Ch 12 Alcohol & Thiol

Reactions

Dehydration of Alcohol• An –H and an –OH of adjacent carbon atoms

are removed to form and alkene and water• Heat and an acid catalyst are needed

Oxidation of Alcohol

• Oxidation – loss of H atoms or gain of O2 atoms

• Oxidation occurs when there is an increase in the number of C-O bonds

• In a reduction, the product has fewer bonds between carbon and oxygen

Oxidation of Primary Alcohol

• Primary alcohol produces and aldehyde– Removes 2 –H atoms (1 –H from the –OH and 1 –H

from the carbon bonded to the –OH)– Use the symbol [O] to show oxidizing agent

Oxidation of Primary Alcohol

• Aldehyde oxidizes further with the addition of another O2 to form carboxylic acid– Very fast reaction…not easily isolated in a lab

Oxidation of Secondary Alcohol

• Secondary alcohols produce ketones– Removes 1 –H atom from –OH and 1 –H atom from

the carbon bonded to the –OH

Oxidation of Secondary Alcohol

• Tertiary alcohols do not oxidize – No –H on carbon bonded to –OH– C-C bonds too strong to oxidize

Oxidation of Thiols• Thiols undergo oxidation by a loss of –H from the –SH

group (more than 1 thiol molecule must be present)• Oxidized product is called a disulfide• Factoid – protein in hair is cross-linked by disulfide

bonds– In a ‘perm’…these bonds are broken and then oxidized while

in the rollers so hair forms disulfide bonds in a new shape

Homework

Page 399 (12.18 and 12.20)