In the reaction shown below, 1-hexene is reacted with a solution of 30% acid in
ID: 491872 • Letter: I
Question
In the reaction shown below, 1-hexene is reacted with a solution of 30% acid in acetic acid to form 1-bromohexane and 2-bromohexane. The products shown are liquid at room temperature. Devise a separation scheme to isolate the products together from the reaction mixture. Assume that 1-hexene is the limiting reagent and has a lower boiling point than the two products. Note: you do not need to separate the two products (1-bromohexane and 2-bromohexane) from one another. Below is a list of reagents available in lab. You may use any of these given reagents (e.g., acids, bases) as needed in your separation scheme and you also have access to a solvent evaporator if a solvent must be evaporated, and a filtration apparatus to filter. Be specific with each reagent name and technique used in your separation scheme. The most efficient separation scheme will receive the most credit.Explanation / Answer
1n a reflux apparatus, a test tube filled with 0.5mL 1-hexene, 2mL HBr, and 150mg tetrabuty1ammonium bromide is heated for two hours. As H-Br, is a strong acid, protonates H2O and as a result, creates a hydronium ion. Along with H3O+,HBr also produces a weaker acid that cannot be protonated as quickly. To add HBr, a very polar molecule, to 1-hexene, a nonpolar alkene, a phase transfer catalyst must be used. The addition of tetrabutylammonium bromide (phase transfer catalyst) to HBr(aq) and I-hexene solution creates 2 immiscible solutions and organic phases.Tetra - buty1 - ammonium bromide is the agent that transfers HBr out of the aqueous phase and in the organic phase in the form of anhydrous HBr to react with I-Hexene.In a reflux reaction, the reactants are heated while the water-cooled condenser coolsdown the vapors, allowing vapors to return to the tube as liquid. heat the compound without adding too much heat and to keep the temperature constant. A stir bar in vial is used to maintain rapid stirring and to prevent bumping. The mixture is stirred rapidly because 1-hexene and HBr are immiscible. Thoroughly mixing optimizes the contact of all particles in the mixture . After two hours, the mixture is cooled to room temperature and 2ml of petroleum -ether is added in preparation for extraction. After shaking and venting, layers are separated andidentified as aqueous or organic by comparing the densities. In this experiment, the bottom layer,or the aqueous layer, is removed. Sodium bicarbonate is added to the organic layer and is stirred. After layers separate, the aqueous layer is removed again.