12-10-13

Chem 2123 Oxidation of Cyclododecanol

Purpose: Oxidation of a secondary alcohol to a ketone.

Required Chemicals:

wk 1: Cyclododecanol (3 grams/student) (MW: 184.32 g/mol), glacial acetic acid (2.5 mls/student), sodium hypochlorite (35 mls/student) (aka. “Bleach”, 0.74 M), saturated aqueous sodium bisulfite (1 ml/student), saturated aqueous NaCl (25 mls/student), MTBE, aqueous NaOH (5% w/v) (40 mls/student), acetone (10 mls/student) anhydrous MgSO4, potassium iodide-starch paper

wk 2: 80/20 methanol/water (20 mls/student),

Reaction:

Procedure:

Week 1

Setup a reflux apparatus and combine stirbar, 3 grams of cyclododecanol, 7 mL of pure acetone and 2.5 mL glacial acetic acid in a 100-mL roundbottom flask. Stir the mixture and bring to a gentle reflux with the acetone. Use an addition funnel disposable pipette to add 30 mL of household bleach (0.74 M sodium hypochlorite) dropwise over 30 minutes. The reaction is somewhat exothermic, so don’t add the bleach too fast. After addition is complete, stop stirring and use a dropper or pipette to suck up a couple drops of the aqueous layer (bottom) and apply the drops to potassium iodide-starch paper. If the paper turns blue/black(maybe just around the edges of the liquid), enough bleach was used and you can continue to the next step. If the paper doesn’t change color, add another 3 mL of bleach and stir the mixture for 5 minutes and perform another potassium iodide-starch paper test.

Stop stirring and allow the layers to separate. After a positive test for bleach is obtained, stir the reaction mixture for an additional 10 minutes and retest for bleach. If test is positive, continue to the next step. If you have added 35 mls of bleach, continue to the next step regardless of if you got a positive test using KI starch paper.

Allow the reaction mixture to cool to room temperature. Add 1 mL of aqueous sodium bisulfite (sat’d) to the reaction mixture, observing the reaction color. The color should change from yellow to white. Perform another potassium iodide-starch paper test, which should be negative before continuing. If not, add additional 1 mL of aqueous sodium bisulfite (sat’d) to the reaction mixture and test until you obtain a negative test.

You will transfer your product to a separatory funnel and rinse the reaction flask with 25 mL of MTBE. Extract the organic layer with 25 mL of aqueous NaCl (sat’d). Wash the organic layer 2X with 20 mL of 5% NaOH. Dry the organic layer with anhydrous MgSO4. Allow the solution to dry for 5 minutes and gravity filter the solution into a preweighed 100-mL roundbottom flask and put in the flammable cabinet. See flow chart at end for visual description of extractions.

Week 2

Setup a simple distillation and distill away the MTBE. Recrystallize the product from 80/20 methanol/water. Refer to your previous lab write up for recrystallization procedure. You do not need to treat solution with activated carbon. Have your procedure written in your lab notebook before you come to class for week 2 (as you always should be doing…).

Determine the mass of your product, melting point and calculate a percent yield.

Obtain an IR spectrum of your product.

EXTRACTION FLOW CHART


Lab Report Guidelines (only a guide-refer to lab report grading scheme)

Short blurb about why reflux is a good technique and what it does

Oxidation mechanism with bleach

Percent yield of your product.

Was your product pure? How do you know?

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