Multistep Three

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Des Moines Area Community College *

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Chemistry

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Apr 3, 2024

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TEMPLATE: Multistep-Step Three Please make your own copy before editing. Name: Edin Muminovic TA’s First Name: Tan TA’s Email: tientan1@iastate.edu Partner’s Name: Will Tidona Partner’s Email: wtidona@iastate.edu Combination: 38293006 18- 32- 38 ‐ ‐ Pre-lab Questions  Do not copy and paste structures or mechanisms from any source.  Answers must be legible, or they will not be graded. Procedure and Safety 6. (10 pts) Write a brief, bullet list overview of the procedure for this experiment. a. Add 0.02 mol of epoxide product to 50mL e-flask w/ stir bar and 5mL of distilled water. b. Stir vigorously and prepare ice-water bath; add few drops of 6 M sulfuric acid. c. Stir for 15min; after 15min, turn off stir plate and let cool to room temp. d. Add 10% of NaOH to neutralize, and check w/ pH paper using glass stir rod. e. Add reaction mixture to separatory funnel, add 25mL of diethyl ether – invert and vent, remove aq and organic layer. f. Return aq layer to separatory funnel, add 25mL of diethyl ether and repeat. g. Dry organic layer with sodium sulfate and move to premassed rotovap flask. h. Recrystallize from hexanes. i. Collect product by vacuum filtration and add to premassed watch glass. j. Spot TLC plate with pure cis product and provided trans product. k. Drip plate in anisaldehyde stain, remove excess w/ paper towel – bring to TA for heat gun. l. Obtain FTIR spectrum and NMR spectrum. 6. (4 pts) Write a one sentence summary of the main safety concerns for this experiment. a. Always handle all the materials in the lab with care. Several of the chemicals used are hazardous and can cause serious damage if not handled properly, and make sure to always follow the TA instructions and always have the proper PPE on. Conditions and Mechanism Recall that the ring opening reaction for this experiment is the third step of a multistep synthesis: 6. The conditions being used for the ring opening reaction involve water as a nucleophile and a catalytic amount of acid. Look at the structure of the epoxide, which is your substrate for this reaction. Where is the most likely spot for protonation? Draw the structure of the protonated epoxide.

Examine the structure of the protonated epoxide. There are two carbons which are likely to undergo nucleophilic attack. Circle these carbons on the structure you drew above. 6. For this reaction, water serves as the nucleophile and protonated oxygen acts as a leaving group. Since epoxide ring opening under the conditions, we are using undergoes an S N 2 mechanism, the nucleophile will attack the carbon on the opposite side of the leaving group. A simple example of this step is shown below: Note that since the epoxide is a ring, the leaving group stays attached to the substrate. a. Draw the mechanism for the nucleophilic attack on the protonated epoxide for the ring opening of cyclohexene oxide (the reaction for this experiment). b. The final step for the ring opening reaction is the deprotonation of -OH 2 + . Add this step to your mechanism. 6. Examine your product below.

a. Draw the product you would get if the water had attacked at position 1 instead of position 2. b. Is this the same or a different product? Explain. (Hint: does the product have chiral carbons?) i. The product is different because there are two chiral carbons present in the compound. Although the two above are enantiomers, they are not the same product. Additionally, no plane of symmetry exists in the compound(s) above. Calculating Amounts 6. (12 pts) Fill in the table below with the necessary product information and calculate amounts to use. Show your work for credit. Amounts In-lab Notes 37.593g empty 50mL Flask 2.00mL of epoxide product (used provided epoxide) 6 drops of H2SO4 15min passed – reaction is exothermic (produced heat) 30 Drops of 10% NaOH – around 8 pH (green/yellow color on pH paper) 67.883g empty 100mL rotovap flask 40.836g empty watch glass 41.933g watch glass w/product #34 NMR Analysis and Application Questions  Do not copy and paste structures or mechanisms from any source.  Answers must be legible, or they will not be graded. Reactant Product Cyclohexene Oxide 1,2-cyclohexanediol Moles 20 mmol 20 mmol MW 98.14 g/mol 116.16 g/mol Density 0.97 g/mL NA Amount 20mmol x (1/1000mol) x 98.14g/mol = 1.96g/mol / 0.97g/mL = 2.02mL 20mmol x (1/1000mol) x 116.16g/mol = 2.32g

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