The Amateur Chemist

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How to get Phthalic Anhydride from Vinyl Gloves


This is the first step in a series of experiments to make Luminol by the process that Nurdrage made. Obviously, the next step will be to make hydrazine sulfate. The process of getting Phthalic Acid/Anhydride from these gloves is a fairly straight forward process that shouldn't take too long. I haven't done much math on it yet, but I am sure that doing it this way is far from economical. If you want a lot of this chemical, then just buy it on the Internet. A website like Elemental Scientific sells it fairly cheaply.

Ingredients

50 grams of vinyl gloves       
 ~400 ml of Isopropyl Alcohol (just enough to completely cover the glove pieces)                                                                                                        
10 ml of 12M Hydrochloric Acid
10 grams Sodium Hydroxide
Water

Process

Cut the gloves up into smaller pieces and put them into a large beaker. Put enough Iso-propanol into the beaker to completely cover the glove pieces. Then put a large round bottom flask filled with cold water onto the top of the beaker. This will act as a crude reflux setup, so we can boil the alcohol for a long time without losing any of it. Then boil/reflux the alcohol for at least 1 hour, preferably 2-3-4 hours.

After you reflux it, filter out the now hard pieces of gloves. Then, distill out about 1/2 of the alcohol from the mixture. So, if you started with 400ml, you should be left with 200ml. The Isopropyl alcohol you distilled out can be reused if you do the experiments again.  Then dissolve 10 grams of NaOH in an equal amount of water to what you have left after distillation. In this case, around 200ml of water.

Combine the sodium hydroxide solution with the what was left after distillation. Reflux this for about another hour. Then, let it cool down to room tempature. It will form 2 layers. Keep the bottom layer, and discard the upper layer.

Add 10 ml of 12M HCl to the lower layer, which is currently Disodium Phthalate.  Adding the HCl, will turn it into Phthalic Acid. Put this into the refridgerator for about 1 hour, then cool it in an ice bath. Poor out the top layer and keep the white crystals of phthalic acid that have precipitated out. Heat the crystals on a hotplate. The water will evaporate and the crystals will melt. 

When it reaches 300*C, the Phthalic Anhydride will start to distill off. It will condense on the walls of the beaker and the flask filled with cold water on top of the beaker as a white cotton candy like deposit.

Harvest this deposit several times until no more is produced. This is quite pure Phthalic Anhydride.

I have tried this several times, and got it to work right a couple of the times. Sometimes, however, I get a weird precipitate or something after refluxing with the sodium hydroxide and before adding the HCl. When that happens, if I continue with the procedure, I will not get any crystals of phthalic acid. I think it has something to do with what kind/brand of vinyl gloves you use. I am pretty sure that some brands are different than others. Otherwise, it could have something to do with what concentration of isopropyl alcohol you use. I usually use 91%. I can get a liter of it at Walmart for about $2. 

The crystals do look very cool. They are so like cotton candy that you think you could eat them. I will post some pictures of my crystals below...