carbonyl compounds i: chapter 11

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Chapter 11 1 Carbonyl Compounds Carbonyl Compounds I: I: Chapter 11 Chapter 11

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Carbonyl Compounds I: Chapter 11. Contents of Chapter 11. Naming Carboxylic Acids and Derivatives Physical Properties of Carbonyl Compounds Reactivity of Carboxylic Acid Derivatives Reactions of Carboxylic Acids and Derivatives. IUPAC Nomenclature of Carboxylic Acids. - PowerPoint PPT Presentation

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Page 1: Carbonyl Compounds I: Chapter 11

Chapter 11 1

Carbonyl Compounds I:Carbonyl Compounds I:Chapter 11Chapter 11

Page 2: Carbonyl Compounds I: Chapter 11

Chapter 11 2

Contents of Chapter 11 Naming Carboxylic Acids and Derivatives Physical Properties of Carbonyl

Compounds Reactivity of Carboxylic Acid Derivatives Reactions of Carboxylic Acids and

Derivatives

Page 3: Carbonyl Compounds I: Chapter 11

Chapter 11 3

IUPAC Nomenclature of Carboxylic Acids

Select as the parent compound the longest chain of carbon atoms that contains the carboxyl group

Change the suffix –e of the parent name to –oic acid

Carboxyl carbon is carbon 1

Page 4: Carbonyl Compounds I: Chapter 11

Chapter 11 4

Examples

CH3

CHCH3 CH2

C

O

OH

CHCH

C

O

OH

3-Methylbutanoic acid 3-Phenyl-2-propenoic acid(cinnamic acid)

12

34

12

3

Page 5: Carbonyl Compounds I: Chapter 11

Chapter 11 5

Dicarboxylic Acids

Dicarboxylic acids are named by adding the suffix –dioic acid to the name of the parent compound that contains both carboxyl groups

Page 6: Carbonyl Compounds I: Chapter 11

Chapter 11 6

Examples

Page 7: Carbonyl Compounds I: Chapter 11

Chapter 11 7

Aromatic Carboxylic AcidsCO2H CO2H

OH

CO2H

CO2H

CO2H

HO2C

benzoic acid 2-hydroxybenzoic acid

1,2-benzenedicarboxylic acid 1,4-benzenedicarboxylic acid

(salicylic acid)

(phthalic acid) (terephthalic acid)

Page 8: Carbonyl Compounds I: Chapter 11

Chapter 11 8

Derivatives of Carboxylic Acids

O

CR O

C

O

R

O

CR O

R

O

CR N

R

R

O

CR Cl

an acid chloride an anhydride

an ester an amide

Page 9: Carbonyl Compounds I: Chapter 11

Chapter 11 9

Nomenclature

Acid chlorides are named by replacing the –ic acid of the carboxylic acid with –yl chloride.

O

CCH3 Cl

C

O

Cl

O2N

acetyl chloride 4-nitrobenzoyl chloride

Page 10: Carbonyl Compounds I: Chapter 11

Chapter 11 10

Nomenclature

Anhydrides are named by adding the word anhydride to the name of the parent acid.

O

CO

C

OO

CCH3 O

C

O

CH3

acetic anhydride benzoic anhydride

Page 11: Carbonyl Compounds I: Chapter 11

Chapter 11 11

Nomenclature• Esters are named as a derivative of the

carboxylic acid from which it is derived.• The alkyl or aryl group attached to the

oxygen is named first.

Page 12: Carbonyl Compounds I: Chapter 11

Chapter 11 12

Nomenclature

Page 13: Carbonyl Compounds I: Chapter 11

Chapter 11 13

Nomenclature

Amides are named as derivatives of their carboxylic acid by dropping the suffix of the acid and adding –amide.

O

CCH3 NH2

O

CNH2

O

CNH2CH

CH3

CH3

acetamide benzamide2-methylpropanamide

Note: the above amides are all primary (1o) amides.

