Alcohols Flashcards

1
Q

Alcohols general formula

A

CnH2n+1OH

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2
Q

What is the suffix nomenclature if there is two OH groups

A

Diol

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3
Q

Primary vs secondary vs tertiary

A

Dependant on the amount of alkyl groups that are bonded to the carbon which contains the OH

Eg. Ch3 ChOH CH3 would be secondary

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4
Q

Combustion of alcohols

A

Alcohol + oxygen —-> carbon dioxide + water

Occurs in air when ignited

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5
Q

What can alcohols be converted to by adding a halogen

A

Halogenoalkanes

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6
Q

How to do chlorination to an alcohol

A

Phosphorus chloride is added to the alcohol resulting in a vigorous reaction at room temperature

Results in the formation of phosphoryl chloride and hydrogen chloride and the halogenoalkane

CH3CH2CH2OH + PCl5 → CH3CH2CH2Cl + POCl3 + HCl

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7
Q

What type of alcohol does chlorination only occur in

A

Tertiary alcohols

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8
Q

Bromination process

A

Add warm potassium bromide and concentrated sulphuric acid

Sulphuric acid oxidises the bromine ions to bromine

2KBr + H2SO4 → K2SO4 +2HBr

The resulting bromide then reacts with the alcohol as HBr

CH3CH2CH2CH2OH + HBr → CH3CH2CH2CH2Br + H2O

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9
Q

Iodination process

A

Add red phosphorus and iodine with the alcohol and heat under reflux

Thus the PI3 is what reacts with the alcohol. Eg

3C2H5OH + PI3 → 3C2H5I + H3PO3

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10
Q

Dehydration of alcohols to alkenes process

A

Heat the alcohol with concentrated phosphoric acid

The OH group and hydrogen of adjacent carbons are remover to form a c=c bond

Hence the name H2O is also produced

CH3CH2OH → CH2=CH2 + H2O

The phosphoric acid doesn’t appear in eq because the water dilutes it

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11
Q

Oxidation of primary alcohols

A

Primary alcohols can be oxidised to ketones (aldehyde) then further oxidised to carboxylate acids

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12
Q

Oxidation of secondary alcohols

A

Can be oxidised to ketones only

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13
Q

Oxidation of tertiary alcohols

A

Can’t be

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14
Q

What is the oxidation agent for the alcohol oxidation

What colour does it go and why

A

Acidified (with sulfuric acid) potassium dichromate

It is reduced by hydrogen ions from the dulfuric acid

It turns green from orange

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15
Q

Process of forming a carboxylic acid from a primary alcohol

A

Add alcohol to oxidation agent
Heat
Distill off aldehyde
Reflux the aldehyde with excess oxidation agent then distill again to form a carboxylic acid

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16
Q

How can the presence of an unknown compound be determined

A

By the oxidising agents - feelings and trolleys reagents

17
Q

What is feelings solution and what happens when added to an aldehyde to test for its presence

A

An alkaline solution containing copper ions which act as an oxidising agent

When warmed with an aldehyde , the aldehyde is oxidised to a carboxylic acid and the cu2+ ions are reduced to Cu +

The clear blue solution turns opaque due to the formation of a red precipitate - copper oxide

Ketones cannot be oxidised so give a negative test when warmed with feelings

18
Q

Tollens reagent and what happens when added to aldehyde

A

An aqueous alkaline solution of silver nitrate in excess ammonia solution

When warmed with an aldehyde, the aldehyde is oxidised to a carboxylic acid and Ag + ions are reduced to Ag

The silver forms a mirror on the inside of the tube

19
Q

How to heat under reflux and why to use the process

A

For when we need full oxidation
Means that any products of oxidation remain in mixture as the products that boil off are recondensed

Contains pear shaped flask
Antibumping granules
Condenser
Open top

20
Q

How to distill and when

A

For when we do not want to complete oxidation and want to obtain an aldehyde rather than carboxylic acid

Only oxidation agent is heated while alcohol is slowly added
Aldehyde is formed and immediately distilled off
The aldehyde is the collected in the receiver

Contains the condenser at an angle to be collected in the recieving flask

21
Q

When to use simple distillation

A

To separate a liquid and a soluble solid from a solution

Eg. Separating pure water from salt water

22
Q

Process of simple distillation

A

Heat solution
Solution evaporates producing a vapour
Vapour passes through condenser into a liquid that can be collected
Once all the liquid has evaporated , only the products will be left

23
Q

When to use fractional distillation

A

To separate 2 or more liquids that can mix with each other

Eg. Water and ethanol

24
Q

Process of fractional distillation

A

Heat to the temperature of the substance with the lowest boiling point

Substance will rise and evaporate first and vapours will pass through the condenser

They are then cooled and collected as liquid

25
Q

When to use solvent extraction

A

To remove a desired organic product from a reaction mixture

Solvent must be
Doesn’t much with the solvent containing the desired organic product
Organic product must be much more soluble than the solvent

26
Q

Process of solvent extraction

A

Place reaction mixture into a separate funnel and add the chosen solvent forming a spreader layer

Add a stopper to the top of the funnel

Allow the contents of the funnel to settle in 2 layers

Remove the stopper and allow lower layer to drain into flask

Pour the remaining layer into a clean dry conical flask and add anhydrous magnesium sulphate

27
Q

When to use crystallisation

A

To separate a dissolved solid from a solution eg. Copper sulphate from a solution of copper sulphate in water

28
Q

Process of crystallisation

A

Heat solution evaporating the solvent
Test if the solution is saturated by dipping glass rod into it
If its saturated crystals will start to form on the rod
Cool saturated solution
Crystals grow
Wash and dry

29
Q

How to determine a liquids purity

A

Measure its boiling point Substance

30
Q

What do impurities do to a liquids boiling temperature