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Zincke Nitration
The Zincke nitration is a nitration reaction in which a bromine is replaced by a nitro group on an electron-rich aryl compound such as a phenol or cresol. Typical reagents are nitrous acid or sodium nitrite. The reaction is a manifestation of nucleophilic aromatic substitution and is named after Theodor Zincke, who first reported it in 1900. Two examples: and: The Zincke nitration should not be confused with the Zincke–Suhl reaction or the Zincke reaction. See also * Menke nitration The Menke nitration is the nitration of electron rich aromatic compounds with cupric nitrate and acetic anhydride. The reaction introduces the nitro group predominantly in the ortho position to the activation group. It may proceed via the interme ... References {{Reflist Nitration reactions Substitution reactions Name reactions 1900 in science ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodor Zincke
Ernst Carl Theodor Zincke (19 May 1843 – 17 March 1928) was a German chemist and the academic adviser of Otto Hahn. Life Theodor Zincke was born in Uelzen on 19 May 1843. He became a pharmacist and graduated in Göttingen with his Staatsexamen. He began studying chemistry with Friedrich Wöhler and received his Ph.D in 1869. He joined the group of August Kekulé at the University of Bonn, and in 1875 became professor at the University of Marburg where he remained until his retirement in 1913. He developed Zincke reaction, Zincke–Suhl reaction in 1906 (together with R. Suhl) and in 1900 Zincke nitration. Theodor Zincke died on 17 March 1928 in Marburg Marburg ( or ) is a university town in the German federal state (''Bundesland'') of Hesse, capital of the Marburg-Biedenkopf district (''Landkreis''). The town area spreads along the valley of the river Lahn and has a population of approxima .... References * * {{DEFAULTSORT:Zincke, Theodor 1843 births 1928 dea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substitution Reactions
A substitution reaction (also known as single displacement reaction or single substitution reaction) is a chemical reaction during which one functional group in a chemical compound is replaced by another functional group. Substitution reactions are of prime importance in organic chemistry. Substitution reactions in organic chemistry are classified either as electrophilic or nucleophile, nucleophilic depending upon the reagent involved, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a radical (chemistry), free radical, and whether the substrate (chemistry), substrate is aliphatic or aromatic. Detailed understanding of a reaction type helps to predict the product outcome in a reaction. It also is helpful for optimizing a reaction with regard to variables such as temperature and choice of solvent. A good example of a substitution reaction is halogenation. When chlorine gas (Cl2) is irradiated, some of the molecules are split into two chlorine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitration Reactions
In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group into an organic compound. The term also is applied incorrectly to the different process of forming nitrate esters between alcohols and nitric acid (as occurs in the synthesis of nitroglycerin). The difference between the resulting molecular structures of nitro compounds and nitrates is that the nitrogen atom in nitro compounds is directly bonded to a non-oxygen atom (typically carbon or another nitrogen atom), whereas in nitrate esters (also called organic nitrates), the nitrogen is bonded to an oxygen atom that in turn usually is bonded to a carbon atom (nitrito group). There are many major industrial applications of nitration in the strict sense; the most important by volume are for the production of nitroaromatic compounds such as nitrobenzene. Nitration reactions are notably used for the production of explosives, for example the conversion of guanidine to nitroguanid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menke Nitration
The Menke nitration is the nitration of electron rich aromatic compounds with cupric nitrate and acetic anhydride. The reaction introduces the nitro group predominantly in the ortho position to the activation group. It may proceed via the intermediary of acetyl nitrate. The reaction is named after the Dutch chemist J.B. Menke. See also * Zincke nitration The Zincke nitration is a nitration reaction in which a bromine is replaced by a nitro group on an electron-rich aryl compound such as a phenol or cresol. Typical reagents are nitrous acid or sodium nitrite. The reaction is a manifestation of nucle ... References Nitration reactions Substitution reactions Name reactions {{Chem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zincke Reaction
The Zincke reaction is an organic reaction, named after Theodor Zincke, in which a pyridine is transformed into a pyridinium salt by reaction with 2,4-dinitro-chlorobenzene and a primary amine. The Zincke reaction should not be confused with the Zincke-Suhl reaction or the Zincke nitration. Furthermore, the Zincke reaction has nothing to do with the chemical element zinc. Reaction mechanism The first reaction is the formation of the ''N''-2,4-dinitrophenyl-pyridinium salt (2). This salt is typically isolated and purified by recrystallization. Upon heating a primary amine with the ''N''-2,4-dinitrophenyl-pyridinium salt (2), the addition of the amine leads to the opening of the pyridinium ring. A second addition of amine leads to the displacement of 2,4-dinitroaniline (5) and formation of the König salt (6a and 6b). The trans-cis-trans isomer of the König salt (6a) can react by either sigmatropic rearrangement or nucleophilic addition of a zwitterionic intermediate to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zincke–Suhl Reaction
