CHAPTER 7

FUNCTIONAL GROUP

• Naming the groups of alcohol,phenol,carbonyls, carboxyls and amines compounds.

• Write the reaction mechanism and give examples of reaction of alcohol,phenol,carbonyls,carboxyls and amines compounds.

Learning Course Outline

NOMENCLATURE

• Oxygen is sp3 hybridized and tetrahedral.• The H—O—H angle in water is 104.5°. • The C—O—H angle in methyl alcohol is 108.9°.• General classifications of alcohols based on substitution on C to

which OH is attached

ALCOHOL & PHENOL

• Find the longest carbon chain containing the carbon with the —OH

group.

• Drop the -e from the alkane name; add -ol.

• Number the chain, giving the —OH group the lowest number

possible.

• Number and name all substituents and write them in alphabetical

order.

IUPAC Nomenclature

ALCOHOL & PHENOL

Examples of Nomenclature

Old: 2-methyl-1-propanolNew: 2-methylpropan-1-ol

Old: 2-methyl-2-propanolNew: 2-methylpropan-2-ol

Old: 2-butanolNew: butan-2-ol

C H3 C

C H3

C H3

OH

CH3 CH

CH3

CH2OH CH3 CH

OH

CH2CH3

3 2 1 1 2 3 4

2 1

ALCOHOL & PHENOL

Alkenols (Enols)

• Hydroxyl group takes precedence. Assign the carbon with the —OH the lowest number.

• End the name in -ol, but also specify that there is a double bond by using the ending -ene before –ol.

Old: 4-penten-2-ol New: pent-4-ene-2-ol

CH2 CHCH2CHCH3

OH

ALCOHOL & PHENOL

ALCOHOL & PHENOL

Naming Priority

1. Acids2. Esters3. Aldehydes4. Ketones5. Alcohols6. Amines 7. Alkenes and Alkynes8. Alkanes9. Ethers10. Halides

Highest ranking

Lowest ranking

• When —OH is part of a higher priority class of compound, it is

named as hydroxy.

Hydroxy Substituent

4-hydroxybutanoic acid

C H2C H2C H2C OOH

OH

carboxylic acid

4 3 2 1

ALCOHOL & PHENOL

• Alcohol can be named as alkyl alcohol.• Useful only for small alkyl groups.

Common Names

isobutyl alcohol

IUPAC: 2-methylpropan-1-ol

sec-butyl alcohol

IUPAC: butan-2-ol

CH3 CH

CH3

CH2OH CH3 CH

OH

CH2CH3

ALCOHOL & PHENOL

ALCOHOL & PHENOL

Naming Diols

• Two numbers are needed to locate the two

—OH groups.

• Use -diol as suffix instead of -ol.hexane-1,6-diol

1 2 3 4 5 6

Glycols

• 1,2-diols (vicinal diol) are called glycols.

• Common names for glycols use the name of the alkene from which

they were made.

IUPAC: ethane-1,2-diol

ethylene glycol

IUPAC: propane-1,2-diol

propylene glycol

• Phenol, C6H5OH (―phenyl alcohol‖) has diverse uses - it gives

its name to the general class of compounds

• OH groups bonded to vinylic sp2-hybridized carbons are called

enols

• —OH group is assumed to be on carbon 1.

• For common names of disubstituted phenols, use ortho- for 1,2;

meta- for 1,3; and para- for 1,4.

• Methyl phenols are cresols.

Phenol Nomenclature

3-chlorophenol

(meta-chlorophenol)

4-methylphenol

(para-cresol)

OH

Cl

OH

H3C

CLASSES OF CARBONYL COMPOUNDS

• The functional group of carboxylic acids consists of a C═O with —

OH bonded to the same carbon.

• Carboxyl group is usually written —COOH.

• Aliphatic acids have an alkyl group bonded to —COOH.

• Aromatic acids have an aryl group.

• The compound named as –oic acid replacing the –e naming of

alkane - IUPAC

• Common name of acids end in –ic acid

CARBOXYLIC ACIDS

CARBOXYLIC ACIDS

Nomenclature

CARBOXYLIC ACIDS

17

In systematic nomenclature, the carbonyl carbon is always C-1

In common nomenclature, the carbon next to the carbonyl is the a-carbon

CARBOXYLIC ACIDS

CARBOXYLIC ACIDS

19

The functional group of a carboxylic acid is called a carboxyl group

CARBOXYLIC ACIDS

• Aldehydes (RCHO) and ketones (R2CO) are characterized by the

carbonyl functional group (C=O)

• The compounds occur widely in nature as intermediates in

metabolism and biosynthesis

ALDEHYDES AND KETONES

• Much of organic chemistry involves the chemistry of carbonyl compounds

• Aldehydes/ketones are intermediates in synthesis of pharmaceutical agents, biological pathways, numerous industrial processes

