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Sunday, December 23, 2012

Make Pure Nitrocellulose - Nitration - Lu Le Laboratory

Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it was originally known as guncotton. Nitrocellulose plasticized by camphor was used by Kodak, and other suppliers, from the late 1880s as a film base in photograph, X-ray films and motion picture films; and was known as nitrate film. After numerous fires caused by unstable nitrate films, safety film started to be used from the 1930s in the case of X-ray stock and from 1948 for motion picture film.

 Units of Nitrocellulose

Units of Nitrocellulose in 3D
In this experiment, we are going to use a strong nitrating agent, Sulfonitric Mixed Acid. In the SNMA (Sulfonitric Mixed Acid), NO2+ ion is a very strong acid, and it would react with –OH group and from –O-NO2 group. The nitro group is a strong oxidizing group, it makes organic compound burns faster and even explode.

The reactions of the SMA are as follow:

Reaction of the SNMA:

Reaction of NO2+ with R-OH:

Side Reaction:

Mix the two acid together is quite an exothermic reaction To prevent the nitric acid decomposes into NO2 and sulfuric acid decompose the cellulose, keep the temperature of mixture below 5.

1.      Cotton wool: ~2g
2.      70% nitric acid: 25mL
3.      98% sulfuric acid: 25mL
4.      NaHCO3 saturated solution: ~ 200mL
5.      Clean water: ~ 1L

1.      Place 25mL 70% nitric acid into a Erlenmeyer flask and put it in an ice bath to cool down below 5.
 The Erlenmeyer flask an nitric acid ice bath

 2.      Add 25mL 98% sulfuric acid into the flask gently, and stir it thoroughly.  Stand the mixture about a minute to let more NO2+ from. Notice the temperature of the mixed acid should not excess 5.
 The Sulfonitric Mixed Acid looks a little yellow
3.      Place 2.17g cotton ball in the mixed acid, and insure the cotton is totally soaked in the mixed acid (squeeze the air out inside the cotton ball with a glass rob).
 Cotton wool in the SNMA, this yellow color is because of Sulfonation but not decomposition of the cellulose

4.      Let the cotton reacts about 20 minutes(also <5or the cotton would turn yellow because of the decomposition that sulfuric acid caused).
5.      Decant the mixed acid out, and pour some iced water into the Erlenmeyer flask to wash the acid inside cotton. Shake the Erlenmeyer flask to insure the water really defuse in the cotton. Repeat the step 2~3 times.
 Decant the mixed acid out

Use clean water wash the cotton

The cotton wool turn back to white because of the side reaction 

6.      Use some saturated NaHCO3(baking soda) solution to wash the cotton until no more bubbles form.
 Saturated soda water

 Bubbles are forming

The solution stop bubbling
7.      Use plenty clean water to wash the cotton until the pH value of the water-cotton mixture is located under 6.80~7.20
 Wash it times and times

It has a perfect pH value
8.      Squeeze water out from the cotton, and put the cotton in a desiccator.
9.      Weight the cotton, and figure out the assay, percentage of nitrogen
 The dried final preduct, 94.2% nitrocellulose.

Weight of Cotton Wool
pH Value of the mixture of water-cotton
Weight of Product(Theory)
2.17 * (297(g/mole)/162(g/mole))
= 3.98g
Weight of dried final product
3.81 g
Percentage of NC (nitrocellulose)
[Set the X=mole of NC
3.81g = (162 * (2.17/162-X)+ 297*X)
=> X= 0.0121
= 94.2% ]

Percentage of Nitrogen(by weight)


  1. do you know if nitrocellulose can be ignited in a container that can keep an such high pressure, that it can detonate by initiation of flame?

    1. Yes, it can. It makes very high pressure in a sealed container. But if you want to ignite it easier, you could purify and reshape the nitrocellulose by acetone.