相关实验视频

Updated: Jun 8, 2025

Facile Preparation of 4-Substituted Quinazoline Derivatives
11:51

Facile Preparation of 4-Substituted Quinazoline Derivatives

Published on: February 15, 2016

11.8K

替代控制四环化合物的热脱酸的非统计动态

Chandralekha Hajra1, Ayan Datta1

  • 1School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur - 700032, Kolkata, West Bengal, India. spad@iacs.res.in.

Physical chemistry chemical physics : PCCP
|November 5, 2024
PubMed
概括

研究人员通过调整潜在能量表面和功能组不对称性来控制化学反应. 这项研究证明了对脱酸产品的动态控制,通过分子结构和同位素效应影响反应途径.

更多相关视频

Synthesis and Purification of Iodoaziridines Involving Quantitative Selection of the Optimal Stationary Phase for Chromatography10:14

Synthesis and Purification of Iodoaziridines Involving Quantitative Selection of the Optimal Stationary Phase for Chromatography

Published on: May 16, 2014

12.5K
Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes09:42

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

Published on: January 16, 2016

9.0K

相关概念视频

meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H01:13

meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H

All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for...
5.4K
Diazonium Group Substitution: –OH and –H01:19

Diazonium Group Substitution: –OH and –H

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.
2.7K
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN101:14

Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1

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.
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...
2.1K
Nucleophilic Aromatic Substitution: Elimination–Addition01:11

Nucleophilic Aromatic Substitution: Elimination–Addition

Simple aryl halides do not react with nucleophiles. However, nucleophilic aromatic substitutions can be forced under certain conditions, such as high temperatures or strong bases. The mechanism of substitution under such conditions involves the highly unstable and reactive benzyne intermediate. Benzyne contains equivalent carbon centers at both ends of the triple bond, each of which is equally susceptible to nucleophilic attack. This 50–50 distribution of products is...
4.0K
Aryldiazonium Salts to Azo Dyes: Diazo Coupling01:11

Aryldiazonium Salts to Azo Dyes: Diazo Coupling

The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the...
2.9K
1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism01:37

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

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.
3.7K