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Updated: Jun 1, 2026
08:43
Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives
Published on: January 19, 2016
4-Chloro-N-(pyrazin-2-yl)aniline.
Wan Ainna Mardhiah Wan Saffiee1, Azila Idris, Zaharah Aiyub
1Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Summary
This study details the crystal structure of a chlorinated nitrogen-containing organic compound. Molecular analysis reveals a specific dihedral angle between aromatic rings and intermolecular hydrogen bonding forming an inversion dimer.
Area of Science:
- Crystallography
- Organic Chemistry
- Molecular Structure
Background:
- Understanding the three-dimensional arrangement of atoms in organic molecules is crucial for predicting their properties and reactivity.
- Chlorinated nitrogen heterocycles represent a significant class of compounds with diverse applications.
Purpose of the Study:
- To elucidate the precise molecular geometry and intermolecular interactions of the title compound, C(10)H(8)ClN(3).
- To characterize the crystal packing and hydrogen bonding network within the solid state.
Main Methods:
- Single-crystal X-ray diffraction was employed to determine the atomic coordinates and unit cell parameters.
- Analysis of bond lengths, bond angles, and dihedral angles provided insights into the molecular conformation.
- Intermolecular interactions, specifically hydrogen bonding, were identified and analyzed.
Main Results:
- The crystal structure of C(10)H(8)ClN(3) was successfully determined.
- A dihedral angle of 43.0(1)° was observed between the two aromatic rings within the molecule.
- An intermolecular hydrogen bond was identified between the amino nitrogen of one molecule and the pyrazinyl nitrogen of an adjacent molecule, leading to the formation of an inversion dimer.
Conclusions:
- The study provides a detailed crystallographic description of C(10)H(8)ClN(3).
- The observed dihedral angle and hydrogen bonding pattern dictate the molecule's assembly in the solid state.
- The formation of an inversion dimer through hydrogen bonding is a key feature of the crystal packing.
Related Concept Videos
01:10Nomenclature 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.
01:19Diazonium 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.
01:11Aryldiazonium 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 para position.
01:26Physical 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.
01:07Preparation of Acid Anhydrides
One of the methods for preparing symmetrical or unsymmetrical acid anhydrides involves the treatment of acid chlorides with the sodium salt of carboxylic acids. The reaction proceeds via a nucleophilic acyl substitution.
The carboxylate ion acts as a nucleophile that attacks the carbonyl carbon of the acid chloride to form a tetrahedral intermediate. Subsequently, the re-formation of the carbonyl group with the loss of the chloride ion as a leaving group leads to the formation of an acid...
The carboxylate ion acts as a nucleophile that attacks the carbonyl carbon of the acid chloride to form a tetrahedral intermediate. Subsequently, the re-formation of the carbonyl group with the loss of the chloride ion as a leaving group leads to the formation of an acid...
01:07Acid Halides to Amides: Aminolysis
Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively.
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...