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Carboxylic Acid Derivatives Acid Chlorides Acid Anhydrides Esters Amides Nitriles Nucleophilic Acyl Substitution.

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Presentation on theme: "Carboxylic Acid Derivatives Acid Chlorides Acid Anhydrides Esters Amides Nitriles Nucleophilic Acyl Substitution."— Presentation transcript:

1 Carboxylic Acid Derivatives Acid Chlorides Acid Anhydrides Esters Amides Nitriles Nucleophilic Acyl Substitution

2

3 Reactivity of Acid Derivatives

4

5 Nucleophilic Acyl Substitution

6 I.U.P.A.C. Nomenclature ( uses carboxylic acid template)

7 Acid Chlorides

8 Acid Anhydrides

9 Esters

10 Amides

11 Lactones (cyclic esters)

12 Gamma Hydroxybutyrate

13 All Acid Derivatives can be Hydrolyzed

14 What are the 3 Hydrolysis Products?

15

16 Draw the Hydrolysis Products

17 Hydrolysis of Penicillin

18 Aspartame

19 Hydrolysis of an Acid Chloride

20 Acid Chloride Preparation

21

22 Nucleophilic Acyl Substitution

23 With Acid Chlorides, No Catalyst is Needed Anhydride Prep.

24

25 Ester Preparation from an acid chloride

26 USES OF ESTERS Despite being fairly chemically unreactive, esters are useful as... flavouringsapple2-methylbutanoate pear3-methylbutylethanoate banana1-methylbutylethanoate pineapplebutylbutanoate rum2-methylpropylpropanoate solventsnail varnish remover - ethyl ethanoate plasticisers

27 TRIGLYCERIDES AND FATS Triglycerides are the most common component of edible fats and oils are triesters of the alcohol glycerol, (propane-1,2,3-triol) and fatty acids glycerol a triglyceride

28 TRIGLYCERIDES AND FATS Triglycerides are the most common component of edible fats and oils are triesters of the alcohol glycerol, (propane-1,2,3-triol) and fatty acidsSaponification alkaline hydrolysis of triglycerol esters produces soaps a simple soap is the salt of a fatty acid as most oils contain a mixture of triglycerols, soaps are not compounds the quality of a soap depends on the oils from which it is made

29 FATTY ACIDS Carboxylic acids that are obtained from natural oils and fats; they can be… Saturated SaturatedCH 3 (CH 2 ) 16 COOH octadecanoic acid (stearic acid)

30 FATTY ACIDS Carboxylic acids that are obtained from natural oils and fats; they can be… Saturated SaturatedCH 3 (CH 2 ) 16 COOH octadecanoic acid (stearic acid) 9 Unsaturated UnsaturatedCH 3 (CH 2 ) 7 CH=CH(CH 2 ) 7 COOHoctadec-9-enoic acid (oleic acid) cis (Z) isomer trans (E) isomer

31 FATTY ACIDS Carboxylic acids that are obtained from natural oils and fats; they can be… Saturated SaturatedCH 3 (CH 2 ) 16 COOH octadecanoic acid (stearic acid) 9 Unsaturated UnsaturatedCH 3 (CH 2 ) 7 CH=CH(CH 2 ) 7 COOHoctadec-9-enoic acid (oleic acid) cis (Z) isomer trans (E) isomer 12 9 CH 3 (CH 2 ) 4 CH=CHCH 2 CH=CH(CH 2 ) 7 COOH octadec-9,12-dienoic acid (linoleic acid)

32 FATTY ACIDS AND HEALTH Saturated Saturated solids at room temperature found in meat and dairy products are bad for health increase cholesterol levels - can lead to heart problems

33 FATTY ACIDS AND HEALTH Saturated Saturated solids at room temperature found in meat and dairy products are bad for health increase cholesterol levels - can lead to heart problems Mono unsaturated unsaturated contain just one C=C thought to be neutral to our health found in olives, olive oil, groundnut oil, nuts, avocados

34 FATTY ACIDS AND HEALTH Saturated Saturated solids at room temperature found in meat and dairy products are bad for health increase cholesterol levels - can lead to heart problems Mono unsaturated unsaturated contain just one C=C thought to be neutral to our health found in olives, olive oil, groundnut oil, nuts, avocadosPoly unsaturated unsaturated are considered to be ‘good fats’ contain more than one C=C bond tend to be liquids at room temperature, eg olive oil. can be split into two main types... Omega 3 - fatty acids Omega 6 - fatty acids

