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Organic Chemistry > 3.5 Alcohols > Flashcards

3.5 Alcohols Flashcards

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1
Q

What is the alcohol group?

A
  • OH
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2
Q

What are the bond angles involved in an alcohol?

A
  • 109.5 between H-C-H and C-C-O because there are 4 bond pairs (tetrahedral)
  • 104.5 between H-O-C because there are two bond pairs and two lone pairs
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3
Q

What is a primary alcohol?

A

1 carbon is attached to carbon with OH

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4
Q

What are the properties of alcohols?

A
  • Polar molecules
  • Soluble in water due to H bonds forming
  • Low volatility
  • Less acidic than water
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5
Q

What is the group of ketones of aldehydes?

A

Carbonyl group - C=O

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6
Q

What is the oxidation agent used with Alcohols?

A
  • Acidified Potassium dichromate (dilute H2SO4)
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7
Q

What does partial oxidation of a Primary alcohol produce?

A
  • Aldehyde
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8
Q

What does partial oxidation of a secondary alcohol produce?

A

Ketone

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9
Q

What does full oxidation of a Primary alcohol produce?

A

Carboxylic acid

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10
Q

What are the conditions for partial oxidation of a primary alcohol?

A

Warm gently and distill out aldehyde, use limited amount of acidified dichromte

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11
Q

What are the conditions for full oxidation of primary alcohols?

A

Excess of dichromate, heat under reflux

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12
Q

What is the test for carboxylic acid?

A

Add sodium carbonate, will fizz if an acid to produce CO2 which can be tested with limewater

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13
Q

What are the conditions to Oxidise a secondary alcohol?

A

Heat under reflux

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14
Q

Why can tertiary alcohols not be oxidised by potassium dichromate?

A

Because there is no hydrogen bonded to carbon with the OH group.

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15
Q

What are the two tests for aldehydes/ketones?

A

Tollens reagent
Feelings solution

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16
Q

What are the reagents,reactions,conditions and observations in using Tollens reagent?

A

Reagent- Formed using aqueous ammonia and silver nitrate
Reaction- Aldehydes are oxidised into carboxylic acid and silver ions become silver atoms
Conditions- Heat gently
Observations- Aldehydes- silver mirror forms inside test tube
Ketones- no visible change

17
Q

What are the conditions,reagent,reaction and observations of Fehilings solution?

A

Reagent- feelings containing blue Cu2+
Conditions- Heat gently
Reaction- Aldehydes oxidised into carboxylic acid, Cu2+ ions reduced to copper
Observation- Aldehydes- Turns from blue to brick red precipitate
Ketones- No change

18
Q

What is the colour change of acidified Potassium Dichromate?

A

Orange to green

19
Q

Why do you not seal the top of a reflux apparatus?

A

Because it will explode

20
Q

Definition of elimination?

A
  • Removal of a small molecule
21
Q

What are the conditions for elimination of alcohols?

A
  • Concentrated H2SO4 in excess
  • Vapours heated over Al2O3
22
Q

What does the elimination of alcohols form?

A

Alkenes and water

23
Q

What are the disadvantages of dehydration (elimination) of alcohols?

A

Conc H2SO4 is a strong oxidising agent:
- CO2 + SO2 can be formed which need to be removed by passing through NaOH solution

So H3PO4 is used which is safer but more expensive

24
Q

What is the equation for fermentation?

A

C6H12O6 —-> 2C2H5OH + 2CO2

25
Q

What are the conditions for fermentation?

A

35c
1 atm
Yeast catalyst

26
Q

What is the equation for industrial production of ethanol?

A

C2H6 + H2O —-> C2H5OH

27
Q

What are the conditions for industrial ethanol production?

A

300 c
60 atm
Phosphoric acid catalyst

28
Q

What comparative points are there between ethanol production by fermentation or industrial?

A

Renewable vs Non renewable
Slow vs Fast
Batch vs Continuous
Impure vs Pure
‘Carbon neutral’ vs CO2 producing

29
Q

What does carbon neutral mean?

A
  • CO2 release when burnt is balanced by CO2 absorbed during photosynthesis
30
Q

Why is carbon neutral not always correct?

A

Doesn’t take in to account CO2 released during farming,transport etc.

31
Q

What is a biofuel?

A

A fuel made from biological material that has recently died

32
Q

What are the advantages/disadvantages of using biofuels?

A

Advantages- Renewable,carbon neutral,regrowing plants

Disadvantages- Engines need to be modified,time consuming,still produces CO2

Organic Chemistry (18 decks)

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