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Due to the moderate dielectric constant of CXB (ε = 7.9 [2]), PMMA acquires charges that can be screened by the addition of salt (e.g. tetrabutyl ammonium bromide), leading to a very good approximation of colloidal hard sphere. [3]
Additionally, the reactivity of two series of ketones are in the orders Cl 3 CCOCH 3 > CH 3 COCH 3 > C 6 H 5 COCH 3 and cyclohexanone > cyclopentanone > cycloheptanone > cyclooctanone. [7] [8] These orders of reactivity are the same as those observed for reactions that are well established as proceeding through nucleophilic attack on a carbonyl ...
A single-displacement reaction, also known as single replacement reaction or exchange reaction, is an archaic concept in chemistry.It describes the stoichiometry of some chemical reactions in which one element or ligand is replaced by an atom or group.
The sulfur radical was found to be more reactive (6*10 8 vs. 1*10 7 M −1.s −1) and less selective (selectivity ratio 76 vs 1200) than the carbon radical. In this case, the effect can be explained by extending the Bell–Evans–Polanyi principle with a factor δ {\displaystyle \delta \,} accounting for transfer of charge from the reactants ...
The carbon-bromine bond is more reactive than the carbon-fluorine bond. If a molecule has several potential reactive sites, the reaction will occur in the most reactive one. When comparing carbon-halogen bonds, lighter halogens such as fluorine and chlorine have a better orbital overlap with carbon, which makes the bond stronger. [4]
Other driving forces including the tighter transition state [10] and higher polarizability of α-nucleophiles, involvement of intramolecular catalysis also plays a role. Another in silico study did find a correlation between the alpha effect and the so-called deformation energy, which is the electronic energy required to bring the two reactants ...
Halogenation of α,β-unsaturated ketone [3] On α,β-Unsaturated ketones or enones, it's possible to halogenate with iodine selectively on the more saturated alpha on the ketone selectively over the unsaturated side. Iodine is preferred due to it being more reactive than alkyl bromides which makes this reaction quite useful. [3]
A corollary of the effect is to explain the existence of one-way enzymes that are much more effective catalysts for one direction of reaction than the other. For example, the limiting rate in the forward direction of the reaction catalyzed by methionine adenosyltransferase is about 2 × 10 5 times higher than it is for the reverse reaction. [5]