Salt metathesis

Under salt metathesis or double decomposition is meant a pairwise interchange (a metathesis ) of cations and anions. The name metathesis means change of place or rearrangement .

${\displaystyle \mathrm {A{-}B\ +\ C{-}D\longrightarrow A{-}D\ +\ C{-}B} }$

Salt metathesis of inorganic salts

In the inorganic salt metathesis reaction, the cations and anions of two salts mutually exchange. Most of these reactions take place in solutions . The driving forces behind this reaction can be the formation of more stable salts and the removal of a product from the equilibrium of the reaction.

Silver chloride is almost insoluble in aqueous solution. For this reason it precipitates as a whitish sediment from a solution of a chloride salt in water when a silver nitrate solution is added (see also halide detection).

${\displaystyle \mathrm {AgNO_{3}\ _{(aq)}\ +\ NaCl\ _{(aq)}\longrightarrow AgCl\ _{(s)}\ +\ NaNO_{3}\ _{(aq)}} }$

On the addition of a silver nitrate solution with sodium chloride solution precipitates silver chloride.

Alkylations

The salt metathesis reactions of organometallic complexes are used to prepare alkyl complexes by reacting chloride complexes with phenyllithium or benzylpotassium .

${\displaystyle {\ce {[N(SiMe2CH2PMe2)]2YCl + PhLi -> [N(SiMe2CH2PMe2)]2YPh + LiCl}}}$

The preparation of dimethyl calcium by salt metathesis from methyl lithium and calcium bis (trimethylsilylamide) in diethyl ether is also known .

${\displaystyle \mathrm {Ca[N\{Si(CH_{3})_{3}\}_{2}]_{2}+2\ LiCH_{3}\longrightarrow Ca(CH_{3})_{2}+2\ Li[N\{Si(CH_{3})_{3}\}_{2}]} }$

Web links

• S. Rudolph, J. Geicke, IP Lorenz, T. Seifert, K. Polborn, M. Hörner: Manganiophosphonium salts: synthesis, properties and structure of complexes of the type [CpMn (CO) (NO) PPh ₂ H] BF ₄ and [Cp'Mn (CO) (NO) PPh ₂ R] X (R = H, CH ₃ , {CpMn (CO) (NO)}; X = BF ₄ , PF ₆ ). In: Journal of Nature Research B . 58, 2003, pp. 553-562 ( PDF , free full text).

See also

• Alkene metathesis

Individual evidence

1. ^ Gerard van Koten, Robert A Gossage: The Privileged Pincer-Metal Platform: Coordination Chemistry & Applications. Springer, Cham, Heidelberg, New York, Dordrecht, London, 2016, ISBN 978-3-319-22926-3 , p. 123.
2. ^ BM Wolf, C. Stuhl, C. Maichle-Mössmer, R. Anwander: Dimethylcalcium In: Journal of the American Chemical Society . 140, 2018, pp. 2373-2383, doi : 10.1021 / jacs.7b12984 .