Thursday, September 20, 2007

Answers to SQ Ch. 30 Amines

1. What are Amines?

Amines are considered as organic derivatives of ammonia obtained by replacing one, two, or all the three hydrogen atoms of ammonia by alkyl or aryl groups.

2. How do you prepare ethylamine?

By treating ethyl iodide with alcoholic ammonia in a sealed tube under pressure at 423 K,a mixture of primary, secondary and tertiary amines along with the quaternary compound(Tetraethyl ammonium iodide) is produced and the individual compounds have to separated. The primary amine ethylamine may be obtained in a good yield by using a large excess of ammonia.

3.How will you prepare diethyl amine?

Reduction of Isocyanide using H-2/Ranye Ni or Pt, LiAlH-4 or Na, C-2H-5OH gives secondary amines.

So, reduction of ethyl isocyanide gives diethyl amine.

The method of reduction of using sodium and alcohol is called Mendius reaction.

4. How is ethyl amine prepared from nitroethane?

Nitroalkanes on heating with metals like tin,iron, or zinc and concentrated hydrochloric or sulphuric acid get reduced to primary amine. Similar reduction can also be brought about by heating the nitroalkane with hydrogen in presence of finely divided nickel catalyst.

Hence ethyl amine can be prepared from nitroethane by either way. Producing nascent hydrogen through reaction between metal and acid and then reaction between nascent hydrogen and nitroethane (C-2H-5NO-2) or by heating it with hydrogen in presence of finely divided nickel.

5. How will you prepare ethyl amine from acetaldoxime?

The nascent hydrogen liberated by the action of metal sodium on ethanol reacts with acetaldoxime (CH-3CH=NOH) and gives ethylamine.

6. How will you prepare ethalamine from methyl cyanide?

Methyl cyanide on reaction with the nascent hydrogen liberated by the action of metal sodium on ethanol gives ethylamine.

7. How do you distinguish primary, secondary and tertiary amines?

Primary amines when treated with nitrous acid give alcohols evolving nitrogen gas.
Secondary amines give oily nitroso compounds.
Tertiary amines do not react at all.

8. What are the Differences between primary, secondary and tertiary amines?

9. What is the action of acetyl chloride on primary amines?
acetal derivatives are formed. By using excess of acetyl chloride diacetyl derivatives can be formed.
10. What is the action of sodium nitrite and hydrochloric acid on ethyl amine?

Ethanol, nitrogen and water are formed.

11. what is the action of nitrous acid in dimethyl amine?(1981 IIT MCQ)

an oily nitroso compound N-Nitroso diethyl amine and water are formed.

12. Give the structure of 2-propanamine.

13. What is methylation of amines?

It is a reaction in which, H-atoms of an amine are replaced by methyl (-CH-3)groups. Methylation can be carried out by treating an amine with a methylating agent such as methyl halid, like methyl iodide.

14. What is the action of acetic anhydride on Triethyl amine?

Tertiary amines do not react with acetic anhydride.

15. What is carbalamine test? (1984, IIT MCQ)

The treatment of a primary amine with chloroform and alcoholic potash produces carbylamine (isocyanide) which has most offensive smell.
This reaction is not exhibited by secondary and tertiary amines.

16. what is Libermann reaction?

It is the reaction of secondary amine with nitrous acid in which nitrosoamine is formed.

17. what is Gatttermann reaction?

Diazonium salt is treated with copper powder and hydrogen halide. The halogen gets introduced into aromatic ring.

18. What is Hinsberg reagent?


19. what is Hoffmann's degradation method?(1983, IIT MCQ)

Primary amines can be prepared from amides by reduction with LiAlH-4 or by treating with Br-2 and NaOH. The reduction with LiAlH-4 gives amine having the same number of C atoms as the original amide while reduction with NaOH and Br-2 gives amine having one carbon atom less than the original amide.

20. What is aniline?

Aniline is benzenamine. one H in NH-3 is replaced benzoil group.

21. How do you prepare diazonium salt?

Primary aromatic amine n cold acqueous mineral acid + sodium nitrite

22. What is sandmeyer reaction?

The diazonium salt is treated with cuprous chloride or cuprous bromide.

23. How do you prepare chlorobenzene? (1984, MCQ)

Sandmeyer reaction or Gattermann reaction. In these chlorine is introduced into benezene ring.

24. What is the effect of alkyl groups C-3H-7, C-2H5 and CH-3 on the basic nature of amines?

Amines are weak bases.

The effect of alkyl groups is

C-3H-7> C-2H5> CH-3

The amines are stronger bases than ammonia.

25. Among Aralkylamines and arylamines whic are more basic? (1990 MCQ)

Aralkylamines. Hence Benzylamine (phenylaminomethane) is a more stronger base than aniline.

No comments: