Hexamine, oxidation

Hexamethylenetetramine Explosives. Several explosive compositions containing hexamine in admixtures with oxidants or as chromium, copper nitrate, perchlorate, peroxide comps are known. Several hexamine/oxidant mixtures have been patented as explosive propellant compositions ... 

The hexamine cobalt (II) complex is used as a coordinative catalyst, which can coordinate NO to form a nitrosyl ammine cobalt complex, and O2 to form a u -peroxo binuclear bridge complex with an oxidability equal to hydrogen peroxide, thus catalyze oxidation of NO by O2 in ammoniac aqueous solution. Experimental results under typical coal combusted flue gas treatment conditions on a laboratory packed absorber- regenerator setup show a NO removal of more than 85% can be maitained constant. 

Recent years, the authors have innovatively proposed a method by using the aqueous ammonia liquor containing hexamine cobalt (II) complex to scrub the NO-containing flue gases[6-9], since several merits of this complex have been exploited such as (1) activation of atmospheric O2 to a peroxide to accelerate the O2 solubility, (2) coordination of NO, as NO is a stronger ligand than NH3 and H2O of Co( II) complexes to enhance the NO absorption and (3), catalysis of NO oxidation to further improve the absorption both of O2 and NO. Thus, a valuable product of ammonium nitrate can be obtained. 

Cyclodehydration of 2-phenylthiocyclohexanone with a variety of reagents yielding 1,2,3,4-tetrahydrodibenzothiophene (64) as an oil has been reported,and represents the simplest way of obtaining this material (88%). Alternatively, reduction of 4-keto-1,2,3,4-tetrahydrodibenzothiophene under Huang-Minlon conditions affords 64 in high yield.Trace amounts of 64 were detected in the reduction of dibenzothiophene with calcium hexamine and during electrolysis in ethylenediamine-lithium chloride solution (Section III, C,4). Peracetic acid oxidizes 64 to its sulfone (65%), which... 

In this method, first established by Herz and later studied by Hale, hexamine is introduced into fuming nitric acid which has been freed from nitrous acid. The reaction is conducted at 20-30 °C and on completion the reaction mixture is drowned in cold water and the RDX precipitates. The process is, however, very inefficient with some of the methylene and nitrogen groups of the hexamine not used in the formation of RDX. The process of nitrolysis is complex with formaldehyde and some other fragments formed during the reaction undergoing oxidation in the presence of nitric acid. These side-reactions mean that up to eight times the theoretical amount of nitric acid is needed for optimum yields to be attained. 

This method is known as the K-process after its discoverer Koffier. Like method 5.15.1.2 it uses ammonium nitrate to compensate for the nitrogen deficiency in hexamine and works to Equation (5.24) where two moles of RDX are produced per mole of hexamine. As observed with method 5.15.1.2, the addition of ammonium nitrate to nitric acid appears to prevent dangerous oxidation reactions from occurring. In fact, this nitrolysis reaction only occurs at elevated temperature and so a constant temperature of 80 °C is usually maintained throughout the reaction. Yields of approximately 90 % are attainable based on one mole of hexamine producing two moles of RDX. 

The presence of HMX as an impurity in RDX is not a problem when the product is used as an explosive. However, the need for an analytical sample of RDX makes other more indirect methods feasible. One such method involves the oxidation of 1,3,5-trinitroso-1,3,5-triazacyclohexane (109) ( R-salt ) with a mixture of hydrogen peroxide in nitric acid at subambient temperature and yields analytical pure RDX (74%) free from HMX." The same conversion has been reported in 32 % yield with three equivalents of a 25 % solution of dinitrogen pentoxide in absolute nitric acid. l,3,5-Trinitroso-l,3,5-triazacyclohexane (109) is conveniently prepared from the reaction of hexamine with nitrous acid at high acidity. ... 

There are several explosives containing hexamine combined with either chromic oxide or chromic acids ... 

Hexamethylenetetramine Explosive. A powerful solid explosive was claimed to have been prepd by oxidizing hexamine with a solution of hydrogen peroxide, treating the resulting product with nitric acid and then, reoxidizing with H202 (Ref 1). After drying, this was mixed with AN, castor oil and turpentine (Ref 2)... 

Acylation or sulfonation of hexamine leads to the diacyl bicyclic tetramines (331) which undergo ring opening in N204 to give the dinitrosotetrazocanes (332) in 50-80% yields. The latter can be further oxidized to nitronitroso or dinitro compounds (73JHC279). 

The oldest and simplest method of preparing cyclonite is based on the introduction of hexamethylenetetramine (hexamine) into an excess of concentrated nitric acid, s. g. 1.50-1.52, free of nitric oxides, at 25-30°C, thereafter pouring the whole into cold water. 

Reaction (39) is a hydrolysis of hexamine resulting in the formation of formaldehyde and ammonia, and reaction (40) consists of the oxidation of formaldehyde with nitric acid. 

In the dihydroxylation of cyclohexene by Me3N+—O-, catalysed by OsC>4, aromatic amines and aliphatic chelating (TMEDA) or bridging (DABCO, hexamine) amines were found to retard the oxidation, owing to the formation of amine adducts of the dioxomonoglycolatoosmium(VI) ester intermediates, which are more resistant to the further oxidation required for product formation.98 Alkenes derived from Gamer s aldehyde, A-Boc-/V,0-acctonide of the aldehyde of L-serine, may be dihydroxylated by OsC>4 with excellent selectivities that may be explained by A1,3 strain.99... 

Multiple arylations of polybromobenzenes have been conducted to generate electron-rich arylamines. Tribromotriphenylamine and 1,3,5-tribromobenzene all react cleanly with A-aryl piperazines using either P(o-tolyl)3 or BINAP-ligated catalysts to form hexamine products [107]. Reactions of other polyhalogenated arenes have also been reported [108]. Competition between aryl bromides and iodides or aryl bromides and chlorides has been investigated for the formation of aryl ethers [109], and presumably similar selectivity is observed for the amination. In this case bro-mo, chloroarenes reacted preferentially at the aryl bromide position. This selectivity results from the faster oxidative addition of aryl bromides and is a common selectivity observed in cross-coupling. Sowa showed complete selectivity for amination of the aryl chloro, bromo, or iodo over aryl-fluoro linkages [110]. This chemistry produces fluoroanilines, whereas the uncatalyzed chemistry typically leads to substitution for fluoride. 

RDX dissolves in HNO3 of conens up to 70% witlr out decompg and may be recovered from soln by dilution with water. It is not attacked by either cold or hot coned HCl. It decomp completely by heating with an equal part of CafOH) fo 4 hrs at 60°. RDX decomposes slowly when heated at 60° with N/10 NaOH for 5 hrs, and rapidly when heated with N/lNaOH. The decompn products of RDX in alkaline solution which have been isolated are N, NH3, nitrates, nitrites, formaldehyde, hexamine and org acids (such as formic). When mixed with oxides of heavy metals (such as Fe Of Cu), RDX forms unstable compds, which may undergo decompn and cause ignition of mixts at temps as low as 100°... 

---