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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 ...
Bases are defined by the Brønsted–Lowry theory as chemical substances that can accept a proton, i.e., a hydrogen ion. In water this is equivalent to a hydronium ion). The Lewis theory instead defines a Base as an electron-pair donor. The Lewis definition is broader — all Brønsted–Lowry bases are also Lewis bases.
A typical example of a Lewis acid in action is in the Friedel–Crafts alkylation reaction. [5] The key step is the acceptance by AlCl 3 of a chloride ion lone-pair, forming AlCl − 4 and creating the strongly acidic, that is, electrophilic, carbonium ion. RCl +AlCl 3 → R + + AlCl − 4
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.
The terms "base" and "alkali" are often used interchangeably, particularly outside the context of chemistry and chemical engineering. There are various, more specific definitions for the concept of an alkali. Alkalis are usually defined as a subset of the bases. One of two subsets is commonly chosen.
a strong base; deprotonates ketones and esters to generate enolate derivative Sodium borohydride: a versatile reducing agent; converts ketones and aldehydes to alcohols Sodium chlorite: in organic synthesis, used for the oxidation of aldehydes to carboxylic acids Sodium hydride: a strong base used in organic synthesis Sodium hydroxide
A variety of amines and nitrogen heterocycles are useful bases of moderate strength (pK a of conjugate acid around 10-13) N,N-Diisopropylethylamine (DIPEA, also called Hünig's Base [1]), pK a = 10.75; 1,8-Diazabicycloundec-7-ene (DBU) - useful for E2 elimination reactions, pK a = 13.5; 1,5-Diazabicyclo(4.3.0)non-5-ene (DBN) - comparable to DBU
The Brønsted–Lowry theory (also called proton theory of acids and bases [1]) is an acid–base reaction theory which was first developed by Johannes Nicolaus Brønsted and Thomas Martin Lowry independently in 1923.