alcohols

Question 1

What are alcohols?

Answer 1

substituted alkanes in which one or more of the hydrogen atoms is replaced with a hydroxyl functional group

Question 2

What can alcohols be prepared from?

Answer 2

-Haloalkanes by substitution
-alkenes by acid-catalysed hydration (addition)
-aldehydes and ketones by reduction using a reducing agent such as lithium aluminium hydride

Question 3

What reactions do alcohols take part in?

Answer 3

-dehydration to form alkenes using aluminium oxide, concentrated sulfuric acid or concentrated phosphoric acid

-oxidation of primary alcohols to form aldehydes and then carboxylic acids and secondary alcohols to form ketones, using acidified permanganate, acidified dichromate or hot copper(Il) oxide

-formation of alcoholic alkoxides by reaction with some reactive metals such as potassium or sodium, which can then be reacted with monohaloalkanes to form ethers

-formation of esters by reaction with carboxylic acids using concentrated sulfuric acid or concentrated phosphoric acid as a catalyst

-formation of esters by reaction with acid chlorides (COCl) -this gives a faster reaction than reaction with carboxylic acids, and no catalyst needed

Question 4

What does the hydroxyl group do?

Answer 4

-make alcohols polar
-gives rise to hydrogen bonding
-explains the properties of alcohols (bp, mp, viscosity, solubility, miscibility in water