Balz–Schiemann reaction

<p>The Balz–Schiemann reaction (also called the Schiemann reaction) is a <a href="/facts/Chemical_reaction/GpqWlKrz">chemical reaction</a> in which a primary <a href="/facts/Aromatic_amine/Az8ttGQT">aromatic amine</a> is transformed to an <a href="/facts/Aryl/M3z7QRXd">aryl</a> <a href="/facts/Fluoride/LpqNMzwa">fluoride</a> via a <a href="/facts/Diazonium_salt/5pkN4G5s">diazonium</a> tetrafluoroborate intermediate. This reaction is a traditional route to <a href="/facts/Fluorobenzene/Rxo48gMy">fluorobenzene</a> and some related derivatives, including <a href="/facts/4-fluorobenzoic_acid/2G77122h">4-fluorobenzoic acid</a>.
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<p>The reaction is conceptually similar to the <a href="/facts/Sandmeyer_reaction/aJUhDKjY">Sandmeyer reaction</a>, which converts diazonium salts to other <a href="/facts/Aryl_halide/zEQlrpun">aryl halides</a> (ArCl, ArBr).  However, while the Sandmeyer reaction involves a <a href="/facts/Copper/I8PEE8oX">copper</a> reagent/catalyst and <a href="/facts/Radical_(chemistry)/qFymuVoT">radical</a> intermediates, the <a href="/facts/Thermal_decomposition/Qqx9RqkW">thermal decomposition</a> of the diazonium <a href="/facts/Tetrafluoroborate/46EEToo6">tetrafluoroborate</a> proceeds without a promoter and is believed to generate highly unstable aryl cations (Ar+), which abstract F− from BF4− to give the fluoroarene (ArF), along with <a href="/facts/Boron_trifluoride/2qa0NIH8">boron trifluoride</a> and nitrogen as the byproducts.
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Balz–Schiemann reaction open-in-new

Balz–Schiemann reaction