alcohols Flashcards
how do you name alcohols
If there are two or more -OH groups then di, tri are used.
functional groups that need a suffix ending(e.g aldehydes or ketones)g then the OH can be
named with the prefix hydroxy-):
describe oxidation of primary alcohol
Potassium dichromate K2Cr2O7
is an oxidising agent
that causes alcohols to oxidise.
primary alcohol turns to aldehyde
Reagent: potassium dichromate (VI) solution and dilute
sulfuric acid.
Conditions: (use a limited amount of dichromate) warm
gently and distil out the aldehyde as it forms:
in the distillation of aldehydes ,how do you maxismise yield
In order
to maximise yield collected, only collect the distillate
at the approximate boiling point of the desired
aldehyde and not higher.
why are electric heaters used in the distillation process
Electric heaters are often used to heat organic
chemicals. This is because organic chemicals
are normally highly flammable and could set on
fire with a naked flame.
what is the full oxidation of primary alcohol
it is in reflux
which is used when heating organic reaction mixtures for long periods.
The condenser prevents organic vapours from escaping
by condensing them back to liquids.
why should you never seal the end of the condenser
The build up of gas
pressure could cause the apparatus to explode.
This is true of any
apparatus where volatile liquids are heated including the distillation
set up.
why are anti bumping granules added
to prevent vigorous, uneven boiling by making small bubbles
form instead of large bubbles.
describe the oxidation of secondary alcohols
Reaction: secondary alcohol –> ketone
Reagent: potassium dichromate(VI) solution and
dilute sulfuric acid.
Conditions: heat under reflux
what are ketones
Ketones end in -one
when the is a double C–O bond in the middle of the carbon chain
when more than five carbons involved you add a number
how do you test whether it is a ketone or an aldehyde
Tollens’ Reagent
Reagent: Tollens’ reagent formed by mixing
aqueous ammonia and silver nitrate. The
active substance is the complex ion of
[Ag(NH3)2]+
. Conditions: heat gently
Reaction: aldehydes only are oxidised by
Tollens’ reagent into a carboxylic acid. The
silver(I) ions are reduced to silver atoms
Silver mirror coating forms around test tube
How do you test using fehlings solution
Fehlings solution contains Cu+ ions
Condition:heat gently
Aldehydes are oxidised into carboxylic acid
Turns from blue to red
Describe reaction of alcohol to alkene
Type of reaction is an acid catalysed reaction
Reagent :concentrated sulfuric acid
Conditions:warm after reflux
Role of reagent :dehydrating catalyst
What is a dehydration reaction
Removal of a water molecule
What is the acid catalyst in the hydration of alkene to alcohol
H3PO4
What are the advantages and disadvantages of fermentation
Advantage :
Production using cheap technology
Sugar is a renewable source of energy
Disadvantage:
Ethanol made is not pure and needs to undergo fractional distillation
