Nitrosamines and Nitramines

Species converted to NO by the molybdenum catalyst of the commercial NO-NO2 analyzer (8). These include N02 HONO, organic nitrates, and possibly nitrosamines and nitramines. 

Although nitrosamine and nitramine formation from UDMH (and similarly substituted hydrazines) will probably be the major reaction pathway as long as the atmosphere into which the hydrazines are emitted contains some ozone (as does the "natural" troposphere), our results indicate that different products would potentially be formed if these compounds are emitted into polluted atmospheres where O3 is suppressed by high levels of NO. 

Nitrosamines are readily produced from the reaction of amines with nitrous acid, i.e., acidified nitrite (3), and are also produced vivo when amines and nitrite are administered, as reflected by tumor induction [reviewed in (3)], and the in vivo appearance of nitrosamines (2> ) Challis and Kyrtopoulos (5) showed that gaseous NO2 reacts directly with amines in neutral or alkaline aqueous solutions to produce nitrosamines and nitramines. The kinetics of the extremely rapid reaction of... 

Irradiation of the UDMH + Oq Reaction Products. One experiment was conducted in which the UDMH + O3 reaction products (with UDMH in slight excess) were irradiated by sunlight. The results are shown in Table I and Figure 1. It can be seen that rapid consumption of UDMH, the nitrosamine, and HONO occurred, with N-nitrodimethylamine (also dimethyInitramine) and additional formaldehyde being formed. The formation of nitramine upon irradiation of the nitrosamine is consistent with results of previous studies in our laboratories (9,10), and probably occurs as shown ... 

Four nitrosamines, seven nitramines, three nitroesters and the explosives Semtex 10 and Composition B have been investigated by TGA. Linear dependence was confirmed between the position of the TGA onsets, as defined in the sense of Perkin-Elmer s TGA-7 standard program, and the samples weights. The slope of this dependence is closely related to the thermal reactivity and molecular structure. The intercept values of the dependence correlate with the autoignition temperatures and with the critical temperatures of the studied compounds, without any clear influence from molecular structure. Results show that Semtex 10 exhibits approximately the same thermostability as its active component pentaerythrityl tetranitrate (PETN, 274). Results also show that TGA data for Composition B do not correlate with analogous data for pure nitramines564. 

D. Naud, R. Brower, Pressure Effects on The Thermal Decomposition of Nitramines, Nitrosamines, and Nitrate Esters, J. Org. Chem., 57 (1992) 3303-3308. J. Wang, K.R. Brower, D.L. Naud, Evidence of an Elimination Mechanism in Thermal Decomposition of Hexahydro-l,3,5-Trinitro-l,3,5-Triazine and Related Compounds Under High Pressure, J. Org. Chem., 62 (1997) 9055-9060. 

Keefer LK, Lunn G. 1985. Reductive destruction of nitrosamines, hydrazines, nitramines, azo- and azoxy-compounds. National Institute of Health, U.S. patent no. 4534154. 

While the chemiluminescence detectors have considerable selectivity for nitrosamines it must also be recognized that the possibility exists that any compound that can produce NO during pyrolysis will produce a signal (20). For example, TEA responses have been observed from organic nitrites, C-nitro and C-nitroso compounds (17,28) and nitramines (29). In the routine analysis of N-nitroso compounds, possible TEA analyzer responses to compounds other than N-nitroso derivatives normally do not represent a problem since the the identity of a compound can be readily established by co-elution with known standards on GC-TEA and/or HPLC-TEA systems (30-34). Additional confirmation could be provided when the sample can be chromatographed on both GC-TEA and HPLC-TEA (30,33). The technique accepted as the most reliable for the confirmation of N-nitrosamines is based on mass spectrometry (22, 35,36). Low-resolution mass spectrometry is satisfactory for the analysis of relatively simple mixtures and in those instances in which extensive clean-up of samples has been performed. However, complex samples require more sophisticated GC and MS procedures (e.g., high resolution-MS). 

The oxidation of nitrosamines to nitramines using alkyl hydroperoxides and Mo complexes, equation (145), can be accom i ed in up to 80% yields over long reaction times [184]. 

N-Nitrosamines, N-nitramines, nitrous and nitric acid esters with dinitrogen tetroxide s. 13, 332 ... 

NGc, Nitrosamines, Nitramines, etc. In this technique, microgram quantities of a sample are added to a column packed with an absorbing medium or phase. Over this is maintained a flow of mobile phase (gas or liq). The sample components separate because of their relative mobility in the absorbing phase, and thus leave the column at different times (See Vol 1,... 

Raman spectroscopy has been utilized in the quant detn of nitramines and nitrosamines (Vol 1, A177-R Ref 61), and ultra-violet spectroscopy is employed for the quant measurement of TNT in HBX compn (Refs 39, 61 63)... 

