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प्रश्न
Write a short note on Hoffmann bromamide degradation.
Explain Hoffmann bromamide degradation reaction
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उत्तर १
(a)Hoffmann Bromanide degradation
(1) The conversion of amides into amine in presence of bromine and alkali is known on Hoffmann degradation of amides.
(2) An important characteristic of this reaction is that on amine with one carbon less than those in the amide is formed.
(3) This reaction is an example of molecular rearrangement and involves migration of an alkyl or aryl group from the carbonyl carbon to this adjacent nitrogen atom.
Example:
उत्तर २
Hoffmann bromamide reaction:
a) Primary amine can be prepared by reaction of amide with bromine and aqueous or
alcoholic sodium hydroxide.
eg. Ethanamine is prepared by reaction of propanamide with bromine and aqueous or
alcoholic sodium hydroxide.
b) This reaction is known as Hoffmann bromamide degradation. It involves molecular
rearrangement. An alkyl or aryl group migrates from the carbonyl carbon to the
adjacent nitrogen atom.
c) This reaction is useful for decreasing the length of carbon chain by one carbon atom.
संबंधित प्रश्न
How are propan-1-amine and propan-2-amine prepared from oxime?
Illustrate the following reaction giving suitable example in each case:Gabriel phthalimide synthesis
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Give the structure of A, B and C in the following reaction:
\[\ce{C6H5NO2 ->[Fe/HCl] A ->[NaNO2 + HCl][273 K] B ->[H2O/H+][\Delta] C}\]
Write the reaction of aliphatic primary amine with nitrous acid.
Give a plausible explanation for the following:
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Give the structures of A, B and C in the following reactions :
Give the structures of A, B and C in the following reactions :
Answer the following
Explain the ammonolysis of alkyl halides.
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Acetamide to methylamine
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\[\ce{Aniline ->[(CH3CO)2O][Pyridine] A}\]
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\[\ce{C2H5NH2 ->[HNO2] A ->[PCl5] B ->[NH3][Alcohol] C}\]
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Which of the following amines exhibits maximum degree of intermolecular hydrogen bonding?
What product is formed when \[\ce{R - C ≡ N}\] is hydrolysed?
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\[\ce{Aniline ->[NaNO2][HCl] A ->[KI] B}\]
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\[\ce{C6H5CH2NH2 + R - X -> C6H5CH2NHR}\]
Which of the following alkylhalides is best suited for this reaction through SN1 mechanism?
Which of the following reagents would not be a good choice for reducing an aryl nitro compound to an amine?
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The best reagent for converting 2–phenylpropanamide into 2-phenylpropanamine is ______.
The best reagent for converting, 2-phenylpropanamide into 1- phenylethanamine is ______.
Among the following amines, the strongest Brönsted base is:
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 amines can be prepared by Gabriel synthesis.
(i) Isobutyl amine
(ii) 2-Phenylethylamine
(iii) N-methylbenzylamine
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Which of the following reactions are correct?
(i)
(ii)
(iii)
(iv)
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: Aromatic 1° amines can be prepared by Gabriel Phthalimide Synthesis.
Reason: Aryl halides undergo nucleophilic substitution with anion formed by phthalimide.
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
A primary amine is formed by an amide on treatment with bromine and alkali. The primary amine has
The compound X is which of the following?
\[\ce{CH3CN ->[Na + C2H5OH] x}\]
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?
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\[\ce{Aniline ->[(CH3CH)2O][Pyridine] A ->[Br2][CH3COOH] B ->[H^+ or OH^-] C}\]
Write a short note on the following:
Ammonolysis
Write the name of reduction product formed when ethyl cyanide is treated with sodium and alcohol.
Write a short note on Ammonolysis.
Write a short note on the following:
Ammonolysis.
