Oxalic Acid

Thank you frogfot for the idea

Oxalic acid is a white, crystaline substance. It is used in stainless-steel cleaning materials usually, but in low concentrations. Though it is generally cheaper and easier to just buy oxalic acid (at a supplier), you can make it using this process. Be careful during heating this as it can decompose into poisonous gasses (such as carbon monoxide) at a fairly low temp. This process is the oxidation of sucrose (sugar) using nitric acid.

C12H22O11 + 9O2 ----> 6(COOH)2 + 5H2O

Materials	Equipment
Sucrose	250ml Erlenmeyer flask
70% Nitric acid	Evaporating Dish

Into a 250ml flask, place 10grams of sucrose. Measure out 55mls of 70% nitric acid and add it to flask with the sucrose. Swirl this for 2-3 minutes then place on a hotplate. A couple minutes after heating has begun, you will notice that the ntiric acid will be a tint of yellow and this will gradually get darker. Eventually it will become a darkish orangish color, this is right about when the oxidation happens. Continue heating for a few more seconds. A very vigorous reaction will start and ungodly ammounts of red-brown NO2 will be evolved from the flask. Turn the hotplate off or place the flask on another surface (make sure its not cold and make sure the surface is not perfectly smooth). The best place to set the flask is on a warm towel. Leave the area for about 30 minutes. By then the reaction should have subsided. Set this up in a water bath and evaporate the solution down to about 20-25mls. NO2 will be evolved during this part. Add rougly 20mls of water and evaporate again to about 20mls of water on the water bath. Pour this solution into an evaporating dish and evaporate the water using steam.

To make the oxalic acid anhydrous:

Put a porcelian tray (or some other material that will not be harmed by this acid) in an oven and heat the oven to 210F (99C). Once it has reached this temp, pull the tray out and pour the oxalic acid over it in a thin layer (2-3cm thick). If the oven temperature drops during this, wait for it to go back to 210F and then set the timer for 2 hours. After 2 hours, remove the oxalic acid and quickly place in an air-tight container. It is recomended that you do not use a kitchen oven for this as some oxalic acid will sublime onto parts of the oven. If a kitchen oven is used, make sure you clean it well if a large ammount of oxalic acid was dried.