Dr. Shatha Alaqeel

ROH ArOHAlcohol Phenol OH SP2

OR HC

SP3

Classification and Nomenclature of alcohols

CH3 OH CH2R OH CHR OH

R'

CR OH

R'

R''

Carbinol Primary alcohol Secondary alcohol Tertiary alcohol

Nomenclature1) Common Nomenclature

Alkyl + alcohol

CH3CH2OH CH2=CHOH CH2=CHCH2OH

Ethyl alcohol Vinyl alcohol Allyl alcohol

2 )IUPAC Nomenclature1) Select the longest continuous

carbon chain to which the hydroxyl is directly attached.

2) Change the name of the alkane corresponding to this chain by dropping the final -e and adding the suffix –ol

3) Number the longest continuous carbon chain so as to give the carbon atom bearing the hydroxyl group the lower number.

CH3CH3

OHCH3

CH3OH

CH3Cl

OH

CH3

4-Ethyl-2-hexanol 5-Chloro-3-methyl-1-heptanol 3-Methyl-1-cyclohexanol

Primary alcohol CH3OH CH3CH2OH

CH2=CHCH2OHCommon Methyl alcohol Ethyl alcohol Allyl

alcoholIUPAC Methanol Ethanol 2-

Propen-1-olSecondary and tertiary alcohol

Isopropyl alcohol Cyclopentyl alcohol

Methylcyclohexyl alcohol 2-Propanol Cyclopentanol 1-Methyl-1-cyclohexanol

CH3 CH CH3

OH

OHCH3

OH

4) OH group is preferred over the double or triple bond in numbering.OH

5-Hepten-2-ol

notice the removal of the (e)

CH3CHC=CH2

CH2CH3

OH

3-Ethyl-3-buten-2-ol

5) If a compound contains both OH and a double or triple bond, choose the chain that include them both even if this is not the longest chain

CH2CH3

OH

CHOH CH3

CH2

CH3OH

3-buten-2-ol 4-Pentyn-1-ol5-Ethyl-5-hexen-3-ol

8

2-Cyclohexenol

4-Chloro-3-methyl-3-octen-1-ol

OH

ClHO

Alcohols containing two hydroxyl groups are commonly called gylcols. In the IUPAC system, the suffix diol is added to the name of the parent hydrocarbon when two hydroxyl groups are present, and the suffix triol is added when there are three OH groups.

OH OH CH3

OHOH

OH

OH

OH

1,2-Ethanediol

Ethylene glycol

1,2-Propanediol

Propylene glycol

1,2,3-Propanetriol

Glycerol or Glycerin

Nomenclature of Phenols2) Compounds that have a hydroxyl group

attached directly to a benzene ring are called phenolsOH OH

NH2

OH

NO2

Br

OH

NO2

NO2

O2N Cl

Cl

ClCl

Cl

OH

Phenol p-Aminophenol 4-Bromo-2-nitrophenol 2,4,6-Trinitrophenol Pentachlorophenol

OH

CH3

OH

CH3

OH

CH3o-Cresol m-Cresol p-Cresol

OH

OH

OH

OH OH

OH OH

OH

OH

Catechol Resorcinol

PyrogallolHydroquinone

Physical Properties of Alcohols & PhenolsSolubility of alcohols The first three members

are completely miscible with water. The solubility rapidly decreases with increase in molecular mass. The higher members are almost insoluble in water but are soluble in organic solvents like benzene, ether etc.

The solubility of lower alcohols is due to the existence of hydrogen bonds between water and polar -OH group of alcohol molecules. Phenols too are sparingly soluble in water. The -OH group in alcohols and phenols contain a hydrogen bonded to an electronegative oxygen atom. Thus they form hydrogen bonds with water molecules.

The solubility increases with branching of chain.

Phenols are sparingly soluble in water but readily soluble in organic solvents such as alcohol and ether.

•Boiling points of alcohols Boiling point of alcohols are much higher than those of alkenes, halo alkenes or ethers of comparable molecular masses. This is because in alcohols intermolecular hydrogen bonding exists due to which a large amount of energy is required to break these bonds.•Among isomeric alcohols, the boiling point

decreases with increase in branching in the alkyl groupBoiling points of 1o alcohol < 2o alcohol < 3o alcohol•As number of hydroxyl groups increase the solubility and boiling points increase.

Alcohols have weak acidic properties.Phenol is a strong acid than alcohols

because the negative charge in oxygen is dispersed by resonance through the benzene ring.

