Student Comments 2008: Azo Dyes --> invite key = ochemrules

Think ahead: wear clothes you aren't worried about staining. --Sarah Perz

When comparing your swatch to the standards, it's a good idea to soak up some of the dye with paper towels in order to get a better comparison. Your swatch will be highly saturated making some of the colors appear darker, which could lead to an incorrect comparison; patting down the swatch will reduce the possibility of error. --Allison Kolman

Make sure that when you record the colors of the multi-fabric swatch, you also record the specific fabric from the swatch that the color corresponds to. For example, don't just draw the multi-fabric swatch and in each section put a color. Make sure you write the "wool", "orlon", "dacron", etc. above the colors because you will need to write that in the lab report for your results. --Megan Wasz

It is necessary to rinse the multi-fiber strip with tap water after boiling. I forgot to rinse it and many of my colors on the strip looked exactly the same. It took Prof. Friesen to come by and tell me I forgot to rinse my strip until I was able to properly compare my strip to the standards. --Patrick Hughes

Don't wear long sleeves to this lab because your sleeves are the most likely to get stain then anyother part of your clothes.--Kendall Moore

In this experiment I was assigned C3 which included 1-bromo-2-naphthol as my nucleophilic benzene and 2-aminobenzene sulfonic acid as my acid. The combination of these two yielded pretty good results (with some bromination impurity still), however the solid product was hard to dissolve in water. I ended up having to use only a very small portion of the solid and had to "chop" it up finely with a stir rod to dissolve in the water. I would advise doing this in the actual beaker of water so as to not make a big mess. I think this problem made it a lighter dye than it could have been, had more product been able to dissolve. -Becki H.

For the lab, make sure you calculate the number of grams in 5.2x10-3 mole of your aromatic coupling reagent before you come to lab so you can mix the correct amount with sodium hydroxide.--Marie-France Likanje

Make sure you are aware of whats around you. If you accidently get some of the dye on your pen, it can easily be tansfered to you hands once you take your gloves off. Also in this lab it pays to think ahead to save time, such as bringing water to a boil for the last few steps in the lab!--Andrea Prosperi

When I performed the experiment, I did not obtain any solids after part II, however, you can still go on with the experiment by skipping the dissolving of the solid and adding the 40 mL to the solution from part II. The only problem is that you won't have a weight to calculate your percent yield for the postlab, but just state that you never obtained any solids to inform the teacher. --Melanie Bonifacio

For this experiment you should definitely wear clothes that you wouldn't mind staining. The colors I observed on my multi fiber strip were different shades of peach, orange, light red/brown. I realized after that I did not rinse the strip with water which would make my colors even more visible! Tamara Pike

If you do not have a lot of product, do not worry. Just dissolve whatever you have in solvent, and when you go to dye your strip, just leave it in solution a little longer than what the procedure calls for. This way you will get more vibrant hues on your strip.

-Laura Volpe

Depending on the meta ortho para directing properties of your nucleophlic benzene derivatives ( 1-naphthol, 2- naphthol, 1-bromo-2-napthol). It is possible that where the

aminobenzenesulfonic acid joins could affect the physical properties of your azo dye product. For my particular reaction which involved Metanilic Acid and 1-naphthol, there were two possible locations on the 1-naphthol where the Metanilic acid could join. For my product, from the major director it came out to be a sludgey type of dark brown goo, which seemed more of a polymer. The minor product which is not benzene directing, the outcome could have been a more refined crytalline structure.

- Ricardo Rodriguez

Don't panic if at times your solution thickens as when adding 2-napthol and letting the solution sit in an ice bath.  Your experiment should still work and you heat the solution later anyway to dissolve any solids--K.S.

When you are finished making the dye, it may be a good idea to weigh out the amount needed to do the fiber strip section and then immediately clean out the beaker containing the rest of the dye. Otherwise, it is easy for the dye to get all over your lab materials. Cleaning up will not be fun. Alicia P.