The Chemistry of Dyes Part I: The Synthesis of Indigo Dye

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4) Now calculate the limiting reactant in this reaction. Clearly show all work: 5) Finally, calculate the theoretical and percent yield of your sample of indigo. Again, clearly show all work: 6) Based on your percent yield, how many grams o-nitrobenzaldehyde would you need to start with if you wanted to produce 1.0 pound of indigo? Explain with calculations 7) Your data table has the cost of 10.0 g of o-nitrobenzaldehyde. Based on this and your answer to 6, would it be cheaper for you to make 1.0 pound of indigo or buy it from a supplier? (Of course you will need to find a supplier of indigo on the web. Please include a website I can look up to verify the supplier price) CONCLUSION:
PROCEDURE: The synthesis of indigo Day One 1) Form a lab group of two people and put on aprons, goggles, and rubber gloves! 2) Add approximately 350 ml of distilled water to a 400 ml beaker. Place an immersion heater in the water, plug it in, and allow the water to come to a boil. DO NOT PULG IN THE HEATER UNTIL IT HAS BEEN IMMERSED IN THE WATER. 3) At your station you will filled a preweighed bottle vial of o-nitrobenzaldehyde. Record the mass of the reactant in the data table and remove the label from the vial. 4) Have a member of your group go to the reagent station with your 10 ml graduated cylinder and obtain 2.5 ml of acetone. Record the volume of the acetone in the graduated cylinder and add the acetone to the reaction vial. Gently mix the solution to dissolve the o-nitrobenzaldehyde. 5) Rinse the graduated cylinder with distilled water and then return to the reagent station to obtain 4 ml of sodium hydroxide. Add the sodium hydoxide to your reaction vial and quickly seal the vial with the Teflon cap. Make sure the cap is tight and shake the reaction mixture again. 6) Wrap a small piece (approx. 6 inches) of copper wire around the cap to serve as a handle. 7) Place the sealed vial in the beaker containing the boiling water. If at any time, small bubbles start coming out of the vial, the cap is not on tight enough. Remove the vial, allow it to cool, and retighten the cap. 8) After 3-4 minutes, remove the vial from the hot water using the copper handle and place it on the tabletop. Allow the mixture to cool for 3-4 minutes or until it is cool enough to touch. Vigorously shake the vial. Tighten the cap again and place the vial back in the boiling water. 9) While the solution is boiling, prepare a Buchner funnel for vacuum filtration by adding a piece of filter paper to the funnel and gently bathe the filter paper with water. In addition, create an ice water bath using a Styrofoam cup filled with an ice / distilled water mixture 10) After 10-12 minutes, use the copper wire handle to remove the vial from the boiling water bath and place on the counter for a few minutes to cool. 11) Place the vial in the cold water bath you created for a few minutes. 12) Carefully open the reaction vial. The contents of the vial are likely pressurized and some solution may squirt out. This will not be a problem if you open the vial slowly. 13) Complete the final setup of your Buchner funnel (Ask if you need help) and gently pour your mixture into the middle of the funnel. Rinse the vial with distilled water twice to make sure you have removed all product. Then wash the product twice with distilled water from your ice bath. 14) Allow the vacuum filtration setup to run for 2-3 minutes. Then remove the filter paper containing your product and place on a labeled watch glass to dry at least overnight. Day Two: 15) Find the mass of an empty weighing boat 16) After the indigo is dry, transfer the product to a massed weighing boat. Obtain the mass of the product and boat and place this mass in the data table. 17) Place your group’s indigo in the provided film canister. Label and give to the instructor to save for part II of the lab later in the semester.
Page 1 and 2: The Chemistry of Dyes Part I: The S
Page 3: OBSERVATIONS AFTER SODIUM HYDROXIDE

The Chemistry of Dyes Part I: The Synthesis of Indigo Dye

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