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AMINA Senyawa yang mengandung gugus NH 2 Senyawa yang mengandung gugus NH 2 Strukrur : RNH 2 Strukrur : RNH 2 Jenis : Amina primer (1 o ) Jenis : Amina.

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Presentasi berjudul: "AMINA Senyawa yang mengandung gugus NH 2 Senyawa yang mengandung gugus NH 2 Strukrur : RNH 2 Strukrur : RNH 2 Jenis : Amina primer (1 o ) Jenis : Amina."— Transcript presentasi:

1 AMINA Senyawa yang mengandung gugus NH 2 Senyawa yang mengandung gugus NH 2 Strukrur : RNH 2 Strukrur : RNH 2 Jenis : Amina primer (1 o ) Jenis : Amina primer (1 o ) Amina sekunder (2 o ) Amina sekunder (2 o ) Amina tersier (3 o ) Amina tersier (3 o )

2 Tata Nama Amina alifatik sederhana dinamakan dengan gugus alkil yang terikat pada atom N dan diberi akhiran amin. Amina alifatik sederhana dinamakan dengan gugus alkil yang terikat pada atom N dan diberi akhiran amin.

3 Sistem IUPAC, gugus NH2 dinamakan gugus amino

4 Tata Nama : Jika atom N mengikat 4 gugus hidrokarbon akan bermuatan positif dam dikenal sebagai ion ammonium kuartener Jika atom N mengikat 4 gugus hidrokarbon akan bermuatan positif dam dikenal sebagai ion ammonium kuartener

5 Tata Nama : Senyawa yang mengandung gugus – NH2 pada cincin benzena dinamakan sebagai derivat anilin. Senyawa yang mengandung gugus – NH2 pada cincin benzena dinamakan sebagai derivat anilin.

6 Tata Nama : Senyawa siklis dimana satu atom C atau lebih diganti dengan atom nitrogen, diberi nama khusus sebagai heterosiklik amin. Senyawa siklis dimana satu atom C atau lebih diganti dengan atom nitrogen, diberi nama khusus sebagai heterosiklik amin.

7 Beberapa Contoh Senyawa Heterosiklis Amin Alkaloid : senyawa yang mengandung nitrogen yang bersifat basa dari tumbuhan dan hewan. Senyawa ini mempunyai struktur yang rumit dan sifat farmakologis (faali) yang nyata Alkaloid : senyawa yang mengandung nitrogen yang bersifat basa dari tumbuhan dan hewan. Senyawa ini mempunyai struktur yang rumit dan sifat farmakologis (faali) yang nyata Nikotin dari tembakau Nikotin dari tembakau Porfirin : senyawa heterosiklis yang mengandung 4 cicin pirol yang saling berikatan. Porfirin membentuk kompleks dengan ion logam. Apabila membentuk kompleks dengan Fe membentuk besi- porfirin yang menyebabkan warna darah merah pada darah arteri  Hemoglobin Porfirin : senyawa heterosiklis yang mengandung 4 cicin pirol yang saling berikatan. Porfirin membentuk kompleks dengan ion logam. Apabila membentuk kompleks dengan Fe membentuk besi- porfirin yang menyebabkan warna darah merah pada darah arteri  Hemoglobin

8 Contoh Senyawa Heterosiklis Klorofil berwarna hijau adalah kompleks Mg dengan porfirin yang termodifikasi. Klorofil berwarna hijau adalah kompleks Mg dengan porfirin yang termodifikasi.

9 Sifat-Sifat Fisik Amina : Amina 1  dan 2  bersifat polar karena mampu membentuk ikatan hydrogen intermolekuler. Amina 1  dan 2  bersifat polar karena mampu membentuk ikatan hydrogen intermolekuler. Larut dalam air karena mampu membentuk ikatan hidrogen dengan air. Larut dalam air karena mampu membentuk ikatan hidrogen dengan air. Ikatan hidrogen Ikatan hidrogen

10 Measures of Basicity The basicity of amines may be measured by: The basicity of amines may be measured by: 1) K b 1) K b 2)pK b 2)pK b 3)K a of conjugate acid 3)K a of conjugate acid 4) pK a of conjugate acid 4) pK a of conjugate acid

