2 Acid Base Extraction.docx

2 Acid Base Extraction.docx - Lab#2 Acid and Base...

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Lab #2: Acid and Base Extraction Yook Teng (Tiffany) Lam February 13, 2015 TA: Lukas Klees Department of Chemistry, Binghamton, University, Binghamton, NY 11362
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Introduction Organic reactions produce products that are often isolated or purified by extraction. Some types of extraction are acid-base, solid-liquid, and liquid-liquid. Difference in solubility makes this method possible because separate layers are created and only substances with the same polarity dissolve in each other. After performing the process, the desired products are separated from the starting materials, side products, and impurities. Separatory funnel, gravity filtration, suction filtration, melting point determination, and recrystallization are techniques used to perform the lab. The ether mixture is placed into a separatory funnel and mixed well while frequently releasing pressure from the opening of the stopper. The different layers are also extracted from the funnel once it has separated. Gravity filtration is used to remove the drying reagent so as to separate it from the product. Suction filtration is used to gather the crystals formed. Melting point of the crystals is taken to determine their identity. If the crystals are not pure, recrystallization can be performed to remove impurities and result in better yield. In this particular lab, an acid-base extraction is performed on an ether mixture containing three unknown substances; acid, base, and neutral component. The base is protonated by a strong acid leading to the formation of its salt at the very bottom layer. The aqueous layer is removed from the funnel and to recover the original content, a different base is used to neutralize the salt resulting in a mixture of base and water. The base is filtered out from the mixture. The process is repeated for the acid component, except it is deprotonated by strong base and restored using a different acid. The neutral component is extracted by evaporating the ether. After extraction, the identity of these products can be determined by testing their melting point. If necessary, recrystallization can be performed to remove impurities.
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Some formulas necessary for this lab include: Percent recovery : Mass of each product Mass of total product x 100 Procedure A 60 mL separatory funnel was obtained and 15 mL distilled water, 2.5 mL concentrated HCl (6M) and 15 mL ether was added into it. About 1.3 – 1.5g of the unknown solid extraction was weighed out and placed into the funnel; 1.4g of the unknown was used for this procedure.
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