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||||||||||||||| USOO5250687A United States Patent (19) 11 Patent Number: 5,250,687 Lukasavage et al. 45) Date of Patent: Oct. 5, 1993 54) PROCESS FOR PREPARATION OF RDX OTHER PUBLICATIONS (75) Inventors: William J. Lukasavage, Las Vegas, Nev.; Steven Nicolich, Saddle Brook; Suri et al., Synthesis, 9,743-5, 1988. Norman Slagg, Wayne, both of N.J. Cooney et al., J. Chem. Soc. Perkin Trans. II, 77-81 1989. (73) Assignee: The United States of America as represented by the Secretary of the Primary Examiner-Mukund J. Shah Army, Washington, D.C. Assistant Examiner-Y. N. Gupta Attorney, Agent, or Firm-Anthony T. Lane; Edward (21) Appl. No.: 936,375 Goldberg; Michael C. Sachs 22 Filed: Aug. 28, 1992 (57) ABSTRACT (51) Int. Cl............................................ CO7D 251/06 1,3,5-TRINITROHEXAHYDRO-1,3,5-TRIAZINE (52) U.S. C. .................................... 544/215; 544/180; (RDX) is prepared in a new simplified and efficient 544/185 manner which provides near quantitative yield. Our (58) Field of Search ......................................... 544/215 process is based upon the nitration of 3,7-DIACETYL (56) References Cited 1,3,5,7 TETRAAZA3.3.1.BICYCLONONANE U.S. PATENT DOCUMENTS (DAPT). 3,937,703 2/976 Meredith ............................. 544/215 5 Claims, 1 Drawing Sheet EFFECT OF INCREMENTAL ADDITION 100 80 70 60 50 40 30 20 10 O 5 10 15 20 25 30 35 40 50 55 60 GRAMS OFDAPT 5,250,687 1 2 PROCESS FOR PREPARATION OF RDX DESCRIPTION OF THE PREFERRED EMBODIMENTS GOVERNMENTAL INTEREST The following examples illustrate specific embodi 5 ments of the method of carrying out the process of the The invention described herein may be manufac present invention. It is to be understood that they are tured, used and licensed by or for the Government. illustrative only and do not in any way limit the inven BACKGROUND OF THE INVENTION tion. Today, RDX is probably the most important high 10 EXAMPLE 1-BACKGROUND brisance explosive; its brisant power is high owing to its Note should be taken, our preparations of RDX have high density and high detonation velocity. It is rela been accomplished on a 5-100 gram scale. On this scale tively insensitive (as compared to say PETN, which is no adverse reactions have been noticed which would an explosive of a similar strength); it is very stable; its indicate any safety hazard on scale-up. A 100 gram performance properties are only slightly inferior to 15 procedure based upon this work is as follows. those of the homologous Octogen (HMX). A 100 ml beaker is charged with 11.3 grams of DAPT In the prior art, RDXvis. hexamethylene tetramine is dissolved in 6.8 grams of acetic acid. To this is added nitrated to hexogen by concentrated nitric acid. After two reactant liquids. These liquids are added alternately the nitration mixture has reacted it is poured into cold and intermittently. Liquid one is comprised of 10.5 20 grams of ammonium nitrate and 13.1 grams of nitric water and the product is thereby caused to precipitate. acid. The second liquid is composed of 30 grams of In the conventional industrial practice hexamethylene acetic anhydride. The addition of these two liquids to tetraamine dinitrate is reacted with ammonium nitrate the initial mixture produces an exotherm. and the necessary excesses of nitric acid and acetic The temperature of the reaction is kept closely to 68 anhydride in acetic acid solvent medium, the hexogen is 25 degrees Centigrade. Cooling is minimal and said cool precipitated by addition of water, and the excess acetic ing is only required from time to time. The addition anhydride is lost by hydrolysis to acetic acid. Waste sequence is started with the nitric acid/ammonium ni acetic acid formed during the reaction is re-concen trate solution and is followed by the acetic anhydride. trated, and subjected to an energy intensive ketene pro The nitric acid solution is added in small portions, as cess being thereby, converted back to useful acetic 30 dictated by the exotherm, a gram or so at a time. After anhydride. The regenerated acetic anhydride is recy a couple of seconds the acetic anhydride is added stoi cled back to the process. The yield of RDX is good, chiometrically in a ratio of 1.8 moles acetic anhydride about 80% based upon two molecules of RDX per to 1.0 mole of ammonium nitrate and the cycle of addi molecule of hexamine. The production of the prior tion of reactants continued. An initial unknown precipi process always contains some HMX contamination. 