DYES AND DYEING CHAPTER 1. Calculate the amounts of salicylic acid, 1-naphthol, 2-naphthol, 8-anilino-1-naph- thalenesulfonic acid ammonium salt, or N,N-dimethylaniline needed for Part 1B of this experiment (use molecules as assigned by your TA). 190mg 3-aminobenzene 2.5mL Sulfonic acid 2.5% sodium carbonate solution 81mg Sodium nitrate 2. What is the purpose of the sodium carbonate in Part 1A? Why do we add glacial acetic acid in Part 13 when we react with N,N-dimethylaniline, but we don’t use it with the other aromatic coupling reagents? (HINT: Look at the functional groups involved.) Purpose of sodium carbonate deprotonates Ht from HSO₃ this makes sulfonic acid, soluble, this also makes it highly activated (electron rich) Malarial acetic acid because it is use lactonate

Chapter 14 Dyes and Dyeing state these salts should be kept suspended in aqueous solutions and used immediately after preparation. The ano dyes formed in this lab are irritants. Be sure to wash your hands well when you finish the experiment. Place any excesso dye solids in the “Solid Waste” container. Pour any liquid waste, including filtrates and your ano dye bath, into the liquid waste container in the waste hood. The fabric pieces you have dyed are safe you can take them with you if you want. Be sure to wash all of your glassware with soap and water to remove any traces of dyes. Be careful not to splash your clothing while you are cleaning up. Experimental Procedures Part 1: Synthesis of Are Dye Each student should synthesize his or her own dye as directed by the teach- in assistant A. Formation of Dlazen Sale Place 190 mg of an aminobenzenesulfonic acid (compounds 1, 2, or 3) and 2.5 ml of 2.5% sodium carbonate solution in a 13 X 100 mm test tube. Add a wooden applicator stick to the tube and heat the mixture in a boiling water bath (250 ml beaker with about 100 ml of water) to dissolve the aminobenzenesulfonic acid. Cool the solution to room temperature, add 80 mg sodium nitrite, and stir until it dissolves. Cool the reaction tube in ice, and add a mixture of 4-5 chips of ice and four drops of concentrated hydrochlo- ric acid to the tube. Be sure to mix the contents of the tube thoroughly. In a couple of minutes, a powdery white precipitate may form. This precipitate is the diazonium salt, and is ready to be used in the next step of the reaction. If no precipitate forms after about 10 minutes, it is OK to go on with Part B of the reaction. B. Synthesis of Azo Dye Follow procedure i or il below depending on your assigned coupling reagent. 1. Coupling with salicylic acid (A), 1.naphthol (B), 2-naphthol (C), or 8-anilino- 1-naphthalenesulfonic acid ammonium salt (D). Place 1 mmol of aromatic coupling reagent (A), (B), (C), or (D) in a 25 ml. Erlenmeyer flask, and add 1 ml. of 3 M aqueous NaOH solution. Mix well using your stirring rod, then place the flask in an ice bath. Add the suspension of diazonium salt from the previous step (stir the suspension well before you pour it in) with stirring to the solution in the Erlenmeyer flask. Use a few drops of water to rinse the diazonium salt residue out of the test tube. Stir the mixture thoroughly and intermittently over the next several minutes. You should notice a color change in the mixture during this time frame. A solid may form in a few minutes, and a thick paste may form in five to 10 minutes. Continue stir. ring to keep the reagents well mixed. After 10 minutes (even if no solids have formed), heat the reaction mixture to boiling on a hot plate, with constant

M string until most of the dye dissolves. Add 0.grams of sodium chloride with st a nd heat for another minute of two this helps precipitate the dyel. Allow the task to cool slowly to room temperature and then in an ice bath, Collect the product using vacuum filtration was the old with about 2 ml of saturated sodium chloride solution to rinse the dark from your product. Use this product in Part Coupling with N Nimethylaniline (EX Place 1 mmol of NN-dimethylaniline and drops of glacial acetic acid in a 25 ml. Erlenmeyer flask. Mix the two liquids well using your tirring rod. Add the suspension of diamonium salt from the previous step stir the suspension well before you pour itin) with stirring to the NN.dimethylaniline solution Use a few drops of water to in the diatonism salt residue out of the test tube. Stir the mixture thoroughly and intermittently over the next several minutes You should notice a color change in the mixture during this time frame. A solid should form in a few minutes, and a thick paste may form in five to 10 minutes. Continue stirring to keep the reagents well mixed. After 10 minutes add 1 ml. of 3 M NaOH to form the sodium salt of the dye. Heat the mixture to boiling on a hot plate, with constant stirring, until most of the dye dissolves. Add 0.5 grams of sodium chloride, with stirring and heat for another minute or two. Allow the flask to cool slowly to room temperature and then in an ice bath. Collect the product using vacuum filtration. Wash the solid with about 2 ml of saturated sodium chloride solution to rinse the dark liquid from your product. Use this product in Part C. C. Dyeing with Your Azo Dye The azo dye that you made has polar sulfonate groups that interact well with other polar sites in fibers. You will see that the dye interacts better with some fibers than others. In this part, you will prepare a dye bath and dye a strip of multifiber fabric. CAUTION: The dyes will also interact with your skin! Use forceps or a stirring rod to handle the cloth, and be sure to wash your hands in warm, soapy water between experiments. Prepare a dye bath as follows: Place approximately 75 mg of your azo dye into a 100 ml beaker. (It may be sticky, so just do your best to get close to 75 mg. The exact amount is not critical. If no solids formed in Part B, just use the liquid reaction mixture to prepare the dye bath.) Add 10 drops of 1 M sodium sulfate solution, 25 mL of distilled water, and five drops of 3 M sulfuric acid, Heat the dye bath almost to the boiling point, and stir to dissolve the dye. Place a strip of multifiber fabric into the dye bath and heat for approximately five min. utes almost at boiling. Use forceps or a stirring rod to remove the fabric strip from the bath, allow it to cool to room temperature, and then rinse it for about 20 seconds with running water. Wash thoroughly with soapy water and rinse well. Squeeze excess water from the fabric and allow the strip to dry. Record your observations of the fabric.