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Synthesis and Characterization of Amphiphilic Gold Nanoparticles
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Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Published on: July 2, 2019

Reaction of gold substrates with diazonium salts in acidic solution at open-circuit potential

Joshua Lehr1, Bryce E Williamson, Benjamin S Flavel

  • 1Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.

Langmuir : the ACS Journal of Surfaces and Colloids
|August 25, 2009
PubMed

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Nitrous acid is a relatively weak and unstable acid prepared in situ by the reaction of sodium nitrite and cold, dilute hydrochloric acid. In an acidic solution, the nitrous acid undergoes protonation when it loses water to form a nitrosonium ion—an electrophile. Nitrous acid reacts with primary amines to give diazonium salts. The reaction is called diazotization of primary amines.
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Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.
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Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The diazonio group in these salts can be easily displaced by different nucleophiles, yielding a wide variety of substituted benzenes. The leaving group departs as nitrogen gas, and this easy elimination is the driving force for the substitution reaction.
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Arenediazonium substitution reactions occur when the diazonium group is substituted by various functional groups such as halides, hydroxyl, nitrile, etc. For instance, arenediazonium salts react with copper(I) salts of chloride, bromide, or cyanide to form corresponding aryl chlorides, bromides, and nitriles. These reactions are named Sandmeyer reactions. Although the mechanism of this reaction is complicated, as illustrated in Figure 1, they are believed to progress via an aryl copper...
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1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Overview

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