AMINES. Points to Remember. 2. Functional groups of 1º, 2º and 3º amines are respectively as given below :

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213 UNIT 13 AMINES Points to Remember 1. Amines are alkyl and/or aryl derivatives of NH 3. 2. Functional groups of 1º, 2º and 3º amines are respectively as given below : 3.

1 213 UNIT 13 AMINES Points to Remember 1. Amines are alkyl and/or aryl derivatives of NH Functional groups of 1º, 2º and 3º amines are respectively as given below : 3. Gabriel phthalimide synthesis can t be used for the preparation of 2º and 3º amines. It gives aliphatic primary amine only. 4. Hoffmann s bromamide reaction gives 1º amines having one carbon atom less than parent primary amide. 5. The order of basic strength of aliphatic amines is : Aliphatic amines are more basic than NH 3. In aqueous solution medium, the order is 2º > 1º > 3º (for group) and 2º > 3º > 1º for C 2 group. In non-aqueous medium or gaseous phase, the order is 3º > 2º > 1º. 6. Basic strength of aromatic amines : Aromatic amines are weaker bases than NH 3. ERGs like, OR, etc. increase basic strength while EWGs like NO 2, CN etc. decrease the basic strength. The effect of substituents is more at para positions and less at meta position. 7. Basic strength of amines is expressed in terms of K b or pk b. 8. 1º, 2º and 3º amines can be distinguished by Hinsberg s test. 9. Hinsberg s reagent is benzenesulphonyl chloride ( SO 2 Cl) º amines like trimethylamine are used as insect attractants. 11. Diazonium salts are represented by the general formula [Ar N N] + X.

2 2 Chemistry-XII 12. Structure of amines : Pyramidal for trimethyl amine 3 3 Lewis bases. CH N. They are 13. Aliphatic amines are known as amino alkanes. 14. Aliphatic amines are more basic than NH 3. i.e., > NH Aniline is less basic than NH 3 (i.e., < NH 3 ). 16. Carbylamine test only given by 1º amines. 17. Manich reaction involves the reaction of ketones with HCHO and NH 3 (or amine) in acidic medium to form Manich bases º amines give effervescence with HNO group in aniline is o- and p- directing and is highly activating in nature. 20. Acylation of aniline is done before subjecting it to nitration or halogenation. 21. Aliphatic diazonium salts are very unstable and do not exist while aromatic salts are relatively stable. 22. These salts are prepared from 1º aryl amines by diazotization reactions. 23. Diazotised salts (diazonium salts) are used to prepare a variety of aromatic compounds. 24. R C N have generally pleasant odours but alkyl isocyanides have highly unpleasant odours. 25. Alkyl isocyanides have lower boiling points than that of isomeric alkyl cyanides due to lower dipole moments. 26. Arenediazonium salts are highly reactive compounds and reactivity is due to excellent leaving ability of diazo group as N 2 gas.

3 Amines 3 VERY SHORT ANSWER TYPE QUESTIONS (1 Mark) Q. 1. Write IUPAC name of NC. Methane carbylamine. Q. 2. Convert m-dinitrobenzene to m-nitro aniline. Q. 3. Draw structure of TNT, an explosive. Q. 4. Write IUPAC name of 3-N-Methyl-N,N-dimethyl pentanamine Q. 5. Give one use of quaternary ammonium salts. It is used as detergents, e.g., [ ( ) 15 N( ] + Cl. Q. 6. What is Hinsberg s reagent? Benzene sulphonyl chloride, Q. 7. Why aniline dissolves in HCl? + HCl [ NH 3 ] + Cl. It dissolves due to its basic nature. Q. 8. How will you test the presence of primary amine? By carbyl amine test. R + CHCl 3 + 3KOH RN C + 3KCl + 3H 2 O Q. 9. What is vapour phase nitration? CH 4 + HNO 3 NO 2 (High temperature and nitration in vapour phase only)

4 4 Chemistry-XII Q. 10. Write one use of dopamine and atropine alkaloid. Dopamine : Neurotransmitter Atropine alkaloid : % solution ophthalmic examination. Q. 11. Direct nitration of aniline is not carried out. Explain. (H 2 SO 4 + HNO 3 ) easily oxidized aniline into tarry complex product due to high e density on the benzene ring of aniline. Q. 12. Among the compounds as following which will react with to give product containing > C = N? ( ) 3 N NH (iv) NH and NH. Q. 13. How will you give expression for K b to indicate its basic strength? K b RNH 3 OH R NH 2 Q. 14. What happens when aniline is treated with bromine? Q. 15. Write a chemical equation to illustrate the ammonolysis. For alcohols : C H OH C H NH C H NH C H N NH3 C2H5OH C2H5OH 2 5 Al2O /620K H2O 2 3 For alkyl halides : C H I NH 3/373 K C2H5I C2H5I C2H5I 2 5 C H NH HI C H NH HI 2 5 C H N C H N I 2 HI HI Q. 16. Write the structure of p-toluene.

