Question

You and your most "trusted" lab partner Benjamin are given an unknown aliphatic alcohol to determine if it's primary, secondary, or tertiary. You decide the best chemical method would be the Lucas reagent and instruct Benjamin to prepare the solution by combining zinc chloride and hydrochloric acid in a 1:1 ratio. Upon testing your unknown and 3 control samples of ethanol, 2-propanol, and t-butanol with the reagent, you get the same result; all did not form 2 phases. You suspect either there is a problem with the Lucas reagent solution. You test the product on IR and see a strong peak around 1600 cm-1. What can you discern from this information, was the reagent correct, is it possible to determine the type of alcohol?

Answer 1

on Ethani H Hel COH Ethanol OH Hel ethene Propene 2-propanol otoH - t-Butanol 2-Methylpropene

We did not get the expected observation because lucas reagent prepared is not correct. We should use 5 mol ZnCl2 and 1 mol HCl to get respective chloro alkanes.

Since, we have used less quantity of ZnCl2, which is essential for C-O bond cleavage, therefore instead of chloro alkanes we get alkenes.

Alkenes have characteristic peak at 1600cm-1.