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Microwave-Assisted Preparation of 1-Aryl-1H-pyrazole-5-amines
Published on: June 23, 2019
3-Chloro-5-(trifluoro-meth-yl)pyridin-2-amine
Acta Crystallographica. Section E, Structure Reports Online
|January 5, 2011
Abstract:
In the title compound, C(6)H(4)ClF(3)N(2), an inter-mediate in the synthesis of the fungicide fluazinam, the F atoms of the trifluoro-methyl group are disordered over two sites in a 0.683 (14):0.317 (14) ratio. In the crystal structure, centrosymmetric dimers arise from pairs of N-H⋯N hydrogen bonds.
Related Concept Videos
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview
In the presence of an aqueous base and a halogen, primary amides can lose the carbonyl (as carbon dioxide) and undergo rearrangement to form primary amines. This reaction, called the Hofmann rearrangement, can produce primary amines (aryl and alkyl) in high yields without contamination by secondary and tertiary amines.
Nomenclature of Aryl and Heterocyclic Amines
The simplest aromatic amine is phenylamine, which contains an –NH2 functionality directly attached to an aromatic ring. The name aniline is designated for this skeleton. As shown in Figure 1, the common names of the functionalized anilines involve prefixes ortho-, meta-, and para- to indicate the substitution position. Different functionalized aniline derivatives also have notable trivial names.
Physical Properties of Amines
Amines with low molecular weight are usually gaseous at room temperature, while those with high molecular weight are liquid or solids in nature. Usually, low molecular weight amines have a rotten fish-like smell. Diamines typically have a pungent smell. For instance, cadaverine and putrescine, depicted in Figure 1, are two molecules responsible for decaying tissue.
Preparation of 1° Amines: Gabriel Synthesis
Direct alkylation is not a suitable method for synthesizing amines because it produces polyalkylated products. Gabriel synthesis is the most preferred method to exclusively make primary amines. The method uses phthalimide, which contains a protected form of nitrogen that participates in alkylation only once to predominantly give primary amines.
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
Structure of Amines
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...
Nomenclature of Primary Amines
Primary, secondary, and tertiary amines are compounds consisting of one, two, and three alkyl groups connected to the amino group (–NH2), respectively. As depicted in Figure 1, the common name of the primary amines is obtained by adding the suffix -amine to the alkyl substituent attached to the amino group as the corresponding alkylamine.

