Azo Violet ex2 - lab report PDF

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Azo Violet Synthesis Lecture Notes This last lab we’re going to be doing is the synthesis of azo violet. Azo violet is a dye. Humans have been messing around with dyes for a long time. Throughout most of human history, dyes came from natural sources, primarily plants. However in 1856 a guy named Perkins worked for a man named Hoffman at 18 years of age. Hoffman was trying to synthesize finine, which is an antimalarial agent. He charged Perkins to go for it. Perkins agreed, went to his dorm room, set up the lab, and started. However, the experiment was a complete failure. But the process they were doing produced this black goop at the bottom of the beaker. He proceeded to clean the whole mess up and tell Hoffman that the reaction didn’t work. The solvent he chose was alcohol. He added alcohol to the beaker and the solution turned purple. Out of that accident came the very first synthetic dye, called Perkins mall (?). He kept this discovery from Hoffman. They set up their own company and became very rich at a very young age. Now, the synthesis of azo dyes is a 2 step process. The first step is where you take an aromatic amine (?), and we are going to take p-nitroaniline in the presence of sodium nitrite and hydrochloric acid to make the azonic (?) salt. This process is called diazotization. Now this particular step is not unique to azo dye synthesis. What we’ve done here is put a really good leaving group on the aromatic ring. We can now convert this particular functional group to a lot of different aromatic functional groups, for instance we can convert it to a chloride, an alcohol, a proton (?), etc. So diazotization is just a way of converting an aromatic amine to a really good leaving group, and then converting it to a different functional group in aromatic nitrogen chemistry. So this particular reaction is not the unique step in azo dye synthesis. It is the second step that is the unique step in azo dye synthesis, and that is where you take the salt plus a second aromatic compound, in our case is resorcinol, and essentially all this is is an electrophilic aromatic substitution reaction, and this is called diazonium coupling. Once we’re done with the second set of the diazonium coupling, we have our azo violet. We call it azo violet, but when you actually isolate the salt, it’s kind of a burnt orange. Now, one of the difficulties in this last reaction that we’re doing is product analysis. We can’t do our normal product analysis. The product degrades before we actually get a reliable melting point. The IR is not a useful IR. So we have to analyze our product in a slightly different manner to show that we’ve actually synthesized methyl orange. So one of the things that we’re going to do, is see if the product behaves like azo violet. So we’re going to see if it dyes cotton. It’s interesting because it’s called azo violet but dyes cotton an orangeish color. We will provide you with cotton balls to see if it will be dyed orange. However, to kick this up a notch, it will dye any cotton orange. So if you wish, you can bring in any old white tshirt that you want, and dye it orange to make your own UT tshirt. This is gonna be done

microscale so you can’t be setting up an assembly line. You’re going to see if our product dyes cotton the way azo violet dyes cotton. Does it product an orange cotton the way it should. Now there’s one last observation that you need to make with your product, and it’s a very simple observation. Is your product when you isolate it an orange-ish color? If it is, you’ve probably made azo violet. If it’s not the correct color when you isolate the product, something might be wrong. Maybe you need to rinse it a little more, or maybe something is a little off. So you have to make the observation if the product is the right color. So it’s a simple observation that you can make about your product to show that you have the correct final product that you’re synthesizing. Now in terms of time, this is one of the faster labs, taking about an hour to an hour and a half. Safety wise there isn’t a lot to worry about in terms of chemical safety, so normal lab safety is really all we need to focus on here. Normal lab attire, goggles, etc. Now one thing I want to point out is that this is of course a dye, so if you spill it on your clothes accidentally, it is on your clothes for a very long time. Just keep that in mind. When you’re done with this experiment, you are done with organic chemistry lab in terms of experiments. We have to check out of the lab. Go through your drawer and clean all your glassware. Then you show your TA what you have, and tell the stock room what you have to pay for that’s broken or missing. During this process, it’s not uncommon for students to produce extra glassware. Don’t get excited because we are not buying it back from you. You should let the entire lab know and ask if anyone needs one. Before you do that make sure it’s actually extra. There’s usually an area in the lab where extra glassware gets set where people can try to find their missing equipment. Once you’re done with checkout, that’s the end of lab. Final reports will be according to the syllabus. Next Monday is when grades will be due on the stockroom computer, and all final grades will be calculated by next Tuesday....