Question

For a nucleophilic substitution reaction answer the questions

Why does naphthol react with sodium hydroxide? Why does ethanol not react to the extent that naphthol does with sodium hydroxide?

Why it was necessary to do extraction step before column chromatography?

What was the purpose of column chromatography? Was it successful?

Answer 1

2. The extraction process is necessary before column chromatography, there are inorganic compounds also present which formed in the reaction.

If we don't extract with aqueous solutions (neutral, acidic and basic) we may carry the impurities also in the crude reaction mixture, we use stationary phase and mobile phase depend on the quantity of the crude (Only organic compounds). Another thing if don't extract with suitable aqueous solutions, the separation on column chromatography might be difficult. The compounds may bind to stationary phase (acids or bases depends on acidic or basic stationary phase) which might be difficult to elute the bined compound from coloumn chromatography.

3. The purpose of column chromatography is to separate individual compound from mixture of compounds irrespective of its quantity. The purity of the compound in this process is very high. It highly useful small scale process.

It is a succesful process in small scale industry, but not for bulk drug industry. In bulk scale process the consumption of stationary phase and mobile phase are very high and which can not be reused all the time. and the adjustment and arrangement of big column at a time highly difficult, number of partitions has to be conducted so that same process has to be done in many number of times.

So that man power and mobile phase and mainly time taking process are all defects in bulk scale process.

Finally it is successful in small scale industry and unsuccessful in bulk scale industry.