Dark Decay of UDMH in Air, UDMH was observed to undergo a gradual dark decay in the 30,000-liter Teflon chamber at a rate which depended on humidity. Specifically, at 41 C and 4% RH the observed UDMH half-life was " 9 hours (initial UDMH 4.4 ppm) and at 40 C and 15% RH, the half-life was -6 hours (initial UDMH 2.5 ppm). The only observed product of the UDMH dark decay was NH3, which accounted for only -5-10% of the UDMH lost. In particular, no nitrosamine, nitramine, or hydrazone were observed. Formaldehyde dimethyIhydrazone was observed in previous studies which employed higher UDMH concentrations and reaction vessels with relatively high surface/volume ratios (, ) ... 

Dark Decay of UDMH in the Presence of NO, When 1.3 ppm of UDMH in air was reacted in the dark with an approximately equal amount of NO, 0.25 ppm of UDMH was consumed and formation of -0.16 ppm HONO and -0.07 ppm N2O was observed after -3 hours. Throughout the reaction, a broad infrared absorption at -988 cm" corresponding to an unidentified product(s), progressively grew in intensity. The residual infrared spectrum of the unknown product(s) is shown in Figure 2a. It is possible that a very small amount (50.03 ppm) of N-nitrosodimethylamine could also have been formed but the interference by the absorptions of the unknown product(s) made nitrosamine (as well as nitramine) detection difficult. No significant increase in NH3 levels was observed, in contrast to the UDMH dark decay in the absence of NO. Approximately 70% of the UDMH remained at the end of the 3-hour reaction period this corresponds to a half-life of -9 hours which is essentially the same decay rate as that observed in the absence of NO. 

Following the above initial period, the remaining UDMH suddenly dropped to concentrations below the FT-IR detection limit, formation of the unknown product(s) stopped, while formation of the nitrosamine continued and formation of the nitramine began. The rate of NO consumption also increased, although not as much as that of UDMH. 

Aromatic nitro and nitroso compounds are easily reduced at carbon and mercury electrodes. Other nitro compounds such as nitrate esters, nitramines, and nitrosamines are also typically easily reduced. The complete reduction of a nitro compound consists of three two-electron steps (nitro-nitroso-hydroxylamine-amine). Since most organic oxidations are only two-electron processes, higher sensitivity is typically found for nitro compounds. Several LCEC based determination of nitro compounds have been reported... 

Nitramines are known to photodissociate from their jt,jt state to give aminyl and nitric oxide radicals in the presence of an acid the aminyl radicals are protonated to give aminium radicals, which can initiate addition to olefins. As a synthetic reaction, photolysis of nitramines in the presence of acids can be conveniently run under oxygen to give oxidative addition similar to those shown in equation 145 indeed TV-nitrodimethylamine is photolysed with triene 299 under such conditions to give a mixture of 301 and 302, similar to results observed in the oxidative nitrosamine photoaddition169. To simplify the isolation, the crude products are reduced with LAH to form the open-chain amino alcohol 303. Some other oxidative photoadditions of N-nitro dimethylamine to other olefins are reported. As the photoreaction has to use a Corex filter and product yields are no better than those shown by nitrosamines, further investigations were scarcely carried out. 

Pitts, J.N., Jr., Grosjean, D., Cauwenberghe, K.V., Schmid, J.P., and Fitz, D.R. Photooxidation of aliphatic amines under simulated atmospheric conditions formation of nitrosamines, nitramines, amides, and photochemical oxidant, Environ. Sci Technol, 12(8) 946-953, 1978. 

Ordinarily, alkyl nitrate esters will not nitrate amines under neutral conditions. However, Schmitt, Bedford and Bottaro have reported the use of some novel electron-deficient nitrate esters for the direct At-nitration of secondary amines. The most useful of these is 2-(trifluoromethyl)-2-propyl nitrate, which nitrates a range of aliphatic secondary amines to the corresponding nitramines in good to excellent yields. Nitrosamine formation is insignificant in these reactions. 2-(Trifluoromethyl)-2-propyl nitrate cannot be used for the nitration of primary amines, or secondary amines containing ethylenediamine functionality like that in piperazine. Its use is limited with highly hindered amines or amines of diminished nucleophilicity due to inductive or steric effects. 

While nitramines are formed from the reaction of secondary amines with nitronium salts the success of the reaction depends on the basicity of the amine (Equation 5.11). Thus, amines of low to moderate basicity are A-nitrated in good yields. The nitration of more basic amines is slow and the nitrosamine is often observed as a significant by-product, a consequence of the partial reduction of the nitronium salt to the nitrosonium salt during the reaction. Increased reaction temperature is also found to increase the amount of nitrosamine formed. The amine substrate is usually used in excess to compensate for the release of the strong mineral acid formed during the reactions. Both nitronium tetrafluoroborate and the more soluble hexafluorophosphate are commonly used for A-nitrations. Solvents like acetonitrile, methylene chloride, nitromethane, dioxane, sulfolane, ethyl acetate and esters of phosphoric acid are commonly used. 

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