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An isodesmic reaction is a chemical reaction in which the type of chemical bonds broken in the reactant are the same as the type of bonds formed in the reaction product. This type of reaction is often used as a hypothetical reaction in thermochemistry. A chemical reaction is a process that results in the interconversion of chemical substances [1]. The substance or substances initially involved in a chemical reaction are called reactants. ...
A chemical bond is the physical phenomenon of chemical substances being held together by attraction of atoms to each other through sharing, as well as exchanging, of electrons -or electrostatic forces. ...
A reactant or reagent is any substance initially present in a chemical reaction. ...
Thermochemistry is a branch of chemistry that deals with the interrelation of heat with chemical reactions or with a physical change of state. ...
An example of an isodesmic reaction is
- CH3- + CH3X → CH4 + CH2X- (1)
- X = F, Cl, Br, I
the deprotonation of a methyl halide by a methyl anion in equation 1. The energy change associated with this exothermic reaction which can be calculated in silico increases going from fluorine to chlorine to bromine and iodine making the CH2I- anion the most stable and least basic of all the halides. Although this reaction is isodesmic the energy change in this example also depends on the difference in bond energy of the C-X bond in the base and conjugate acid. This difference is small in fluorine but large in iodine (in favor of the anion) and therefore the energy trend is as described despite the fact that C-F bonds are stronger than C-I bonds [1]. Deprotonation is a chemistry term that refers to the removal of a proton (hydrogen ion H+) from a molecule, forming the conjugate base. ...
A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. ...
In chemistry a methyl-group is a hydrophobic Alkyl functional group which is derived from methane (CH4). ...
An anion is an ion with negative charge. ...
Exothermic has several meanings, including: In biology, an exothermic or poikilothermic animal is one that requires external sources of heat (usually sunlight) to maintain its internal temperature: for example, reptiles. ...
in silico is an expression used to mean performed on computer or via computer simulation. ...
General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance pale greenish-yellow gas Atomic mass 18. ...
General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Atomic mass 35. ...
General Name, Symbol, Number bromine, Br, 35 Chemical series halogens Group, Period, Block 17, 4, p Appearance gas/liquid: red-brown solid: metallic luster Atomic mass 79. ...
General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ...
The common (Arrhenius) definition of a base is a chemical compound that absorbs hydronium ions when dissolved in water (a proton acceptor). ...
In chemistry, bond energy (E) is a measure of bond strength in a chemical bond. ...
Within the Brønsted-Lowry (protonic) theory of acids and bases, a conjugate acid is the acid member, HX, of a pair of two compounds that transform into each other by gain or loss of a proton. ...
In chemistry, bond strength is measured between two atoms joined in a chemical bond. ...
External links
The Gold Book or Compendium of Chemical Terminology (ISBN 0865426848) is a book published by IUPAC containing internationally accepted definitions for terms in chemistry. ...
References - ^ Stabilization of Carbanions: Fluorine Is More Effective than the Heavier Halogens F. Matthias Bickelhaupt, Holger L. Hermann, Gernot Boche Angewandte Chemie International Edition Volume 45, Issue 5 , Pages 823 - 826 2006 DOI abstract
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