Assistant lect. Nora . Zawar. Assistant lect. . Zeina. Dawood. Assistant . lect. . Zahraa. . Amer. . Simple Solution. Solutions. : are liquid pharmaceutical preparations. Which contain one or more soluble chemical substance dissolved in one or more suitable solvent and produce single-phase system. The Discovery of Benzene. Benzene was discovered in . 1825. by the English chemist . Michael Faraday . (Royal Institution). Faraday called this new hydrocarbon “. bicarburet. of hydrogen”.. Faraday isolated benzene from a compressed illuminating gas that had been made by . 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.. D. r. . Zamir G Khan . Assistant Professor . H R Patel Institute of Pharmaceutical Education and Research Shirpur, Dist. Dhule, (M.S) 425405. Copyright @ Mr. Z G Khan. 2. If benzene is 1,3,5-cyclohexatriene as .