• An understanding of their properties is essential

ALDEHYDES AND KETONES

Aldehydes are named by replacing the terminal –e of the

corresponding alkane name with –al

The parent chain must contain the –CHO group

The –CHO carbon is numbered as C1

If the –CHO group is attached to a ring, use the suffix

carbaldehyde

ALDEHYDES AND KETONES

ALDEHYDES

• Replace the terminal -e of the alkane name with –one• Parent chain is the longest one that contains the ketone group

– Numbering begins at the end nearer the carbonyl carbon

• The carbonyl is assumed to be at the 1-position in cyclic ketones:

KETONES

25

KETONES

If a ketone has a second functional group of higher priority…

Common Names:• IUPAC retains well-used but unsystematic names for a few ketones

KETONES

• On a molecule with a higher-priority functional group, a ketone is an oxo and an aldehyde is a formyl group.

• Aldehydes have a higher priority than ketones.

Carbonyl as Substituent

• Organic derivatives of ammonia, NH3

• Nitrogen atom with a lone pair of electrons, making amines both basic and nucleophilic

• Occur in plants and animals

AMINES

• Primary (1): Has one alkyl group bonded to the nitrogen (RNH2).• Secondary (2): Has two alkyl groups bonded to the nitrogen

(R2NH).• Tertiary (3): Has three alkyl groups bonded to the nitrogen (R3N). • Quaternary (4): Has four alkyl groups bonded to the nitrogen and

the nitrogen bears a positive charge (R4N+).

Classes of Amines

AMINES

AMINES

Quaternary Ammonium Salts

• The nitrogen atom has four alkyl groups attached.

• The nitrogen is positively charged.

AMINES

Common Names

• Common names of amines are formed from the names of the

alkyl groups bonded to nitrogen, followed by the suffix -amine.

• Name is based on longest carbon chain.

• The -e of alkane is replaced with -amine.

IUPAC Names

AMINES

Amine as Substituent

• On a molecule with a higher-priority functional group, the amine

is named as a substituent.

AMINES

AMINES

Aromatic Amines

• In aromatic amines, the amino group is bonded to a benzene

ring.

• Parent compound is called aniline.

Heterocyclic Amines

When naming a cyclic amine, the nitrogen is assigned position number 1.

AMINES

REACTION

• Dehydration to alkene

• Oxidation to aldehyde, ketone

• Substitution to form alkyl halide

• Esterification

• Tosylation

• Williamson synthesis of ether

Types of Alcohol Reactions

REACTION : ALCOHOLS

Summary Table

• The general reaction: forming an alkene from an alcohol through loss of O-H and H (hence dehydration) of the neighboring C–H to give bond

• Specific reagents are needed

1) Dehydration of Alcohols to Yield Alkenes

• Phosphorus oxychloride in the amine solvent pyridine can lead to

dehydration of secondary and tertiary alcohols at low temperatures

• An E2 reaction via an intermediate ester of POCl2

Dehydration with POCl3

• Can be accomplished by inorganic reagents, such as KMnO4, CrO3,

and Na2Cr2O7 or by more selective, expensive reagents

2) Oxidation Of Alcohols

• To form aldehyde: pyridinium chlorochromate (PCC, C5H6NCrO3Cl) in dichloromethane

• Other reagents produce carboxylic acids

Oxidation of Primary Alcohols

• Effective with inexpensive reagents such as cromic acid reagent,

Na2Cr2O7 in acetic acid

• PCC is used for sensitive alcohols at lower temperatures

• Product is ketones

Oxidation of Secondary Alcohols

• Conversion of alcohols into alkyl halides:

- 3˚ alcohols react with HCl or HBr by SN1 through carbocation

intermediate

- 1˚ and 2˚ alcohols converted into halides by treatment with SOCl2 or

PBr3 via SN2 mechanism

3) Substitution Of Alcohols

Reactions of 1˚ and 2˚ alcohols

5) Esterification

• Reaction of an alcohol and a carboxylic acid produces an ester.

• Sulfuric acid is a catalyst.

• The reaction is an equilibrium between starting materials and

products, and for this reason the Fischer esterification is seldom

used to prepare esters.

Reaction of Alcohols with Acyl Chlorides

• The esterification reaction achieves better results by reacting

the alcohol with an acyl chloride.

• The reaction is exothermic and produces the corresponding

ester in high yields with only HCl as a by-product.

Esterification cont..

6) Tosylation

• Alcohols can be converted to tosylate esters (ROTs) through a

condensation with p-toluenosulfonic acid.

• The tosylate group is an excellent leaving group.

Substitution and Elimination Reactions Using Tosylates

7) Alkoxide Ions: Williamson Ether Synthesis

• Ethers can be synthesized by the reaction of alkoxide ions with

primary alkyl halides in what is known as the Williamson ether

synthesis.

