Question

The following question is regarding an experiment converting 1-bromobutane from 1-butanol.

We performed three extractions (separatory funnels) during this

First: H20 and 1-bromobutane

Second: 1 bromobutane and H2SO4 (cold)

Third: Potassium carbonate and 1-bromobutane

Here is the question

The organic layer can also be extracted with NaOH (aq) instead of using potassium carbonate. However, sometimes, initially two layers form in the separatory funnel when the base is first added to the organic layer. But during extraction, the solution has been reported to become warm (when we added H2SO4). When the separatory funnel is put back into the ring stand to let separation occur, no separation is observed not even after standing for 5 minutes. What happened? Explain using a chemical reaction.

Answer 1

Synthesis of 1-bromobutane from 1-butanol

Extraction of products from reaction mixture

NaOH is a strong base, which when added to 1-bromobutane may help in Sn2 reaction and the reactant may be obtained back. Thus K2CO3 is used which is a weaker base than NaOH for extraction. the reaction becoems warm due to acid-base neutralization reaction between NaOH (or K2CO3) and H2SO4 present in solution. The reaction forms salt NaCl. In some cases as emulsion is formed due to this salt in organic-aqueous phase and therefore the two layers are not separated.

2NaOH + H2SO4 ---> Na2SO4 + 2H2O