Question

1st picture is the questions and the next two pictures are the experiment the questions are based off of

Prelab Questions 1) Based on the Material Safety Data Sheets (MSDS) for the compounds, which of the compounds in this experiment is the most hazardous, and why? 2) Fill in the reagent table below. Make sure you correctly calculate the molar amounts of your materials. Name Formula Mol.-eq. Mw mmol Density/Conc. Amount 10 400 mg Meso-Stilbene Dibromide Potassium Hydroxide 5.75 Triethylene Glycol Product 3) What is the limiting reagent in this reaction? 2 ml 4) Potassium hydroxide is hygroscopic (absorbs water). Will you be able to accurately weigh the amount from your reagent table? Will the exact amount of potassium hydroxide be critical to this reaction, and why? Figure 3. Dehydrohalogenation of Stilbene dibromide Br OH Ph кон Solvent Ph Ph HO Triethyleneglycol (Solvent) Br

Answer 1

1) Meso-stilbene dibromide is the most hazardous as it is lacrymetric and corrosive. 2) Name: Meso stilbene dibromide Formula: C14H12Br2 mol. eq: 1.0 Mw: 340.1 g/mol mmol: = mass / molar mass = (400/0.340) = 1.177 mmol Density: -- Amount: 400 mg Name: Potassium hydroxide Formula: KOH mol. eq: 5.75 Mw: 56.11 g/mol mmol: = 1.177*5.75 = 6.768 mmol Density: -- Amount: 6.768*10^-3 * 56.11 = 0.3798 g = 379.8 mg Q3 and 4) KOH is an excess reagent hence even if it is little more excess or little less will not affect the result of a reaction. Product: Diphenylacetylene (C14H10) Expected mmol = 1.177 mmol Mw = 178.2g/mol Theoretical yield = 178.2 * 1.177*10^-3 = 0.2097 g = 209.7 mg KOH is the limiting reagent.

Post lab: B 2) The prefered orientation for the E2 elimination is "Anti-periplaner". 3) The intermediate does not have a preferred antiperiplaner geometry and hence we heat the reaction mixture to force the reaction to happen.