6. Organic molecules (ALCOHOLS) Flashcards
Give the 3 types of alcohols you can form
Primary - 1 carbon attached to the carbon adjoining the O-H
Secondary - 2 carbons attached to the carbon adjoining the O-H
Tertiary - 3 carbons attached to the adjoining the O-H
Give the oxidation agent used for oxidising alcohols
Potassium or Sodium dichromate
Give the symbol for an oxidising agent
[O]
What are primary alcohols oxidised to
Aldehydes (after immediate distillation) , then carboxylic acids (under reflux)
(remember to add H2O)
Give the colour change for the oxidation of primary alcohols
Orange to green
How many oxidising agents do you need for reflux for carboxylic acids
2 [O]
What are secondary alcohols oxidised to
Ketones
What are tertiary alcohols oxidised into
Nothing, they cannot be oxidised
Describe Fehling’s test in order to distinguish between a aldehyde ( O double bonded to C, single bonded to H) or a ketone (O double bonded to C in the middle of the chain)
1) add Fehlings solution to the test tube
2) needs to be warmed in alkaline conditions
3) if an aldehyde is present a brick red precipitate forms
4) ketones don’t give a positive result
What is the condition required and product of dehydrating an alcohol
Produces an alkene –> The alcohol is heated with hot concentrated phosphoric acid- H2SO4
(elimination reaction) and removes a molecule of water
Dehydration of primary alchol produces a single alkene
Dehydration of secondary alchol produces a mixture of alkenes
Describe the process of distillation
1) heat liquids in a pear shaped flask and lowest boiling point will evaporate first
2) rises out of flask and into a condenser
3) liquid condensed and is collected in a separate flask
Which way does the water come in from in a condenser
Top - out
Bottom - in
–> this ensures water fills up the condensor
Describe how to produce chloroalkanes from alcohols
React the alcohol with PCl5
- HCl and POCl3 are also formed
Describe how to produce bromoalkanes from alcohols
React the alcohol with HBr (formed by reacting 50% conc sulfuric acid with KBr)
- also forms H2O
Describe how to produce idoalkanes from alcohols
React alcohol with PI3 (formed by reacting red phosphorous with Iodine, I2)
- also forms H3PO3
Using the apparatus for distillation instead of reflux is not an efficient way to produce
ethanoic acid from ethanol. Explain why.
Because ethanol will be oxidised into ethanal as that has a lower boiling point than ethanoic acid
Explain the purpose of anti bumping crystals in distillation or reflux
Prevents large bubbles from forming
Describe important features of a diagram showing reflux or distillation
Have to show the separate apparatus being joined
Thermometer in distillation must be opposite the entrance of the lieburg condenser during distillation
Cant be a gap
Should not be a bung on reflux as pressure builds up
What is reflux
continuous evaporating and condensation
