Question

The conversion of alcohols to esters, particularly acetates, was a very common practice to identify alcohols before NMR was widely available. What properties make it easier to analyze and separate the two acetate ester derivatives than their starting alcohols? (not NMR properties)

Answer 1

Here you are saying about two different ester formation reactions from two different alcohols. What ever may be the reaction is, but explanation is same for both reactions.

Chromatography is the specialized manual technique to identify organic molecules. Generally organic molecules are non polar in nature, but presence of hetero atoms (O, N, halogens etc.) bring polarity in to the molecules. By means of chromatography, we can distinguish organic molecules on the basis of their polarity differences.

In general alcohols are more polar than ester/ ecetate molecules.

Chromatography is two types, analytical and quantitative. Thin layer chromatography (TLC) is used for identification of compounds on thin layered silica plate. less polar compounds are more travelled and appear at higher distances than the polar compounds. Esters appear at higher distance than the alcohols.

Quantitative Chromatography/ Coloumn chromatography is working with stationary phase silica (inorganic polar compound) and it runs with mobile phase like organic solvents/ mixture of solvents. Silica is polar compound and it can bind relatively polar compounds in the sample than the non polar compounds. Run the chromatographic coloumn with mobile phase, during this process easily binded/ non polar compounds coming fast and we can collect them in first fractions than the polar ones. Here we know, esters are comparatively non polar than alcohols, thus they are less binded with silica coming out first from the coloumn. Alcohols are coming later/ we can collect alcohols in later fractions. This technique is used for quantitative purification of organic compounds from their mixture.