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प्रश्न
Explain the following reaction with a suitable example.
Hofmann elimination reaction
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उत्तर
- When tetraalkylammonium halide is heated with moist silver oxide, it gives quaternary ammonium hydroxide.
- Quaternary ammonium hydroxides on strong heating undergo β-elimination to give an alkene. This reaction is called Hofmann elimination.
- The least substituted alkene is obtained as a major product (in contrast to Saytzeff elimination).
e.g. Hofmann elimination reaction of N, N, N-Triethylpropylammonium iodide
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संबंधित प्रश्न
Write a short note on Hoffmann bromamide degradation.
Illustrate the following reaction giving suitable example in each case:Gabriel phthalimide synthesis
Give the structures of A, B and C in the following reactions :
Write a short note on the following:
Hoffmann’s bromamide reaction
Give the structure of A, B and C in the following reaction:
\[\ce{CH3CH2I ->[NaCN] A ->[OH-][Partial hydrolysis] B ->[NaOH + Br2] C}\]
Give the structure of A, B and C in the following reaction:
\[\ce{C6H5N2Cl ->[CuCN] A ->[H2O/H+] B ->[NH3][\Delta] C}\]
Give the structure of A, B and C in the following reaction:
\[\ce{CH3CH2Br ->[KCN] A ->[LiAlH4] B ->[HNO2][0^\circ C] C}\]
Identify 'A' and 'B' in the following reaction and rewrite the complete reaction :
Arrange the following in the increasing order of their pKb values:
C6H5NH2, C2H5NH2, C6H5NHCH3
Account for the following:
Gabriel phthalimide synthesis is not preferred for preparing aromatic primary amines.
Answer in one sentence.
Predict the product of the following reaction.
\[\ce{Nitrobenzene ->[Sn/conc.HCl]?}\]
Mendius reaction is used to convert _____________
Write the order of reactivity of alkyl halides with ammonia.
Explain Hoffmann’s exhaustive alkylation with suitable reactions.
Write reactions for the preparation of ethanamine using Gabriel phthalimide synthesis.
Acetamide on reduction using Na/C2H5OH gives ____________.
Alkyl cyanides on reduction by sodium and ethanol give primary amines. This reaction is called as ____________.
Identify the major product (B).
____________ can be prepared exclusively by Gabriel phthalimide synthesis.
What is the molar mass of the amine formed when acetamide undergoes Hofmann bromamide degradation?
\[\ce{CH3-CN ->[Na/C2H5OH]}\]
The product formed is ____________.
Identify the product obtained when benzamide is treated with bromine and aqueous sodium hydroxide?
The reduction of alkyl cyanide with sodium and ethanol to give primary amines is, ____________.
In aqueous phase the order of basic strength of alkylamine is ______.
Which of the following reagents is used in Mendius reduction reaction of alkyl cyanide?
Which of the following amines cannot be prepared by Gabriel phthalimide synthesis?
Which of the following reagents is used in Hofmann's elimination reaction of amines?
Which of the following does NOT give carbylamine test?
For producing amines, the reaction of nitro compounds with iron scrap is preferred because:
Given below are two statements labelled as Assertion (A) and Reason (R).
Assertion (A): Alkyl halides are insoluble in water.
Reason (R): Alkyl halides have halogen attached to sp3 hybrid carbon.
Select the most appropriate answer from the options given below:
Amongst the following, the strongest base in aqueous medium is ______.
The source of nitrogen in Gabriel synthesis of amines is ______.
Best method for preparing primary amines from alkyl halides without changing the number of carbon atoms in the chain is ______.
Which of the following methods of preparation of amines will give same number of carbon atoms in the chain of amines as in the reactant?
The reagents that can be used to convert benzenediazonium chloride to benzene are:
(i) \[\ce{SnCl2/HCl}\]
(ii) \[\ce{CH3CH2OH}\]
(iii) \[\ce{H3PO2}\]
(iv) \[\ce{LiAlH4}\]
Which of the following reactions are correct?
(i)
(ii)
(iii)
(iv)
How will you carry out the following conversion?
How will you carry out the following conversions?
Assertion: Hoffmann’s bromamide reaction is given by primary amines.
Reason: Primary amines are more basic than secondary amines.
Assertion: Only a small amount of \[\ce{HCl}\] is required in the reduction of nitro compounds with iron scrap and \[\ce{HCl}\] in the presence of steam.
Reason: \[\ce{FeCl2}\] formed gets hydrolysed to release \[\ce{HCl}\] during the reaction.
Account for the following:
Aniline cannot be prepared by the ammonolysis of chlorobenzene under normal conditions.
The Gabriels' phthalimide synthesis is used in the synthesis of
Which of the following reactions will not give a primary amine?
Ethylamine can be prepared by the action of bromine and caustic potash on which compound?
In the given reaction what is the X?
\[\begin{array}{cc}
\ce{O}\phantom{.......................}\\
||\phantom{.......................}\\
\phantom{}\ce{R - C - OH <-[H3O] Χ ->[H] RCH2NH2}
\end{array}\]
When primary amines are treated with HCl, the product obtained is which of the following?
Which of the following CANNOT be prepared by ammonolysis of alkyl halide?
Which of the following amines can be prepared by Gabriel phthalimide reaction?
Write the name of the product formed by the action of LiAlH4/ether on acetamide.
Write short note on the following:
Ammonolysis
Identify the compo ds A and B in the following reactions:
\[\ce{A ->[Nitrating mixture] B ->[(i) Sn/cone. HCI][(ii) NaOH] Aniline}\]
Write the name of reduction product formed when ethyl cyanide is treated with sodium and alcohol.
Write short note on the following:
Ammonolysis
Write short note on the following.
Ammonolysis.
Assertion: Amimonolysis of alkyl halides involves the reaction between alkyl halides and alcoholic ammonia.
Reason: Ammonolysis of alkyl halides produces secondary amines only.