Acidity of Alcohols & Phenols

Introduction of electron-withdrawing groups, such as NO2 or CN, on the ring increases the acidity of phenol, introducing EDG decrease the acidity of phenols

OH

NO2

NO2

O2N

OH

NO2

NO2

> >

OH

NO2

OH

> >

OH

CH3

Alcohols react with Na (or K) like water to give the alkoxide

Preparation of alcoholsPreparation of alcohols1- From alkenes

CH3

+CH3

H

OHOH2H2SO4

KMnO4 / OH-

OH

OH

1) RCO3H

2) H3O+

OH

OH

2- From alkyl halide

3- From aldehyde, ketone and carboxylic acid

Cl dil KOHOH

CH3

CH3

CH3BrOH2

CH3

CH3

CH3OH

R C

O

H

1) LiAlH4 0r NaBH4

2) H3O+

R CH2 OH

1) LiAlH4 0r NaBH4

2) H3O+

R CH OH

R'

R C R'

O

R C

O

OH

1) LiAlH4

2) H3O+

R CH2 OH

4- From Grignard reagent

R C

O

H

R CH OH

R'

R C OH

R'

R''

R C R'

O

R C

O

OR'

R C OH

R''

R''

+ R'MgX1) Dry ether

2) H2O

+ R''MgX

+ 2 R''MgX

1) Dry ether

2) H2O

1) Dry ether

2) H2O

CH3 C

O

H

CH3 CH

OH

C2H5+ C2H5MgX1) Dry ether

2) H2O

+ CH3MgX1) Dry ether

2) H2O

OCH3

OH

CH3 C

O

OC2H5

CH3 C OH

CH3

CH3

+ 2 CH3MgX 1) Dry ether

2) H2O

Preparation of Phenols1- Hydrolysis of Diazonium salts

2- Fusion of sodium with benzene-sulfonates:

3- From alkyl halide:

N2+Cl

-

H2SO4 / H2O

Heat

OH

+ N2

SO3H

NaOH / 350

O-Na

+

H3O+

OH

Cl

NaOH / 350

O-Na

+

H3O+

OH

300 atm

Reaction of Alcohols and PhenolsReaction of Alcohols and Phenols1- Salt Formation

R OH + 2 Na R O-Na

+2 + H2

Sodium alkoxideAlcohol as acid

CH3 OH + Na CH3 O-Na

+

Sodium MethoxideMethanol

2

OH

+ Na

O-Na

+

Sodium Phenoxide

2- Dehydration

3- Ester formation

CH3 CH3

OH

CH2CH3

CH3 CH3

+ OH2

+ OH2

1-Butene minor

2-Butene major

R C

O

OHR C

O

OR'

+ R'OHH

+

+ OH2

COOH

+ CH3OHH

+C

O

OCH3

+ OH2

4- Reaction with alkyl halide

R OH + HX or SOX2 , PX3, PX5 Heat

R XZnCl2

H H

R C O + [O] R C O + H2O

H H

H H

R C O + [O] R C O + H2O

R R

R H

R C O + [O]

R

This is possible in 1° and 2° alcohols but not in 3° alcohols.

1°

2°

3°

21

For oxidation to take place easily you must have two hydrogen atoms on adjacent C For oxidation to take place easily you must have two hydrogen atoms on adjacent C and O atoms.and O atoms.

Alcohols can be oxidised depending on their classAlcohols can be oxidised depending on their class5)5) Oxidation Of AlcoholsOxidation Of Alcohols

R CH2 OHCu or CrO3 / pyridine

heat

OR

HPrimary alcohol adehyde

CH3 CH2 OHCu or CrO3 / pyridine

heat

OCH3

H

weak oxidizing reagent

R CH2 OHH2Cr2O7 or K2Cr2O7/ H

+

or KMnO4 / heat

OR

OHPrimary alcohol carboxylic acid

R CH OH

R'

K2Cr2O7 or KMnO4

heat

OR

R'Secondary alcohol ketone

OHOK2Cr2O7 / H

+

R C OH

R'

R''

H2CrO7 / H+

heat

Tertiary alcohol

No reaction

OH

H2CrO7 or Na2CrO7 / H+

or KMnO4 / heat

O

O

OH

OHPhenolp-Benzoquinone Hydroquinone

KMnO4 / heat

6- Reaction of aromatic ring of phenols

OH

Br2 / H2O

OH

Br

BrBr

Br2 / CCl4

Br

OH

+Br

OH

dil HNO3

O2N

OH

+NO2

OH

conc HNO3

OH

NO2

NO2

O2N

conc H2SO4

OH

SO3H

+

OH

SO3H