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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
Identify the compounds 'A' and 'B' in the following equation:
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 :
How do you convert the following: C6H5CONH2 to C6H5NH2
Give the structures of A, B and C in the following reactions :
Give the structures of A, B and C in the following reactions :
Accomplish the following conversion:
Benzyl chloride to 2-phenylethanamine
Accomplish the following conversion:
Benzamide to toluene
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 a plausible explanation for the following:
Why are amines less acidic than alcohols of comparable molecular masses?
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
Give the structures of A, B and C in the following reactions :
Answer the following
Write a reaction to convert acetic acid into methylamine.
Answer the following
Explain the ammonolysis of alkyl halides.
Name the process of breaking C-X bond by ammonia in preparation of amines.
Write reactions to bring about the following conversions.
Acetamide to methylamine
Explain Hoffmann’s exhaustive alkylation with suitable reactions.
Why cannot aniline be prepared by Gabriel phthalimide synthesis?
Identify compound 'B' in following series of reactions?
\[\ce{Acetonitrile ->[Na/alcohol] A ->[NaNO2/dil.HCI] B}\]
Identify the product 'A' in the following reaction.
\[\ce{Aniline ->[(CH3CO)2O][Pyridine] A}\]
Identify the product obtained, when benzamide is treated with bromine and aqueous sodium hydroxide.
____________ can be prepared exclusively by Gabriel phthalimide synthesis.
What product is formed when \[\ce{R - C ≡ N}\] is hydrolysed?
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?
Which of the following amines forms a clear solution when treated with benzene sulphonyl chloride and excess of potassium hydroxide?
The reduction of alkyl cyanide with sodium and ethanol to give primary amines is, ____________.
Identify 'A' and 'B' in the following conversions.
\[\ce{CH3 - I ->[Alc. KCN][\Delta] A ->[Na/C2H5OH] B}\]
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 compounds is obtained when quaternary ammonium hydroxide is strongly heated?
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:
Amongst the following, the strongest base in aqueous medium is ______.
Which of the following reagents would not be a good choice for reducing an aryl nitro compound to an amine?
The source of nitrogen in Gabriel synthesis of amines is ______.
The best reagent for converting 2–phenylpropanamide into 2-phenylpropanamine is ______.
Best method for preparing primary amines from alkyl halides without changing the number of carbon atoms in the chain is ______.
Among the following amines, the strongest Brönsted base is:
Reduction of nitrobenzene by which of the following reagent gives aniline?
(i) \[\ce{Sn/HCl}\]
(ii) \[\ce{Fe/HCl}\]
(iii) \[\ce{H2 - Pd}\]
(iv) \[\ce{Sn/NH4OH}\]
Under which of the following reaction conditions, aniline gives p-nitro derivative as the major product?
(i) Acetyl chloride/pyridine followed by reaction with conc.\[\ce{H2SO4 }\] + conc. \[\ce{HNO3}\].
(ii) Acetic anyhdride/pyridine followed by conc.\[\ce{H2SO4}\] + conc.\[\ce{HNO3}\].
(iii) Dil. HCl followed by reaction with conc.\[\ce{H2SO4}\] + conc.\[\ce{HNO3}\].
(iv) Reaction with conc.\[\ce{HNO3}\] + conc.\[\ce{H2 SO4}\].
What is the product when \[\ce{C6H5CH2NH2}\] reacts with \[\ce{HNO2}\]?
What is the best reagent to convert nitrile to primary amine?
Suggest a route by which the following conversion can be accomplished.
Write following conversions:
acetanilide `->` p-nitroaniline
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: 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.
Assertion: Aromatic 1° amines can be prepared by Gabriel Phthalimide Synthesis.
Reason: Aryl halides undergo nucleophilic substitution with anion formed by phthalimide.
Describe Gabriel's phthalimide synthesis. (Give reaction)
The Gabriels' phthalimide synthesis is used in the synthesis of
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?
Reduction of nitro alkanes yields which compound?
Which of the following compound is expected to be most basic?
- Phenyl methenamine
- N, N - Dimethylaniline
- N - Methyl aniline
- Benzenamine
Choose the correct order of the basic nature of the above amines.
The amine 'A' when treated with nitrous acid gives yellow oily substance. The amine A is ______.
Identify the product ‘C’ in the following reaction.
\[\ce{Aniline ->[(CH3CH)2O][Pyridine] A ->[Br2][CH3COOH] B ->[H^+ or OH^-] C}\]
Write the name of the product formed by the action of LiAlH4/ether on acetamide.
Write short note on the following:
Ammonolysis
Identify A and B in the following reaction.
\[\ce{C6H5CH2Br ->[Alco.][KCN] A ->[Na/Ethanol][reduction] B}\]
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 short note on the following:
Ammonolysis
Write short note on the following.
Ammonolysis.
Write a short note on the following:
Ammonolysis.
Write short notes on the following:
Ammonolysis