• This is an SN2 displacement reaction and as such, works better

with primary alkyl halides to facilitate back-side attack.

• If a secondary or tertiary alkyl halide is used, the alkoxide will

act as a base and an elimination will take place.

• Undergoes the same reaction of aromatic substitution.

• Type of rxns:

– Formation of ether

– Cleavage of alkyl aryl ethers

– Bromination

– Nitration

REACTION : PHENOLS

• Phenol can be converted to ether through Williamson synthesis

• Phenols react with alkyl halides in alkali solution to form phenyl

ethers

– The alkali first forms the phenoxide ion which react with aklyl

halide

1) Formation of Ether

Ar-OH Ar-Ona Ar-O-R + NaXNaOH R - X

CH3

OH ONa

CH3

OCH2CH3

CH3

NaOH CH3CH2I

• Alkyl aryl ether reacts with strong acid such as HI and HBr –

produce alkyl halide and a phenol

2) Cleavage Of Aklyl Aryl Ethers

Ar-O - R Ar-O-R + NaXconc. acid

CH3 OCH3 CH3 OH

HBr

• Hydroxyl group is powerful activating group and o,p director

• Phenol reacts with bromine water (aqueous bromine) to give

precipitate of 2,4,6-trinitrophenol

3) Bromination

OH OH

Br

Br

Br3Br

H2OBrH+

• If the reaction carried out in carbon disulfide (CS2) at low

temperature, monobromination of phenol can be formed.

OH OH

Br

+Br2

OH

CH3

CS2

• Phenol reacts with dilute nitric acid to yield mix of o,p product

4) Nitration

• If phenol reacts with concentrated nitric acid, picric acid is formed

OH OH

O2N

+

OH

NO2

HNO3

H2SO4

OH OH

O2N NO2

NO2

conc HNO3

REACTION: CARBOXYLIC ACIDS

• Oxidation of a substituted alkylbenzene with KMnO4 or Na2Cr2O7

gives a substituted benzoic acid

• 1° and 2°alkyl groups can be oxidized, but tertiary groups are not

Preparing Carboxylic Acids

• Oxidative cleavage of an alkene with KMnO4 gives a carboxylic acid

if the alkene has at least one vinylic hydrogen

From Alkenes

• Oxidation of a primary alcohol or an aldehyde with CrO3 in aqueous

acid

From Alcohols

1) Fischer Esterification

• Reaction of a carboxylic acid with an alcohol under acidic

conditions produces an ester.

• Reaction is an equilibrium; the yield of ester is not high.

• To drive the equilibrium toward the formation of products, use a

large excess of alcohol.

2) Synthesis of Amides

• The initial reaction of a carboxylic acid with an amine gives an

ammonium carboxylate salt.

• Heating this salt to well above 100 °C drives off steam and forms

an amide.

3) LiAlH4 or BH3 Reduction of Carboxylic Acids

• LiAlH4 reduces carboxylic acids to primary alcohols. • The intermediate aldehyde reacts faster with the reducing agent

than the carboxylic acid.• Borane can also reduce the carboxylic acid to the alcohol.

4) Synthesis of Acid Chlorides

• The best reagents for converting carboxylic acids to acid

chlorides are thionyl chloride (SOCl2) and oxalyl chloride

(COCl2).

• They form gaseous by-products that do not contaminate the

product.

5) Conversion of Carboxylic Acids to Ketones

• A general method of making ketones involves the reaction of a carboxylic acid with two equivalents of an organolithium reagent.

REACTION: ALDEHYDE & KETONE

The partial positive charge on the carbonyl carbon causes that carbon to

be attacked by nucleophiles:

An aldehyde has a greater partial positive charge on its carbonyl carbon than

does a ketone:

65

• The carbonyl carbon of an aldehyde is more accessible to the nucleophile.

• Ketones have greater steric crowding in their transition states, so they have

less stable transition states.

• Steric factors contribute to the reactivity of an aldehyde.

Aldehydes Are More Reactive Than Ketones

1) Formation of Acetals

2) Oxidation of Aldehydes

Aldehydes are easily oxidized to carboxylic acids.

3) Reduction using Sodium Borohydride

• NaBH4 can reduce ketones and aldehydes, but not esters,

carboxylic acids, acyl chlorides, or amides.

4) Reduction using Lithium Aluminum Hydride

R R(H)

OH

HR R(H)

O

LiAlH4

ether

aldehyde or ketone

• LiAlH4 can reduce any carbonyl because it is a very strong

reducing agent.

• Difficult to handle

5) Additon of Hydrogen

Hydrogen cyanide adds to aldehydes and ketones to form cyanohydrins:

+ HCN