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Questions and Answers
What is the boiling point of pyrrole?
What is the boiling point of pyrrole?
131°C
What is the boiling point of furan?
What is the boiling point of furan?
31.4°C
What is the boiling point of thiophene?
What is the boiling point of thiophene?
357 K
What is the chemical formula for pyrrole?
What is the chemical formula for pyrrole?
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What is the chemical formula for furan?
What is the chemical formula for furan?
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What is the chemical formula for thiophene?
What is the chemical formula for thiophene?
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Which of the following is the most reactive heterocyclic compound?
Which of the following is the most reactive heterocyclic compound?
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Pyrrole is highly sensitive to air and turns brown when exposed to air.
Pyrrole is highly sensitive to air and turns brown when exposed to air.
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Furan is insoluble in water.
Furan is insoluble in water.
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Thiophene is soluble in water.
Thiophene is soluble in water.
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What is the name of the reaction used to prepare 2-formylpyrrole from pyrrole?
What is the name of the reaction used to prepare 2-formylpyrrole from pyrrole?
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What is the name of the reaction used to prepare 2-nitrothiophene from thiophene?
What is the name of the reaction used to prepare 2-nitrothiophene from thiophene?
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What is the name of the reaction used to prepare furan from mucic acid?
What is the name of the reaction used to prepare furan from mucic acid?
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What is the name of the reaction used to prepare thiophene from n-butane?
What is the name of the reaction used to prepare thiophene from n-butane?
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Which of the following heterocyclic compounds is the strongest base?
Which of the following heterocyclic compounds is the strongest base?
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Which of the following heterocyclic compounds is the weakest base?
Which of the following heterocyclic compounds is the weakest base?
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The order of basicity of the heterocyclic compounds from weakest to strongest is pyrrole, pyridine, piperidine.
The order of basicity of the heterocyclic compounds from weakest to strongest is pyrrole, pyridine, piperidine.
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Electrophilic substitution reactions of pyrrole, furan, and thiophene occur primarily at the 2-position.
Electrophilic substitution reactions of pyrrole, furan, and thiophene occur primarily at the 2-position.
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The electrophilic attack at the 2-position in pyrrole, furan, and thiophene is favored due to the formation of three resonating structures.
The electrophilic attack at the 2-position in pyrrole, furan, and thiophene is favored due to the formation of three resonating structures.
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Which of the following is NOT a characteristic reaction of aromatic compounds?
Which of the following is NOT a characteristic reaction of aromatic compounds?
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The Diels-Alder reaction is a type of cycloaddtion reaction.
The Diels-Alder reaction is a type of cycloaddtion reaction.
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Furan is the only heterocyclic compound that undergoes the Diels-Alder reaction.
Furan is the only heterocyclic compound that undergoes the Diels-Alder reaction.
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The intermediate formed when the electrophile approaches at position C-2 in pyrrole, furan, and thiophene is more stable than the intermediate obtained when the electrophile approaches at position C-3.
The intermediate formed when the electrophile approaches at position C-2 in pyrrole, furan, and thiophene is more stable than the intermediate obtained when the electrophile approaches at position C-3.
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The reaction of pyrrole with bromine in the absence of a halogen carrier gives 2,5-dibromothiophene.
The reaction of pyrrole with bromine in the absence of a halogen carrier gives 2,5-dibromothiophene.
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The reaction of thiophene with bromine in the presence of yellow mercuric oxide gives 2-iodothiophene.
The reaction of thiophene with bromine in the presence of yellow mercuric oxide gives 2-iodothiophene.
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Thiophene undergoes electrophilic substitution at the 2-position similar to pyrrole and furan.
Thiophene undergoes electrophilic substitution at the 2-position similar to pyrrole and furan.
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The Gattermann-Koch synthesis is a method used to convert furan to furfural.
The Gattermann-Koch synthesis is a method used to convert furan to furfural.
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The tetrehydrofuran (THF) is a common solvent used in Grignard reactions.
The tetrehydrofuran (THF) is a common solvent used in Grignard reactions.
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The Friedel-Crafts acylation of thiophene with acetic anhydride in the presence of H3PO4 gives 2-acetylthiophene.
The Friedel-Crafts acylation of thiophene with acetic anhydride in the presence of H3PO4 gives 2-acetylthiophene.
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The reduction of thiophene on catalytic hydrogenation gives tetrehydrothiophene (thiophane).
The reduction of thiophene on catalytic hydrogenation gives tetrehydrothiophene (thiophane).
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The ______ is a cycloaddtion reaction of a 4π-system to a 2π-system.
The ______ is a cycloaddtion reaction of a 4π-system to a 2π-system.
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The ______ reaction involves the reaction of a compound with chloroform in the presence of KOH.
The ______ reaction involves the reaction of a compound with chloroform in the presence of KOH.
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The ______ reaction involves the reaction of a compound with sulfur trioxide in the presence of pyridine.
The ______ reaction involves the reaction of a compound with sulfur trioxide in the presence of pyridine.
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The ______ reaction involves the reaction of a compound with nitric acid in the presence of acetic anhydride.
The ______ reaction involves the reaction of a compound with nitric acid in the presence of acetic anhydride.
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The ______ reaction involves the reaction of a compound with an acyl halide or anhydride in the presence of a Lewis acid catalyst.
The ______ reaction involves the reaction of a compound with an acyl halide or anhydride in the presence of a Lewis acid catalyst.
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The ______ reaction involves the reaction of a compound with hydrogen gas in the presence of a metal catalyst.
The ______ reaction involves the reaction of a compound with hydrogen gas in the presence of a metal catalyst.
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The ______ is used to describe the process of adding a functional group to an aromatic compound.
The ______ is used to describe the process of adding a functional group to an aromatic compound.
