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Lab1 - Eleanore An Chem 215H(216-200 Experiment 1...

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Eleanore An Chem 215H (216-200) Experiment 1: Friedel-Crafts Acylation 1/30/2012 Background: Electrophilic aromatic substitution reactions take place between the nucleophilic π electrons of an aromatic ring and a strong electrophilic. The intermediate carbocation rapidly loses H+ to reform the aromatic system. In the case of Friedel-Crafts acylation, the electrophilic is an acylium ion, formed by the reaction of an acid chloride with aluminum chloride.* In this experiment, we work on the reaction of anisole, ethylbenzene, and toluene. The procedure is divided into 4 parts, each of which is conducted by a different group of classmates. Experiment : Place Anhydrous aluminum chloride (0.055 mol, 1.1 equiv) and 15mL of methylene chloride in a 100mL round-bottomed flask with an additional funnel (grease the joints) capped with a septum, reflux condenser capped with septum, and a septum. The system is flushed with Nitrogen, venting first through the top of the reflux condenser and then through the addition funnel. Nitrogen was bubbled through the solution venting through the condenser. The mixture is cooled to 0°C in an ice/water bath. Acetyl Chloride (0.055mol, 1.1 equiv) as a solution in 10mL of methylene chloride was added to the addition funnel using a syringe and then to aluminum chloride dropwise over 10 min. After the addition is complete, the aromatic compound (0.050mol) as a solution in 10mL of methylene chloride was added in the same manner, The addition rate is adjusted so the solution does not boil excessively. After addition is complete, the ice bath is removed and the reaction is allowed to come to room temperature. After stirring for an additional 15 min at room temperature, the reaction mixture is poured carefully and slowly, with stirring into about 25g of ice and 15mL of concentrated HCl in a beaker. The mixture is transferred to a sep funnel and collect the organic layer. The aqueous layer is extracted with 20mL of methylene chloride. The combined organic layers are extracted with 2 portions of saturated sodium bicarbonate and dried over anhydrous MgSO4. The drying agent is removed by gravity filtration into an appropriately sized round- bottomed flask. The Methylene chloride was removed by rotary evaporation. TLC is used to quickly assess presence of starting material. If necessary, a flask is set up for simple distillation and insulated with aluminum foil or glass wool. The mixture is distilled, raising the setting on the variac as necessary. If residual starting material is present, it distilled around 150C, while each of the products has a boiling point greater than 200C. The product is weighed and analyzed by IR and NMR spectroscopy and TLC (ethylacetate:hexanes = 1:4) in comparison with the proposed starting material.* The three starting material: Reactants Products Anisole C6H5OCH3 Liquid bp 154 4'-methoxyacetophenone CH3OC6H4C(O)CH3 Liquid bp 154/26 mm Hg Ethylbenzene Liquid bp 136 4'-ethylacetophenone Liquid bp 125/20mm
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CH3CH2C6H5 CH3CH2C6H4C(O)CH3 Hg Toluene CH3C6H5 Liquid bp 110 4'-methylacetophenone CH3C6H4C(O)CH3 bp 226 Group 1: Set up reaction including glassware and stoichiometry.
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