REQUIRED PRACTICAL 6 - Organic compound testing Flashcards
What bonding do alcohols have?
Hydrogen bonding - highest bp (out of aldehydes/ketones, alkanes/alkenes)
What bonding do aldehydes and ketones have?
Permanent dipoles - lower bp
What bonding do alkenes and alkanes have?
Van der Waal - low bp (lower group members are gases
During oxidation reactions, what does a primary alcohol produce?
Aldehyde. This can also be oxidised further to produce a carboxylic acid (carboxylic acid cannot be oxidised further)
During oxidation reactions, what does a secondary alcohol produce?
Ketone. This cannot be oxidised further
Can tertiary alcohols be oxidised?
No
What is the test for reagent acidified potassium dichromate? (K2Cr2O7/H+)
Must add acid 1st before dichromate
What is the result of acidified potassium dichromate on alcohols?
Bright orange to green solution for primary and secondary alcohols.
Tertiary alcohols - it will remain an orange colour
What is the result of acidified potassium dichromate on aldehydes?
Bright orange to green solution
What is the result of acidified potassium dichromate on Ketones?
No reaction as ketones don’t react further
What is the test for reagent potassium permanganate (KMnO4-/H+)
Must add acid 1st then permanganate
What is the result of potassium permanganate on alcohols?
Purple to colourless solution
What is the result of potassium permanganate on aldehydes?
Purple to colourless solution
What is the result of potassium permanganate on ketones?
No reaction
What is the test for Fehlings solution + warm?
MUST WARM SOLUTION
1) In lean test tube mix Fehling’s a and Fehling’s B solution of equal volumes resulting in dark blue solution
2) Add 5 drops of this test to 1cm3 sodium carbonate solution in test tube. Add antibumping granules. Then add 5cm3 ethanol/ propanal.
3) Warm test tube for 2 minutes and gradually bring to boil for a few minutes
4) Using test tube holder, remove from hot beaker and allow contents to stand for a few minutes
What is the result of Fehling’s test on alcohols?
No reaction