Differentiating organic Compounds

Question 1

Differentiating halogens

Answer 1

1. Heat with NaOH (aq)
2. Cool mixture.
3. Add HNO3 to remove excess alkaline otherwise there will be AgO, a black solid.
4. Add AgNO3.

Cl2- white
Br2- off white/cream
I2 - yellow

Question 2

Purpose of tollens reagent + heat and result?

Answer 2

Differentiate aldehydes from ketones. All aldehydes react.

Result: silver mirror formed around wall of test tube

Question 3

Purpose of Fehling’s reagent + result?

Answer 3

Differentiate aliphatic aldehydes because fehling’s is weak.

Result: brick-red ppt formed.

Question 4

2,4-dinitrophenylhydrazine is FOR WHAT?????

Answer 4

Differentiate aldehydes and ketones from the rest of the bitches.

Orange ppt formed. :)

Question 5

Differentiate phenol functional group

Answer 5

1. Add neutral FeCl3 (aq)

2. Phenol present -> violet colouration

Question 6

Identifying aliphatic alcohols?

Answer 6

PCl5 or SOCl2 white fumes of HCl produced

Question 7

Differentiate carboxylic acids from phenols and alcohols?

Answer 7

Acid-carbonate reaction - phenols and alcohols do not react with carbonates or hydrogencarbonates.

CO2 evolved will form white ppt with limewater