Related Experiment Video
Updated: Jun 1, 2026
11:51
Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
N-[(E)-Quinoxalin-2-ylmethyl-idene]-1H-indazol-5-amine
P Leeju1, V Arun, Manju Sebastian
1Department of Applied Chemistry, Cochin University of Science and Technology, Cochin 682 022, Kerala, India.
Summary
This study details the crystal structure of a molecule containing quinoxaline and indazole fragments. It reveals specific hydrogen bonding and pi-pi interactions that influence molecular arrangement in the solid state.
Area of Science:
- Crystallography
- Materials Science
- Organic Chemistry
Background:
- Understanding molecular interactions is crucial for designing new materials.
- The specific arrangement of molecules in crystals dictates their physical and chemical properties.
Purpose of the Study:
- To elucidate the crystal structure of the molecule C(16)H(11)N(5).
- To identify and characterize intermolecular interactions, including hydrogen bonding and pi-pi interactions.
Main Methods:
- Single-crystal X-ray diffraction was employed to determine the molecular and crystal structure.
- Analysis of the crystal structure revealed the dihedral angle between molecular fragments and intermolecular contacts.
Main Results:
- The molecule C(16)H(11)N(5) exhibits a dihedral angle of 10.62° between its quinoxaline and indazole fragments.
- Intermolecular N-H⋯N hydrogen bonds form zigzag chains, and pi-pi interactions create stacks of molecules parallel to the a axis.
Conclusions:
- The crystal packing is stabilized by a combination of hydrogen bonding and pi-pi interactions.
- These interactions dictate the specific supramolecular architecture of the compound in the solid state.
Related Concept Videos
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.
01:10Nomenclature 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.
01:11Aryldiazonium 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.
01:14Nucleophilic 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, or cyano...
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
01:20Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Arenediazonium substitution reactions occur when the diazonium group is substituted by various functional groups such as halides, hydroxyl, nitrile, etc. For instance, arenediazonium salts react with copper(I) salts of chloride, bromide, or cyanide to form corresponding aryl chlorides, bromides, and nitriles. These reactions are named Sandmeyer reactions. Although the mechanism of this reaction is complicated, as illustrated in Figure 1, they are believed to progress via an aryl copper...
01:29Indirect-Acting Cholinergic Agonists: Chemistry and Structure-Activity Relationship
Indirect-acting cholinergic agonists are agents that interact with the acetylcholinesterase enzyme in the synaptic cleft, preventing the breakdown of acetylcholine into choline and acetate. Consequently, the concentration of acetylcholine in the synaptic cleft increases. These agonists can be classified into reversible and irreversible inhibitors based on their duration of action.
Reversible inhibitors display short to medium durations of action. Short-acting agents include simple alcohols with...
Reversible inhibitors display short to medium durations of action. Short-acting agents include simple alcohols with...