Solubility of HMX

The different solubilities of HMX and RDX in organic solvents means that pure HMX is easily isolated from RDX-HMX mixtures the higher solubility of RDX in acetone means that recrystallization of such mixtures from hot acetone yields pure HMX. ... 

The Spec method (Ref 30) requires a special reagent prepared by stirring 1,2-dichloroethane at RT for 4 hrs in contact with HMX crysts. The solubility of HMX in 1,2-dichloroethane at 24° is 0.02/100 ml of solvent. Weigh a dried 0.02g/100ml sample of HMX, to the nearest milligram, in a 125... 

The low solubility of HMX has caused exptl difficulties that have cast in doubt the validity... 

Very low solubility of HMX (as compared with RDX) makes experiments on toxicity of the compounds less conclusive than with RDX. So far it appears that HMX is less toxic than RDX (1). 

Table 8-12 lists the solubility of HMX by volume for various solvents. 

HMX The low solubility of HMX has caused difficulties that have cast in doubt the validity of all toxicological research done on this compound to date. It would appear that, weight-for-weight, HMX is somewhat less toxic than RDX but exhibits similar effects. Experiments are in progress to confirm or contradict this opinion. ... 

HMX is non-hygroscopic and insoluble in water. It behaves like RDX with respect to its chemical reactivity and solubility in organic solvents. However, HMX is more resistant to attack by sodium hydroxide and is more soluble in 55% nitric acid, and 2-nitropropane than RDX. In some instances, HMX needs to be separated from RDX and the reactions described above are employed for the separation. As an explosive, HMX is superior to RDX in that its ignition temperature is higher and its chemical stability is greater however, the explosive power of HMX is somewhat less than RDX. Some of the properties of HMX are presented in Table 2.16. 

This test is based on the formation of AN on hydrolysis with a mineral acid. HMX and other nitramines, such as Tetryl and ammonium salts interfere. However, Tetryl may be removed before the test with benzene (solubility of RDX is only 0.05%) and ammonium salts with water... 

Sitzmann and Foti (Ref 2) detd the approx solubilities of representative expls (RDX, HMX, HNS, DATB, etc) in various solvents in a search for a general solvent for expls. This work was occasioned by the use in recent years of new... 

M.E. Sitzman S.C. Foti, Solubilities of Explosives , JChemEngrgData 20 (1), 53 55 (1975) CA 82,100890 (1975) [Dimethyl form-amide (DMF) is the best solvent for HMX, except that it forms a complex, and therefore is not recommended as being a true solvent. Butyrlactone and dimethylsulfoxide ot their mixts axe also excellent solvents for HMX, resulting in true solns)... 

Force field validation. In addition to ensuring that the force field reproduces results of QC calculations we have compared predictions of MD simulations using this force field with the available experimental data. Gas phase MD simulations using the quantum-chemistry based force field accurately reproduced the gas phase structure of DMNA as determined from electron diffraction studies. Liquid phase MD simulations of DMNA predicted the densities and solubility parameter as well as the activation energy and correlation times associated with molecular reorientation that are in good agreement with experimental data [34], As we will show in Section 4, comparison to structural and thermal data for the three pure crystalline polymorphs of HMX support the overall validity of our formulation and parameterization. 

HMX has similar properties of RDX with respect to the chemical reactivity and solubility in organic solvent. HMX is superior to RDX as an explosive because of its high ignition temperatime and chemical stability. The disadvantage of HMX compared to RDX is reflected in its lower explosive power [4, 6,]. 

In the presence of RDX the quantitative determination of HMX is by the formation of the stable complex of HMX with dimethylformamide insoluble in CCI4. Another method consists in the separation of HMX by low solubility in J,2-dichloroethane. For detailed description of the methods see the Encyclopedia (127). 

Octahydro-l,3,5,7-tetranitro-l,3,5,7-tetrazocine, most commonly known as HMX, has low solubility ( 22.3 pmoles L 1 at 20°C ) [71] and, based on little available information, low toxicity to aquatic organisms. Its reported 48-h and 96-h LC50 values to several freshwater fish, microcrustaceans, and algae were above solubility [72] (Table 4.6). Similarly, saturated solutions of HMX were not toxic in 15- and 30-min Microtox tests [30,32], and in experiments with the estuarine copepod N. spinipes [13],... 

RDX was shown to be inactive in the UDS in WI-38 human fibroblasts, with and without S9 metabolic activation [47], Reported test concentrations were in the range of 250 to 4000 pg ml-1, well over the aqueous solubility of the compound (approximately 70 pg ml-1) [48], Similarly, in the HGPRT-V79 assay with or without metabolic activation, both RDX and HMX were inefficient in inducing 6-thioguanine resistant cells. The test concentrations used were up to 40 pg ml1 for RDX and 10 pg ml-1 for HMX, close to the solubility limit of these compounds in water [2], Another confirmation of the lack of mutagenic activity of RDX was provided recently when the compound was found inactive in the mouse lymphoma forward mutation assay using the L5178Y cell line [49],... 

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