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प्रश्न
Write a short note on the following:
Hoffmann’s bromamide reaction
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उत्तर
Hoffmann developed a method for preparation of primary amines by treating an amide with bromine in an aqueous or ethanolic solution of sodium hydroxide. In this degradation reaction, migration of an alkyl or aryl group takes place from carbonyl carbon of the amide to the nitrogen atom. The amine so formed contains one carbon less than that present in the amide.
\[\begin{array}{cc}
\ce{O}\phantom{.............................................................}\\
||\phantom{.............................................................}\\
\ce{R - C - NH2 + Br2 + 4NaOH -> R - NH2 + Na2CO3 + 2NaBr + 2H2O}
\end{array}\]
संबंधित प्रश्न
How is ethyl amine prepared from methyl iodide?
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
An aromatic compound 'A' of molecular formula C7H7ON undergoes a series of reactions as shown below. Write the structures of A, B, C, D and E in the following reactions :
Accomplish the following conversion:
Benzyl chloride to 2-phenylethanamine
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:
\[\ce{C6H5NO2 ->[Fe/HCl] A ->[NaNO2 + HCl][273 K] B ->[H2O/H+][\Delta] C}\]
Give the structures of A, B and C in the following reaction:
\[\ce{CH3COOH ->[NH3][\Delta] A ->[NaOBr] B ->[NaNO2/HCl] C}\]
Give a plausible explanation for the following:
Why are amines less acidic than alcohols of comparable molecular masses?
Explain the mechanism of action of hydroiodic acid on 3-methylbutan-2-ol.
Give the structures of A, B and C in the following reactions :
Give the structures of A, B and C in the following reactions :
Give the structures of A, B and C in the following reactions :
Write structures of compounds A and B in each of the following reactions:
Answer the following
Write a reaction to convert acetic acid into methylamine.
Answer the following
Explain Gabriel phthalimide synthesis.
Write reactions to bring about the following conversions.
Acetamide to methylamine
Explain Hoffmann’s exhaustive alkylation with suitable reactions.
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 product obtained, when benzamide is treated with bromine and aqueous sodium hydroxide.
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 ____________.
Which nitrogen containing compound amongst the following would undergo Mendius reduction to furnish primary amine \[\ce{(R - NH2)}\]?
Which of the following reactions is appropriate for converting benzamide to aniline?
The reduction of alkyl cyanide with sodium and ethanol to give primary amines is, ____________.
Which of the following reagents is used in Hofmann's elimination reaction of amines?
Which of the following compounds is obtained when quaternary ammonium hydroxide is strongly heated?
Which of the following does NOT give carbylamine test?
Which of the following reactions does NOT yield an amine?
Nitro compounds are reduced by iron scrap and hydrochloric acid to yield one of the following compounds:
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:
In order to prepare a 1° amine from an alkyl halide with simultaneous addition of one \[\ce{CH2}\] group in the carbon chain, the reagent used as source of nitrogen is ______.
Amongst the given set of reactants, the most appropriate for preparing 2° amine is ______.
The best reagent for converting, 2-phenylpropanamide into 1- phenylethanamine is ______.
Hoffmann Bromamide Degradation reaction is shown by ______.
Reduction of aromatic nitro compounds using \[\ce{Fe}\] and \[\ce{HCl}\] gives ______.
Best method for preparing primary amines from alkyl halides without changing the number of carbon atoms in the chain 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
(iv) Aniline
Suggest a route by which the following conversion can be accomplished.
Identify A and B in the following reaction.
Write following conversions:
nitrobenzene `->` acetanilide
How will you carry out the following conversion?
How will you carry out the following conversions?
Match the reactions given in Column I with the statements given in Column II.
| Column I | Column II | ||
| (i) | Ammonolysis | (a) | Amine with lesser number of carbon atoms |
| (ii) | Gabriel phthalimide synthesis | (b) | Detection test for primary amines. |
| (iii) | Hoffmann Bromamide reaction | (c) | Reaction of phthalimide with \[\ce{KOH}\] and \[\ce{R-X}\] |
| (iv) | Carbylamine reaction | (d) | Reaction of alkylhalides with \[\ce{NH3}\] |
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.
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
Which of the following reactions will not give a primary amine?
The compound X is which of the following?
\[\ce{CH3CN ->[Na + C2H5OH] x}\]
Ethylamine can be prepared by the action of bromine and caustic potash on which compound?
Acetamide and ethyl amide can be distinguished by reacting with.
Which of the following compound is expected to be most basic?
A compound 'A' on reduction with iron scrap and hydrochloric acid gives compound 'B' with molecular formula C6H7N. Compound 'B' on reaction with CHCl3 and alcoholic KOH produces an obnoxious smell of carbylamine due to the formation of 'C'. Identify 'A', 'B' and 'C' and write the chemical reactions involved.
Give reasons for the following:
Ammonolysis of alkyl halides is not a good method to prepare pure primary amines.
Methyl amine on reaction with chloroform in the presence of NaOH gives ______.
The amine 'A' when treated with nitrous acid gives yellow oily substance. The amine A is ______.
Which of the following statement(s) is/are incorrect in case of Hofmann bromamide degradation?
What is the IUPAC name of \[\ce{(CH3)2 - N - CH3}\]?
Identify the product ‘C’ in the following reaction.
\[\ce{Aniline ->[(CH3CH)2O][Pyridine] A ->[Br2][CH3COOH] B ->[H^+ or OH^-] C}\]
Identify A and B in the following reaction.
\[\ce{C6H5CH2Br ->[Alco.][KCN] A ->[Na/Ethanol][reduction] B}\]
Write short note on the following:
Ammonolysis
Write a short note on the following:
Ammonolysis.
