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Why use potassium iodide instead of copper iodide in Sandmeyer reaction?
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Mizanur Rahman
Why use potassium iodide instead of copper iodide in Sandmeyer reaction?
Sandmeyer reactions using iodides, water, and thiols do not require the copper(I) ion as a catalyst for the reaction to proceed whereas your other nucleophiles do (though not necessarily stoichiometrically).
As you can see the copper(I) ion is important in reducing the diazonium to nitrogen and forming a radical. Iodine, oxygen, and sulfur must be able to be oxidized by diazonium and therefore do not require copper.
Sandmeyer reactions using iodides, water, and thiols do not require the copper(I) ion as a catalyst for the reaction to proceed whereas your other nucleophiles do (though not necessarily stoichiometrically).
As you can see the copper(I) ion is important in reducing the diazonium to nitrogen and forming a radical. Iodine, oxygen, and sulfur must be able to be oxidized by diazonium and therefore do not require copper.
Is there any evidence that thiols, water (and presumably alcohols), and iodide are oxidized? Oxidation of thiols and iodide are (relatively) facile, but I dont consider oxidation of water to be in the same class. If it has something to do with nucleophilic strength, surely cyanide is a stronger nucleophile than water, yet cyanide requires presence of copper(I). Its probably not appropriate to call copper a catalyst, since its present in stoichiometric amounts.More
The answer says that oxygen must be oxidized by diazonium in order to avoid the need for copper. Is there evidence that water is oxidized in this reaction?More
This is incorrect conclusion - only catalytic reaction is with redox steps. Its not like it wont work at all with Cl and Br, but Cu makes an improvement.More
Sandmeyer reactions using iodides, water, and thiols do not require the copper(I) ion as a catalyst for the reaction to proceed whereas your other nucleophiles do (though not necessarily stoichiometrically).
As you can see the copper(I) ion is important in reducing the diazonium to nitrogen and forming a radical. Iodine, oxygen, and sulfur must be able to be oxidized by diazonium and therefore do not require copper.
Sandmeyer reactions using iodides, water, and thiols do not require the copper(I) ion as a catalyst for the reaction to proceed whereas your other nucleophiles do (though not necessarily stoichiometrically).
As you can see the copper(I) ion is important in reducing the diazonium to nitrogen and forming a radical. Iodine, oxygen, and sulfur must be able to be oxidized by diazonium and therefore do not require copper.
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