11 Basicity Constant (K b ) and pK b K b is the equilibrium constant for the reaction: K b is the equilibrium constant for the reaction: R3NR3NR3NR3N + HOH R3NR3NR3NR3N+H – OH + K b = [R 3 NH + ][HO – ] [R 3 N] pK b = - log K b and

12 K a and pK a of Conjugate Acid K a = [R 3 N][H + ] [R 3 NH + ] pK a = - log K a and R3NR3NR3NR3N R3NR3NR3NR3N+H + H+H+H+H+ K a is the equilibrium constant for the dissociation of the conjugate acid of the amine: K a is the equilibrium constant for the dissociation of the conjugate acid of the amine:

13 Relationships between acidity and basicity constants pK a + pK b = 14 K a K b =

14 The beverage reportedly produced using the extract of leaves of Erythroxylon coca: The compound: cocaine, it is an organic base: Merck Index, #2450, 11th ed.: Caution: May be habit forming….

15 Acid -Base Chemistry (Physical Properties) m.p. 98 o C m.p. 98 o C b.p. (very volatile > 90 o C) b.p. (very volatile > 90 o C)Solubility: Water: 1.67 x g/mL Water: 1.67 x g/mL CHCl 3 : 1.43 g/mL CHCl 3 : 1.43 g/mL Ether: 0.29 g/mL Ether: 0.29 g/mL What structural feature makes cocaine a base? What simple compound can you relate it to?

16 “Regular” Cocaine Conjugate Acid of Cocaine (Physical Properties) m.p. >195 o C m.p. >195 o CSolubility: Water: 2.5 g/mL Water: 2.5 g/mL CHCl 3 : 0.08 g/mL CHCl 3 : 0.08 g/mL Ether: insoluble Ether: insoluble What accounts for the differences in solubilities of the base and conjugate acid?

17 Acid -Base Reactions

18 Acid Base Reactions

19 AmineConj. AcidpK a AmineConj. AcidpK a NH 3 NH NH 3 NH CH 3 CH 2 NH 2 CH 3 CH 2 NH CH 3 CH 2 NH 2 CH 3 CH 2 NH Basicity of Amines in Aqueous Solution CH 3 CH 2 NH 3 + is a weaker acid than NH 4 + ; therefore, CH 3 CH 2 NH 2 is a stronger base than NH 3.

20 Effect of Structure on Basicity 1. Alkylamines are slightly stronger bases than ammonia. 1. Alkylamines are slightly stronger bases than ammonia. 2. Alkylamines differ very little in basicity. 2. Alkylamines differ very little in basicity.

21 AmineConj. AcidpK a AmineConj. AcidpK a NH 3 NH NH 3 NH CH 3 CH 2 NH 2 CH 3 CH 2 NH CH 3 CH 2 NH 2 CH 3 CH 2 NH (CH 3 CH 2 ) 2 NH(CH 3 CH 2 ) 2 NH (CH 3 CH 2 ) 2 NH(CH 3 CH 2 ) 2 NH (CH 3 CH 2 ) 3 N(CH 3 CH 2 ) 3 NH (CH 3 CH 2 ) 3 N(CH 3 CH 2 ) 3 NH Basicity of Amines in Aqueous Solution Notice that the difference separating a primary, secondary, and tertiary amine is only 0.3 pK units.

22 Effect of Structure on Basicity 1. Alkylamines are slightly stronger bases than ammonia. 1. Alkylamines are slightly stronger bases than ammonia. 2. Alkylamines differ very little in basicity. 2. Alkylamines differ very little in basicity. 3. Arylamines are much weaker bases than ammonia. 3. Arylamines are much weaker bases than ammonia.

23 AmineConj. AcidpK a AmineConj. AcidpK a NH 3 NH NH 3 NH CH 3 CH 2 NH 2 CH 3 CH 2 NH CH 3 CH 2 NH 2 CH 3 CH 2 NH (CH 3 CH 2 ) 2 NH(CH 3 CH 2 ) 2 NH (CH 3 CH 2 ) 2 NH(CH 3 CH 2 ) 2 NH (CH 3 CH 2 ) 3 N(CH 3 CH 2 ) 3 NH (CH 3 CH 2 ) 3 N(CH 3 CH 2 ) 3 NH C 6 H 5 NH 2 C 6 H 5 NH C 6 H 5 NH 2 C 6 H 5 NH Basicity of Amines in Aqueous Solution

