منابع مشابه
Aromatic rings act as hydrogen bond acceptors.
Simple energy calculations show that there is a significant interaction between a hydrogen bond donor (like the greater than NH group) and the centre of a benzene ring, which acts as a hydrogen bond acceptor. This interaction, which is about half as strong as a normal hydrogen bond, contributes approximately 3 kcal/mol (1 cal = 4.184 J) of stabilizing enthalpy and is expected to play a signific...
متن کاملLack of resonance interaction between the aromatic rings
Electronic spectra of a homo-molecular but inequivalent dimer ion, (C6H5OH)2 +, are measured by photodissociation spectroscopy. A broad band appeared in the 340–440 nm region is characteristic of the C ← X transition of a phenol ion chromophore, suggesting that the dimer ion consists of a phenol ion and a neutral phenol. No strong band is observed in the 450–1400 nm region, whereas other aromat...
متن کاملPacking of aromatic rings against tryptophan residues in proteins.
The geometry of the interaction of the aromatic side chains of phenylalanine (Phe), tyrosine (Tyr), tryptophan (Trp) and histidine (His) with the indole ring of Trp has been analyzed using the structures in the Protein Data Bank in order to understand the dependence of the packing behaviour on the size and chemical nature of the aromatic rings. The Phe ring prefers to interact either perpendicu...
متن کاملPoly(P-N-Chlorostyrenesulphonamide): A New and Efficient Chlorinating Agent for Aromatic Rings
Poly(p-N-chlorostyrenesulphonamide) synthesized via direct chlorination of poly[(p-styrene) sulphonamide], can be used for selective chlorination of aromatic compounds. Aromatic rings of the anisole, p-xylene, ethylbenzene and toluene are chlorinated with good yields. The polymer can be recovery, rechlorinated and reused several times.
متن کاملIdentification and Analysis of the Migration of Primary Aromatic Amines from Flexible Food Packaging by High-performance Liquid Chromatography (HPLC)
Background and Objectives: Primary Aromatic Amines (PAAs) are contaminants that can migrate from food flexible packaging. The main origin of these compounds is polyurethane adhesives used in the laminating process of multilayer films. Residual aromatic di-isocyanates of the reaction of adhesive polymerization migrate into the food, and are hydrolyzed to PAAs by the moisture of food. 2,4- and 2,...
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ژورنال
عنوان ژورنال: Tetrahedron Letters
سال: 1973
ISSN: 0040-4039
DOI: 10.1016/s0040-4039(01)87293-2