Gun cotton from 50% nitric acid?

I don't think the fumes would be much of a problem if you do the distillation outside. I'd suggest a fume hood, but those are very expensive (probably worth 10 respirators ). You could consider scaling down your setup. Microscale glassware, while more expensive in the short run, saves money on reagents and fosters good lab technique. In addition, any fumes generated would be much easier to deal with. Perhaps even an "improvised" fume hood, of the sort you make from a water aspirator and a funnel, would work with such a setup. On the cleaning question my old ochem lab manual advises simple neutralization with baking soda before washing down the drain after a nitration experiment. Heck, it even uses reasonably dilute nitric acid to clean stubborn glassware. Given that, I think that if you neutralize your acids and rinse with plenty of water you should be fine.
PS: Two more benefits of a microscale setup include reduction of waste and the setup being harder to find and confiscate by customs

I might try googling homemade fume hoods at some point in the future, but really it's a bit more than I care to bite off right now. My apartment has a decent terrace where I can do some work outside, however there's a police substation right in front of my building and having a fume hood on my terrace would attract more attention than I would like (and I would like no attention at all).

The microscale idea sounds interesting, I'll check into that. Still hoping someone will come along and say they've used 50% HNO3 to make gun cotton and that it works as good as 70%. Probably shouldn't hold my breath though. I think I'm gonna give it a try here in the next few days and find out for myself the truth of the matter.

Thanks for the info on clean up. I've seen lots of videos and read lots of posts but no one ever mentions the clean up aspect. I guess probably because it's so basic huh? I'm gonna buy The Organic Chem Lab Survival Manual: A Student's Guide to Techniques. It sounds like a good primer that should hopefully get me pointed in the right direction.

Quote: Originally posted by Oscilllator

Theres no chance at all 50% nitric acid will work aswell as 70%, simply because the more water you have the lower your yeild.

Quote: Originally posted by Simbani

A ratio of 1:5 is just plain nonsense IMHO. The procedure works well even with 53% HNO3, I used a ratio of 1:2 HNO3 to H2SO4 by volume when I had no stronger acid available. The cellulose should be added at 0-5°C and the reaction time should not be longer than 3-4 hours, longer reaction time is contraproductive. Wash well with water and then in Na2CO3 solution, if a acid-free product is wanted you can boil it in ammonia water for a few hours because NH3 can more easily go into the nitrated cotton-fibers. There will always be residual acid in your NC, recrystallizing is the only way to neutralise it completely.

Quote: Originally posted by chemcam

Quote: Originally posted by Oscilllator   Theres no chance at all 50% nitric acid will work aswell as 70%, simply because the more water you have the lower your yeild. That is definitely incorrect I have made tons of nitrocellulose by using 70%, and lower is possible as long as you add enough H2SO4 to deal with the water. I am certain 50% would work it may take longer and you will need more sulfuric obviously.

Ok I'm starting to feel like this might work. Need to get my hands on some more glass so I can find out for sure. You guys in the states are really lucky with the easy availability of chemicals. 69%-70% HNO3 all over the place, on ebay, amazon, etc. not to mention stuff like KNO3, sulfur, percholrates/chlorates etc etc. All that stuff is tightly controlled here.