PowerLabs Styphnic Acid Synthesis

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Styphnic Acid
(2,4,6-Trinitro-1,3-benzenediol) Laboratory synthesis:

INTRODUCTION:

2,4,6-TriNitroResorcinol, 2,4-dihydroxy-1,3,5-trinitrobenzene.
C6H3N3O8. Molar Weight; 245.11.
Percentage composition; C: 29.40%, H: 1.23%, N: 17.14%, O: 52.22%. Styphnic Acid
is a dibasic acid which forms into hexagonal yellow crystals from dilute acid,
but becomes almost colorless on vacuum sublimation. It becomes deep yellow on
contact with air. Anhydrous, it melts at 175.5C. One gram dissolves in 156mL
water at 14C, 88mL water at 62C. Freely soluble in alcohol and ether. Acid to
litmus. It deflagrates on rapid heating. Styphnic acid is used in the
manufacture of dyes, pigments, inks, medicines, and explosives. It deflagrates
on rapid heating. (Source: Merck
Index 12th edition).
I have been interested in manufacturing this
acid for quite a while now, for experimentation purposes. However, I have never
been able to find a detailed article on its synthesis. Thanks to my lab skills,
and some pointers from Merck, which outlined the industrial synthesis as being
similar to that of Picric Acid (2,4,6-TriNitroPhenol), I have been able to
devise the synthesis below which is an adaptation of that to make Picric Acid.
It seems to work safely and with good yield. Since the Internet as a whole lacks
such a document, I am making it available here. Please do not copy this
synthesis as it is a product of my individual work. Instead, link back to this
site.
As with any other nitration, this procedure is hazardous and
involves the use of highly corrosive acids. The final product is toxic and
dangerous. This should only be attempted by experienced chemists!

MATERIALS:

Reactants:

Glassware:

98% Concentrated Sulfuric Acid
(H2SO4(l))

150mL Glass
beaker.

68% Concentrated Nitric Acid
(HNO3(aq))

Pipette

Resorcinol
(C6H6O2(s))

Stirring
Rod

Ethanol (C2H6O(l))

Funnel/filter
paper

Distilled Water (H2O(l))

Ice
bath

Here all the chemicals used in the synthesis are seen, from left
to right, back to front: Absolute Ethanol, Resorcinol, Sulphuric Acid (98%),
Nitric Acid (68%), Distilled water. In front of the picture a tall measuring
tube is seen holding 8 grams of powdered Resorcinol, and it sits next to a
beaker holding 10mL of concentrated Sulphuric Acid.

PROCEDURE:

A note on proportions: 0.8grams of
resorcinol are reacted for every 1.5ml of Nitric acid and 1ml of sulfuric
acid.

C6H6O2(s)
+ H2SO4(l)  =>
C6H7O5S + HNO3(aq) =>
C6H3N3O8

8grams of powdered resorcinol are weighted and added to the 150ml
beaker containing the 10ml  (18.5g) of concentrated sulfuric acid. The
mixture is stirred for several minutes untill the resorcinol dissolves and forms
into a yellow liquid. It is than heated on a hotplate set for 100C for 30
minutes, during which it quickly solidifies into a pink cream (Resorcinol
Sulphate). Stirring is continued untill the 30 minutes are over and the
resultant product is than chilled to -5C on a water bath with salt added,
becoming a solid pink mass to which 15ml of nitric acid are added inside a fume
cupboard.

Shortly after the Resorcinol Sulphate and the Nitric Acid are stirred,
a reaction takes place which produces Nitrogen Dioxide (NO2) in large amounts.
The red colored gas is highly toxic and corrosive and should therefore be
avoided. The mixture is allowed to stand for a few minutes until the reaction
subsides, and the beaker is once again put in a hot plate at 100C for 1 and a
half hours, so as to complete the reaction. The liquid is stirred occasionally
and the mixture gives off some more NO2 fumes.

Once the heating is complete 100mL of distilled water are added to the
mixture, causing the Styphnic acid to precipitate as small crystals in the
bottom of an orange liquid. The mixture is cooled to 5C so as to precipitate
most of the remaining Styphnic acid, and than is quickly filtered and washed
with 450mL of cold distilled water so as to remove any traces of the nitration
acids.

The filtrate appears as the fine yellowish mass of crystals seen to
the left. Yield is approximately 10grams for the 8 grams of resorcinol started
out with. These crystals are high purity and have all of the properties
attributed to reagent grade Styphnic Acid. However, they can be
purified:

PURIFICATION:

Making use of Resorcinol's high water solubility, and the higher
solubility of lower nitration portions of resorcinol, the Styphnic Acid can be
purified to near analytical grade by re-crystallization from a solvent mixture
of 1 volume ethanol and 2 volumes  water, roughly 8ml of solvent being
required per gram of Styphnic Acid.

The final product: The crystals are than removed by vacuum filtering,
are vacuum dried in a dissector, and form into a nearly yellow mass of mp
175,5C.
It is advisable to store Styphnic acid wet with at least 30%
water and in rubber stoppered flasks.

This filter paper is witness to Styphnic acid's incredible staining
power: With only a small amount the entire paper became bright yellow; almost
fluorescent!

RESULTS:

The melting point and the deflagration show that the result
of this synthesis is indeed Styphnic Acid. The picture to the right shows a
fireball produced by 300mG of the product as it is heated over an alcohol lamp.
Clicking on it downloads the 157kb .mpg movie that shows how the product
deflagrates from flame.
This acid may be used for many other synthesis.
The one of greatest importance is its heavy metal salt Lead
Styphnate:
Lead Styphnate
Synthesis.

Questions? Comments? Suggestions? E-mail me!

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22/05/01.

Last updated 30/01/04

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