Chapter 16,17 & 18 Amines, Aldehydes, Ketones and Carboxylic Acids Chemistry B11

Chapter 16,17 & 18

Amines, Aldehydes, Ketones and Carboxylic Acids

Chemistry B11

Amines

Amines:

• Are derivatives of ammonia NH3.

• Contain N attached to one or more alkyl (Aliphatic amine) or aromatic groups (Aromatic amine).

CH3-NH2 CH3-NH-CH3

Amines

-NH2 amino group

CH2CH3 CH3 CH=CH2

TolueneEthylbenzene Styrene

NH2

Amines are classified into three groups:

depending on the number of carbon groups bonded to nitrogen.

CH3 CH3

CH3—NH2 CH3—NH CH3—N—CH3

Amines

Primary 1° Secondary 2° Tertiary 3°

Naming Amines

The same method as we did for alcohols.

- Drop the final “-e” of the parent alkane and replace it by “-amine”.

- Use a number to locate the amino group (-NH2) on the parent chain.

IUPAC name – 1° amines

CH3CHCH3

NH2

NH2

H2NNH2

1,6-HexanediamineCyclohexanamine2-Propanamine

CH3-CH-CH3

NH2

2-propanamine

CH3-CH-CH-CH3

NH2

Cl

3-chloro-2-butanamine 1,6-hexanediamine

123 1 2

3

4

1234

56

Common name

Names of alkyl groups (In alphabetical order) + “amine”

CH3—CH2—NH2 ethylamine

CH3—NH —CH3 dimethylamine

CH3

|

CH3—N—CH2—CH3 ethyldimethylamine

Naming Amines

CH2CH3 CH3 CH=CH2


CH2CH3 CH3 CH=CH2


CH2CH3 CH3 CH=CH2


Aniline (common name)

NO2

CH3 CH3

Aniline

4-Nitroaniline 3-Methylaniline 4-Chloro-3-methylaniline

NH2

NH2NH2 NH2

Cl

1 2

3

4

1 2

3

1 2

34

CH2CH3 CH3 CH=CH2


Naming Amines

– Take the largest group bonded to nitrogen as the parent amine.

– Name the smaller group(s) bonded to nitrogen, and show their locations on nitrogen by using the prefix “N”.

IUPAC name – 2° and 3° amines

NCH3

CH3

NHCH3

N,N-Dimethyl- cyclopentanamine

N-Methylaniline

NCH3

CH3

NHCH3

N,N-Dimethyl- cyclopentanamine

N-Methylanilineaniline

CH3-N-CH2-CH3

CH3

N,N-Dimethylethanamine

Heterocyclic amines

When N is one of the atoms of a ring.

N

HHCH3

Pyrrolidine Pyridine Nicotine

Physical properties of Amines

1. They have unpleasant odors (rotting fish like ammonia).

2. They are polar compounds.

Difference in electronegativity between N - H (3.0 – 2.1 = 0.9)

3. 1° and 2° amines have hydrogen bonds (N-H).

Weaker than alcohols (O-H).

3° amines do not form hydrogen bonds (no H atom).

4. Boiling points: Hydrocarbons< Amines < Alcohols

5. Almost soluble in water (hydrogen bonding).

Chemical properties of Amines

They are weak bases (like ammonia): react with acids.

N

H

H

CH3 .. + H – O – H....N

H

H

CH3 H+

O – H......

-

Some amines present in our blood and make it approximately basic (pH = 7.4).

(to form water-soluble salts)

Chemical properties of Amines

C6H5NH2

CH3CH2NH2Aliphatic

Ammonia

Aromatic

3.0 - 4.0

4.74

8.5 - 9.5

Class pKb Example Name

Ethanamine

Aniline

Stronger base

Weaker base

Aliphatic amines are weak bases by comparison with inorganic bases

such as NaOH, they are strong bases among organic compounds.

Aliphatic amines are stronger bases than aromatic amines.

(slightly stronger than NH3)

Complete each acid-base reaction and name the salt formed.

(CH3CH2)2NH HCl

NCH3COOH

+(a)

(b) +

Examples

Complete each acid-base reaction and name the salt formed.

Examples

Solutions:

(CH3CH2)2NH HCl

NCH3COOH

NH

(CH3CH2)2NH2+Cl-

CH3COO-

Diethylammoniumchloride

+Pyridinium acetate

+(a)

(b) +

Aldehydes

Ketones

Carbonyl group

C

=O

Aldehydes Ketones Carboxylic acids Esters

CH3COCH2CH3

ONaOH

H2OCH3CO-Na+

O

CH3CH2OH

Sodiumhydroxide

+ +

Ethyl acetate Sodiumacetate

Ethanolheat

• In an aldehyde, at least one H atom is attached to a carbonyl group.

• In a ketone, two carbon groups are attached to a carbonyl group.

Aldehydes and Ketones

C=O

Step 1Select the longest carbon chain

that contains the carbonyl group (C=O).

Step 2Number from the end nearest C=O group.

Step 3Change the ending of parent alkane from -e to -al.No number for carbonyl group C=O (it always comes first).

Step 4Give the location and name of each substituent

(alphabetical order) as a prefix to the name of themain chain.