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The ______ reaction does not occur with pyrrole, furan, or thiophene because their stable pi system resists addition reactions.
The ______ reaction does not occur with pyrrole, furan, or thiophene because their stable pi system resists addition reactions.
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The ______ reactions, including halogenation, nitration, sulfonation, and Friedel-Crafts reactions, are typical of aromatic compounds.
The ______ reactions, including halogenation, nitration, sulfonation, and Friedel-Crafts reactions, are typical of aromatic compounds.
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The ______ of an aromatic compound is determined by the availability of the lone pair of electrons on the nitrogen atom.
The ______ of an aromatic compound is determined by the availability of the lone pair of electrons on the nitrogen atom.
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The ______ of an aromatic compound is determined by the stability of the intermediate that is formed during the reaction with an electrophile.
The ______ of an aromatic compound is determined by the stability of the intermediate that is formed during the reaction with an electrophile.
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The ______ reaction is used to prepare furfural from furan.
The ______ reaction is used to prepare furfural from furan.
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The ______ reaction is used to prepare 2-acetylthiophene from thiophene.
The ______ reaction is used to prepare 2-acetylthiophene from thiophene.
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The ______ is commonly used as a solvent in Grignard reactions.
The ______ is commonly used as a solvent in Grignard reactions.
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The ______ is a type of cycloaddtion reaction that involves the reaction of a 4π-system with a 2π-system.
The ______ is a type of cycloaddtion reaction that involves the reaction of a 4π-system with a 2π-system.
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The ______ reaction involves the reaction of a compound with chloroform in the presence of potassium hydroxide.
The ______ reaction involves the reaction of a compound with chloroform in the presence of potassium hydroxide.
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Study Notes
Heterocyclic Compounds - Methods of Preparation and Chemical Reactions of Pyrrole
-
Pyrrole Preparation (Bone Oil):
- Bone oil contains pyrrole.
- Impurities are removed using acidic and basic solutions.
- Fractional distillation separates a fraction between 373K and 423K.
- Potassium hydroxide (KOH) purifies the fraction to potassiopyrrole.
- Steam distillation of potassiopyrrole yields pure pyrrole.
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Pyrrole Preparation (Succinimide):
- Succinimide, when distilled with zinc dust, reduces to pyrrole.
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Pyrrole Preparation (Furan):
- Industrially, pyrrole is produced by passing a mixture of furan and ammonia over alumina at 400°C.
Properties of Pyrrole
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Physical:
- Colorless liquid
- Boiling point: 131°C
- Sensitive to air, turning brown and resinifying over time
- Slightly soluble in water, completely miscible in ether and ethanol
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Chemical:
- Aromatic compound
- More reactive than benzene
- Undergoes electrophilic substitution reactions at position C-2
- Electrophilic attack at position C-2 is more stable than at position C-3 due to resonance structures
Pyrrole Reactions
- Halogenation: Reacts with halogens (Cl₂, Br₂, I₂) to form tetrahalopyrroles (e.g., tetrabromopyrrole).
- Nitration: Reacts with nitric acid (HNO₃) in acetic anhydride, yielding 2-nitropyrrole, where –NO₂ acts as an electrophile.
- Sulphonation: Reacts with sulfur trioxide (SO₃) - pyridine mixture in ethylene chloride to form pyrrole-2-sulfonic acid.
- Friedel-Crafts Acylation: Produces 2-acetylpyrrole upon reaction with acetic anhydride.
- Diazotization: Reacts with benzenediazonium chloride in acidic medium to form 2-phenylazopyrrole.
- Reimer-Tiemann Reaction: Reacts with chloroform (CHCl₃) in the presence of KOH to produce 2-formylpyrrole.
- Reduction: Hydrogen gas (H₂) over Raney nickel (Ni) at high temperature (473K) reduces pyrrole to pyrrolidine (tetrahydropyrrole).
- Oxidation: Reacts with Chromium trioxide (CrO₃) in sulfuric acid (H₂SO₄) to form malecimide.
Methods for Furan Preparation
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From Mucic Acid:
- Dry distillation of mucic acid yields furoic acid.
- Decarboxylation of furoic acid produces furan.
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From Furfural:
- Acid hydrolysis of pentose sugars creates furfural.
- Furan is synthesized from furfural.
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Paal-Knorr Synthesis:
- Dehydration of 1,4-diketone using P₂O₅ leads to furan derivatives.
Properties of Furan
- Physical: Colorless liquid, boiling point 31.4°C, chloroform-like odor, insoluble in ether, soluble in organic solvents
- Chemical: Aromatic, more reactive than benzene, electrophilic substitution at position C-2
Methods for Thiophene Preparation
-
From n-Butane:
- Heating n-butane with sulfur at high temperature (923K)
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Laboratory Method:
- Sodium succinate reacted with phosphorus sulfide (P₂S₃) yields thiophene.
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Industrial method:
- Acetylene and hydrogen sulfide flow through an alumina (Al₂O₃) tube at 673 K.
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Pall-Knorr Synthesis:
- Dehydration of 1,4-diketone using P₂S₅ creates thiophene derivatives.
Properties of Thiophene
- Physical: Colorless liquid, boiling point 357 K, benzene-like odor, soluble in alcohol and ether, insoluble in water
- Chemical: Aromatic, more reactive than benzene, undergoes electrophilic substitutions at C-2. Undergoes halogenation, nitration, sulphonation, and Friedel-Crafts acylation. Reduction forms tetrahydrothiophene
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Description
Explore the fascinating world of heterocyclic compounds with a focus on pyrrole. This quiz covers the various methods of preparation, including techniques using bone oil and succinimide, as well as important physical and chemical properties of pyrrole. Test your knowledge on this significant aromatic compound.
