Analysis of Nitrocellulose

[Secong Nature]

Backgroud story: Last year of high school chemistry assignment is to undertake a quantative analysis. I though studying the effect of nitrating equalibriums upon cellulose polymers would be a good one.

Basically I was wondering what people know about analysing NC. My ideas are to purify with acetone and reweigh the product as well as before and after weights of the cotton/NC.
Is it possible to titrate NC somehow? Could the polymer be broken down while in acetone and therefore measured?

All thoughts and ideas are welcome.

Note: I would have put this as a think tank about the properties of NC elsewhere but as this is for selfish reasons I don't think it deserves a place anywhere else, but feel free to move it.

[megalomania]

What exactly are you trying to determine? Yield of nitrated cellulose, the degree of nitration of the polymer, or something else? What are you trying to determine with a titration?

[deinewelt]

So far, I have never performed the synthesis of NC on my own, but I'm hoping to give you some useful ideas. As I am myself interested in this problem, I searched the net for a bit of information and found a method of determining the nitrogen content in NC by using potentiometric titration with Fe(II)-salt which is also used in industrial production of NC.

the firm metrohm provides a datasheet/ instruction for its analysis apparatus. It basically states:
- weigh 150mg sample of NC into a 100ml flask and add 80ml conc. H2SO4 to dissolve. place the whole thing into ice cooled bath
- fill up to the mark the flask
- take 20 ml of the sample solution and titrate with c[(NH4)2Fe(SO4)2] = 0.12 mol/L
note that the firm mentions a "combined Pt-electrode" whatever that means, perhaps you know it Mega.
A guy from another forum makes his electrodes out of copper wire and Pt. using a standard ohmmeter. At this point I see some problems as I have no information on the distance of the two electrodes AND more imortant: the measurement error you might have if you don't use exactly the same materials they use.
I haven't tried this out at the lab I am currently but probably I will in the following month.

the final calculation will be according to the instructions given by metrohm (sorry for this being just copy and paste):

%N = a*b*c*d/(e*f*g)
a - titrant consumption in mL
b - 20.0 (volume of the sample solution used for the titration in
mL)
c - 0.12 (concentration of the titrant in mol/L)
d - 14.01 (M(N) in g/mol)
e - 100 (conversion factor for %)
f - 2 (stoichiometric factor: 2 Fe2+ react with 1 N)
g - ca. 1.5 (mass concentration of the sample solution in g/L nitocellulose)

I have read that you can pretty well calibrate the whole thing by doing it with KNO3 or salts of the like. Sorry for not providing you with real lab experience, but that is just the knowledge I got together from an evening of searching the net.

[Secong Nature]

Thanks heaps for that ill try it when i get back from holidays (just started) as i cannot titrate at home.
Mega I've decided to calculate the number of nitro groups, or the % nitrogen, possibly both.
I know that its possible to calculate the amount of OH groups replaced with NO2 groups by molecular mass but can it be done when both OH and H groups are being replaced?
In theory is it easier to nitrate OH groups than H groups? So if there was more than 3 nitro groups present you could see this and switch the calculations to nitration of a C-H bond.

[Secong Nature]

Sorry for the double post but could you please post where you got this Deinewelt info from as UTFSE hasn't helped me with this.

[Hinckleyforpresident]

Sorry for the double post but could you please post where you got this Deinewelt info from as UTFSE hasn't helped me with this.

Surely users will be more likely to help you out if you demonstrate some basic English skills.

Also, clearly you have not UTFSE as google brings up the page at the top of the list (*hint: metrohm nitrocellulose).


In theory is it easier to nitrate OH groups than H groups? So if there was more than 3 nitro groups present you could see this and switch the calculations to nitration of a C-H bond.

I believe that in general, it's easier to nitrate OH's than just H's.

[Secong Nature]

Sorry for my inept search, I used the wrong keywords.
The grammer/english problems can be attributed to a problem that I have with written english.
Now all I need to do is some mathwork to see how to make all this work.

Thanks for the help guys!