Experiment 8 2020 скачать в хорошем качестве

Experiment 8 2020

This video is intended for students in CHM 221 Organic Chemistry 1 at Geneva College. This video is related to SN1/SN2 Reactivity of Alkyl Halides. Procedure You will do this experiment in teams of two to help with timing. Include the name of your partner. For the data section, use tables to organize the (many) results you will observe. Record these results clearly and legibly. The following alkyl halides are the substrates (RX) which will be tested in both parts 1 and 2. Make a table in your lab notebook with each compound and note the observations for each reagent. 1. 1-chlorobutane 2. 1-bromobutane 3. cyclopentyl chloride 4. 2-chlorobutane 5. 2-bromobutane 6. 2-chloro-2-methylpropane 7. 2-bromo-2-methylpropane Part 1. SN1 – favoring Reaction Conditions (1% AgNO3 in ethanol) Label seven clean, dry test tubes with the appropriate alkyl halide number or name. Add 3 drops of each halide to its respective test tube. Immediately cover each test tube with a piece of parafilm. Measure out 10 mL of 1% silver nitrate/ethanol solution in a graduated cylinder. Note that in this system, the silver nitrate is the indicator and the ethanol is both solvent and nucleophile. Add 1 mL of this solution, using a plastic pipet, to the first test tube and note the time. Cover the test tube with cork or parafilm and shake the test tube to ensure complete mixing. Continue to add the 1% silver nitrate/ethanol solution to the additional test tubes noting the time and ensuring that each test tube remains covered. Record the time it takes to see the first signs of turbidity or actual precipitation in each test tube. Test tubes that show no signs of reactivity after 5 minutes should be warmed to 50oC (water bath) for 15 min. It is very important that the water bath not be permitted to go above 50oC. During the 15 minute incubation period check for turbidity or precipitation. Part 2. SN2 –favoring Reaction Conditions (15% NaI in acetone) Label seven dry test tubes. (dry is important – very important to avoid any water). Place 3 drops of each alkyl halide in its respective test tube. Immediately cover each test tube with a cork or a piece of parafilm. Next, obtain 10 mL of 15% NaI/acetone in a clean dry graduated cylinder. Note that in this system, the iodide is the nucleophile and the acetone is the solvent. Add 1 mL of this solution, using a clean dry plastic pipet, to the first test tube and note the time. Cover the test tube with parafilm and shake the test tube to ensure complete mixing. Continue to add the 15% NaI/acetone solution to the additional test tubes noting the time and ensuring that each test tube remains covered. Record the time it takes to see the first signs of turbidity or actual precipitation in each test tube. Test tubes that show no signs of reactivity after 5 minutes should be warmed to 50oC (water bath) for 15 min. It is very important that the water bath not be permitted to go above 50oC. During the 15 minute incubation period check for turbidity or precipitation. Calculations/ Interpretation of Data – post lab questions 1. Draw the structures of the seven alkyl halides used in this experiment. 2. List the alkyl halides in order of decreasing reactivity toward each of the reaction conditions as you observed it. Explain why this order of reactivity was observed using theoretical trends. 3. Order the reactivity of primary halides to each reagent. Briefly explain. 4. Order the reactivity of secondary halides to each reagent. Briefly explain. 5. Order the reactivity of tertiary halides to each reagent. Briefly explain. 6. Write out the specific complete reactions with structures for all 14 tests. (use NR as the product for no reaction). 7. In the procedure for SN2 –favoring conditions, you are instructed to be sure the temperature does not exceed 50 oC. Why is this instruction given?