AlcoholsAlcohols

AS Chemistry lesson 48AS Chemistry lesson 48

Textbook reference: p148-151Textbook reference: p148-151

Next lesson: 152-155Next lesson: 152-155

Learning outcomesLearning outcomes

Describe the industrial production of Describe the industrial production of ethanol from both sugars and etheneethanol from both sugars and ethene

Outline the uses of ethanol and methanolOutline the uses of ethanol and methanol

Explain the terms hydrogen bonding, the Explain the terms hydrogen bonding, the water of solubility and the relatively low water of solubility and the relatively low volatility of alcoholsvolatility of alcohols

Classify alcohols into primary, secondary Classify alcohols into primary, secondary and tertiary alcoholsand tertiary alcohols

Making alcohol from etheneMaking alcohol from ethene

1.1. What is an alcohol?What is an alcohol?

2.2. Write out the mechanism for the Write out the mechanism for the hydration of ethene using waterhydration of ethene using water

3.3. What are the reacting conditions?What are the reacting conditions?

Addition of a hydrogen halide (HBr)Addition of a hydrogen halide (HBr)

Industrial alcoholIndustrial alcohol

Most alcohol that is made is made industrially Most alcohol that is made is made industrially from the hydration of ethenefrom the hydration of ethene

This is a REVERSIBLE reaction (so when This is a REVERSIBLE reaction (so when some of it is being made some of it is also some of it is being made some of it is also being converted back into its products)being converted back into its products)

The reacting conditions:The reacting conditions:

1.1. 300300°C °C

2.2. 60 atmospheres of pressure60 atmospheres of pressure

3.3. Using Phosphoric acid (HUsing Phosphoric acid (H33POPO44) catalyst) catalyst

Phosphoric acidPhosphoric acid

What is phosphoric acid’s conjugate base?What is phosphoric acid’s conjugate base?

Alcohol from yeastAlcohol from yeast

The traditional way to make ethanol is The traditional way to make ethanol is through through FERMENTATIONFERMENTATION of sugar using of sugar using yeastyeast

This is how all alcohol that is in drinks is This is how all alcohol that is in drinks is mademade

Balance this equation:Balance this equation:

CC66HH1212OO66 (aq) (aq) CHCH33CHCH22OH (l) + OH (l) + COCO22 (g) (g)

FermentationFermentation

Relies on the enzyme ZYMASE in yeastRelies on the enzyme ZYMASE in yeast

Most concentrated it can make a solution Most concentrated it can make a solution is 14% alcohol (afterwards the enzyme is 14% alcohol (afterwards the enzyme denatures)denatures)

Reaction conditions: Reaction conditions:

3737°C°C

Yeast catalysedYeast catalysed

Anaerobic (no oxygen)Anaerobic (no oxygen)

Using alcoholUsing alcohol

The best way to use ethanol is to drink itThe best way to use ethanol is to drink it

However, most ethanol that is made is used as However, most ethanol that is made is used as FUELFUEL (up to 10% of petrol in the US is ethanol) (up to 10% of petrol in the US is ethanol)

Ethanol has a high octane ratingEthanol has a high octane rating

What is the octane rating scale? What 2 alkanes What is the octane rating scale? What 2 alkanes does it use in its comparison?does it use in its comparison?

Write out the equation for the combustion of Write out the equation for the combustion of ethanol ethanol

The octane ratings for different The octane ratings for different fuelsfuels

Methylated spiritsMethylated spirits

Made mostly from ethanol Made mostly from ethanol with a small amount of with a small amount of methanol and dyemethanol and dye

Used as a solvent for Used as a solvent for removing non-polar stains removing non-polar stains like paint and inklike paint and ink

MethanolMethanol

Highly toxic alcohol (but tastes and smells Highly toxic alcohol (but tastes and smells just like ethanol)just like ethanol)

Sometimes found in illegal versions of Sometimes found in illegal versions of spiritsspirits

Used as a fuel in high performance racing Used as a fuel in high performance racing enginesengines

Also used as a starting point in industry for Also used as a starting point in industry for making other chemicalsmaking other chemicals

Hydrogen bondingHydrogen bonding

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

What does volatile mean?What does volatile mean?

VolatilityVolatility

The more volatile something is the lower The more volatile something is the lower its boiling point isits boiling point is

Alcohols have a much higher boiling point Alcohols have a much higher boiling point (are less volatile) then their alkane (are less volatile) then their alkane counterparts because of they can H-bond counterparts because of they can H-bond with each otherwith each other

SolubilitySolubility

Alkanes are insoluble in water (because Alkanes are insoluble in water (because they are non-polar)they are non-polar)

The first three alcohols, however, because The first three alcohols, however, because they can form hydrogen bonds, are solublethey can form hydrogen bonds, are soluble

Longer chain alcohols are not soluble Longer chain alcohols are not soluble because too much of the molecule is non-because too much of the molecule is non-polarpolar

Classes of alcoholsClasses of alcohols

&

Types of alcoholTypes of alcohol

There are three classes of alcohol:There are three classes of alcohol:

1° (Primary) – the OH is on a carbon that is 1° (Primary) – the OH is on a carbon that is attached to 1 other carbonattached to 1 other carbon

22° (Secondary) – The OH is on a carbon ° (Secondary) – The OH is on a carbon attached to two other carbonsattached to two other carbons

33° (Tertiary) – The OH is on a carbon ° (Tertiary) – The OH is on a carbon attached to three other carbonsattached to three other carbons