PDF-Aromatic Aromatic Interactions in Crystal Structures o

Karle and Padmanabhan Balaram Contribution from the Department of Physics Molecular Biophysics Unit and Department of Inorganic and Physical Chemistry Indian Institute of Science Bangalore560 012 India and Laboratory for the Structure of Matter Na. Captain Tim specializes in private, and semi-private charters for families or small groups of people. Family Adventure Charters can also accommodate large groups for specialized tours. Benzene is aromatic: a cyclic conjugated compound with 6 . . electrons. Reactions of benzene lead to the retention of the aromatic core. Types of Reactions. Electrophilic. substitution. Diazonium. 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.. Most common reactions for aromatics involve replacement of ring . hydrogens. by other atoms or groups . (substitution reactions). Mechanism of Electrophilic Aromatic Substitution Reactions. Electrophile. 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. Krissinel. CCP4, . STFC . Research Complex at Harwell. Didcot. , . United Kingdom. krissinel@googlemail.com. CCP4 Study Weekend, Nottingham, UK, 7-8 January 2010. Macromolecular Complexes. in Crystals and Solutions. Crystals:. Basis with infinite space lattice. Infinite periodicity.. Real crystals: . are finite in extent. Therefore, they have surface at boundary where some atomic bonds are broken. Surface itself is an imperfection.. How do single crystals differ from polycrystalline samples?. Atomic . arrays that are periodic in three dimensions, with repeated distances are called single crystals. . Single crystal specimens maintain translational symmetry over macroscopic distances (crystal dimensions are typically 0.1 mm – 10 cm).. In 1825, Michael Faraday isolated a hydrocarbon called benzene, which consists of a six-carbon ring with alternating double bonds and the molecular formula C. 6. H. 6. . . Learning Goal . Describe the bonding in benzene; name aromatic compounds, and draw their line-angle structural formulas.. 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. 1. Nomenclature . of Polycyclic Aromatic Compounds. Polycyclic . aromatic compounds have two or more benzene rings fused together. 2. Naphthalene, anthracene and phenanthrene are obtained from . coal tar. 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!. 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 . Arenium Ion Mechanism . Some Aromatic Electrophilic Substitution Reactions Viz. Nitration, Sulphonation, Halogenation, Friedel- Crafts Reaction. Orientation & Reactivity in Mono Substituted Benzene.