CHEM 3A Lecture Notes - Lecture 10: Rac (Gtpase), Stereochemistry

each of these washes and wRy Is ou anhydrous sodium sulfate. a. Why is this done? b. Could solid sodium hydroxide or potassium hydroxide be used for this 3. After the washes described in Exercise 2, the 1-bromobutane is treated w ith purpose? Explain. final step of the purification process in the Miniscale Procedure in volves a simple distillation. What impurities are removed by this distillation? 5. Using curved arrows to symbolize the flow of electrons, propose a mechanism for formation of the by-product(s) from elimination that could be produced when 1-butanol is treated with HBr. Specify whether your mechanism is E1, E2, or both. 6. List two factors, one in the substrate R-L and the other in the nucleophile /base Nu: being used, that should increase the yield of E2 relative to Sy2 products in the reaction of R-L with Nu: 7. Treating 1-butanol with sulfuric acid establishes an equilibrium with 1-butyl bisulfate and water as shown. 1-Butanol I-Butyl bisulfate Using curved arrows to symbolize the flow of electrons, propose a mecha- 1-Butyl bisulfate may serve as the precursor to an ether and an alkene, as i. Provide the structures expected for the ether and the alkene that might a. nism for the conversion of 1-butanol to 1-butyl bisulfate. b. well as the desired 1-bromobutane. be produced from 1-butyl bisulfate. i. Using curved arrows to symbolize the flow of electrons, provide reac tion mechanisms for the formation of each of these by-products and specify whether the mechanisms you write are SNl, SN2, E1, E2,or none of these. ii Explain why you would expect bisulfate to be a good leaving group for substitution or elimination reactions. 8. Consider the mechanistic step in the conversion of 1-butanol to 1-bromobu 14.10) e in which bromide ion displaces water from the oxonium ion 1 (Eq.1 What evidence, if any, is there that this step involves backside attack by a. the nucleophile?

If you were to take a quantity, of PbCI_2, a sparingly soluble salt - maybe 10g - and put it into water, some of it would dissolve based on its K_sp. The equation for this reaction is: PbCI_2 (s) Pb^2+ (aq) + 2CI^- (aq). What will the ratio of the concentrations of Pb^2+ to CI^- be? In other words, wat will be [Pb^2+]/[CI^-]? Equal volumes of 1.0 M Pb(NO_3)_2j and 0.001 M NaI are mixed in a beaker and PbI_2 precipitates out as the solution reached equilibrium. What will the ratio of the concentrations of Pb^2+ to I be in the beaker at equilibrium? Is this the same ratio as you found in problem #1? Why not? In this lab you will be working with potassium chromate (find the SDS here). Please list at list three specific hazards associated with potassium chromate.

If you were to take a quantity, of PbCl_2, a sparingly soluble salt- maybe 10g-and put it into water, some of it would dissolve based on its K_sp. The equation for this reaction is PbCl_2(s). D Pb^2+_(aq) + 2Cl^-_(aq). What will the ratio of the concentrations of Pb^2+ to Cl^- be? In other words, what will be [Pb^2+]/[Cl]? Equal volumes of 1.0 M Pb(NO_3)_2, and 0.001 M NaI are mixed in a beaker and PbI_a precipitates out as the solution reached equilibrium, what will the ratio of the concentrations of Pb^2+ to I^- be in the beaker at equilibrium? Is this the same ratio as you found in problem #1? Why not? In this lab, you will be working with potassium chromate (find the SDS here). Please list at list three specific hazards associated with potassium chromate.