35 tate forms almost from the first addition of ammonium The amount of HMX may vary greatly when enhanced nitrate/nitric acid to the system. The precipitate redis by variation of the reaction conditions. solves and the solution clears. The solution remains clear until about 2/3 of the additional reactants are SUMMARY OF THE INVENTION added. A second precipitate now forms which we dis covered to be RDX. As the additions are continued the DAPT is an intermediate in the synthesis of HMX. RDX precipitate will become noticeably heavier. After Our method for the conversion of DAPT to RDX pro complete addition a small sample may be assayed. The vides the "GARDEC PROCESS" a greatly expanded moist filtered cake will be found to contain about 0.035 nitramine capability and does not require extensive grams of RDX/gram of reaction mixture. duplication or modification of facilities when pure 45 HMX is desired. In fact our yield of either RDX or EXAMPLE 2 HMX is quantitative. We have achieved at least 97% We found, using the method, reactants, and quantities efficiency. as set forth in example 1, that by modifying and continu An object of the present invention is to provide a ing the addition of the DAPT to the system, that the practical and cost effective process for preparing high 50 yield could be greatly improved. These results are set yields of RDX from 3,7-DIACETYL 1,3,5,7-TET forth in Table 1. RAAZA3.3.1BICYCLONONANE (DAPT). Other objects will become apparent from the following de TABLE 1 scription of the invention. APPROXIMATE YELD DATA 55 SAMP. RDX % DAPT TOTAL Outstanding features which are unique to this inven # G CAKE/G MIX YIELD ADDITION G DAPT tion are the quantitative yield, reduced reactant require 1 0.026 G 7.6% 11.3 G 1.3 G ments, and added flexibility; all due to the fact that we 2 0.36 G 39% 2.8 G 4.1 G are starting with a preacetylated reactant. 3 0.166 G 48% 2.8 G 16.9 G 4 0.196 G 56% 2.8 G 9.7 G The process of the present invention is considered to 5 0.21 G 60% 2.8 G 22.5 G be unobvious in view of the fact that RDX formation 6 0.339 G 98% 12.5 G 35.0 G does not follow logically as being readily derivable from the structure of DAPT. The structure of DAPT is It is obvious from Table 1 that after the first addition such that those skilled in the field would generaliy con of DAPT, very little RDX is formed. However, even clude that it would naturally react instead to provide 65 small incremental increases of DAPT dramatically in HMX. It is not apparent or easily explainable why the creases the RDX yield, as shown. As can be seen for a DAPT structure is so completely broken down and less that 10% increase in DAPT, we have achieved a reassembled to provide very high yields of RDX. 500% increase in yield. As dramatically shown in Table 5,250,687 3 4. l, the yield of RDX is dramatically increased by our used are of less critical importance and may be varied method. Using the same method, reactants and quanti plus or minus about 25% without effecting the yield. ties except for incremental addition of DAPT). It is SUMMARY readily observed that the concentration of RDX in In conclusion, the process of the present invention is creases dramatically as soon as the first small portion of an improvement on the prior art. Note should be taken additional DAPT is made. By the time the last addition that the use of hexamine instead of DAPT may result in is made, the reacting mixture has about reached equilib violent eruptions from the solution. On the other hand, rium. Further additions of reactants may now be contin use of DAPT allows for invention to be simple, effec ued indefinitely without a decrease in efficiency. Alter O tive, efficient, and facile in use. It is very safe to carry natively a portion of the reaction mixture may be taken out because of the much reduced exothermicity relative out and identical processing being made to it. In other to the art. In fact, if a total nitramine facility were con words, we may have a continuous process of a batch structed, our RDX process would offer substantial sav system if desired. This all depends upon requirements ings. We get quantitative yields and in several cases the such as the quantity of product needed. The high level 5 yields are greater than those achieved by other pro of efficiency will be maintained indefinitely so long as cesses of the art. nothing is done to disrupt the equilibrium. What is claimed is: 1. The process of making RDX which comprises EXAMPLE 3 reacting DAPT with ammonium nitrate, nitric acid and We found using, the method, and reactants as set 20 acetic anhydride. forth in example 2, that the quantities of reactant liquids 2.