My guess:

i) removes the bulk of water-soluble inorganics;

ii) removes bases like amino compounds, etc. by protonation;

iii) removes/neutralizes remainings of the acid from previous wash;

iv) removed traces of sodium hydrogen carbonate from previous wash (most of the time not really necessary);

Hope it helps.

Hey,

First washing:

• Removing inorganic impurities (NaBr, NaHSO4, H2SO4) and traces of butan-1-ol
• Dissolution, migration of inorganic compounds to the aqueous layer

2nd washing:

• Concentrated sulphuric acid is used to make water-soluble products of compounds that did not reacted, as well as byproducts (ether, but-1-diene)
• Alkene + sulphuric acid (addition)

3rd washing:

• Used to get rid of H2SO4(conc.) that was used in previous washing
• Neutralization: H2SO4 + 2 NaHCO3 --> Na2SO4 + 2 H2CO3 (H2O + CO2)

4th washing:

• I am not sure if this step is necessary, but it can be used to eliminate traces of sodium bicarbonate
• Similar to the first washing

All the best,

Rafal

educa.fc.up.pt › documents › 1_bromobutane_protocol_macroscale

Hi;

Please see the stages of synthesis and purification of 1-bromobutanol in attached file:

The reactions have been discussed in RG link:

researchgate.net/post/What_is_the_equation_to_explain_how_one_possible_organic_side_product_is_formed_in_the_synthesis_of_1-bromobutane.

With my best regards