Purity, commercial formaldehyde solutions

Summary In this procedure, propionitrile and sulfuric acid are heated together, and then a solution of trioxane (formaldehyde trimer) in propionitrile is slowly added a short time later. Shortly after the addition, a triazine compound is formed. This triazine compound is only an intermediate and need not be isolated. The triazine slurry is then added to ten times it volume of 99% nitric acid. The resulting mixture is then cooled, heated, and then cooled again. The mixture is then drowned into 5 times its volume of water. The RDX then precipitates in high purity. Commercial Industrial note For related, or similar information, see Application No. 522,153, November 8, 1974, by The United States Army, to Joseph A. Meredith, Bluff City, TN. Part or parts of this laboratory process may be protected by international, and/or commercial/industrial processes. Before using this process to legally manufacture the mentioned explosive, with intent to sell, consult any protected commercial or industrial processes related to, similar to, or additional to, the process discussed in this procedure. This process may be used to legally prepare the mentioned explosive for laboratory, educational, or research purposes. 

A laboratory method 2 for the preparation of sodium hyposulphite depends on the interaction of sodium formaldehydesulphoxylate,3 NaCH303S,2H20, and sodium hydrogen sulphite, the product having a purity of 80 to 85 per cent., and the yield being 55 to 60 per cent, of that theoretically possible. The sodium formaldehydesulphoxylate can be obtained2 by the reduction of commercial hydro-sulphite by zdnc-dust and zinc oxide in presence of formaldehyde solution, the crude product being recrystallized from water at 70° C. 

In general, commercial formaldehyde is a uniform solution of high purity capable of meeting stringent pioduct requirements. The following figures are representative of typical product specifications. 

Formaldehyde is a gas with a boiling point of -21 °C. It is usually supplied as a stabilised aqueous solution ( 40% formaldehyde) known as formalin. When formalin is used as the source of the aldehyde, impurities present generally include water, methanol, formic acid, methylal, methyl formate and carbon dioxide. The first three of these impurities interfere with polymerisation reactions and need to be removed as much as possible. In commercial polymerisation the low polymers trioxane and paraformaldehyde are convenient sources of formaldehyde since they can be obtained in a greater state of purity. 

Materials and Instrumentation. Diallylamine and the various starting materials for monomer synthesis were readily available commercial materials of the highest available purity and were used without further treatment. The formaldehyde used was either BDH analytical reagent solution with 37-40% w/v formaldehyde and 11-14% w/v methanol or BDH analytical reagent paraformaldehyde. 

---