Changes to published procedure
We doubled the quantities used in the JCE article.
Summary of Experiment
The 2.6% aqueous sodium carbonate solution was prepared ahead of time.
The first part was done in beakers and no test tubes.
In 2008, we used the 3 positional isomers of aminobenzenesulfonic acid with 1-naphthol, 2-napthol, and 1-bromo-2-napthol. The latter nucleophile was a new addition to the scheme.
In 2009 we substituted 1,5-dihydroxynaphthalene for 1-bromo-2-napthol which gave a strong odor of bromine when taken out of the fume hood. 1,5-dihydroxynaphthalene worked well.
IN 2011 we used the 3 positional isomers of aminobenzenesulfonic acid with 1-naphthol, 2-napthol, and 1-nitroso-2-naphthol. The latter nucleophile was a new addition to the scheme.
Positive
+This experiment goes well with the "reactions of benzene derivatives" chapter.
+ Its colorful. The multifabric strip is a unique analysis technique - a little variation from the characterization of a white solid by melting point.
+ I really like these combinatorial schemes where students can contrast and compare their products.
Neutral
±A precipitation is not really necessary in Part I.
±In Part II, a little additional concentrated HCl helps with the final precipitation.
±If the student does not get a precipitate, they use the colored solution as a dye bath in Part III.
±The 1-bromo-2-naphthol behaved well. Unfortunately it had a pretty strong bromine odor.
Negative
-It may be rather difficult to determine the actual structure of the products. Has this ever been done? Is it a mixture, or what?
Inquiry & Extension ideas
=Combinatorial schemes are always interesting to contrast and compare products.
=Could be incorporated with alot more information and discussion on the interactions between dyes and fabrics. Why do certain fabrics "hold" certain dyes?
=It is possible to vary the nucleophile (e.g. naphthol derivative). It may be possible to vary the sulfonilic acid too. Alot of possibilities!
=At one time in the past. used a study of chemical dyes as a semester-long project. There is so much chemistry history associated with the dying industry. There is also a whole field of natural dyes that can be explored.
=I ofen pair this up with a "Natural Dyes" lab where we dye the same multifiber strips that we use in the "Azo Dyes" lab. Natural Dyes.doc
=I am interested in learning how to use a document scanner to measure (quantitate) the optical properties of the different fibers on the dyed strips.