24 + HOH NH2NH2NH2NH2 + NH3NH3NH3NH3 +– OH Aniline (reactant) is stabilized by conjugation of nitrogen lone pair with ring  system. Aniline (reactant) is stabilized by conjugation of nitrogen lone pair with ring  system. This stabilization is lost on protonation. This stabilization is lost on protonation. Decreased basicity of arylamines

25 C 6 H 5 NH 2 (C 6 H 5 ) 2 NH (C 6 H 5 ) 3 N KbKbKbKb 3.8 x x ~ Increasing delocalization makes diphenylamine a weaker base than aniline, and triphenylamine a weaker base than diphenylamine. Increasing delocalization makes diphenylamine a weaker base than aniline, and triphenylamine a weaker base than diphenylamine.

26 Effect of Substituents on Basicity of Arylamines 1. Alkyl groups on the ring increase basicity, but only slightly (less than 1 pK unit). 1. Alkyl groups on the ring increase basicity, but only slightly (less than 1 pK unit). 2. Electron withdrawing groups, especially ortho and/or para to amine group, decrease basicity and can have a large effect. 2. Electron withdrawing groups, especially ortho and/or para to amine group, decrease basicity and can have a large effect.

27 XpK b pK a XpK b pK a H H CH CH CF CF O 2 N O 2 N Basicity of Arylamines X NH 2 X NH 3 +

28 p-Nitroaniline NH 2 O N O – + O N O – – NH Lone pair on amine nitrogen is conjugated with p-nitro group—more delocalized than in aniline itself. Delocalization lost on protonation. Lone pair on amine nitrogen is conjugated with p-nitro group—more delocalized than in aniline itself. Delocalization lost on protonation.

29 Effect is Cumulative Aniline is 3800 times more basic than p-nitroaniline. Aniline is 3800 times more basic than p-nitroaniline. Aniline is ~1,000,000,000 times more basic than 2,4-dinitroaniline. Aniline is ~1,000,000,000 times more basic than 2,4-dinitroaniline.

30 Heterocyclic Amines N H N piperidinepyridine is more basic than K b = 1.6 x K b = 1.4 x (an alkylamine) (resembles an arylamine in basicity)

31 Preparation and Reactions of Amines

32 The Gabriel Synthesis of Primary Amines

33 Reductive Amination

34 The aldehyde or ketone equilibrates with the imine faster than hydrogenation occurs. The aldehyde or ketone equilibrates with the imine faster than hydrogenation occurs. Synthesis of Amines via Reductive Amination O CRR' + NH3NH3NH3NH3 fast NHNHNHNH CRR' + H2OH2OH2OH2O In reductive amination, an aldehyde or ketone is subjected to catalytic hydrogenation in the presence of ammonia or an amine.

35 Synthesis of Amines via Reductive Amination H 2, Ni O CRR' + NH3NH3NH3NH3 fast NHNHNHNH CRR' + H2OH2OH2OH2O NH2NH2NH2NH2RR' C H The imine undergoes hydrogenation faster than the aldehyde or ketone. An amine is the product.

36 Example: Ammonia gives a primary amine. O + NH3NH3NH3NH3H NH2NH2NH2NH2 H 2, Ni ethanol (80%) via: NHNHNHNH

37 Example: Primary amines give secondary amines H 2, Ni ethanol (65%) CH 3 (CH 2 ) 5 CH 2 NH + H2NH2NH2NH2N CH 3 (CH 2 ) 5 CH O

38 Example: Primary amines give secondary amines H 2, Ni ethanol (65%) via: CH 3 (CH 2 ) 5 CH 2 NH + H2NH2NH2NH2N CH 3 (CH 2 ) 5 CH O N

39 Example: Secondary amines give tertiary amines H 2, Ni, ethanol (93%) + CH 3 CH 2 CH 2 CH O N H N CH 2 CH 2 CH 2 CH 3

40 Reductive Amination Is Versatile Ammonia, primary amines, and secondary amines yield primary, secondary, and tertiary amines, respectively Ammonia, primary amines, and secondary amines yield primary, secondary, and tertiary amines, respectively

