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N-[4-(4-Nitro-phen-oxy)phen-yl]penta-n-amide
Acta Crystallographica. Section E, Structure Reports Online
|September 13, 2012
Summary
This study reveals distinct molecular conformations and crystal packing in C(17)H(18)N(2)O(4). Amide-amide and C-H⋯O interactions drive the formation of parallel molecular chains within the crystal structure.
Area of Science:
- Crystallography
- Organic Chemistry
- Molecular Structure
Background:
- Understanding the crystal structure of organic compounds is crucial for predicting their physical and chemical properties.
- The specific compound C(17)H(18)N(2)O(4) has not been extensively studied in terms of its solid-state conformation and intermolecular interactions.
Purpose of the Study:
- To elucidate the crystal structure of C(17)H(18)N(2)O(4).
- To analyze the conformational differences between independent molecules in the asymmetric unit.
- To investigate the intermolecular interactions governing crystal packing.
Main Methods:
- Single-crystal X-ray diffraction was employed to determine the molecular and crystal structure.
- Conformational analysis was performed on the independent molecules (A and B).
- Intermolecular interactions, including hydrogen bonding and van der Waals forces, were identified and analyzed.
Main Results:
- The asymmetric unit contains two independent molecules (A and B) with differing alkyl chain conformations (anti for A, gauche for B).
- The dihedral angles between aromatic rings were measured at approximately 82.5° for both molecules.
- Crystal packing is characterized by parallel chains formed through amide-amide (N-H⋯O=C) interactions and supported by C-H⋯O interactions.
Conclusions:
- The crystal structure of C(17)H(18)N(2)O(4) exhibits conformational polymorphism within the asymmetric unit.
- Specific intermolecular interactions dictate the formation of one-dimensional chains in the solid state.
- This structural information provides a foundation for understanding the compound's behavior and potential applications.
Related Concept Videos
01:11Nomenclature of Carboxylic Acid Derivatives: Amides and Nitriles
Naming Amides
The IUPAC and common names of amides are derived from the parent carboxylic acid, by replacing the suffix “oic acid” and “ic acid,” respectively, with “amide.” In the following example, the IUPAC name ethanamide is derived from ethanoic acid, and the common name, acetamide, is obtained from acetic acid.
The IUPAC and common names of amides are derived from the parent carboxylic acid, by replacing the suffix “oic acid” and “ic acid,” respectively, with “amide.” In the following example, the IUPAC name ethanamide is derived from ethanoic acid, and the common name, acetamide, is obtained from acetic acid.
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.
01:371° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism
Nitrous acid is a relatively weak and unstable acid prepared in situ by the reaction of sodium nitrite and cold, dilute hydrochloric acid. In an acidic solution, the nitrous acid undergoes protonation when it loses water to form a nitrosonium ion—an electrophile. Nitrous acid reacts with primary amines to give diazonium salts. The reaction is called diazotization of primary amines.
01:17Nomenclature 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.
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...