35 FATTY ACIDS AND HEALTH Saturated Saturated solids at room temperature found in meat and dairy products are bad for health increase cholesterol levels - can lead to heart problems Mono unsaturated unsaturated contain just one C=C thought to be neutral to our health found in olives, olive oil, groundnut oil, nuts, avocadosPoly unsaturated unsaturated are considered to be ‘good fats’ contain more than one C=C bond tend to be liquids at room temperature, eg olive oil. can be split into two main types... Omega 3 - fatty acids Omega 6 - fatty acids

36 OMEGA 3 and 6 FATTY ACIDS Omega 3 - fatty acids Omega 3 - fatty acidslower the total amount of fat in the blood and can lower blood pressure and decrease the risk of cardiovascular disease 3  (omega) endCH 3 CH 2 CH=CHCH 2 CH 2 CH 2 CH 2 CH=CH(CH 2 ) 7 COOH The omega numbering system starts from the opposite end to the carboxylic acid group

37 OMEGA 3 and 6 FATTY ACIDS Omega 3 - fatty acids Omega 3 - fatty acidslower the total amount of fat in the blood and can lower blood pressure and decrease the risk of cardiovascular disease 3  (omega) endCH 3 CH 2 CH=CHCH 2 CH 2 CH 2 CH 2 CH=CH(CH 2 ) 7 COOH Omega 6 - fatty acids Omega 6 - fatty acidsreduce the risk of cardiovascular disease but can contribute to allergies and inflammation 6  (omega) endCH 3 CH 2 CH 2 CH 2 CH 2 CH=CHCH 2 CH=CH(CH 2 ) 7 COOH

38 CHOLESTEROL a fatty substance which is found in the blood it is mainly made in the body plays an essential role in how every cell in the body works eating too much saturated fat increases cholesterol levels too much cholesterol in the blood can increase the risk of heart problems

39 CHOLESTEROL a fatty substance which is found in the blood it is mainly made in the body plays an essential role in how every cell in the body works eating too much saturated fat increases cholesterol levels too much cholesterol in the blood can increase the risk of heart problems Ways to reduce cholesterol levels cut down on saturated fats and trans fats (trans fats are more stable and difficult to break down in the body) replace them with monounsaturated fats and polyunsaturated fats eat oily fish have a high fibre diet; porridge, beans, fruit and vegetables exercise regularly

40 BIOFUELS What are they? Liquid fuels made from plant material and recycled elements of the food chainBiodiesel An alternative fuel which can be made from waste vegetable oil or from oil produced from seeds. It can be used in any diesel engine, either neat or mixed with petroleum diesel. It is a green fuel, does not contribute to the carbon dioxide (CO 2 ) burden and produces drastically reduced engine emissions. It is non-toxic and biodegradable. vegetable oilglycerolbiodiesel

41 BIOFUELS Advantages Advantages renewable - derived from sugar beet, rape seed dramatically reduces emissions carbon neutral biodegradable non-toxic fuel & exhaust emissions are less unpleasant can be used directly in unmodified diesel engine high flashpoint - safer to store & transport simple to make used neat or blended in any ratio with petroleum diesel

42 BIOFUELS Advantages Advantages renewable - derived from sugar beet, rape seed dramatically reduces emissions carbon neutral biodegradable non-toxic fuel & exhaust emissions are less unpleasant can be used directly in unmodified diesel engine high flashpoint - safer to store & transport simple to make used neat or blended in any ratio with petroleum diesel Disadvantages Disadvantages poor availability - very few outlets & manufacturers more expensive to produce poorly made biodiesel can cause engine problems

43 BIOFUELS Advantages Advantages renewable - derived from sugar beet, rape seed dramatically reduces emissions carbon neutral biodegradable non-toxic fuel & exhaust emissions are less unpleasant can be used directly in unmodified diesel engine high flashpoint - safer to store & transport simple to make used neat or blended in any ratio with petroleum diesel Disadvantages Disadvantages poor availability - very few outlets & manufacturers more expensive to produce poorly made biodiesel can cause engine problemsFuture problems problems there isn’t enough food waste to produce large amounts crops grown for biodiesel use land for food crops a suitable climate is needed to grow most crops some countries have limited water resources