Naming Aldehydes

• Common names for the first two aldehydes use the prefixes “form” (1C) and “acet” (2C) followed by “aldehyde”.

O O O ║ ║ ║

H─C─H CH3─ C ─H CH3─CH2─ C ─H methanal ethanal propanal(formaldehyde) (acetaldehyde)

Naming Aldehydes

O ║CH3─CH─CH2─ C─H 3-Methylbutanal

O

║ Cl─CH2─CH2─ C─H 3-chloropropanal

CH3

1234

123

Step 1Select the longest carbon chain

that contains the carbonyl group (C=O).

Step 2Number from the end nearest C=O group.

Step 3Change the ending of parent alkane from -e to -one.

Use the number to show the location of C=O.

Step 4Give the location and name of each substituent

(alphabetical order) as a prefix to the name of themain chain.

Naming Ketones

Naming Ketones

• In the common name, name the “alkyl groups” alphabetically attached to the carbonyl group and add the word “ketone”.

O O

║ ║

CH3 ─ C ─CH3 CH3─C─CH2─CH3

propanone 2-butanone

(dimethyl ketone) (ethyl methyl ketone)

1 2 3 4

O

Acetone 2-Methylcyclohexanone5-Methyl-3-hexanone

OO

12

34

56

12

O


OO

12

34

56

12

CH

O

Benzoic acidBenzaldehyde

+ O2

COH

O

2 2

3-ChloroO


OO

12

34

56

12

O


OO

12

34

56

12O


OO

12

34

56

12

CH

O


+ O2

COH

O

2 2

Cl

O

H

OOH

NH2

3-Hydroxy-4-methylpentanal 3-Amino-4-ethyl-2-hexanone

1345 12346

O

H

OOH

NH2


1345 12346

O

H

OOH

NH2


1345 12346

O

H

OOH

NH2


1345 12346

3-Methylbutanal 2-Propenal(Acrolein)

Hexanal

12

34H

O

H

O1

23

45

6

123

H

O3-Methylbutanal 2-Propenal

(Acrolein)Hexanal

12

34H

O

H

O1

23

45

6

123

H

O

Physical properties of Aldehydes and Ketones

1. They have strong odors (ketones have pleasant odors).

2. They are polar compounds.

3. Only dipole-dipole interactions (no hydrogen bonding).

4. Low boiling points compare to amines and alcohols.

5. Soluble in water (no soluble in nonpolar compounds).

δ+

δ-

δ+

δ-H

OHδ+

Hydrogen bond with water.

Higher than hydrocarbons.

C-O 3.5-2.5 = 1

Chemical properties of Aldehydes and Ketones

1. Oxidation: only for aldehydes (not for ketones).

K2Cr2O7

H2SO4

CH3─CH2─CH2─CH2─C─OH

=

O

CH3─CH2─CH2─CH2─C─H

=

O

Pentanal Pentanoic acidK2Cr2O7: Oxidizing agent

CH

O


+ O2

COH

O

2 2Liquid aldehydes

are sensetive to oxidation.

No oxidizing agent


2. Reduction:

Like reducing the alkene (C = C) to alkane (C – C):

– Reduction of an aldehyde gives a primary alcohol (-CH2OH).

– Reduction of a ketone gives a secondary alcohol (-CHOH-).

H2

tran sition

metal catalyst+

1-Pen tan ol

CH3─CH2─CH2─CH2─C─ H

=

O

PentanalCH3─CH2─CH2─CH2─CH2─ OH

H2

tran si tion

metal cataly st+CH3─C─CH2─CH3

=

O

CH3─CH─CH2─CH3

-OH

2-butanol2-butanone

O NaBH4O-

HH3O+ O-H

H

H - C O H C O - H3O+

H C O-H: +

Hydrideion


Reduction mechanism:

NaBH4 Sodium borohydride: produces hydride ion: H-

-

Reducing agent

Carboxylic Acids

A carboxylic acid contains a carboxyl group, which is a carbonyl group attach to a hydroxyl group.

carbonyl

group

O

CH3 — C—OH hydroxyl group or CH3COOH

carboxyl group

Carboxylic Acids

CH3CO2H

• In the IUPAC name of carboxylic acids, the “-e” in the name of the longest chain is replaced by “-oic acid”.

• The common names use prefixes “form-” and “acet-” for the first

two carboxylic acids.

H-COOH methanoic acid formic acid

CH3-COOH ethanoic acid acetic acid

CH3-CH2-COOH propanoic acid

CH3-CH2-CH2-COOH butanoic acid

Naming Carboxylic Acids

Naming Carboxylic Acids

– Number the chain beginning with the carbon of the carboxyl group.

– Because the carboxyl carbon is understood to be carbon 1, there is no need to give it a number.

13

3-Methylbutanoic acid

OH

OOHH2N COOH15

4-Aminobenzoic acid5-Hydroxylhexanoic acid

4

CH3─CH2─CH─COOH

CH2 – CH3

2-Ethylbutanoic acid

2CH3─CH─CH2─COOH

CH3

1

1

Naming Dicarboxylic Acids

– Add the suffix “-dioic acid”dioic acid” to the name of the parent alkane that contains both carboxyl groups; thus, “-ane”ane” becomes “-anedioic acid”anedioic acid”.

