5.4 - Organics II Flashcards
What is an alcohol?
Alcohols are organic molecules containing an —OH functional group.
How are the names of alcohols formed?
- The start of the name shows how many carbon atoms it has.
- The end of the name is ‘-ol’ to show it’s an alcohol.
How do we show where the —OH group is attached to the alcohol?
We include a number in the name to indicate where it’s attached
What are the methods used to produce alcohols?
Hydration of Ethene
Fermentation of Glucose
What conditions are needed for the hydration of ethene?
- 300 degrees C
- 65 atm pressure
- Phosphoric acid (H3PO4) catalyst
How is ethene provided in ethene hydration?
Crude oil provides the ethene.
Advantages of ethene hydration?
- Makes pure ethanol.
- Can run continuously.
Disadvantages of ethene hydration?
- Conditions require lots of energy.
- Non-renewable raw material used.
What conditions are needed for the fermentation of glucose?
- Yeast (provides enzymes)
- 30 degrees C: enzymes’ optimum temperature
- Anaerobic (no air): prevents oxidation
Where do the glucose come from in the fermentation of glucose?
Sugar cane provides the glucose
Advantages of fermenting glucose?
- Renewable raw material used.
- Conditions not energy-intensive
Disadvantages of fermenting glucose?
- Makes impure ethanol.
- Must be done in individual batches
How can ethanol be oxidised?
- Combustion
- Microbial Oxidation
- Chemical oxidation
What happens when ethanol is combusted?
Ethanol tends to combust completely because of the oxygen atom in the —OH group.
This results in a non-luminous, blue flame.
What happens when ethanol oxidised via microbial methods?
Many micro-organisms, such as bacteria and fungi, can use the oxygen in the air to oxidise ethanol into ethanoic acid. This process can only happen if aerobically
How do we represent the microbial use of oxygen?
Using the [O] symbol
What do we heat ethanol with if we want to oxidise it chemically?
We heat it with a mixture of:
* Potassium dichromate(VI) (K2Cr2O7)
* Dilute sulfuric acid (H2SO4)
What does chemical oxidation form?
It forms ethanoic acid
What colour change can be seen with the chemical oxidisation of ethanol?
Orange → Green
What are carboxylic acids?
Carboxylic acids are organic molecules containing an —COOH functional group.
How are the names of carboxylic acids formed?
- The start of the name shows how many carbon atoms it has.
- The end of the name is ‘—oic acid’ to show it’s a carboxylic acid.
An example of an aqueous solution of ethanoic acid?
Vinegar
What happens when a carboxylic acid loses its H+?
The name changes from ‘-oic acid’ in the carboxylic acid to ‘-oate’ in the salt because it becomes negatively charged.
What is an ester?
Esters are a family of organic molecules which form when a carboxylic acid and an alcohol join together by losing an H2O molecule.
What is the functional group of an ester?
—COO—
Equation for the formation of an ester?
Carboxylic acid + Alcohol → Ester + Water
What happens when ethanoic acid and ethanol react?
Ethyl ethanoate and water is produced.
What are the names given to the process that forms esters?
Condensation (because of the production of water vapour)
OR
Esterification (because an ester is formed)
How would we prepare an ester?
- Mix the carboxylic acid and alcohol together.
- Add a few drops of concentrated sulfuric acid (H2SO4). (this acts as a catalyst for the reaction)
- Warm it for a while.
- Tip the mixture into sodium carbonate (Na2CO3) solution.
(this neutralises the sulfuric acid catalyst, which is otherwise really corrosive)
What are esters used for?
Food flavourings and perfumes
What is a polyester?
A polyester is a polymer made of lots of molecules joined together in a chain by ester groups.
How do we make a polyester?
To make a polyester, you need to mix two types of monomers
What two monomers are needed to make a polyester?
A dicarboxylic acid (has -COOH at both ends)
AND
A diol (has -OH at both ends)
What this type of polymerisation called?
condensation polymerisation
What are the uses of polyestsers?
Clothing and Sportswear.
What are bio-polyesters?
Biodegradable polyesters
This means microbes such as bacteria and fungi can use enzymes to break down the polymer into its monomers and use them as an energy supply.
