Question

I need to come up with a separation and purification scheme procedure of a mixture containing 45% 4-aminoacetophenone, 45% 1,2,4,5-tetrachlorobenzene, and 10% 1,4-dibromobenzene. How would I go about this? Please explain step by step.

We also need recrystallization.

Addition Information ( The mixture will contain 45% of the neutral compound, 45% of acidic/basic compound, and 10% of neutral impurity (1,4-dibromobenzene). The goal is to isolate the neutral compound (which is present in your mixture up to 45%) and the acidic/basic compound (which is present in your mixture up to 45%). The 10% neutral impurity will be removed during recrystallization step)

Answer 1

4-amino acetophenone   is basic since it has basic amino group ( NH2)

It can be protonated and can be converted to ionic and thus solubility in water increases ( NH2 + H+ -->NH3+ )

40% m-toulic acid is acidic since it has acdic COOH group

COOH can be deprotonated and can be converted to ion and thus solubility in water increases

COOH + NaHCO3 ---> COO- + Na+ + H2O + CO2

1,4 dibromobenzene is non polar compound.

So we dissolve mixture in non polar solvent ether , 1,4 dibromobenzen readily dissolves in it.

When we add water to mixture along with basic compound like NaHCO3 the acidic compound toulic acid will gets dissolved in aquoes solution. Thus aqueos layer which is heavier than ether layer will be at bottom of funnel and can be seperated out and later acid can be extracted by treating it with HCl. ( HCl gives H+ to COO- and converts it back COOH)

Now ether layer has 4-amino acetophenone and 1,4-dibromo benzene. When we add water solution which is acidic like aqueous HCl   then 4-amino acetophenone which is basic gets dissolved in aquoes layer. Later this layer can be seperated out and we treate with strong base NaOH to get back our base . ( NaOH gives OH- which reacts with NH3+ and converts it back to NH2)