– The numbers of the carboxyl carbons are not indicated because they can be only at the ends of the chain.

O

HOOH

O

HO OH

O

OOH

O

OH

O

O

HO

O

HO

1 1

1 1

2 3

4 6OH

O

HO15

O

Ehanedioic acid Propanedioic acid

Butanedioic acid Pentanedioic acid Hexanedioic acid

Physical properties of Carboxylic Acids

1- The carboxyl group contains three polar covalent bonds;

C=O, C-O, and O-H. So they are so polar.

2- Carboxylic acids have higher boiling points than other types of organic compounds (with the same molecular weight) because of hydrogen bonding.

3- They are more soluble in water than alcohols, ethers, aldehydes, and ketones because of stronger hydrogen bonding.

4- Liquid carboxylic acids have sharp and disagreeable odors.

5- They taste sour (exist in pickle, lime, and lemon).

H3C C

O

O

H

CH3C O

O

H- +

+ -

Hydrogen bondingbetween two molecules

Fatty Acids

• Long, unbranched chain carboxylic acids and they are found in animal fats, vegetable oils, or phospholipids of biological membranes.

• Most have between 12 and 20 carbons in an unbranched chain.

• In most unsaturated fatty acids, the cis isomer is usually existed and the trans isomer is rare.

• Unsaturated fatty acids have lower melting points than their saturated counterparts.

COOH

COOH

COOH

COOH

Stearic acid (18:0)(mp 70°C)

Oleic acid (18;1)(mp 16°C)

Linoleic acid (18:2)(mp-5°C)

Linolenic acid (18:3)(mp -11°C)

COOH

COOH

COOH

COOH

Stearic acid (18:0)(mp 70°C)

Oleic acid (18;1)(mp 16°C)

Linoleic acid (18:2)(mp-5°C)

Linolenic acid (18:3)(mp -11°C)

Cis

Fatty Acids

Saturated fatty acids are solids at room temperature.

COOH

COOH

COOH

COOH

COOH

Packed together Maximum London dispersion forces

Fatty Acids

Unsaturated fatty acids are liquids at room temperature.

Can not packed together London dispersion forces

COOH

COOH

COOH

COOH

COOH

Cis

In an ester, the H in the

carboxyl group is replaced

by an alkyl group.

O

CH3 — C—O —CH3

ester group

Esters

• Natural soaps are sodium or potassium salts of fatty acids.

• They are prepared from a blend of tallow and coconut oils (triglycerides).

• Triglycerides are triesters of glycerol.

• the solid fats are melted with steam and the water insoluble triglyceride layer that forms on the top is removed.

Soaps

CH2 – CH – CH2

OH OHOH

1,2,3-Propanetriol(glycerol, glycerin)

• Preparation of soaps begins by boiling the triglycerides with NaOH. The reaction that takes place is called saponification.

• Boiling with KOH gives a potassium soap.

Soaps

Sodium soaps1,2,3-Propanetriol(Glycerol; glycerin)

A triglyceride( a triester of glycerol)

+saponification

+

CH2OCR

CH2OCR

CHOH

CH2OH

CH2OH

RCOCH 3NaOH 3RCO-Na

+O

O

O

O



+saponification

+

CH2OCR

CH2OCR

CHOH

CH2OH

CH2OH

RCOCH 3NaOH 3RCO-Na

+O

O

O

O



+saponification

+

CH2OCR

CH2OCR

CHOH

CH2OH

CH2OH

RCOCH 3NaOH 3RCO-Na

+O

O

O

O

Soaps

Hydrophobic part: nonpolar

Hydrophilic part: polar (remains in contact with environment)

When soap is mixed with dirt (grease, oil, and …), soap

micelles “dissolve” these nonpolar, water-insoluble molecules.

Soaps

Chemical properties of Carboxylic Acids

1- They are weak acids.

Substituents of high electronegativity, especially -OH, -Cl, and -NH3+, near

the carboxyl group increase the acidity of carboxylic acids.

2- Reaction with bases:

They react with NaOH, KOH, NH3, and other strong bases to form water-soluble salts.

COOH NaOHH2O

COO- Na

+H2O+ +

Benzoic acid(slightly soluble in water)

Sodium benzoate(60 g/100 mL water)

COOH NH3H2O

COO- NH4

++

Ammonium benzoate(20 g/100 mL water)

Benzoic acid(slightly soluble in water)

Chemical properties of Carboxylic Acids

3- Fischer Esterification:

- A carboxylic acid reacts with an alcohols to form an ester.

- Using an acid catalyst such as concentrated sulfuric acid.

CH3C-OHO

H-OCH2CH3

H2SO4CH3COCH2CH3

OH2O

Ethanoic acid(Acetic acid)

++

Ethyl ethanoate(Ethyl acetate)

Ethanol(Ethyl alcohol)

The best way to prepare an ester.

Documents

Chapter 16,17 & 18 Amines, Aldehydes, Ketones and Carboxylic Acids Chemistry B11