Mixture of Three Unknowns Lab

Background Reading: Keeping a Notebook (CH 2), Extraction (CH 15), Distillation (CH 19),

Chromatography (CH 26-28), Recrystallization (CH 13) Spectroscopy (CH 32, 33)

Purpose

Previously, we have solved two different unknowns when the stockroom supplied us with pure

samples to analyze. In this lab you are given three unknowns that have all been put in the same

bottle (unfortunately). In most cases when you are practicing organic chemistry (synthetic

reactions, metabolism studies, natural product isolations, etc.) analysis will start with a mixture

of organic compounds. We will first separate and purify each of the three compounds and then

analyze them to solve the structure and name. We will include 1H NMR and IR to assist in

determining purity and structure in this complicated experience.

Notes

We will use the format for investigative experiments for your laboratory report.

In this lab you will have either (a) one acid and two neutrals; (b) one base and two neutrals; or

(c) one acid, one base and one neutral. Start on a small scale and experiment with extractions

(acid first, base first, use ether or dichloromethane.

Acidic compounds (Carboxylic Acids) = solubility in aqueous base

Basic compounds (Amines) = solubility in aqueous acid

Neutral compounds = Alcohols, Aldehydes, Amides, Esters, Ethers, Halides, Hydrocarbons, and

Ketones.

We will determine melting points (after recrystallization) for solid unknowns and boiling points

(during distillation) for liquid unknowns.

Each chemical classification test will be performed according to our laboratory textbook and

your notes from qualitative functional group analysis. Be aware that many molecules contain