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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.
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.
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 ...
Other strong non-nucleophilic bases are sodium hydride and potassium hydride. These compounds are dense, salt-like materials that are insoluble and operate by surface reactions. Some reagents are of high basicity (pK a of conjugate acid around 17) but of modest but not negligible nucleophilicity.
Likewise, any aqueous base with an association constant pK b less than about 0, corresponding to pK a greater than about 14, is leveled to OH − and is considered a strong base. [22] Nitric acid, with a pK value of around −1.7, behaves as a strong acid in aqueous solutions with a pH greater than 1. [23] At lower pH values it behaves as a ...
[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.
The Brønsted–Lowry theory (also called proton theory of acids and bases [1]) is an acid–base reaction theory which was developed independently in 1923 by physical chemists Johannes Nicolaus Brønsted (in Denmark) and Thomas Martin Lowry (in the United Kingdom).