Coupon Accepted Successfully!


Formation of Alkoxides

Alcohols when treated with Group I metals like sodium and potassium result in alkoxides.

Sample reaction

image\Ch 21 sam 21-5.png

Formation of Alkyl Halides

Sample reaction

image\Ch 21 sam 21-6.png

Sample reaction

image\Ch 21 sam 21-7.png

Oxidation of Alcohols

Primary alcohols can be oxidized to aldehydes by reagents like pyridinium dichromate (PDC), and pyridinium chlorochromate (PCC).

Sample reaction

image\Ch 21 sam 21-8.png

Secondary alcohols can also be oxidized. The product is a ketone.

Sample reaction

image\Ch 21 sam 21-9.png

Since tertiary alcohols do not have a hydrogen atom in the carbon carrying the hydroxyl group, they cannot be easily oxidized.
Strong oxidizing agents can oxidize alcohols to carboxylic acids. We can use potassium permanganate or chromic acid to do this conversion.

Sample reaction

image\Ch 21 sam 21-10.png


image\26288 ch 21.png

Acid-Catalyzed Dehydration

Alcohols undergo acid-catalyzed dehydration reactions to form alkenes. The reaction is accomplished by the formation of a carbocation intermediate. Thus there is the possibility of rearrangement in the process. First, we will take a look at the mechanism of this reaction.

Mechanism of Acid-Catalyzed Dehydration of Alcohols

Sample reaction

image\Ch 21 sam 21-11.png

The formation of carbocation.

image\Ch 21 sam 21-11b.png

The formation of double bond.

image\Ch 21 sam 21-11c.png

Rearrangement – An Example

Organic chemists have conducted experiments to understand the formation of multiple products in acid-catalyzed reactions such as that of 3,3-dimethyl-2-butanol. Let's consider the acid-catalyzed dehydration reaction of 3,3-dimethyl-2-butanol and explore the possibility of rearrangement.

image\26322 ch 21.png

image\Ch 21 fig 21-2.png

Figure 21-2

The major product formed in this reaction is 2,3-Dimethyl-1-butene. Notice (Figure 21-2) the rearrangement that occurs in this reaction. The rearrangement results in a more stable carbocation (A tertiary carbocation is more stable than a secondary carbocation).

Test Your Skills Now!
Take a Quiz now
Reviewer Name