CHML211 Exp. 8 Bromination of Stilbene—Green Synthesis IN-LAB ASSIGNMENT: (EACH STUDENT will record the following data in his/her laboratory notebook in a well organized manner during lab period. Yellow carbon copies will be submitted for grading along with Post-Lab assignment.) …..max score = 20 pts. 6. Data/Calculations a. b. c. d. e. f. g. h. i. j. k. Initial mass of trans-stilbene used Initial volumes of 48% HBr and 30% H2O2 used Mass of small filter paper Mass of empty watch glass Mass of watch glass+ filter+ product Mass of final product Physical state and color of product Theoretical yield calculations based on all 3 reactants! % yield calculation TLC diagram All Rf calculations 7. In-lab Questions (The following question should be answered in laboratory notebook.) a. Draw the complete mechanism for the synthesis of the product formed from the addition of Br 2 to 1,2dimethylcyclohexene using curved arrows to indicate the movement of electrons. CH3 CH3 + Br Br ? MW: 110.2 g/mol b. Based on the previous question, calculate the theoretical yield based on 1.0 g of the 1,2-dimethylcyclohexene. The molecular weight of the starting alkene is given, but the molecular weight of the product must be determined using the product structure. Be sure to include units. CHML211 Exp. 8 Bromination of Stilbene—Green Synthesis POST-LAB ASSIGNMENT: (EACH LAB GROUP will submit one copy of a typewritten, paragraph style report addressing all of the points listed below. Must be written using PAST TENSE, PASSIVE VOICE. ) …..max score = 50 pts. 8. Experimental (Write 1-2 paragraphs including all of the following. Do NOT present a bulleted outline.) What type of reaction was performed? Describe the actual synthetic procedure. Include names of any reactants used and desired product, as well as name of solvent and catalyst used (if any). Be sure to give actual volumes/masses of compounds used during the synthesis (not just what the lab manual tells you to use). Describe the purification technique used to isolate the desired product. Be sure to give names and actual volume/mass of any compounds used during the purification process. Describe the analytical technique (TLC) used to evaluate the product, including preparation of TLC sample, names and actual volume of TLC solvent used during analysis, visualization method used to detect compounds, and how compounds were identified using this technique. 9. Results (Complete, then copy/paste completed tables into your document.) Table 8.1 Experimental results Final Mass of product (g) Theoretical Yield (g) Percent Yield Product Appearance Compound Table 8.2 TLC results TLC Rf values Standard Sample Stilbene Dibromostilbene 10. Discussion (Write 1-2 pages addressing all of the following points.) Describe in detail the two conditions that used in this experiment that made it “greener” than typical bromination procedures. Restate the name of the reactants combined and the name of the product formed during the synthesis. State the final product mass and the calculated percent yield for the synthesis. Be sure to report these values using the correct units. Based on the TLC results, were the reactants completely converted to the desired product? Explain this conclusion by stating the calculated Rf values of each standard provided, along with the calculated Rf value(s) of any compound which appears in the sample lane. Be sure to report Rf values using correct significant figures. Include a short comment addressing what could be done differently to improve the experimental results if repeated.