Sciencemadness Discussion Board


Johnny - 6-8-2004 at 08:59

A little history on this.....I have been working on this for some time and have been wanting to post this as a finished effort. I have been working on an efficient method for the production of styphnic acid from Resorcinol. I have seen other methods in the past and the results were far from optimum. What I wanted to accomplish was a technique that produced a reagent grade product and did so consistently; finding the variables and documenting them clearly so that reproduction would be consistent (key word) and a large amount of styphnic acid could be produced. After some work I have some success that I confidently say would work on a lab scale. For this post I have reduced the amounts but then when multiplied, the process continues to funtion uniformly.

This was my pet project for amonth. A friend, who I deeply respect had trouble making styphic acid of a high grade & with consistency. I gave him my efforts and he reproduced them with no trouble. I got some real gratification for this and am happy to share it here:

Styphnic Acid
Needed are:
24 grams Resorcinol
30ml H2SO4 @ 95% - 55.5 gr
45ml H2SO4 @ (72%) – 75 grams
175 NHO3 @ 70%
+ H2O

Add 24 gr Resorcinol and 30 ml of H2SO4 (concentrated) to a 250ml beaker and stir at 50C (158 F) for 30 minutes (sulfonation process)*. After the solution has been sitting at this temperature, stir and watch for solidification (it should turn to a brownish pink solid, somewhat creamy). After the material has stood and started to solidify, it is broken up & diluted with 40ml H2O: clean the sulfonation vessel and all is added to the nitration beaker (this also serves to loosen the solid mass of Resorcinol / H2SO4 that occurs as part of the sulfonation process: a mix of H2O and the sulfonated Resorcinol). Here you should have a 500ml beaker with the broken sulfonated Resorcinol and poured into it, 40ml H2O. At this point it is appropriate to further stir the Resorcinol mixed solution from a solid mass to a solution again, add. 46 ml of 62% sulfuric acid (75 grams) to the product and mix /stir as thoroughly as possible then it is ready for nitration. Pour the solution from the mixing vessel into another 500-mL beaker. To review: we have a sulfonated product that is broken into chips and 40ml H2O is added to it, producing a red solution (all is dissolved) and that is readied to be nitrated by adding 62% H2SO4 (45ml /75gr). Then placing this in a water bath, using a separator funnel add 175 ml of 70% nitric acid. Add the acid very slowly, a drop at a time (see note). The addition of nitric acid will cause a vigorous reaction and release toxic gas, use a fume hood or process outdoors. When all of the acid has been added and the reaction has subsided, the mixture is heated for 2 hours on a steam bath or hot plate at 110 C (238 F) to complete the nitration (continue to stir). When this is completed the beaker is placed in another water bath (10 C) and covered. After 8 to 12 hours the Styphnic Acid crystals should have separated. These crystals will need to be filtered with glass filter paper because of the solutions high acidity. Otherwise, pour off most of the acid, dilute with water and filter with regular filter paper. Wash the crystals with several small portions of water and allow it to dry in the open air. Product will be yellow / orange high grade Styphnic Acid.
NOTE: Several elements are very important to the success of this process. First, that the sulfonation be very through. When the H2SO4 is added to the Resorcinol a complete stirring take place so as o create a pink cream solid. This is the basis for sulfonation for Resorcinol. After which H2O is added in correct proportion and the pink solid is allowed to dissolve into the H2O thus creating a red solution of sulfonated Resorcinol. This is the basis for nitration. Any thing less that total solution is bound to oxidize much of the product. Second, is imperative that after nitration takes place with the addition of HNO3 that the solution be heated; this is the element of the nitration process and must be present to achieve a reagent grade material. After that has been accomplished the product will precipitate from the nitration acids and may be filtered off (after a period of time, wherein the whole is allowed to return to room temp). Third: it is very important to the yield percentage that the heat be monitored; too hot and oxidization will occur, too cold and the Styphnic Acid product will not be nitrated to the fullest extent possible and the product will have a high hydrogen content (as would be the case if alkali impurities were introduced to the mix. A critical element in Styphnic acid production is controlling the reaction temperature. A vigorous reaction from nitration will result in loss and low yield through oxidation. Thus it very important to nitrate slowly with corresponding low levels of heat and NO fumes.
Following these steps exactly and this process will result in reagent grade material with consistency. Turning inexpensive technical grade Resorcinol in very expensive, pure, Styphnic Acid crystals!

* This proportion of H2SO4 & Resorcinol may solidify very quickly, thus creating sulfonation. Maintain observation! The pink solid must be achieved (Resorcinol Sulfate) and that broken & dissolved into 40 ml H2O. Proportions may be multiplied or divided to achieve larger or smaller lots. MAINTAIN THESE PROPORTIONS!