44 Amide Preparation from an Acid Chloride

45 Amide from Anhydride

46 Fischer Esterification

47 Fischer Esterification Shows Oxygen “Scrambling” a methanolysis

48

49 Diazomethane Preparation of Methyl Esters

50 Diazomethane has a Basic Carbon

51 Mechanism

52 Flavors and Fragrances

53 Intramolecular Fischer Esterification - GHB

54

55 Lactam (cyclic amide) Formation

56  -Lactams as Antibiotics

57 Acid Catalyzed “Olysis” Reactions

58 Transesterification a Methanolysis

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60 Aspirin Synthesis

61

62 Basic Hydrolysis Saponification

63 Basic Hydrolysis of an Amide

64 Mechanism

65

66 Reduction of Esters with LiAlH 4

67 DIBAH Diisobutyl Aluminum Hydride

68 Reactivity of carboxylic acids and their derivatives towards nucleophilic reactions 1. Aldehydes/ketones undergo Ad N rather than S N Carboxylic acids/derivatives undergo S N rather than Ad N

69 Strong bases, unstable A discussion on the reactivity of carboxylic acids and their derivatives towards nucleophilic rxs 1. Aldehydes/ketones undergo Ad N rather than S N

70 Reactivity of carboxylic acids and their derivatives towards nucleophilic reactions 1. Carboxylic acids/derivatives undergo S N rather than Ad N Weak base, stable

71 Strength of acids : - HCl > RCOOH > HOH > ROH > H 2 NH > RH > HH Strength of bases : - Cl  < RCOO  < HO  < RO  < H 2 N  < R  < H 

72 Reactivity : -

73 (i)Ease of leaving(Stability of bases) : - Cl  > RCOO  > HO  > RO  > H 2 N  > R  > H  ∵ Strength of bases : - Cl  < RCOO  < HO  < RO  < H 2 N  < R  < H  Reasons : -

74 Increasing resonance effect ( 2p ) (3p) ( 2p) (ii)Resonance effect : - Efficiency of orbital overlap : 2p/2p > 3p/2p Less stable More reactive More stable Less reactive

75 Reactivity : - The less reactive derivatives can be prepared from the more reactive derivative via nucleophilic substitution reactions.

76 Preparation of Acid Derivatives

77

78 Non-S N reactions

79 C – O  bond of benzoyl chloride has less mesomeric effect  Carbonyl C of benzoyl chloride is less positive  Less susceptible to nucleophilic attack

80  + ++  The carbonyl C is attached to TWO electron-withdrawing atoms  more positive  more susceptible to electrophilic attacks

81  + ++  Also, the nucleophile experiences less steric hindrance with acyl chloride because the reaction site is planar

82 A.Preparation of Acid Chlorides SOCl 2 : thionyl chloride or sulphur oxychloride

83 (l) (s) b.p. = 106 ℃ sublimes at 160 ℃ (1)Acid chloride with high b.p. Higher b.p. than acid chloride due to intermolecular H-bonds removed first by fractional distillation Phosphorus oxychloride (>170  C)

84 (2)Acid chloride with high/intermediate/low b.p. can be removed easily b.p. = 74.6 ℃ (l) (85  C < b.p. < 170  C) Most useful or b.p. < 65  C

85 (3)Acid chloride with low b.p. decomposes at 200 ℃ b.p. = 79 ℃ (l) (3)Acid chloride with low b.p. (< 69  C) Removed first by fractional distillation

86 Q.76 b.p.=197.2  C b.p.=106  C b.p.=249  C s.t.=160  C b.p.=74.6  C

87 Q.76 b.p.  51  Cb.p.=118  C d.c.  200  C b.p.=76  C Removed first by fractional distillation

88 B. Preparation of Acid Anhydrides Acyl chlorides must be stored in anhydrous conditions  they hydrolyze rapidly in the presence of even a trace amount of water(p.122) RCOCl + H 2 O  RCOOH + HCl

89 B. Preparation of Acid Anhydrides R  R’  unsymmetrical anhydride R = R’  symmetrical anhydride

90 B. Preparation of Acid Anhydrides pyridine Equilibrium position shifts to the right  Yield 

91 B. Preparation of Acid Anhydrides R  R’  unsymmetrical anhydride R = R’  symmetrical anhydride

92 B. Preparation of Acid Anhydrides NaCl(s) produced is removed by precipitation  Equilibrium position shifts to the right  Yield 

93 B. Preparation of Acid Anhydrides Only suitable for preparing symmetrical anhydrides dehydrating agent P 4 O 10 = P 2 O 5 Non-S N reaction

94 Q.77 It gives a mixture of three acid anhydrides. RCOOH + R’COOH P 4 O 10 heat

95 Preparation of Acid Amides Ammonolysis NH 3


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