5 Q. 17. Prepare/convert nitrobenzene into aniline. Amines 5 Q. 18. Convert COOH to. Q. 19. Write isomerism exhibited by different amines. Chain, position, metamerism, functional. Q. 20. Classify the following as 1º, 2º and 3º amines : (C 2 CH (iv) (C 2 NH 1º 3º 1º (ivº SHORT AN SWER TYPE QUESTIONS (2 Marks) Q. 1. Complete the following acid-base reactions and name the products : + HCl ( ) 3 N + HCl N + H 3 Cl (n-propyl ammonium chloride) ( ) 3 N + HCl (Triethyl ammonium chloride) Q. 2. Write chemical reaction of + COCl and name product obtained.

6 6 Chemistry-XII Q. 3. How will you convert : 3-methylaniline 3-nitrotoluene Aniline 1, 3, 5-tribromobenzene Q. 4. How will you convert : Propanoic acid Ethanoic acid Nitromethane Dimethylamine C H COOH C H CONH C H NH CH CH OH CH CHO CH COOH NH Br /KOH HNO [O] [O] H 2 /Ni CH3Cl/KOH H 2 /Ni CH NO CH NH CH N C CH NH CH Q. 5. Draw the structures of the following compounds : N-isopropylaniline t-butylamine Q. 6. Why N + ( ) 3 OH a stronger base than NH 4 OH? Due to EW I effect of phenyl group, it decreases e density on nitrogen atom but no such group in NH 4 OH. Q. 7. Explain Kb order : Et 2 NH > Et 3 N > Et in aqueous solution. Basicity of amines in aqueous solution depends upon : + I effect of an alkyl group. Extend of hydrogen bonding with H 2 O. Steric effects of alkyl groups.

7 Q. 8. Distinguish between 1º, 2º and 3º amines by HNO 2 acid test. Amines 7 1º gives N 2 gas. 2º gives yellow oily compound. 3º form water soluble salts. + HNO 2 C 2 OH + N 2 + H 2 O R 2 NH + HNO 2 R 2 N N = O + H 2 O Q. 9. A compound A having molecular formula C 3 H 7 ON reacts with Br 2 in presence of NaOH to give compound B. This compound B reacts with HNO 2 to form alcohol and N 2 gas. Identify compound A and B and write the reaction involved. Br2 HNO 2 A is CO C 2 OH + N 2 + H 2 NaOH (B) Q. 10. Write chemical equation for the following conversions : Cl Cl With NaCN and reduction. i.e., C 2 Cl Cl Q. 11. Account for : C 2 C N Ethanol NaCl Ethanol NaCN red n H 2/Ni C N Amino group in aniline is o- and p- directing in aromatic electrophilic substitution reactions. Aniline on nitration gives a substantial amount of m-nitroaniline. Aniline does not go Friedel Crafts reaction. It is because aniline is formed by protonation with N H3 i.e., EWG hence it is m-directing i.e., 47%. It is because aniline is basic, can form adduct with AlCl 3, electrophile cannot be generated.

8 8 Chemistry-XII Q. 12. Account for the following : Electrophilic substitution in aromatic amines takes place more readily than benzene. Nitro compounds have higher boiling points than hydrocarbons having almost same molecular mass. is ERG, electrophilic substitution takes place faster. Nitro compounds are more polar than hydrocarbons therefore have more van der Waal s forces of attraction. Q. 13. Write short notes on : Coupling reaction Ammonolysis. Ammonolysis : R X + NH 3 R + HX R + R X (R N + HX (R NH + R X (R) 3 N + HX (R) 3 N + R X [R 4 N] X Q. 14. Prepare pure sample of 1º amine from 1º alkyl halide. SHORT A ANSWER-II TYPE QUESTIONS (3 Marks) Q. 1. What happens when : An alkyl halide reacts with AgNO 2 and product is reduced. An alkyl halide is treated with AgCN and product is hydrolysed. Methyl magnesium is treated with cyanogens chloride.

9 Amines 9 R X + AgNO 2 R NO 2 R R X + AgCN RNC R + HCOOH MgBr + CN Cl CN + Mg< Q. 2. How would you prepare : from NO 2 from C 2 C 2 from C 2 C 2 OH COOH COONH 4 CO OH Cl CN Q. 3. Write the structure of the products in each case : CONH CN NHCO, COOH + COOH + NH 4

10 10 Chemistry-XII Q. 4. Write the structure of reagents/organic compounds A to F : F LONG ANSWER TYPE QUESTIONS (5 Marks) Q. 1. Arrange the following : In decreasing order of pkb values : C 2, NH, (C 2 NH and In increasing order of basic strength : (a) Aniline, p-nitroaniline and p-toluidine (b), NH, In decreasing order of basic strength :, N(, (C 2 NH, (iv) Decreasing order of basic strength in gas phase : C 2, (C 2 NH, (C 2 ) 3 N and NH 3 (v) Increasing order of boiling point : C 2 OH, ( NH, C 2 C 2 > NH > > (C 2 NH (a) p-nitroaniline < aniline < p-toluidine (b) < NH <

