Question

1. draw a mechanism for the conversion of methoxybenzyl alcohol to methoxybenzaldehyde.

2.The ethyl acetate layer was extracted with 0.2M NaOH to remove traces of methoxybenzoic acid that result from additional oxidation of the aldehyde to the carboxylic acid. Explain how crystals of methoxybenzoic acid could be isolated from the NaOH solution.

3. Explain how TLC could be used to monitor the reduction of methoxybenzaldehyde to methoxybenzyl alcohol using NaBH4 as a reducing agent.

Answer 1

Question 1:

Question 2:

whyen NaOH was added to to the solution, benzoic acid became sodium benzoate salt hence it was dissolved in water.

Now if we want to get benzoic acid crystals back, we need to neutralize or even slightly acidify the solution by using diluet HCl solution.

As the sodium benzoate converts to the bezoic acid upon the addition of HCl , crystals will begin to appear. simple filteration will afford the pure benoic acid.

Question 3:

TLC principle is more polar compound will bind to the silica gel of thin layer chromatogram plate more strongly than less polar compound since silica gel present on TLC plate is composed of polar functional groups.

In benzaldehyde and bezyl alcohol, the ,later one binds more strongly to the plate compared to the former, hence moves less distance than benzaldehyde. Overall, benzyl alcohol will be seen with less Rf than benzaldehyde in the TLC plate.