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Updated: Jun 1, 2026
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Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives
Published on: January 19, 2016
A second monoclinic polymorph of N-(pyrazin-2-yl)aniline.
Zanariah Abdullah1, Seik Weng Ng
1Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Summary
This study details the crystal structure of a nitrogen-containing aromatic compound, C(10)H(9)N(3). Intermolecular hydrogen bonds form chains, influencing the compound's molecular arrangement in its solid state.
Area of Science:
- Crystallography
- Organic Chemistry
- Materials Science
Background:
- Understanding the molecular structure and intermolecular interactions of organic compounds is crucial for predicting their bulk properties.
- Aromatic compounds with nitrogen heteroatoms often exhibit unique electronic and structural characteristics.
- Crystal engineering relies on characterizing hydrogen bonding and molecular packing.
Purpose of the Study:
- To elucidate the crystal structure of the title compound, C(10)H(9)N(3).
- To investigate the intermolecular interactions, specifically hydrogen bonding, within the crystal lattice.
- To analyze the resulting supramolecular architecture and its relationship to the molecular geometry.
Main Methods:
- Single-crystal X-ray diffraction was employed to determine the three-dimensional structure.
- Analysis of bond lengths, bond angles, and torsion angles provided molecular geometry details.
- Intermolecular interactions, including hydrogen bonds, were identified and characterized.
Main Results:
- The crystal structure of C(10)H(9)N(3) was successfully determined.
- The two aromatic rings within the molecule exhibit a dihedral angle of 23.4(1)°.
- Intermolecular N-H⋯N hydrogen bonds link molecules into a chain motif, with a repeat distance of half the b-axis (4.44255 Å).
Conclusions:
- The crystal packing is dominated by intermolecular N-H⋯N hydrogen bonds, forming a one-dimensional chain structure.
- The observed molecular and crystal structure provides fundamental data for understanding the solid-state behavior of this nitrogen-containing aromatic compound.
- This structural information can guide future research in related compounds for potential applications.
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.
01:25Basicity of Heterocyclic Aromatic Amines
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
01:202° Amines to N-Nitrosamines: Reaction with NaNO2
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.
01:12Nomenclature of Secondary and Tertiary Amines
The secondary and tertiary amines are derivatives of ammonia, where two and three of its hydrogens are replaced by alkyl groups, respectively. Secondary and tertiary amines can be symmetrical with identical alkyl groups attached to the nitrogen atom or unsymmetrical when more than one type of alkyl group is present. The standard nomenclature of secondary and tertiary amines is similar to the names given to the primary amines. They are generally named alkylamines. As depicted in Figure 1, for...
01:19Structure 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...
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.