Page 14: Carbonyl Compounds I: Chapter 11

Chapter 11 14

NomenclatureIf a hydrogen atom of an amide is replaced by an alkyl or aryl group, the substituent is named and its location on

nitrogen indicated by N- (or N,N- if there are two groups)

O

CH N

CH3

CH3

O

CCH3CH2CH2 N

H

N,N-dimethylformamide N-phenylbutanamide(a 3o amide) (a 2o amide)

Page 15: Carbonyl Compounds I: Chapter 11

Chapter 11 15

Physical Properties of Carboxylic AcidsCarboxylic acids can form H-bonding molecule pairs, so the boiling points of carboxylic acids are somewhat higher than even alcohols with the same molar mass because they often boil away from the liquid as molecule pairs:

δ+

δ+

δ−

δ−

CH3 C

O

O

H

CH3C

O

OH

Page 16: Carbonyl Compounds I: Chapter 11

Chapter 11 16

Physical Properties of Carboxylic Acids

CH3CH2CH2CH2OH CH3CH2COH

O

propanoic acid 1-butanol (propionic acid) (n-butyl alcohol)MW = 74; bp = 141oC MW = 74; bp = 117oC

CH3CH2CH2CH2CH2OH CH3CH2CH2CH2CH

O

CH3CH2CH2COH

O

butanoic acid MW = 88

pentanalMW = 84

1-pentanol MW = 88

bp = 164oC bp = 103oC bp = 137oC

Page 17: Carbonyl Compounds I: Chapter 11

Chapter 11 17

Physical Properties of Amides

Hydrogen bonding is possible.

C

R

O NH

H

R

CO N

H

H

Page 18: Carbonyl Compounds I: Chapter 11

Chapter 11 18

Acidity of Carboxylic Acids

All carboxylic acids, whether soluble or insoluble in water, react quantitatively with NaOH, KOH, and other strong bases to form salts

CO2H CO2 Na

+ H2O + NaOH

benzoic acid(only slightly soluble in H2O)

sodium benzoate(very soluble in water)

Page 19: Carbonyl Compounds I: Chapter 11

Chapter 11 19

Preparation of EstersA carboxylic acid can be converted to an ester by heating with an alcohol in the presence of an acid

catalyst, usually concentrated sulfuric acid. O

CCH3 OH

O

CCH3 O

CH2CH3

+ HOCH2CH3/H

+ H2O

Δ

acetic acid

ethanol

ethyl acetate

Page 20: Carbonyl Compounds I: Chapter 11

Chapter 11 20

Stabilities of Carboxylic Acid Derivatives• In principle carboxylic acid derivatives should be able to be

interconverted into one another using a scheme like the one shown below

• In the scheme below LG represents the original group, like OR, attached to the starting compound (OR would make this an ester)

• Nu (nucleophile) forces LG (leaving group) to leave and replaces it, making a new compound

• In this scheme if Nu is amine and LG is alkoxy (OR) then an ester is converted into an amide

Page 21: Carbonyl Compounds I: Chapter 11

Chapter 11 21

Stabilities of Carboxylic Acid Derivatives

• Scheme on previous slide will only work if Nu is less stable than LG, so reaction goes downhill

• Relative energy of Nu or LG given by pKa of conjugate acid• In table below the derivatives at the top are less stable than

those beneath• In neutral or basic media you can convert a derivative higher up

into one lower down, but not vice-versa

Page 22: Carbonyl Compounds I: Chapter 11

Chapter 11 22

Stabilities of Carboxylic Acid Derivatives

• In acidic media interconversion of carboxylic acid derivatives works by a different mechanism

• In this mechanism LG can be protonated before it leaves• In this case the leaving group is no longer negatively charged

when it leaves; therefore it leaves more easily (more stable)• In acidic media you can interconvert any of the carboxylic acid

derivatives into one another

Page 23: Carbonyl Compounds I: Chapter 11

Chapter 11 23

Reactions Carboxylic Acid Derivatives

• To work out the product of a carboxylic acid derivative reaction first make sure the reaction will work

• If the reaction is done in acid or goes from a less stable derivative to a more stable derivative polarize the most polar bonds in the reactants and swap partners

• Always polarize the carbonyl carbon positive and the leaving group negative in these reactions