Qualitative Analysis Lab

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Qualitative Analysis Lab

By | April 2012
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Qualitative Analysis Lab Report

Organic Chemistry Laboratory II

The purpose of this lab was to separate and purify two unknown compounds, one solid and one liquid, from an ethereal solution using the techniques of chemically active extraction, vacuum filtration, simple distillation, and recrystallization. Then identifying information was compiled about these unknowns by obtaining experimental melting/boiling point ranges, and analyzing IR and proton/carbon NMR spectrums It was determined that the unknown solid’s identity was m-nitrobenzoic acid and the unknown liquid’s identity was 4,4-dimethyl-2-pentanone. The calculated percent recovery for the purified crystals was 20.75% INTRODUCTION: 2

The goal of this lab was to isolate two unknowns, one solid and one liquid, from an ethereal solution using chemically active, or acid-base, extraction. These unknowns were then to be purified and identified using melting and boiling point ranges, IR spectrums, and proton/carbon NMR spectrums.

The first technique used in this lab was chemically active, or acid-base, extraction. This technique takes advantage of the fact that organic acids and bases in their neutral form are soluble in organic solvents, but the corresponding salts are water-soluble. Therefore if one converts these acids and bases to their corresponding salts, they can be separated from the rest of the solution by trapping them in an aqueous layer. A solution of an acid component, a basic component, and a neutral component that has been dissolved in an organic solvent, such as diethyl ether, can be separated using this type of extraction. To extract the acidic component aqueous from this solution aqueous NaOH must be added to convert the acid to its corresponding sodium carboxylate. The base and the neutral components will not react and will remain in the organic layer, while the carboxylate salt will be soluble in water and be contained in the aqueous layer. These two layers can then be...

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