4.8 Alcohols and alcohol related reactions

What are the 3 main types of reaction regarding alcohols

• Hydration reaction

• Dehydration reaction

• Substitution reaction

What is a hydration reaction

A hydration reaction is the process of converting an alkene into alcohol by adding water and a proton catalyst

What is a dehydration reaction

a dehydration reaction is the process of reacting an alcohol with an H₂SO₄ catalyst to convert it into an alkene and water

What is a substitution reaction

A substitution reaction is the reaction of an alcohol with a concentrated hydrogen halide to form an alkyl halide and water

• The OH group and the halogen directly swap places regardless of markovnikov’s rule

How to reverse a substitution reaction?

React the produced alkyl halide with a strong base to form an alcohol and water.

• The OH and the halogen will directly swap regardless of Markovnikov's rule

What are the three steps to naming an alcohol?

• Step 1: Change the ending of the parent name from "-e" to "-ol."

• Step 2: Alcohols take priority over alkyls, halogens, and double/triple bonds and thus must be given the lowest possible carbon number

• Step 3: Different future-looking functional groups will take priority over alcohols; when this occurs, alcohols take the name "hydroxyl."

NOTE: Alcohols must always be linked to the parent chain; this may cause a scenario where the parent chain is shorter than a side group present in the compound (see example 2 under challenging nomenclature)

What is the polarity and solubility of alcohols?

O-H bonds have a high EN difference and thus are highly polar. This allows for hydrogen bonds to form in alcohols, thus allowing them to be incredibly soluble.

However, as the parent chain of an alcohol gets longer, the neutrality of C-H bonds overwhelms the polarity of the O-H bond, making the molecule increasingly more neutral.

• As a result, the longer the parent chain of an alcohol, the less soluble it becomes.

What is the difference between the M/B points of alcohols vs alkanes with the same number of carbons?

Because of the hydrogen bonds possessed by alcohols, alcohols have higher M/B points than alkanes with the same number of carbons

• This difference between them decreases as the length of the parent chain increases.

• M/B points in alcohols also decrease as branching on an alcohol decreases.