11 Amines 11 (C 2 NH > > N( > (iv) (C 2 ) 3 N > (C 2 NH > C 2 > NH 3 (v) ( NH < C 2 < C 2 OH Q. 2. How will you convert : (iv) Ethanoic acid into methanamine Hexane nitrile into 1-aminopentane Methanol into ethanoic acid Ethanamine into methanamine Conc. H2SO4 CH COOH HN CH NH N CO 3 3 heat Ethanoic acid Hydrazoic Methylamine acid Conc. HCl Br 2 /KOH partial hydrolysis CH CH CN CH CH CONH CH CH NH Hexane nitrile Hexanamide 1-Aminopentane SOCl2 KCN (alc) H /H2O CH OH CH Cl CH CN CH COOH Methanol Ethanoic acid HNO3 KMnO 4 /H NH4OH (iv) NaNO HCl CH CH NH CH CH OH CH COOH CH COONH Ethanamine Q. 3. Write short note on the following : (iv) (v) Carbylamine reaction Diazotization heat Hoffmann s bromide reaction Coupling reaction Ammonolysis Br 2 /KOH 3 2 CH3NH2 Methanamine CH CONH Carbylamine reaction : When primary amine (aromatic or aliphatic) warmed with chloroform and alc. KOH, isocyanides are formed which can be identified by their offensive smell. This test is used to identify the presence of primary amine or chloroform.

12 12 Chemistry-XII R + CHCl 3 + 3KOH (alc.) R NC + 3KCl + 3H 2 O (b) Diazotization : When primary aromatic amine is treated with NaNO 2 and HCl at K, diazonium salt is obtained. This reaction is known as diazotization. Benzenediazonium chloride is a very important synthetic compound, which can be changed into heloarenes, phenol, cyanobenzene, benzene etc. (c) Hoffmann s bromide reaction : When any primary amide (aliphatic or aromatic) is treated with bromine and alkali, it gives the amine of one carbon atom less. (d) (e) This reaction is used to reduce one carbon atom from a compound. Coupling reaction : When benzenediazonium chloride is treated with phenols or aromatic amines, azo dyes are produced in which diazo ( N = N ) group is retained. Coupling reactions generally take place at p-position of phenol or aromatic amines. Ammonolysis : Reaction of alkyl halides with ammonia is known as ammonolysis. Ammonolysis generally gives the mixture of 1º, 2º, 3º amines and quaternary ammonium salt.

13 Amines 13 Q. 4. Complete the following reactions : (iv) (v) + H 2 SO 4 (conc.) N 2 Cl + C 2 OH + ( CO O N 2 Cl + H 3 PO 2 + H 2 O + CHCl 3 + 3KOH (alc.). H 6 + N 2 + HCl + CHO NHCO + COOH (iv) H 6 + H 3 PO 3 + HCl + N 2 (v) NC + 3KCl + 3H 2 O Q. 5. Write A, B and C in the given reactions : H 2O/H NH 3 CuCN C H N Cl A B C KCN 4 2 LiAlH HNO CH CH Br A B C (iv) (v) 3 2 0º C Fe/HCl HNO H O/H K 2 C H NO A B C CH COOH A B C 3 NH 3 NaOBr NaNO 2 /HCl NaCN OH 3 2 partial hydrolysis NaOH/Br CH CH I A B 2 C CN, COOH, CO CN,, OH, N 2 Cl, OH (iv) CO,, NH 3+ Cl (v) CN, CO,

14 14 Chemistry-XII Q. 6. Accomplish the following conversions : NO 2 COOH Benzene m-bromophenol COOH (iv) (v) Aniline 2, 4, 6 tribromoaniline Benzylchloride 2-phenyl ethanamine (iv) (v)

15 VALUE BASED QUESTIONS (4 Marks) Amines 15 Q. 1. Sushil s friend want to play Holi with synthetic colours. Ramesh persuades his friends to play Holi with natural colours as synthetic colours may cause skin allergy. Sushil s friends agreed and prepared natural colours using flowers and leaves. How are following dyes prepared from phenol : (iv) p-hydroxyazobenzene p-aminoazobenzene Write the name of one pigment present in natural colours. (Hint : Cartenoids) Mention the values shown by Sushil. Q. 2. Neetu and Asha took organic compound synthesis as their chemistry project. They prepared benzene diazonium chloride and stored it at room temperature. Due to holiday, they start preparing azo dye but it cannot be prepared. Then, their friend Reena told them to prepare benzene diazonium chloride again and to use it immediately to prepare azo dye and they proceeds accordingly and prepared azo dye successfully. Write the chemical reaction involved in azo dye formation. Write the values associated with the suggestion given by Reena. How is diazonium salt used in the preparation of following dyes : p-hydroxyazobenzene (iv) p-aminoazobenzene

Unit 13-NITROGEN CONTAINING ORGANIC COMPOUNDS

Unit 13-NITROGEN CONTAINING ORGANIC COMPOUNDS Two marks: 1. Name the product obtained when a nitrile is reduced by H 2 /Ni,. Give the equation. H 2 /Ni, Primary amine: RCN RCH 2 NH 2. 2. How is nitrobenzene