The Zincke–Suhl reaction is a special case of a Friedel-Crafts alkylation and was first described by Theodor Zincke and Suhl in 1906.M Newman. ''A Study of the Zincke and Suhl Reaction'', ''J. Am. Chem. Soc.'' 19(6) (1954) p978M Newman. ''The Aluminum Chloride-catalyzed Reaction of Benzotrichloride with p-Cresol'', ''J. Am. Chem. Soc.'' 19(6) (1954) p985 Unlike the traditional Friedel-Crafts reaction, the reduction of the phenyl ring leads to a higher energy final product that can be used as starting material in the dienol–benzene rearrangement, among other reactions. The classic example of this reaction is the conversion of p-cresol to a cyclohexadienone (with the aid of aluminium chloride as a catalyst and tetrachloromethane as a solvent). Melvin Newman, a scientist from the U.S. intensively studied the reaction in the 1950s and reported several improved procedures as well as mechanistic studies. Since then, studies investigating the impact of alternate reagents have been con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleophilic Aromatic Substitution
A nucleophilic aromatic substitution is a substitution reaction in organic chemistry in which the nucleophile displaces a good leaving group, such as a halide, on an aromatic ring. Aromatic rings are usually nucleophilic, but some aromatic compounds do undergo nucleophilic substitution. Just as normally nucleophilic alkenes can be made to undergo conjugate substitution if they carry electron-withdrawing substituents, so normally nucleophilic aromatic rings also become electrophilic if they have the right substituents.This reaction differs from a common SN2 reaction, because it happens at a trigonal carbon atom (sp2 hybridization). The mechanism of SN2 reaction does not occur due to steric hindrance of the benzene ring. In order to attack the C atom, the nucleophile must approach in line with the C-LG (leaving group) bond from the back, where the benzene ring lies. It follows the general rule for which SN2 reactions occur only at a tetrahedral carbon atom. The SN1 mechanism is p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitration
In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group into an organic compound. The term also is applied incorrectly to the different process of forming nitrate esters between alcohols and nitric acid (as occurs in the synthesis of nitroglycerin). The difference between the resulting molecular structures of nitro compounds and nitrates is that the nitrogen atom in nitro compounds is directly bonded to a non-oxygen atom (typically carbon or another nitrogen atom), whereas in nitrate esters (also called organic nitrates), the nitrogen is bonded to an oxygen atom that in turn usually is bonded to a carbon atom (nitrito group). There are many major industrial applications of nitration in the strict sense; the most important by volume are for the production of nitroaromatic compounds such as nitrobenzene. Nitration reactions are notably used for the production of explosives, for example the conversion of guanidine to nitrog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Nitrite
Sodium nitrite is an inorganic compound with the chemical formula NaNO2. It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite salt. It is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides, but it is probably best known as a food additive used in processed meats and (in some countries) in fish products. Uses Industrial chemistry The main use of sodium nitrite is for the industrial production of organonitrogen compounds. It is a reagent for conversion of amines into diazo compounds, which are key precursors to many dyes, such as diazo dyes. Nitroso compounds are produced from nitrites. These are used in the rubber industry. It is used in a variety of metallurgical applications, for phosphatizing and detinning. Sodium nitrite is an effective corrosion inhibitor and is used as an additive in industrial greases, as an aq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrous Acid
Nitrous acid (molecular formula ) is a weak and monoprotic acid known only in Solution (chemistry), solution, in the gas phase and in the form of nitrite () salts. Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reagents in azo coupling reactions to give azo dyes. Structure In the gas phase, the planar nitrous acid molecule can adopt both a ''syn'' and an ''anti'' form. The ''anti'' form predominates at room temperature, and infrared spectroscopy, IR measurements indicate it is Gibbs free energy, more stable by around 2.3 kJ/mol. p. 462. Image:Trans-nitrous-acid-2D-dimensions.png , Dimensions of the ''anti'' form(from the rotational spectroscopy, microwave spectrum) Image:Trans-nitrous-acid-3D-balls.png , ball-and-stick model, Model of the ''anti'' form Image:Cis-nitrous-acid-3D-balls.png , ''syn'' form Preparation Nitrous acid is usually generated by acidification of aqueous solutions of sodium nitrite with a mineral acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
