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A portion of Kistiakowsky's work involved a comparison of other unsaturated compounds in the form of CH 2 =CH(CH 2)n-CH=CH 2 (n=0,1,2). These experiments revealed an important result; when n=0, there is an effect of conjugation to the molecule where the ΔH value is lowered by 3.5 kcal. This is likened to the addition of two alkyl groups into ...
The gauche effect is very sensitive to solvent effects, due to the large difference in polarity between the two conformers.For example, 2,3-dinitro-2,3-dimethylbutane, which in the solid state exists only in the gauche conformation, prefers the gauche conformer in benzene solution by a ratio of 79:21, but in carbon tetrachloride, it prefers the anti conformer by a ratio of 58:42. [9]
Hydrogen–deuterium exchange (also called H–D or H/D exchange) is a chemical reaction in which a covalently bonded hydrogen atom is replaced by a deuterium atom, or vice versa. It can be applied most easily to exchangeable protons and deuterons, where such a transformation occurs in the presence of a suitable deuterium source, without any ...
In organic chemistry, negative hyperconjugation is the donation of electron density from a filled π- or p-orbital to a neighboring σ *-orbital. [1] This phenomenon, a type of resonance, can stabilize the molecule or transition state. [2] It also causes an elongation of the σ-bond by adding electron density to its antibonding orbital. [1]
A primary kinetic isotope effect (PKIE) may be found when a bond to the isotopically labeled atom is being formed or broken. [3] [4]: 427 Depending on the way a KIE is probed (parallel measurement of rates vs. intermolecular competition vs. intramolecular competition), the observation of a PKIE is indicative of breaking/forming a bond to the isotope at the rate-limiting step, or subsequent ...
Deuterium (hydrogen-2, symbol 2 H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen; the other is protium, or hydrogen-1, 1 H. The deuterium nucleus (deuteron) contains one proton and one neutron, whereas the far more common 1 H has no neutrons. The name deuterium comes from Greek deuteros, meaning "second".
The following table shows a series of Gibbs free energy of binding between benzene and several cations in the gas phase. [ 2 ] [ 6 ] For a singly charged species, the gas-phase interaction energy correlates with the ionic radius , r i o n {\displaystyle r_{\mathrm {ion} }} (non-spherical ionic radii are approximate).
The alpha effect refers to the increased nucleophilicity of an atom due to the presence of an adjacent (alpha) atom with lone pair electrons. [2] This first atom does not necessarily exhibit increased basicity compared with a similar atom without an adjacent electron-donating atom, resulting in a deviation from the classical Brønsted-type ...