Heterocyclic Compounds
Heterocyclic Compounds - Related Videos
01:13
Five-Membered Heterocyclic Aromatic Compounds: Overview
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2023
Heterocyclic aromatic compounds are cyclic compounds that are aromatic and have one or more heteroatoms—atoms other than carbon, in the ring. Depending upon the number of atoms present in the ring, they can be either five or six-membered. Examples of five-membered heterocyclic aromatic compounds include pyrrole, furan, thiophene, and imidazole. Pyrrole consists of one nitrogen atom having one lone pair of electrons. Furan and thiophene have one oxygen and one sulfur heteroatom, respectively.
01:25
Basicity of Heterocyclic Aromatic Amines
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2023
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). Figure 1. The comparison of the basicity of piperidine and pyridine. This difference in basicity may be...
01:10
Nomenclature of Aryl and Heterocyclic Amines
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2025
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. Figure 1. Common names for functionalized anilines based on substitution. For the systematic...
05:17
Functionalized Spirocyclic Heterocycle Synthesis and Cytotoxicity Assay
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Cited by 2 •
2021
Here, we describe a bioassay using 3-(4′,5′-dimethylthiazol-2′-yl)-2,5- diphenyltetrazolium bromide (MTT) to test previously synthesized spirocyclic oximes.
09:38
Compound Administration II
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2016
Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN Compound administration is often an integral component of an animal study. Many factors need to be evaluated to ensure that the compound is delivered correctly. The route of administration affects the mechanisms of absorption. The characteristics of the substance to be introduced (the pH, viscosity, and concentration) may dictate which route of administration is selected.
FAQs
Heteroatoms redistribute electron density within a ring, changing its polarity and influencing how the molecule interacts with chemical reagents. These electronic effects also affect aromaticity, the electron arrangement associated with enhanced ring stability, and help determine whether a ring is more suitable for electrophilic or nucleophilic substitution. Consequently, heteroatom selection is central to controlling reactivity during molecular design.
Aromaticity affects how a ring balances stability with chemical reactivity. Because heteroatoms modify electron distribution, they can change the ring’s response to electrophiles or nucleophiles while preserving or altering its aromatic character. Examining this relationship helps chemists anticipate substitution behavior and select ring systems whose electronic properties support a desired synthesis or molecular function.
The ring’s electron distribution is a primary factor in determining its substitution pathway. Heteroatoms influence polarity and the availability of electron density, which affects how the ring responds to electrophilic or nucleophilic reagents. Comparing these properties allows chemists to connect molecular structure with reaction behavior and to choose a heterocyclic framework appropriate for controlled chemical transformation.
Ring formation is controlled by selecting a reaction pathway that assembles the cyclic framework while establishing the intended heteroatom-containing structure. The resulting ring must then be considered in terms of electron distribution, aromaticity, polarity, and reactivity. This approach connects synthetic planning with the desired molecular properties, helping researchers prepare compounds suited to later chemical modification or application.
Their frameworks occur across pharmaceuticals, agrochemicals, dyes, polymers, and natural products. In each area, the ring’s electronic properties can contribute to a different performance goal, such as biological activity, solubility, stability, or material behavior. This broad utility makes heterocyclic chemistry relevant to medicinal chemistry, organic synthesis, and the development of functional molecular systems.
Researchers select and modify these frameworks to tune properties rather than treating the ring as a passive structural feature. Changes affecting electron distribution, polarity, aromaticity, and reactivity can support goals such as specific biological activity, improved solubility or stability, and targeted material performance. The same principles therefore connect drug-oriented molecular design with polymers, dyes, and other functional systems.