Alcohols Flashcards

1
Q

What are primary alcohols?

A

One carbon is attached to the carbon that has a hydroxyl group attached to it.

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2
Q

What are secondary alcohols?

A

Two carbons are attached to the carbon that has a hydroxyl group attached to it.

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3
Q

What are tertiary alcohols?

A

Three carbons are attached to the carbon that has a hydroxyl group attached to it.

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4
Q

What is the mechanism for the dehydration of an alcohol to make an alkene?

A

elimination

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5
Q

What conditions are needed for the dehydration of alcohols to make alkenes?

A

The alcohol is heated under reflux with concentrated sulfuric acid.

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6
Q

Name and outline the mechanism for the dehydration of propane-2-ol using sulfuric acid.

A
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7
Q

What are the products of the partial oxidation of primary alcohols?

A

aldehydes

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8
Q

What conditions are needed for the partial oxidation of alcohols?

A
  1. potassium dichromate
  2. dilute sulfuric acid
  3. warm gently and distil the products out as they are made
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9
Q

What are the products of the full oxidation of primary alcohols?

A

a carboxylic acid

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10
Q

What conditions are needed for the full oxidation of alcohols?

A
  1. an excess of potassium dichromate
  2. dilute sulfuric acid
  3. heat under reflux and distil the product after the reaction has finished
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11
Q

What are the products of the oxidation of secondary alcohols?

A

a ketone

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12
Q

What conditions are needed for the oxidation of secondary alcohols?

A
  1. Potassium dichromate and dilute sulfuric acid.
  2. Heat under reflux
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13
Q

How does potassium dichromate oxidise the alcohols?

A

The orange dichromate ion is reduced to a green chromium 3+ ion and this oxidises the alcohols.

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14
Q

How is Tollen’s reagent used to test for aldehydes and ketones?

A

In the presence of an aldehyde, a silver mirror will form and in the presence of a ketone, there will be no change.

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15
Q

What is Tollen’s reagent made out of?

A

aqueous ammonia and silver nitrate to form a complex ion. [Ag(NH3)2]+

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16
Q

How does Tollen’s reagent work?

A

The silver ions are reduced to silver atoms and this causes the aldehydes to be reduced into carboxylic acids.

17
Q

How is Fehling’s solution used to test for aldehydes and ketones?

A

In the presence of an aldehyde, the blue solution will turn into a red precipitate.

18
Q

What is Fehling’s solution made out of?

A

Cu 2+ ions

19
Q

How does Fehling’s solution work?

A

The blue copper ions are reduced to form a red precipitate and the aldehydes are reduced into a carboxylic acid.

20
Q

How do you test for a carboxylic acid?

A

You add sodium carbonate and there will be fizzing as CO2 is produced.

21
Q

Why is there no reaction with the ketones?

A

The functional group does not contain hydrogen so the ketones can’t be oxidised.

22
Q

Write the equation for the production of ethanol from the fermentation of glucose.

A
23
Q

What conditions are needed for fermentation?

A
  1. Yeast
  2. No air
  3. Temperatures of 30 to 40 degrees
24
Q

Why do the conditions need to be anaerobic?

A

So the ethanol isn’t oxidised into ethanoic acid.

25
Q

What are the advantages of fermentation?

A
  1. Sugar is renewable
  2. relatively cheap
26
Q

What are the disadvantages of fermentation?

A
  1. the ethanol produced is not pure and needs to be purified
  2. this is a batch process which is slow and expensive
  3. uses land that could be used to grow crops
26
Q

Write the equation for the production of ethanol from ethene and steam.

A
27
Q

What conditions are needed for the hydration of ethene?

A
  1. high temperatures of 300 degrees
  2. high pressure of 70 atm
  3. strong acid catalyst
28
Q

What are the advantages of the hydration of ethene?

A
  1. the product made is pure
  2. continuous process meaning that less manpower is needed to keep it going
29
Q

What are the disadvantages of the hydration of ethene?

A
  1. ethene is not a renewable resource
  2. expensive equipment needed
  3. expensive to maintain high pressures
30
Q

Why can the use of ethanol as a biofuel be considered carbon neutral?

A

6 carbon molecules are taken in for photosynthesis and the production of glucose and 6 molecules of carbon dioxide are released in the combustion of ethanol. This means there is no net contribution to carbon dioxide emissions.

31
Q

Why might the use of ethanol as a biofuel not be considered carbon neutral?

A

Carbon dioxide is released when plants are watered, transportation and distilling the impure product.