Cationic micellar catalysis of the aqueous alkaline hydrolyses of 1,3,5-triaza-1,3,5-trinitrocyclohexane and 1,3,5,7-tetraaza-1,3,5,7-tetranitrocyclooctane

Croce, Michael; Okamoto, Yoshiyuki

doi:10.1021/jo01327a012

Cited by 57 publications

(59 citation statements)

References 3 publications

(3 reference statements)

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“…In the latter case, cleavage of an N-NO 2 bond proceeds via a one-electron transfer process (8). Also, N denitration of RDX to compound IV has frequently been reported during alkaline hydrolysis (9,17), in which the latter compound is found to decompose with a rate constant (k) that is 10 5 times larger than that of RDX (17). Sequential reduction of the nitro group(s) (ONO 2 ) in RDX to the corresponding nitroso (ONO) derivative(s) did not seem to be a major degradation route for strain SCZ-1.…”

Section: Resultsmentioning

confidence: 99%

Biodegradation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine and Its Mononitroso Derivative Hexahydro-1-Nitroso-3,5-Dinitro-1,3,5-Triazine by Klebsiella pneumoniae Strain SCZ-1 Isolated from an Anaerobic Sludge

Zhao

Halasz

Paquet

et al. 2002

Appl Environ Microbiol

102

103

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In previous work, we found that an anaerobic sludge efficiently degraded hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), but the role of isolates in the degradation process was unknown. Recently, we isolated a facultatively anaerobic bacterium, identified as Klebsiella pneumoniae strain SCZ-1, using MIDI and the 16S rRNA method from this sludge and employed it to degrade RDX. Strain SCZ-1 degraded RDX to formaldehyde (HCHO), methanol (CH 3 OH) (12% of total C), carbon dioxide (CO 2 ) (72% of total C), and nitrous oxide (N 2 O) (60% of total N) through intermediary formation of methylenedinitramine (O 2 NNHCH 2 NHNO 2 ). Likewise, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) was degraded to HCHO, CH 3 ). These findings suggested the possible involvement of a common initial reaction, possibly denitration, followed by ring cleavage and decomposition in water. The trace amounts of MNX detected during RDX degradation and the trace amounts of hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine detected during MNX degradation suggested that another minor degradation pathway was also present that reduced ONO 2 groups to the corresponding ONO groups.Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a widely used explosive that severely contaminates soil and groundwater (13,22). RDX has been found to be toxic in various terrestrial and aquatic environments (26,29). The toxicity of cyclic nitramines means that contaminated soil and groundwater must be remediated, preferably by bioremediation. Biodegradation of RDX with anaerobic sludge was extensively studied by McCormick et al. (21) and Kaplan (19), who proposed a pathway based on the sequential reduction of RDX to hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX). It was proposed that the nitroso compounds undergo further transformation to hydroxylamino derivatives (HOHN-RDX), which are subsequently cleaved to produce formaldehyde (HCHO), methanol (CH 3 OH), hydrazine (NH 2 NH 2 ), and dimethyl hydrazine [(H 3 C) 2 NNH 2 ].Other research groups have employed mixed anaerobic microbial cultures that have included methanogens (1, 2), acetogens (4), nitrate reducers (12), and individual isolates such as isolates of Desulfovibrio sp. and Serratia marcescens (31) to biotransform RDX, but in most cases no clear details concerning ring cleavage products or mineralization were provided in the descriptions. Subsequent work in our laboratory (14,15,16) showed that RDX could be degraded in anaerobic sludge via intermediary formation of methylenedinitramine (O 2 NNHCH 2 NHNO 2 ), which decomposes in water to nitrous oxide (N 2 O) and HCHO. Recently, Oh et al. (23) confirmed the formation of O 2 NNHCH 2 NHNO 2 during RDX degradation with anaerobic sludge. Despite these previous efforts, there is still insufficient information regarding the roles of individual anaerobic isolates and their products during RDX degradation. Without these details, particularly details concerning...

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Section: Resultsmentioning

confidence: 99%

Biodegradation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine and Its Mononitroso Derivative Hexahydro-1-Nitroso-3,5-Dinitro-1,3,5-Triazine by Klebsiella pneumoniae Strain SCZ-1 Isolated from an Anaerobic Sludge

Zhao

Halasz

Paquet

et al. 2002

Appl Environ Microbiol

102

103

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“…RDX hydrolyzes in an alkaline solution (pH 12) via a bimolecular elimination of HNO 2 to initially produce a 1,3,5-triaza-3,5-dinitrocyclohex-1-ene intermediate (I) (7). The intermediate (I) decomposes at a rate 10 5 times faster than the initial rate of RDX degradation by E2 (13).…”

