Presentation is loading. Please wait.

Presentation is loading. Please wait.

Nitrogen compounds (Chapter 37). Nitrogen containing compound T.N.T. Proteins Enzymes Drugs CH 3 NO 2.

Similar presentations


Presentation on theme: "Nitrogen compounds (Chapter 37). Nitrogen containing compound T.N.T. Proteins Enzymes Drugs CH 3 NO 2."— Presentation transcript:

1 Nitrogen compounds (Chapter 37)

2 Nitrogen containing compound T.N.T. Proteins Enzymes Drugs CH 3 NO 2

3 Amines Aliphatic 1 o amine 2 o amine 3 o amine 4 o ammonium cpds Aromatic R-NH 2 R-N-H R R-N-R R R + R-N-R Br - R NH 2

4 IUPAC names CH 3 NH 2 Methanamine (CH 3 ) 2 NH N-methylmethanamine (CH 3 ) 3 N N,N-dimethylmethanamine C 6 H 5 NH 2 Phenylamine (aniline)

5 Formation of amines Alkylation of NH 3 RX + NH 3 R-NH 2 + R 2 -NH + R 3 N + R 4 N + X - (NH 3 in large excess, 1 o amine as main product) 1 o Amine from Amides and Nitriles R-C N RCH 2 NH 2 (H 2 /Ni or LiAlH 4 ) RCONH 2 RCH 2 NH 2 (LiAlH 4 /ether than H + )

6 Formation of Amines C 6 H 5 -NO 2 C 6 H 5 -NH 2 Reducing agent: H 2 /Ni or HCl,Fe (or Zn, Sn, SnCl 2 ) then OH-

7 Basicity of Amines NH 3 pK b = 4.74 CH 3 NH CH 3 CH 2 NH CH 3 CH 2 CH 2 NH (CH 3 ) 2 NH3.28 (CH 3 ) 3 N4.30 C 6 H 5 NH 2 9.4

8 Basicity of Amines R H H N: H O H R H H N H + OH - Order of basicity: 2 o > 1 o > 3 o > NH 3 > C 6 H 5 NH 2 Why?

9 Explanation Solvation of protonated amine in water by hydrogen bonding (more H, better solvation) NH 3 >1 o >2 o >3 o R H H N H + H2OH2O H2OH2O H2OH2O

10 Explanation Effect of the inductive electron push of the R groups Increase the basicity Stabilize the alkylammonium ion 3 o >2 o >1 o >NH 3 R R R N: R R R N H +

11 Explanation Lone pair e - partly incorporated into benzene ring Less ready for protonation NH 2.. NH

12 NH 2 + HCl Reactions Salt Formation NH 3 + Cl - NaOH ? NH 2 + H 2 O + NaCl

13 Reactions Amide Formation O O R-NH 2 + CH 3 CCl CH 3 CNHR + HCl O O R-NH 2 + C 6 H 5 CCl C 6 H 5 CNHR + HCl High m.p. Used in identification

14 Reaction with Nitrous acid HNO 2 prepared by NaNO 2 + HCl 1 o aliphatic amines RNH 2 + NaNO 2 + HCl [R N + N]Cl - Aliphatic Diazonium salt (unstable) R + + N 2 (evolution of N 2 serves as a test for 1 o amine) H2OH2O ROH -H + C=C X-X- R-X

15 Reaction with Nitrous acid 1 o aromatic amine NH 2 + NaNO 2 + HCl N + N Cl - (stable at temp.<5 o C, greater stability by dispersing charge into the benzene ring)

16 Mechanism HONO.. H2O+H2O+ NO N+N+ O N O ArNH 2.. N+N+ O ArNH 2 + NO.. ArNHNO.. ArNNOH.. ArNNOH 2 + ArNN: +.. ArNN: + + H+H+ -H 2 O -H + H+H+ -H 2 O

17 Stability of Ar-N + N N N: +

18 Benzenediazonium salt C 6 H 5 -N 2 + Cl - C-N bond heavily polarized away from benzene ring C atom accept Nu: (against the norm of aromatic chemistry) Has considerable synthetic value

19 Benzenediazonium salt Can be replaced by a variety of function groups High yield No multiple substitution Ar-N 2 + CuCl ArCl CuBr ArBr CuCN ArCN I-I- ArI H2OH2O ArOH + N 2

20 Coupling reaction OH NaOH Orange II, Azo dye (1876) Also serve as a test for 1 o aromatic amine N=N + : +.. O-O- 1 (Napthalen-2-ol) N + = N- HO Ice cold 1


Download ppt "Nitrogen compounds (Chapter 37). Nitrogen containing compound T.N.T. Proteins Enzymes Drugs CH 3 NO 2."

Similar presentations


Ads by Google