Posts Tagged ‘Electrophilic aromatic substitution’
Sunday, January 13th, 2019
Linear free energy relationships (LFER) are associated with the dawn of physical organic chemistry in the late 1930s and its objectives in understanding chemical reactivity as measured by reaction rates and equilibria.
(more…)
Tags:Benzoic acid, Chemical IT, Chemical kinetics, chemical reaction, chemical reactivity, chemist, Chemistry, Electrophilic aromatic substitution, energy point, Equations, Equilibrium chemistry, Equilibrium constant, free energy overall route, Hammett equation, Interesting chemistry, Linear free energy relationships, Natural sciences, Organic chemistry, Physical organic chemistry, Physical sciences, Reactivity
Posted in reaction mechanism | No Comments »
Thursday, January 7th, 2016
This is the third and final study deriving from my Ph.D.[1]. The first two topics dealt with the mechanism of heteroaromatic electrophilic attack using either a diazonium cation or a proton as electrophile, followed by either proton abstraction or carbon dioxide loss from the resulting Wheland intermediate. This final study inverts this sequence by starting with the proton abstraction from an indolinone by a base to create/aromatize to a indole-2-enolate intermediate, which only then is followed by electrophilic attack (by iodine). Here I explore what light quantum chemical modelling might cast on the mechanism.
(more…)
References
-
B.C. Challis, and H.S. Rzepa, "Heteroaromatic hydrogen exchange reactions. Part VIII. The ionisation of 1,3-dimethylindolin-2-one", Journal of the Chemical Society, Perkin Transactions 2, pp. 1822, 1975. http://dx.doi.org/10.1039/P29750001822
Tags:Arenium ion, Bases, diazo, Diazonium compound, Electrophile, Electrophilic aromatic substitution, Equilibrium chemistry, Fortran, Historical, Indole, light quantum chemical modelling, Metal ions in aqueous solution, Nuclear physics, Simple aromatic rings, Solutions
Posted in reaction mechanism | No Comments »
Friday, April 17th, 2015
The knowledge that substituents on a benzene ring direct an electrophile engaged in a ring substitution reaction according to whether they withdraw or donate electrons is very old.[1] Introductory organic chemistry tells us that electron donating substituents promote the ortho and para positions over the meta. Here I try to recover some of this information by searching crystal structures.
(more…)
References
-
H.E. Armstrong, "XXVIII.—An explanation of the laws which govern substitution in the case of benzenoid compounds", J. Chem. Soc., Trans., vol. 51, pp. 258-268, 1887. http://dx.doi.org/10.1039/CT8875100258
Tags:above search, Aromatic compounds, aromaticity, Birch reduction, Chemical IT, Chemistry, electron donating, Electrophile, Electrophilic aromatic substitution, Ether, Functional groups, little search, Organic chemistry, Physical organic chemistry, Substitution reactions
Posted in crystal_structure_mining | 1 Comment »