Extraction Case

Experiment 3: Extraction

Toni DeSanto

October 6, 2011

Dr. Reiko Mary Simmons

Organic Chemistry Lab 1 223 Section 54

Objective

The purpose of the experiment was to separate a mixture of two compounds using a technique called extraction. The two compounds may be carboxylic acid, phenol, amine or a neutral compound. Extraction is the process of transferring a substance from liquid or solid mixture to a solvent. Extraction is used to separate a desired organic substance from a reaction mixture or it is used to remove impurities from a desired organic substances. The organic substance is most often dissolved in an organic solvent. Liquid-Liquid extraction is based on the principle of mixing two liquids and a substance, if soluble, can be transferred from one liquid to another (Lehman, 2008).

Physical Properties of reactants, products and solvents

Diethly ether was used to dissolve the unknown compound. Diethly ether has a boiling point of 35ᴼC and a melting point and its density is 0.71 g/mL. The organic material separated to the top because it is less dense than water. In order to extract a compound, a basic or acidic aqueous solution was used to extract the desired compound out of the ether solution. The desired compound was transferred from the ether solution to the aqueous solution. The unknown could be composed of two out of four possible compounds:

Table 1. (Lehman, 2008).

Compound Properties Melting point

Carboxylic acid

Acidic Compound molecule; not an ion Dissolve in ether; not water 101ᴼC-118ᴼC

Phenol

Weakly acidic Dissolve in ether not water 40ᴼC-43ᴼ C

Amine

Basic, Dissolve in ether not water 79ᴼC-81ᴼC

Neutral Not acidic or basic, dissolve in ether only

Procedure

An O-ring and separatory funnel were obtained. An unknown sample was obtained, #326, 20mL of ether was added to the sample. Once the sample had dissolved it was transferred to the separatory funnel. 15mL of HCl was put into the separatory funnel and the aqueous solution was extracted from the funnel. The extraction was done two more times with 15mL of HCl. Once the aqueous solution was extracted it was neutralized with concentrated NaOH. NaOH was added to the solution until it was basic. The aqueous layer was then cooled for 15 min. If there was a solid present, one of the compounds in the unknown sample was amine. There was a solid formed, therefore the unknown did contain amine.

The ether layer now needed to be extracted in order to determine what other compounds were in the unknown sample. The ether solution was extracted with 15mL of 5% Na2Co3 solution three times. The aqueous extract was then collected and concentrated HCl was added, dropwise, until the solution was acidic. The acidified solution