Chapter 21 carboxylic acid derivatives continued
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Organic Chemistry , 6 th Edition L. G. Wade, Jr. Chapter 21 Carboxylic Acid Derivatives (continued). Jo Blackburn Richland College, Dallas, TX Dallas County Community College District ã 2006, Prentice Hall. =>. Hydrolysis of Acid Chlorides and Anhydrides.

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Chapter 21 carboxylic acid derivatives continued l.jpg

Organic Chemistry, 6th EditionL. G. Wade, Jr.

Chapter 21Carboxylic Acid Derivatives(continued)

Jo Blackburn

Richland College, Dallas, TX

Dallas County Community College District

ã 2006,Prentice Hall


Hydrolysis of acid chlorides and anhydrides l.jpg

=>

Hydrolysis of Acid Chlorides and Anhydrides

  • Hydrolysis occurs quickly, even in moist air with no acid or base catalyst.

  • Reagents must be protected from moisture.

Chapter 21


Acid hydrolysis of esters l.jpg

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Acid Hydrolysis of Esters

  • Reverse of Fischer esterification.

  • Reaches equilibrium.

  • Use a large excess of water.

Chapter 21


Saponification l.jpg
Saponification

  • Base-catalyzed hydrolysis of ester.

  • “Saponification” means “soap-making.”

  • Soaps are made by heating NaOH with a fat (triester of glycerol) to produce the sodium salt of a fatty acid - a soap.

  • One example of a soap is sodium stearate, Na+ -OOC(CH2)16CH3. =>

Chapter 21


Hydrolysis of amides l.jpg

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Hydrolysis of Amides

Prolonged heating in 6 M HCl or 40% aqueous NaOH is required.

Chapter 21


Hydrolysis of nitriles l.jpg

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Hydrolysis of Nitriles

  • Under mild conditions, nitriles hydrolyze to an amide.

  • Heating with aqueous acid or base will hydrolyze a nitrile to an acid.

Chapter 21


Reduction to alcohols l.jpg

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Reduction to Alcohols

Lithium aluminum hydride reduces acids, acid chlorides, and esters to primary alcohols.

Chapter 21


Reduction to aldehydes l.jpg

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Reduction to Aldehydes

Acid chlorides will react with a weaker reducing agent to yield an aldehyde.

Chapter 21


Reduction to amines l.jpg

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Reduction to Amines

  • Lithium aluminum hydride reduces amides and nitriles to amines.

  • Nitriles and 1 amides reduce to 1 amines.

  • A 2 amide reduces to a 2 amine.

  • A 3 amide reduces to a 3 amine.

Chapter 21


Organometallic reagents l.jpg

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Organometallic Reagents

Grignard reagents and organolithium reagents add twice to acid chlorides and esters to give alcohols after protonation.

Chapter 21


Grignard reagents and nitriles l.jpg

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Grignard Reagentsand Nitriles

A Grignard reagent or organolithium reagent attacks the cyano group to yield an imine which is hydrolyzed to a ketone.

Chapter 21


Acid chloride synthesis l.jpg

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Acid Chloride Synthesis

  • Use thionyl chloride, SOCl2, or oxalyl chloride, (COCl)2.

  • Other products are gases.

Chapter 21


Acid chloride reactions 1 l.jpg

acid anhydride

=>

Acid Chloride Reactions (1)

acid

ester

amide

Chapter 21


Acid chloride reactions 2 l.jpg

acylbenzene

=>

Acid Chloride Reactions (2)

3° alcohol

ketone

1° alcohol

aldehyde

Chapter 21

AlCl3


Industrial synthesis of acetic anhydride l.jpg

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Industrial Synthesis of Acetic Anhydride

  • Four billion pounds/year produced.

  • Use high heat (750°C) and triethyl phosphate catalyst to produce ketene.

Chapter 21


Lab synthesis of anhydrides l.jpg

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Lab Synthesisof Anhydrides

  • React acid chloride with carboxylic acid or carboxylate ion.

  • Heat dicarboxylic acids to form cyclic anhydrides.

Chapter 21


Anhydride reactions l.jpg

acylbenzene

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Anhydride Reactions

acid

ester

amide

AlCl3

Chapter 21


Anhydride vs acid chloride l.jpg

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Anhydride vs. Acid Chloride

  • Acetic anhydride is cheaper, gives a better yield than acetyl chloride.

  • Use acetic formic anhydride to produce formate esters and formamides.

  • Use cyclic anhydrides to produce a difunctional molecule.

Chapter 21


Synthesis of esters l.jpg

acid

acid chloride

acid anhydride

=>

methyl ester

Synthesis of Esters

Chapter 21


Reactions of esters l.jpg

3° alcohol

=>

Reactions of Esters

acid

ester

amide

1° alcohol

Chapter 21


Lactones l.jpg

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Lactones

  • Formation favored for five- and six-membered rings.

  • For larger rings, remove water to shift equilibrium toward products

Chapter 21


Polyesters l.jpg

Dacron® thread

Mylar® tape

Glyptal resin

PET bottles

=>

Polyesters

Chapter 21


Synthesis of amides l.jpg

acid

acid chloride

acid anhydride

ester

=>

nitrile

Synthesis of Amides

Chapter 21


Reactions of amides l.jpg

nitrile

=>

Reactions of Amides

acid and amine

amine

1° amine

Chapter 21


Lactam formation l.jpg
Lactam Formation

  • Five- and six-membered rings can be formed by heating - and -amino acids.

  • Smaller or larger rings do not form readily. =>

Chapter 21


Lactams l.jpg

Amide  ester !!

=>

-Lactams

  • Highly reactive, 4-membered ring.

  • Found in antibiotics isolated from fungi.

Chapter 21


Polyamides l.jpg
Polyamides

Nylon 6.6

=>

Chapter 21


Synthesis of nitriles l.jpg

1° amide

alkyl halide

diazonium salt

aldehyde or ketone

cyanohydrin

=>

Synthesis of Nitriles

Chapter 21


Reactions of nitriles l.jpg

amide

acid

ketone

=>

Reactions of Nitriles

1° amine

Chapter 21


Thioesters l.jpg

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Thioesters

More reactive than esters because:

  • -S-R is a better leaving group than -O-R

  • Resonance overlap is not as effective.

Chapter 21


Carbonic acid esters l.jpg

phosgene

=>

Carbonic Acid Esters

  • CO2 in water contains some H2CO3.

  • Diesters are stable.

  • Synthesized from phosgene.

Chapter 21


Urea and urethanes l.jpg

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Urea and Urethanes

  • Urea is the diamide of carbonic acid.

  • Urethanes are esters of a monoamide of carbonic acid.

Chapter 21


Polycarbonates l.jpg

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Polycarbonates

Long-chain esters of carbonic acid

Chapter 21


Polyurethanes l.jpg

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Polyurethanes

A diol reacts with a diisocyanate.

Chapter 21


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End of Chapter 21

Chapter 21


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