39 Questions
What is the primary mechanism involved in the nitration of furan?
Addition-elimination mechanism
What is the role of pyridine in the nitration reaction of furan?
It acts as a base to eliminate acetic acid
Where does electrophilic substitution normally occur in 2,5-disubstituted heterocycles?
At the 3-position
What is the result of sulfonating furan with the usual strong acid reagents?
Decomposition of furan
What is the complex used to sulfonate furan and its derivatives?
Pyridine-sulfur-trioxide complex
What is the condition required for the disubstitution of furan to occur?
Room temperature
What is the position of sulfonation in furan substituted with an electron-withdrawing substituent at the 2-position?
5-position
What is the reagent used to sulfonate furan substituted with an electron-withdrawing substituent at the 2-position?
Oleum
What is the reaction of furan with iodine at room temperature?
It does not react at all
What is the product of bromination of furan in dimethylformamide at room temperature?
2-bromo-furan or 2,5-dibromo-furan
What is the reagent used to produce 2-bromo-furan at -5°C?
Dioxane-dibromide
What is the major product of bromination of furan substituted with an electron-withdrawing substituent at the position-2?
5-bromo-derivative
What is the product of oxidation of pyridine by peracids?
N-oxide pyridine
What is the characteristic of N-oxide pyridine?
It is more activated for electrophilic and nucleophilic attack
What is the advantage of N-oxide pyridine?
It is very important intermediates for preparing pyridine derivatives
What is the primary position of nitration of pyridine?
Position 3
What is the distribution of charges in N-oxide pyridine?
Positive and negative charges at positions 2 and 4
Why is 3-aminopyridine most conveniently made via nicotinic acid?
Because of the difficulty of nitrating pyridine
What is the role of peroxy-benzoic acid in pyridine conversion?
It converts pyridine into its N-oxide
What is the primary position of nitration of pyridine N-oxide?
Position 4
Why does 2-aminopyridine undergo nitration or sulfonation under milder conditions?
Because of the electron donating nature of the amine group
What is the relative basicity of amines (RCH2NH2) compared to imines (RCH=NH) and nitriles (RCN)?
Amines are more basic than imines and nitriles
Why does pyridine N-oxide undergo nitration more readily than pyridine itself?
Because of the electron withdrawing nature of the oxygen atom
What is the synthesis of 3-aminopyridine from beta-picoline?
Through reduction of nicotinic acid followed by decarboxylation
What is the major reason for the difficulty of nitration of pyridine?
Pyridine has a low electron density at the 3-position
Which of the following statements is true about the nitration of pyridine N-oxide?
It occurs at the 4-position
What is the primary reason for the difference in reactivity between pyridine and pyridine N-oxide towards nitration?
Pyridine N-oxide has a higher electron density
Why is 2-aminopyridine more susceptible to nitration and sulfonation than pyridine?
It has a higher electron density at the 5-position
What is the role of peroxy-benzoic acid in the conversion of pyridine?
It is an oxidizing agent
What is the primary reason for the low yield of nitration of pyridine?
Pyridine has a low electron density at the 3-position
What is the relative basicity of amines (RCH2NH2) compared to imines (RCH=NH) and nitriles (RCN)?
Amine > imine > nitrile
What is the primary advantage of using pyridine N-oxide in nitration reactions?
It is more susceptible to nitration
Why is the synthesis of 3-aminopyridine from beta-picoline a convenient route?
It avoids the difficulties of nitrating pyridine
What is the primary reason for the difference in reactivity between pyridine and its derivatives towards electrophiles?
The derivatives have a higher electron density
What is the primary reason for the difference in reactivity between pyridine and pyridine N-oxide towards nitration?
The electron-withdrawing property of the oxide group
Why is the synthesis of 3-aminopyridine from beta-picoline a convenient route?
It avoids the difficult nitration of pyridine
What is the primary reason for the substitution occurring chiefly at the 5-position in 2-aminopyridine?
The presence of the amino group increases the electron density at the 5-position
What is the role of the oxygen in pyridine N-oxide in the nitration reaction?
It directs the nitration to the 4-position
What is the advantage of using pyridine N-oxide in nitration reactions?
It directs the nitration to a more favorable position
Test your knowledge of reactions of furan and derivatives of pyridine, including electrophilic aromatic substitution, nitration, and other reactions. This quiz covers the concepts learned in Lecture 10 of Organic Chemistry III. Evaluate your understanding of the reaction mechanisms and their applications.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
