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Define heterocyclic compounds.
Define heterocyclic compounds.
Heterocyclic compounds are cyclic hydrocarbons containing one or more heteroatoms in a ring.
What is the chemical formula of Quinoline?
What is the chemical formula of Quinoline?
C₉H₇N
Quinoline is characterized by a double ring structure composed of a ______ and a pyridine ring fused at two adjacent carbon atoms.
Quinoline is characterized by a double ring structure composed of a ______ and a pyridine ring fused at two adjacent carbon atoms.
benzene
Which resonance rule does Quinoline satisfy?
Which resonance rule does Quinoline satisfy?
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Quinoline is soluble in cold water.
Quinoline is soluble in cold water.
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What is the definition of heterocyclic compounds?
What is the definition of heterocyclic compounds?
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What is the chemical formula of Quinoline?
What is the chemical formula of Quinoline?
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Which of the following are examples of heterocyclic compounds? (Select all that apply)
Which of the following are examples of heterocyclic compounds? (Select all that apply)
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How does Quinoline react with acids?
How does Quinoline react with acids?
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Quinoline is slightly soluble in cold water.
Quinoline is slightly soluble in cold water.
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Study Notes
Heterocyclic Compounds
• Heterocyclic compounds are cyclic hydrocarbons that contain one or more heteroatoms in a ring, which can be aromatic, partially or fully saturated. • Examples of heterocyclic compounds include nucleic acids, pharmaceuticals, agrochemicals, naturally occurring pigments, vitamins, and antibiotics.
Quinoline
• Quinoline is a heterocyclic aromatic organic compound with the chemical formula C₉H₇N, also known as benzo-pyridine or 1-aza-naphthalene. • Quinoline has a double ring structure composed of a benzene and a pyridine ring fused at two adjacent carbon atoms. • Physical properties of quinoline include a boiling point of 238°C, melting point of -15°C, density of 1.09 g/cm³ at 25°C, and solubility in hot water and most organic solvents.
Resonance Structures of Quinoline
• Quinoline shows aromatic properties due to its molecular orbital satisfying Huckle's rule (4n+2 rule). • The nitrogen lone pair is not released into the aromatic system, but is perpendicular to the p system. • The nitrogen withdraws electrons by resonance, resulting in an electron-deficient ring system.
Methods of Preparation
• Skraup synthesis: Quinoline can be synthesized by heating aniline with sulphuric acid, glycerol, and an oxidizing agent. • Combes Quinoline Synthesis: Quinoline can be synthesized by condensing unsubstituted anilines with β-diketones. • Friedländer Synthesis of Multisubstituted Quinolines: Quinoline can be synthesized by condensing o-amino benzaldehyde with acetaldehyde in the presence of an alkali. • Niementowski quinoline synthesis: Quinoline can be synthesized by reacting anthranilic acids with ketones or aldehydes. • Dobener Reaction: Quinoline can be synthesized by reacting an aniline with an aldehyde and pyruvic acid.
Chemical Reactions
• Basic Character: Quinoline is a slightly weaker base than pyridine and reacts with acids to form sparingly soluble salts. • Electrophilic Substitution Reaction: Quinoline undergoes electrophilic substitution reactions on the benzene ring, with the electrophile attacking positions 8 and 5. • Nucleophilic Substitution Reaction: Quinoline undergoes nucleophilic substitution reactions on the pyridine ring, reacting with Sodium Amide to form 2-Aminoquinoline.
Pharmaceutical and Medical Applications
• Quinoline has antimalarial, antibacterial, antifungal, anthelmintic, cardiotonic, anticonvulsant, anti-inflammatory, and analgesic activity. • Quinoline family compounds are used as a parent compound to make drugs, fungicides, and biocides, such as Chloroquine and hydroxychloroquine. • Quinaldine is used as an anti-malarial and in preparing other anti-malarial drugs. • Quinazoline is used as a chemical intermediate for making medicines and other organic compounds. • Quinoxaline is used as a chemical intermediate for making fungicides and other organic compounds. • Quinine is an anti-malarial natural product isolated from the bark of the Cinchona tree.
Heterocyclic Compounds
• Heterocyclic compounds are cyclic hydrocarbons that contain one or more heteroatoms in a ring, which can be aromatic, partially or fully saturated. • Examples of heterocyclic compounds include nucleic acids, pharmaceuticals, agrochemicals, naturally occurring pigments, vitamins, and antibiotics.
Quinoline
• Quinoline is a heterocyclic aromatic organic compound with the chemical formula C₉H₇N, also known as benzo-pyridine or 1-aza-naphthalene. • Quinoline has a double ring structure composed of a benzene and a pyridine ring fused at two adjacent carbon atoms. • Physical properties of quinoline include a boiling point of 238°C, melting point of -15°C, density of 1.09 g/cm³ at 25°C, and solubility in hot water and most organic solvents.
Resonance Structures of Quinoline
• Quinoline shows aromatic properties due to its molecular orbital satisfying Huckle's rule (4n+2 rule). • The nitrogen lone pair is not released into the aromatic system, but is perpendicular to the p system. • The nitrogen withdraws electrons by resonance, resulting in an electron-deficient ring system.
Methods of Preparation
• Skraup synthesis: Quinoline can be synthesized by heating aniline with sulphuric acid, glycerol, and an oxidizing agent. • Combes Quinoline Synthesis: Quinoline can be synthesized by condensing unsubstituted anilines with β-diketones. • Friedländer Synthesis of Multisubstituted Quinolines: Quinoline can be synthesized by condensing o-amino benzaldehyde with acetaldehyde in the presence of an alkali. • Niementowski quinoline synthesis: Quinoline can be synthesized by reacting anthranilic acids with ketones or aldehydes. • Dobener Reaction: Quinoline can be synthesized by reacting an aniline with an aldehyde and pyruvic acid.
Chemical Reactions
• Basic Character: Quinoline is a slightly weaker base than pyridine and reacts with acids to form sparingly soluble salts. • Electrophilic Substitution Reaction: Quinoline undergoes electrophilic substitution reactions on the benzene ring, with the electrophile attacking positions 8 and 5. • Nucleophilic Substitution Reaction: Quinoline undergoes nucleophilic substitution reactions on the pyridine ring, reacting with Sodium Amide to form 2-Aminoquinoline.
Pharmaceutical and Medical Applications
• Quinoline has antimalarial, antibacterial, antifungal, anthelmintic, cardiotonic, anticonvulsant, anti-inflammatory, and analgesic activity. • Quinoline family compounds are used as a parent compound to make drugs, fungicides, and biocides, such as Chloroquine and hydroxychloroquine. • Quinaldine is used as an anti-malarial and in preparing other anti-malarial drugs. • Quinazoline is used as a chemical intermediate for making medicines and other organic compounds. • Quinoxaline is used as a chemical intermediate for making fungicides and other organic compounds. • Quinine is an anti-malarial natural product isolated from the bark of the Cinchona tree.
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Test your knowledge of heterocyclic compounds, including quinoline, and their characteristics in this chemistry quiz.
