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The tetrafluoroborate can be obtained from crude benzenediazonium chloride by salt metathesis using tetrafluoroboric acid. [C 6 H 5 N 2]Cl + HBF 4 → [C 6 H 5 N 2]BF 4 + HCl. The tetrafluoroborate is more stable than the chloride. [2]
The traditional Balz–Schiemann reaction employs HBF 4 and involves isolation of the diazonium salt. Both aspects can be profitably modified. Other counterions have been used in place of tetrafluoroborates, such as hexafluorophosphates (PF 6 −) and hexafluoroantimonates (SbF 6 −) with improved yields for some substrates.
Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group [R−N + ≡N]X − where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. The parent compound where R is hydrogen, is diazenylium.
More recently, trifluoromethylation of diazonium salts has been developed and is referred to as a 'Sandmeyer-type' reaction. Diazonium salts also react with boronates, iodide, thiols, water, hypophosphorous acid and others, [6] and fluorination can be carried out using tetrafluoroborate anions (Balz–Schiemann reaction). However, since these ...
In organic chemistry, an azo coupling is an reaction between a diazonium compound (R−N≡N +) and another aromatic compound that produces an azo compound (R−N=N−R’).In this electrophilic aromatic substitution reaction, the aryldiazonium cation is the electrophile, and the activated carbon (usually from an arene, which is called coupling agent), serves as a nucleophile.
Other electrophiles are aromatic diazonium salts in diazonium couplings, carbon dioxide in the Kolbe–Schmitt reaction and activated carbonyl groups in the Pechmann condensation, hydroxycarbenium ion in the Blanc chloromethylation via an intermediate (hydroxymethyl)arene (benzyl alcohol), chloryl cation (ClO 3 +) for electrophilic perchlorylation.
The Gattermann reaction (also known as the Gattermann formylation and the Gattermann salicylaldehyde synthesis) is a chemical reaction in which aromatic compounds are formylated by a mixture of hydrogen cyanide (HCN) and hydrogen chloride (HCl) in the presence of a Lewis acid catalyst such as aluminium chloride (AlCl 3). [1]
A small percentage of the intermediate loses the chloride to become the product (2,4-dinitrophenol, 3), while the rest return to the reactant (1). Since 2,4-dinitrophenol is in a lower energy state, it will not return to form the reactant, so after some time has passed, the reaction reaches chemical equilibrium that favors the 2,4-dinitrophenol ...