41 Mechanism of Reductive Amination Imine is intermediate Imine is intermediate

42 Hofmann and Curtius Rearrangements Carboxylic acid derivatives can be converted into primary amines with loss of one carbon atom by both the Hofmann rearrangement and the Curtius rearrangement Carboxylic acid derivatives can be converted into primary amines with loss of one carbon atom by both the Hofmann rearrangement and the Curtius rearrangement

43 Hofmann Rearrangement RCONH 2 reacts with Br 2 and base RCONH 2 reacts with Br 2 and base Gives high yields of arylamines and alkylamines Gives high yields of arylamines and alkylamines

44 Curtius Rearrangement Heating an acyl azide prepared from substitution an acid chloride Heating an acyl azide prepared from substitution an acid chloride Migration of  R from C=O to the neighboring nitrogen with simultaneous loss of a leaving group Migration of  R from C=O to the neighboring nitrogen with simultaneous loss of a leaving group

45 45 COPE REACTION N-OXIDE LESS HINDERED BETA HYDROGEN SYN ELIMINATION

46 46 Amine Oxides Undergo a Cope Elimination Reaction

47 47 COPE EXAMPLE Mild conditions

48 Reactions of Amines Alkylation and acylation have already been presented Alkylation and acylation have already been presented

49 Arylamines Are Not Useful for Friedel-Crafts Reactions Arylamines Are Not Useful for Friedel-Crafts Reactions The amino group forms a Lewis acid–base complex with the AlCl 3 catalyst, preventing further reaction The amino group forms a Lewis acid–base complex with the AlCl 3 catalyst, preventing further reaction Therefore we use the corresponding amide Therefore we use the corresponding amide

50 Diazonium Salts: The Sandmeyer Reaction Primary arylamines react with HNO 2, yielding stable arenediazonium salts Primary arylamines react with HNO 2, yielding stable arenediazonium salts NaNO 2 + HClHONO

51 Uses of Arenediazonium Salts The N 2 group can be replaced by a nucleophile The N 2 group can be replaced by a nucleophile

52 Diverse Reactions of Arenediazonium Salts Sequence of (1) nitration, (2) reduction, (3) diazotization, and (4) nucleophilic substitution leads to many different products Sequence of (1) nitration, (2) reduction, (3) diazotization, and (4) nucleophilic substitution leads to many different products

53 Preparation of Aryl Halides Reaction of an arenediazonium salt with CuCl or CuBr gives aryl halides (Sandmeyer Reaction) Reaction of an arenediazonium salt with CuCl or CuBr gives aryl halides (Sandmeyer Reaction) Aryl iodides form from reaction with NaI without a copper(I) salt Aryl iodides form from reaction with NaI without a copper(I) salt

54 Aryl Nitriles and Carboxylic Acids An arenediazonium salt and CuCN yield the nitrile, ArCN, which can be hydrolyzed to ArCOOH An arenediazonium salt and CuCN yield the nitrile, ArCN, which can be hydrolyzed to ArCOOH

55 Formation of Phenols (ArOH) From reaction of the arenediazonium salt with copper(I) oxide in an aqueous solution of copper(II) nitrate From reaction of the arenediazonium salt with copper(I) oxide in an aqueous solution of copper(II) nitrate

56 Reduction to a Hydrocarbon By treatment of a diazonium salt with hypophosphorous acid, H 3 PO 2 By treatment of a diazonium salt with hypophosphorous acid, H 3 PO 2

57 Mechanism of Diazonium Replacement Through radical (rather than polar or ionic) pathways Through radical (rather than polar or ionic) pathways

58 Diazonium Coupling Reactions Arenediazonium salts undergo a coupling reaction with activated aromatic rings, such as phenols and arylamines, to yield brightly colored azo compounds, Ar  N=N  Ar Arenediazonium salts undergo a coupling reaction with activated aromatic rings, such as phenols and arylamines, to yield brightly colored azo compounds, Ar  N=N  Ar

59 How Diazonium Coupling Occurs The electophilic diazonium ion reacts with the electron-rich ring of a phenol or arylamine The electophilic diazonium ion reacts with the electron-rich ring of a phenol or arylamine Usually occurs at the para position but goes ortho if para is blocked Usually occurs at the para position but goes ortho if para is blocked

60 Azo Dyes Azo-coupled products have extended  conjugation that lead to low energy electronic transitions that occur in visible light (dyes) Azo-coupled products have extended  conjugation that lead to low energy electronic transitions that occur in visible light (dyes)


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