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Preparation of 1° Amines: Azide Synthesis01:22

Preparation of 1° Amines: Azide Synthesis

4.7K
Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
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1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism01:37

1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism

5.1K
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.
5.1K
2° Amines to N-Nitrosamines: Reaction with NaNO201:20

2° Amines to N-Nitrosamines: Reaction with NaNO2

5.6K
Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.
5.6K
Diazonium Group Substitution: –OH and –H01:19

Diazonium Group Substitution: –OH and –H

3.4K
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.
3.4K
1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Overview01:26

1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Overview

4.0K
Nitrous acid and nitric acids are two types of acids containing nitrogen, among which nitrous acid is weaker than nitric acid. Nitrous acid with a pKa value of 3.37 ionizes in water to give a nitrite ion and the hydronium ion.
The nitrous acid is unstable. Hence, it is formed in situ from a solution of sodium nitrite and cold aqueous acids such as hydrochloric or sulfuric acid. In an acidic solution, the –OH group of nitrous acid undergoes protonation to give oxonium ion, followed by...
4.0K
Electrophilic Aromatic Substitution: Nitration of Benzene01:20

Electrophilic Aromatic Substitution: Nitration of Benzene

9.1K
The nitration of benzene is an example of an electrophilic aromatic substitution reaction. It involves the formation of a very powerful electrophile, the nitronium ion, which is linear in shape. The reaction occurs through the interaction of two strong acids, sulfuric and nitric acid.
9.1K

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Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx
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Modifications to the azide method for nitrate isotope analysis.

Ying Tu1,2, Yunting Fang1,2, Dongwei Liu1,2

  • 1Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.

Rapid Communications in Mass Spectrometry : RCM
|March 23, 2017
PubMed
Summary
This summary is machine-generated.

This study simplifies nitrate stable isotope analysis by directly using cadmium powder and reducing toxic azide use. The modified method offers faster preparation and is suitable for small sample volumes.

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Measuring Nitrite and Nitrate, Metabolites in the Nitric Oxide Pathway, in Biological Materials using the Chemiluminescence Method
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Area of Science:

  • Environmental Chemistry
  • Analytical Chemistry
  • Isotope Geochemistry

Background:

  • The azide method for nitrate (NO3-) stable isotope analysis is established but requires difficult-to-prepare spongy cadmium or activated cadmium powder and uses toxic azide.
  • Simplifying the preparation of reagents and reducing the amount of toxic azide are key challenges for this analytical method.

Purpose of the Study:

  • To develop a simplified and safer azide method for measuring nitrate stable isotope ratios (δ15N and δ18O).
  • To enable direct use of cadmium powder, reduce azide concentration, and adapt the method for small sample volumes.

Main Methods:

  • Optimized reaction conditions for nitrate (NO3-) reduction to nitrite (NO2-) using directly added cadmium powder.
  • Diluted azide buffer (10- to 10000-fold) with or without sodium acetate was used for subsequent reduction of nitrite to nitrous oxide (N2O).
  • Nitrous oxide (N2O) isotope ratios were measured using isotope ratio mass spectrometry (IRMS) coupled with a purge and cryogenic trap system.

Main Results:

  • Direct use of cadmium powder for NO3- to NO2- reduction was successful.
  • A 100-fold diluted azide buffer sufficed for δ15N measurement, while dilution plus sodium acetate was effective for both δ15N and δ18O.
  • The modified method achieved standard deviations of 0.1–1.0‰ for δ15N and often better than 0.3‰ for δ18O in nitrate standards.

Conclusions:

  • The modified azide method simplifies reagent preparation by using non-activated cadmium powder.
  • The method substantially reduces toxic azide use (>60-fold) and is suitable for small sample volumes (5 mL).
  • This approach enhances safety and efficiency in nitrate stable isotope analysis.