Alcohols

What is the functional group of alcohols?

-OH

What is the general formula for alcohols?

CnH2n+1OH

What is a primary alcohol?

An alcohol which has one carbon bonded to the one with the -OH group

What is a secondary alcohol?

An alcohol which has two carbons bonded to the one with the -OH group

Why do alcohols have a much higher boiling point than alkanes?

They have hydrogen bonding between molecules which is much stronger than the vdw forces in alkanes

Why do short chain alcohols dissolve in water?

The -OH group bonds with water but not the rest of the chain

What 2 ways can ethanol be made?

Fermentation

Electrophilic addition of alkenes

Why is fermentation a renewable process?

It uses sugar, which can be regrown quickly

What conditions are required for fermentation?

35 degrees

dissolved sugar

anaerobic conditions

What is an elimination reaction?

A reaction where a small molecule is removed from an organic molecule

What are the conditions for an elimination reaction of alcohols?

Excess concentrated sulfuric acid or aluminium oxide

Describe the mechanism for elimination of alcohols.

1. The H+ ion bonds to the lone pair of electrons on the oxygen

2. The oxygen is now making too many bonds, so the electrons in the C-O bond move to the oxygen and the water molecule leaves

3. The electrons in the adjacent C-H bond move to the C-C bond to create a double bond

What products are formed in an elimination reaction with alcohols?

Water and an alkene

What do primary alcohols oxidise into?

Aldehydes and carboxylic acids

State the reaction for the oxidation of alcohols into aldehydes.

alcohol + [O] —→ aldehyde +H2O

State the reaction for the oxidation of aldehydes into carboxylic acids.

aldehyde + [O] —→ carboxylic acid

What do secondary alcohols oxidise into?

Ketones

State the equation for the oxidation of alcohols into ketones.

alcohol + [O] —→ ketone + H2O

What oxidising agent is used in the oxidation of alcohols?

acidified potassium dichromate IV

What conditions are used to oxidise an alcohol into an aldehyde?

Distillation apparatus

Excess alcohol

What conditions are used to oxidise an alcohol into a carboxylic acid?

Reflux conditions

Excess oxidising agent

What is a carbonyl group?

C=O

Where is the carbonyl group in an aldehyde?

At the end of the chain

Where is the carbonyl group in an ketone?

In the middle of the chain

How does tollen’s reagent identify an aldehyde?

The Ag+ ions are reduced when reacting with an aldehyde and a silver mirror is formed

How does fehling’s solution identify an aldehyde?

the blue copper (II) ions change into a brick red copper (I) precipitate when the aldehyde is oxidised