Carboxylic Acid Derivatives Acid Chlorides Acid Anhydrides Esters

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

Reactivity of Acid Derivatives

Nucleophilic Acyl Substitution

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

Acid Chlorides

Acid Anhydrides

Esters

Amides

Lactones (cyclic esters)

Gamma Hydroxybutyrate

All Acid Derivatives can be Hydrolyzed

What are the 3 Hydrolysis Products?

Draw the Hydrolysis Products

Hydrolysis of Penicillin

Aspartame

Hydrolysis of an Acid Chloride

Acid Chloride Preparation

Nucleophilic Acyl Substitution

With Acid Chlorides, No Catalyst is Needed Anhydride Prep.

Ester Preparation from an acid chloride

USES OF ESTERS Despite being fairly chemically unreactive, esters are useful as. . . • flavourings apple pear banana pineapple rum • solvents nail varnish remover - ethyl ethanoate • plasticisers 2 -methylbutanoate 3 -methylbutylethanoate 1 -methylbutylethanoate butylbutanoate 2 -methylpropanoate

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 a triglyceride glycerol

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 Saponification • 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

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

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

FATTY ACIDS Carboxylic acids that are obtained from natural oils and fats; they can be… Saturated CH 3(CH 2)16 COOH octadecanoic acid (stearic acid) 9 Unsaturated CH 3(CH 2)7 CH=CH(CH 2)7 COOH octadec-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)

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

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

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

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

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

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

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

BIOFUELS What are they? Liquid fuels made from plant material and recycled elements of the food chain Biodiesel 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. vegetable oil glycerol biodiesel 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.

BIOFUELS 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

BIOFUELS 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 • poor availability - very few outlets & manufacturers • more expensive to produce • poorly made biodiesel can cause engine problems

BIOFUELS 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 • poor availability - very few outlets & manufacturers • more expensive to produce • poorly made biodiesel can cause engine problems Future 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

Amide Preparation from an Acid Chloride

Amide from Anhydride

Fischer Esterification

Fischer Esterification Shows Oxygen “Scrambling” a methanolysis

Diazomethane Preparation of Methyl Esters

Diazomethane has a Basic Carbon

Mechanism

Flavors and Fragrances

Intramolecular Fischer Esterification - GHB

Lactam (cyclic amide) Formation

b-Lactams as Antibiotics

Acid Catalyzed “Olysis” Reactions

Transesterification a Methanolysis

Aspirin Synthesis

Basic Hydrolysis Saponification

Basic Hydrolysis of an Amide

Mechanism

Reduction of Esters with Li. Al. H 4

DIBAH Diisobutyl Aluminum Hydride

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

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

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

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

Reactivity : -

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

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

Preparation of Acid Derivatives

Preparation of Acid Derivatives Non-SN reactions

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

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

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

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

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

(2) Acid chloride with high/intermediate/low b. p. (85 C < b. p. < 170 C) or b. p. < 65 C (l) b. p. = 74. 6℃ Most useful can be removed easily

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

Q. 76 s. t. =160 C b. p. =249 C b. p. =106 C b. p. =197. 2 C b. p. =74. 6 C

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

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

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

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

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

B. Preparation of Acid Anhydrides Na. Cl(s) produced is removed by precipitation Equilibrium position shifts to the right Yield

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

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

Preparation of Acid Amides Ammonolysis NH 3 N NH 3