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Classification and Identification of Alcohols and Phenols.

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Classification and Identification of Alcohols and Phenols
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Page 1: Classification and Identification of Alcohols and Phenols.

Classification and Identification of Alcohols and Phenols

Page 2: Classification and Identification of Alcohols and Phenols.

Types of Alcohols

Alcohols may be classified as either primary, secondary or tertiary depending on the number of carbon-containing groups attached to the

carbon- bearing hydroxyl group.

R CH2 OH

Primary Alcohol

CH R'

OH

Secondary Alcohol

R

R C

R'

R''

OH

Tertiary Alcohol

Page 3: Classification and Identification of Alcohols and Phenols.

Examples of Alcohols

CH3CH2 OH

ethanola primary alcohol

H3CHC

CH3

OH

2-propanola secondary alcohol C

CH3

H3C

CH3

OH

2-methyl-2-propanola tertiary alcohol

Page 4: Classification and Identification of Alcohols and Phenols.

Phenols

A phenol has a hydroxyl group bonded directly to a carbon that is part of an aromatic ring.

OH

phenol

CH3

OH

CH

CH3H3C

2-isopropyl-5-methylphenol

Page 5: Classification and Identification of Alcohols and Phenols.

Properties of Alcohols and Phenols

• Alcohols and phenols are polar because of the hydroxyl group

• The polar side and hydrogen bonding allows them to dissolve in water

• The non-polar side allows them to dissolve in certain organic solvents

• Alcohols are not acidic• Phenols are acidic

OR

H

O H

HHydrogen bonding of the hydroxyl group with water

Page 6: Classification and Identification of Alcohols and Phenols.

Chemical Properties

A series of tests can be used to distinguish between alcohol types and phenols:

• Solubility• pH• Lucas Test• Chromic Acid Test• Iodoform Test• Iron(III)chloride Test

Page 7: Classification and Identification of Alcohols and Phenols.

Lucas Test

Used to distinguish between a primary, secondary and tertiary alcohol.

CH3CH2 OH + HCl + ZnCl2 No reaction

Primary alcohol

(CH3)2CH OH + HCl + ZnCl2 (CH3)2CH Cl + H2O (10 min. heat)Secondary alcohol Insoluble

(CH3)3C OH + HCl + ZnCl2 (CH3)3C Cl + H2O (< 5 min.)

Tertiary alcohol Insoluble

Page 8: Classification and Identification of Alcohols and Phenols.

Chromic Acid Test

Used to distinguish primary and secondary alcohols from tertiary alcohols.

Phenols produce a brown tarry mass when combined with chromic acid.

CH3CH2 OH + 4H2CrO4 + 6H2SO43 H3C C OH

O

+ 2Cr2(SO4)3 + 13H2O3

Primary alcohol Brown-red Carboxylic acid Blue-green

H3C CH

OH

CH3 +3 2H2CrO4 + 3H2SO4 3H3C C CH3

O

+ Cr2(SO4)3 + 8H2O

Secondary alcohol Brown-red Ketone Blue-green

(CH3)3C OH + H2CrO4 + H2SO4 No reaction

Tertiary alcohol Brown-red

Page 9: Classification and Identification of Alcohols and Phenols.

Iodoform Test

This test is used to distinguish alcohols with the partial structure R-CH3CH(OH) from other alcohols. Phenols also react.

R CHCH3

OH

+ 4I2 + 6NaOH R C O-Na+

O

+ 5NaI + 5H20 + HCI3 (s)

Iodoformyellow

OH

+ 3I2

I

OH

II

+ 3HI

Triiodophenolyellow precipitate

Page 10: Classification and Identification of Alcohols and Phenols.

Acidity of Phenol

Phenols are acidic and dissolve in a basic solution. Alcohols are not acidic and will not dissolve in a basic solution.

OH O-

+ +HO- H2O

Page 11: Classification and Identification of Alcohols and Phenols.

Iron(III) Chloride Test

This test distinguishes between alcohols and phenols.

OOHFe

Cl

Cl+ +FeCl3 HCl

Light yellow Violet color

The resulting color change can vary from green to purple.

Alcohols produce no color change.

Page 12: Classification and Identification of Alcohols and Phenols.

Caution!

• Chromic acid is very corrosive.

• Phenols are toxic, avoid skin contact.

• Your instructor will dispense all of the chromic acid as well as police the hazardous waste.

DO NOT THROW ANY CHEMICALS DOWN THE DRAIN!!!

EACH HAS AN APPROPRIATE WASTE CONTAINER IN THE HOOD!!

Page 13: Classification and Identification of Alcohols and Phenols.

Potential Health Effects

• Inhalation: difficulty breathing, sore throat, coughing, dizziness, dullness, headache, drowsiness, sneezing, wheezing, central nervous system depression, narcosis, unconsciousness, choking, inflammation of the upper respiratory system, pulmonary edema, circulatory failure, coma, increased sweating, pulmonary edema, reduced body temperature, euphoria, cyanosis, tissue necrosis, convulsion, chemical pneumonitis and death

• Ingestion: sore throat, narcosis, abdominal pain, nausea, headache, dizziness, diarrhea, kidney damage, liver damage, hearing damage, burns and inflammation of the mouth, throat, esophagus and stomach, brown stains around the mouth, low blood pressure, tachycardia, vomiting , muscular weakness, increased sweating and death

• Skin contact: sensitization, irritant, redness, pain, drying, cracking, defatting of the skin ulcers, rash and can be absorbed through the skin

• Eye contact: stinging, tearing, redness, pain of the eyes, blurred vision, corneal damage and blindness

• Tumorigens, mutagens, carcinogens and reproductive effectors


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