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Carboxylic Acid Derivatives, Study Guides, Projects, Research of Chemistry

A comprehensive overview of five classes of organic compounds related to carboxylic acids: acid halides, sulfonyl chlorides, acid anhydrides, esters, and amides. It covers the structure, nomenclature, and characteristic reactions of these compounds, including hydrolysis, esterification, and reduction. The document also discusses the relative reactivities of these acid derivatives and their applications in organic synthesis. The detailed explanations and step-by-step reaction mechanisms make this document a valuable resource for students and researchers studying organic chemistry, particularly in the areas of functional group transformations and synthetic methodology.

Typology: Study Guides, Projects, Research

2023/2024

Uploaded on 07/21/2024

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CHAPTER 18
FUNCTIONAL DERIVATIVES
OF CARBOXYLIC ACIDS
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CHAPTER 18

FUNCTIONAL DERIVATIVES

OF CARBOXYLIC ACIDS

• In this chapter, we study five classes of organic

compounds, each related to carboxylic acids.

• Under the structural formula of each is a drawing to help you

see its relationship to the carboxyl group.

RC-OH H-Cl H-OR' H-NH 2

O

H-OCR'

O

RC=N

HO H

RC-OH

O

RC-OH

O

RC-OH

O

-H 2 O -H 2 O^ -H 2 O^ -H 2 O^

-H 2 O

RCNH 2 RC N

O

RCCl

O

RCOR'

O

RCOCR'

O O

Th e enol of an amide

A n acid chloride

An acid An ester anhydride

An amide A nitrile

Carboxyl Derivatives

• Replacement of -OH of a sulfonic acid by -Cl gives a sulfonyl

chloride.

H 3 C S-OH

O

O

H 3 C S-Cl

O

O

CH 3 -S-Cl

O

O

CH 3 -S-OH

O

O Methanes ulfon ic acid

p- Toluen esulfon ic acid

Methanes ulfonyl ch loride (Mesyl ch loride, MsCl)

p- Toluen esulfon yl chloride (Tosyl chlorid e, TsCl)

Sulfonyl Chlorides

 The functional group of an carboxylic anhydride is two

acyl groups bonded to an oxygen atom.

 The anhydride may be symmetrical (two identical acyl

groups) or mixed (two different acyl groups).

 To name, replace acid of the parent acid by anhydride.

COC

O O

CH 3 COCCH 3

O O

Acetic anh ydrid e Benzoic anh ydride

Acid Anhydrides

• A phosphoric anhydride contains two phosphoryl

groups bonded to an oxygen atom.

Triphosphoric acid

Diphosphate ion (Pyrophosphate ion)

Diphosphoric acid (Pyrophosphoric acid)

HO- P-O- P-OH

  • O- P-O-P- O -

HO- P-O- P-O-P- OH

  • O- P-O-P- O-P- O -

Triphosphate ion

OH

O

OH

O

O-

O

O-

O

O-

O

O-

O

O-

O

O-

O

O-^ O-

O O

Phosphoric Anhydrides

 The functional group of a carboxylic ester is an acyl

group bonded to -OR or -OAr.

 Name the alkyl or aryl group bonded to oxygen followed by

the name of the acid.

 Change the suffix -ic acid to -ate.

O

O

EtO O

OEt

O

O

O

Ethyl ethan oate (Ethyl acetate)

D iethyl butaned ioate (D ieth yl s uccin ate)

Is op ropyl ben zoate

Carboxylic Esters

Esters of Phosphoric Acid

 Phosphoric acid forms mono-, di-, and triesters.

 Name by giving the name of the alkyl or aryl group(s) bonded

to oxygen followed by the word phosphate.

 In more complex phosphoric esters, it is common to name

the organic molecule and then indicate the presence of the

phosphoric ester by the word phosphate or the prefix

phospho-.

OCH 3

CH 3 O-P-O-

O C-H CH 2 -O-P-O-

CHO HO

O-

O

N

HO

H 3 C

CH 2 O-P-O- O-

CHO O CO- C CH 2

O P O- O-

O

O

Glyceraldehyde 3-ph os phate

Pyrid oxal p hos phate (^) Phosp hoenol- p yruvate

D imethyl p hosph ate

 The functional group of an amide is an acyl group

bonded to a nitrogen atom.

 IUPAC: drop -oic acid from the name of the parent acid and

add -amide.

 Common name, drop -ic of the parent name and add

-amide.

 If the amide nitrogen is bonded to alkyl or aryl groups, name

the group and show its location on nitrogen by N -.

CH 3 CNH 2

O CH 3 C-N

H

CH 3

O H-C-N

CH 3

CH 3

O

N- Methylacetamide (a 2° amid e)

Acetamide (a 1° amide)

N,N- D imethyl- formamid e (DMF) (a 3° amide)

Amides

Penicillins

• The penicillins are a family of -lactam antibiotics.

NH

H 2 N

H H

HO

N

S

COOH

O

Amoxicillin (a-lactam an tib iotic)

The penicillin s differ in the grou p bond ed to the acyl carb on-lactam

O

• The cephalosporins are also -lactam antibiotics.

N

S

Me

COOH

O

O

N

NH H

2

H H

The cephalosporins d iffer in the

group bonded to the acyl carbon an d

the s ide chain of the thiazin e rin g

Cep halexin

(Keflex)

 -lactam

Cephalosporins

• Amides are comparable in acidity to alcohols.

• Water-insoluble amides do not react with NaOH or other

alkali metal hydroxides to form water-soluble salts.

• Sulfonamides and imides are more acidic than amides.

CH 3 CNH 2

O

O

O

SNH 2 NH

O

O

NH

O

O

p K a 10 p K a 9.7 p K a 8.

Acetamide Ben zenesu lfonamide Succinimide Phth alimide p K a 15-

Acidity of N-H bonds

• Imides (pKa 8-10) are more acidic than amides

because:

1. the electron-withdrawing inductive of the two adjacent C=O

groups weakens the N-H bond, and

2. the imide anion is stabilized by resonance delocalization of

the negative charge.

O

O

N N

O

O

A resonance-stabi l i zed an i on

N

O

O

Acidity of N-H bonds

Acidity of N-H

• Saccharin, an artificial sweetener, is an imide.

The imide is sufficiently acidic that it reacts with NaOH and

aqueous NH 3 to form a water-soluble salt. The ammonium salt is

used to make liquid Saccharin. Saccharin in solid form is the Ca2+

salt.

S

NH

O

O O S accharin

  • (^) NH 3 H 2 O (^) S

N-^ NH 4 +

O

O O S accharin

A water-soluble ammonium salt

 Nucleophilic acyl substitution: An addition-elimination

sequence resulting in substitution of one nucleophile

for another.

Characteristic Reactions