Alcohols

Alcohols can be primary, secondary or tertiary. It is decided on which group the OH is bonded to, and how many methyl groups there are. If there is 3 methyl groups and the OH is bonded to one of them, it is tertiary

Ethanol can be produced via fermentation, this is how -

• Fermentation is exothermic reaction, carried out by yeast anaerobically (no oxygen required)
• Yeast produces an enzyme which converts sugars (glucose). This enzymes optimum work rate is at 30-40 degrees celsius
• If it is too hot or cold, the enzyme will denature and stop working
• When the solution reaches about 15% ethanol, the yeast dies

Advantages - Cheap, uses renewable sources

Disadvantages - High labour costs, very impure, very slow

Ethanol is almost a carbon neutral fuel. This means that the CO2 released when the fuel was burned was removed by the crop as it grew. But its not 100% carbon neutral, take into account the whole process, the machines used and the fertilisers.

You can make ethene by eliminating water from ethanol in a dehydration reaction.

This reaction allows you to produce alkenes from a renewable source

Primary Alcohols oxidise into Aldehyde's and Carboxcylic acid's

Aldehyde's have a hydrogen and a oxygen (double bonded) to a carbon, must be the first carbon. This is the functional group of an aldehyde.

An aldehyde can then be vigorously oxidised into a carboxcylic acid. The functional group of a carboxcylic acid is COOH.

How to oxidise a primary alcohol -

• Gently heat the ethanol with acidified potassium dichromate (IV)
• To just get an aldehyde, you need to remove the solution as soon as its formed. You can do this via distillation
• To produce a carboxcylic acid, you need to oxidise the solution vigorously.
• The solution has oxidising agents added to it under reflux. Once the vaporised solutions are cooled, they are carboxcylic acids.

A secondary alcohol oxidises into a Ketone. A functional group of a ketone is =O

When refluxing a secondary alcohol, it forms a ketone. You must mention that you oxidise it with acidified potassium dichromate (IV)

Tertiary alcohols do not oxidise unless burnt.

How to distinguish between secondary/primary -

• Fehlings solution and Benedicts solution are both deep blue copper complexes, which reduce to brick red when warmed with an aldehyde, but stay blue with a ketone
• Tollens reagent is reduced to a silver mirror when warmed with an aldehyde but does not change with a ketone. The silver will coat the inside of apparatus.
• Limewater fizzes and goes cloudy when a carboxcylic acid is present.