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Strong superbases can be designed by utilizing various approaches [7] [8] [9] to stabilize the conjugate acid, up to the theoretical limits of basicity. [ 10 ] Organometallic superbases, sometimes called Lochmann–Schlosser superbases, result from the combination of alkali metal alkoxides and organolithium reagents. [ 11 ]
The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase.The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (E pa = 1843 kJ/mol), [3] followed by the methanide anion (E pa = 1743 kJ/mol) and the hydride ion (E pa = 1675 kJ/mol), [4] making methane the weakest proton acid [5] in the gas phase, followed by dihydrogen.
Pages in category "Superbases" The following 17 pages are in this category, out of 17 total. This list may not reflect recent changes. * Superbase; B. N-Butyllithium;
[1] [2] The three isomers of the dianion are the three strongest known superbases ever, with the ortho isomer being the strongest, with a proton affinity of 1,843.987 kJ/mol (440.723 kcal/mol). [1] The meta isomer is the second-strongest, and the para isomer is the third-strongest.
A strong base is a basic chemical compound that can remove a proton (H +) from (or deprotonate) a molecule of even a very weak acid (such as water) in an acid–base reaction. Common examples of strong bases include hydroxides of alkali metals and alkaline earth metals, like NaOH and Ca(OH) 2, respectively. Due to their low solubility, some ...
They are strong electron-withdrawing groups that increase the acidity of alpha-protons on the aromatic ring. In the presence of two DMGs, metalation often occurs ortho to the stronger directing group, though mixed products are also observed. A number of heterocycles that contain acidic protons can also undergo ortho-metalation.
On the other hand, if a chemical is a weak acid its conjugate base will not necessarily be strong. Consider that ethanoate, the conjugate base of ethanoic acid, has a base splitting constant (Kb) of about 5.6 × 10 −10, making it a weak base. In order for a species to have a strong conjugate base it has to be a very weak acid, like water.
An acidity function is a measure of the acidity of a medium or solvent system, [1] [2] usually expressed in terms of its ability to donate protons to (or accept protons from) a solute (Brønsted acidity).