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Flashcards in Alcohols Deck (67)
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1

What is the functional group of alcohols?

What is this called?

-OH

The hydroxyl group

2

What is the general formula for alcohols ?

Cn H2n+1 OH

3

How do you classify an alcohol?

By the number of carbons attached to the carbon carrying the OH

4

What is the equation for the fermentation of glucose?

(Yeast)
C6H12O6 ———-> 2ethanol +2CO2

5

Give the conditions of the fermentation of ethanol

Yeast provides enzymes as a catalyst
35 degrees C so enzymes don’t denature
Anaerobic respiration (oxygen free atmosphere)

6

What is the yield of ethanol from fermentation?

15%

7

What process is used to separate ethanol from the reaction mixture?

Fractional distillation

8

What are the conditions for the direct hydration of ethene?

Steam and concentrated H2SO4 or H3PO4

9

Give the details of a fermentation reaction

Rate: slow
Quality of product: impure
Raw material: sugar (renewable)
Type of process: batch

10

Give details on the hydration of ethene

Rate: slow
Quality: pure
Raw material: ethene from oil (finite)
Process: Continuous

11

Compare batch vs continuous processes

Batch: cheap equipment but expensive on manpower

Continuous: cheap on manpower, expensive equipment

12

What is a biofuel?

A fuel produced from renewable biological resources

13

Define carbon neutral

An activity that has no net annual carbon emissions to the atmosphere

14

Why is fermentation considered carbon neutral?

Photosynthesis absorbs 6 moles of CO2
Fermentation releases 6 moles of CO2

15

Is fermentation actually carbon neutral?

No: CO2 is produced in other processes involved eg transport and harvest

16

Is ethanol a biofuel?

Yes it is used as motor fuel when mixed with petrol

17

Mechanism for an alcohol to an alkene

Conditions??

Elimination

Heated with concentrated H2SO4

18

What is the name of the reaction turning an alcohol to an alkene?

Dehydration

(Water is eliminated)

19

What are the stages of an elimination reaction?

The alcohol oxygen’s lone pair is donated to a H+ provided by acid catalyst

Oxygen gains H+ and a positive charge

A hydrogen is lost from an adjacent carbon and the e- in the C-H bond move into the positively charged oxygen

20

What are the stages of separation for an impure organic liquid eg cyclohexene

Place impure organic liquid into a separating funnel and add a small amount (10cm3) of sodium hydrogen carbonate solution to eliminate XS acid catalyst

Stopper separating funnel and shake

Periodically invert and open tap to release pressure

Allow funnel to stand and layers to separate

Remove stopped and run off top and bottom layers into separate beakers

Discard aqueous layer

21

Why must you periodically open the tap of the separating funnel?

To release a build up of pressure coming from the acid catalyst reaction with the sodium hydrogen carbonate, creating CO2

22

Once you have separated the organic liquid, there may be a little water left. What do you do now???

Add a spatula of drying agent (eg Calcium Chloride or MgSO4) to organic liquid

Swirl and add drying agent until the liquid changes from cloudy to clear

Filter to remove drying agent

23

List the equipment for distillation reaction

Round bottom flask
Thermometer
Condenser
Heat

24

What is the distillate?

The product that evaporated and is condensed

25

Describe the method for distillation

Place mixture in round bottom flask attached to side arm with condenser, with a few anti-bumbing granules and heat

As product is formed it will evaporate, travel up the neck and down the condenser, where it will cool and drip into the collection vessel

26

How do we prevent the evaporation of the distillate?

Cool the distillate by placing the collection vessel in an ice bath

27

What is used to oxidise alcohols?

How is this presented in equations?

Acidified potassium dichromate

[O]

28

What is observed when an alcohol is oxidised?

Colour change from orange to green

29

What does the oxidation of a primary alcohol produce?

What if this is further oxidised?

Aldehyde

Carboxylic acid

30

What does the oxidation of a secondary alcohol produce?

Ketone