Section: Discussionmentioning

confidence: 99%

Determination of Key Metabolites during Biodegradation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine with Rhodococcus sp. Strain DN22

Fournier

Halasz

Spain

et al. 2002

Appl Environ Microbiol

161

174

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N]-RDX, the [M-H] appeared at 120 Da, indicating that two of the three N atoms in the metabolite originated from the ring in RDX. When [U-14 C]-RDX was used in the experiment, 64% of the original radioactivity in RDX incorporated into the metabolite with a molecular weight (MW) of 119 (high-pressure LC/radioactivity) and 30% in 14 CO 2 (mineralization) after 4 days of incubation, suggesting that one of the carbon atoms in RDX was converted to CO 2 and the other two were incorporated in the ring cleavage product with an MW of 119. Based on the above stoichiometry, we propose a degradation pathway for RDX based on initial denitration followed by ring cleavage to formaldehyde and the dead end product with an MW of 119.The two cyclic nitramine explosives hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) are powerful energetic compounds that are commonly used in conventional munitions and various military applications. Activities associated with manufacturing, training, waste disposal, and closures of bases have resulted in severe soil and groundwater contamination with the two explosives (9, 14, 21). RDX and HMX are both toxic (25, 29), thus necessitating their removal from the environment.Previous studies have focused on the degradation of RDX by microorganisms under anaerobic conditions (1,17,18,20,24,30). McCormick et al. (20) reported the formation of the three nitroso derivatives, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), which after further reduction to the corresponding hydroxylamines undergo ring cleavage to produce hydrazine, dimethyl hydrazine, and methanol, respectively. No microorganisms or enzymes were identified in the study by McCormick et al. (20). Recently, Kitts et al. (19) reported the involvement of a type I nitroreductase in the degradation of RDX, but no products were identified. Using anaerobic sludge, Hawari et al.(11) reported that in addition to the occurrence of a ring cleavage via the nitroso route, other ring cleavage pathways, such as direct ring cleavage and/or denitration followed by ring cleavage, might be possible. In the latter study, several key intermediate ring cleavage products, including bis(hydroxymethyl)nitramine, methylenedinitramine (MEDINA), nitrous oxide, and formaldehyde, accumulated, but hydrazines were not detected (11, 12).Several groups described RDX biodegradation under aerobic conditions, but little information was provided on the degradation pathway (5,6,16,27). Products from biodegradation of cyclic nitramine explosives under aerobic conditions are poorly understood, particularly ring cleavage products (5, 10). Jones et al. (16) isolated a Rhodococcus sp. strain A from explosives-contaminated soil and demonstrated its potential for the degradation of RDX but did not report any products. Coleman et al. (6) reported the isolation and characterization of another Rhodococcus sp. strain DN22,...

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“…A significant background of data has now been established for the alkaline hydrolysis of nitroaromatic, nitramine and nitrate ester energetic compounds: Arienzo (1999), Balakrishnan et al (2003), Croce and Okamoto (1979), Davis et al (2006, Emmrich (1999Emmrich ( , 2001), Epstein and Winkler (1951), Felt et al (2001aand b, 2002), Garg et al (1991, Hansen et al (2001), Heilmann et al (1994), Heilmann et al, (1996), Hoffsomer and Rosen, (1973), Hoffsommer et al (1977), HSDB 2001, Huang et al (2005, 2006, Kayser andBurlinson 1988, Saupe et al (1997), Saupe and Wiesmann (1996), Wu, 2001. The nitroaromatic compounds degrade the most rapidly, however the half-life for both TNT and RDX at pH >10.5 in soil has been determined to be < 1 day.…”

Section: Base Hydrolysismentioning

confidence: 99%

A Sustainable NATO/EU Partnership for the Future

Pfrengle¹

2008

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Cationic micellar catalysis of the aqueous alkaline hydrolyses of 1,3,5-triaza-1,3,5-trinitrocyclohexane and 1,3,5,7-tetraaza-1,3,5,7-tetranitrocyclooctane

Cited by 57 publications

References 3 publications

Biodegradation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine and Its Mononitroso Derivative Hexahydro-1-Nitroso-3,5-Dinitro-1,3,5-Triazine by Klebsiella pneumoniae Strain SCZ-1 Isolated from an Anaerobic Sludge

Biodegradation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine and Its Mononitroso Derivative Hexahydro-1-Nitroso-3,5-Dinitro-1,3,5-Triazine by Klebsiella pneumoniae Strain SCZ-1 Isolated from an Anaerobic Sludge

Determination of Key Metabolites during Biodegradation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine with Rhodococcus sp. Strain DN22

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