Alcohols AS Chemistry lesson 48 Textbook reference: p Next lesson:

Learning outcomes Describe the industrial production of ethanol from both sugars and ethene Outline the uses of ethanol and methanol Explain the terms hydrogen bonding, the water of solubility and the relatively low volatility of alcohols Classify alcohols into primary, secondary and tertiary alcohols

Making alcohol from ethene 1. What is an alcohol? 2. Write out the mechanism for the hydration of ethene using water 3. What are the reacting conditions?

Addition of a hydrogen halide (HBr)

Industrial alcohol Most alcohol that is made is made industrially from the hydration of ethene This is a REVERSIBLE reaction (so when some of it is being made some of it is also being converted back into its products) The reacting conditions: °C atmospheres of pressure 3. Using Phosphoric acid (H 3 PO 4 ) catalyst

Phosphoric acid What is phosphoric acid’s conjugate base?

Alcohol from yeast The traditional way to make ethanol is through FERMENTATION of sugar using yeast This is how all alcohol that is in drinks is made Balance this equation: C 6 H 12 O 6 (aq)  CH 3 CH 2 OH (l) + CO 2 (g)

Fermentation Relies on the enzyme ZYMASE in yeast Most concentrated it can make a solution is 14% alcohol (afterwards the enzyme denatures) Reaction conditions: 37°C Yeast catalysed Anaerobic (no oxygen)

Using alcohol The best way to use ethanol is to drink it However, most ethanol that is made is used as FUEL (up to 10% of petrol in the US is ethanol) Ethanol has a high octane rating What is the octane rating scale? What 2 alkanes does it use in its comparison? Write out the equation for the combustion of ethanol

The octane ratings for different fuels

Methylated spirits Made mostly from ethanol with a small amount of methanol and dye Used as a solvent for removing non-polar stains like paint and ink

Methanol Highly toxic alcohol (but tastes and smells just like ethanol) Sometimes found in illegal versions of spirits Used as a fuel in high performance racing engines Also used as a starting point in industry for making other chemicals

Hydrogen bonding Draw two molecules of ethanol hydrogen bonding with each other with as much detail as possible

What does volatile mean?

Volatility The more volatile something is the lower its boiling point is Alcohols have a much higher boiling point (are less volatile) then their alkane counterparts because of they can H-bond with each other

Solubility Alkanes are insoluble in water (because they are non-polar) The first three alcohols, however, because they can form hydrogen bonds, are soluble Longer chain alcohols are not soluble because too much of the molecule is non- polar

Classes of alcohols &

Types of alcohol There are three classes of alcohol: 1° (Primary) – the OH is on a carbon that is attached to 1 other carbon 2° (Secondary) – The OH is on a carbon attached to two other carbons 3° (Tertiary) – The OH is on a carbon attached to three other carbons