N-dealkylation Reaction Research Articles

Dechlorination of Chloroacetanilide Herbicides Alachlor and Metolachlor by Iron Metal

Granular iron metal has been found to cause the reductive dechlorination of two important chloroacetanilide herbicides, alachlor and metolachlor. Aqueous solutions (113 mL) of the herbicides were contacted with 40 g of granular cast iron (CCI coarse, 40 mesh) with mild agitation at room temperature. First-order degradation rate constants were 0.12 and 0.10 h-1 for 10 mg/L solutions of alachlor and metolachlor, respectively. A two-site, rate-limited sorption and first-order degradation model was applied to both batch data sets, with excellent agreement for alachlor and fair agreement for metolachlor. The products of the reaction were chloride (84% mass balance for alachlor and 68% for metolachlor) and dechlorinated acetanilides. Supported by GC/EIMS analysis, two sequential reactions may have occurred for alachlor, hydrogenolysis of the chloroacetyl group followed by an N-dealkylation reaction. However, only one product was confirmed by GC/FID, and the mechanism for the N-dealkylation reaction is unknown. ...

Dechlorination of the Chloroacetanilide Herbicides Alachlor and Metolachlor by Iron Metal

Granular iron metal has been found to cause the reductive dechlorination of two important chloroacetanilide herbicides, alachlor and metolachlor. Aqueous solutions (113 mL) of the herbicides were contacted with 40 g of granular cast iron (CCI coarse, 40 mesh) with mild agitation at room temperature. First-order degradation rate constants were 0.12 and 0.10 h-1 for 10 mg/L solutions of alachlor and metolachlor, respectively. A two-site, rate-limited sorption and first-order degradation model was applied to both batch data sets, with excellent agreement for alachlor and fair agreement for metolachlor. The products of the reaction were chloride (84% mass balance for alachlor and 68% for metolachlor) and dechlorinated acetanilides. Supported by GC/EIMS analysis, two sequential reactions may have occurred for alachlor, hydrogenolysis of the chloroacetyl group followed by an N-dealkylation reaction. However, only one product was confirmed by GC/FID, and the mechanism for the N-dealkylation reaction is unknown. Metolachlor was found to produce one dechlorinated product consistent with hydrogenolysis. These results are encouraging, as granular iron may be used at spill sites contaminated with these herbicides and related compounds.

Preparatively useful transformations of steroids and morphine alkaloids byMucor piriformis

A versatile fungus isolated in our laboratory and identified as Mucor piriformis has been shown to effect novel and preparatively useful transformations in steroids and morphine alkaloids. The organism very effectively carries out hydroxylation of various C-19 and C-21 steroids at 7 and 14-positions. Although the organism is capable of catalysing hydroxylation at 6 beta and 11 alpha-positions, these are not the major activities. The 14 alpha-hydroxylase appears to have a broad substrate specificity. However, steroids with a bulky substitution at C-17 alpha-position or without the 4-en-3-one group are not accepted as substrates by the 14 alpha-hydroxylase system. Studies have demonstrated how various C-19 and C-21 steroids can be modified to yield new structures which are either difficult to prepare by traditional methods or hitherto unknown. The organism also very efficiently and selectively carries out the N-dealkylation of thebaine and its N-variants. Interestingly, the nor-compound formed does not get further metabolized. Since thebaine is very often used as a starting material to synthesize various morphine agonists as well as antagonists, and one of the steps involved in their preparation is the N-dealkylation reaction, the microbial process could certainly offer an alternative approach.

Oxidative pathways in the degradation of triazine herbicides: a mechanistic approach

Studies about the chemical reactivity of compounds widely used in the environment are needed. The chemical reactivity of triazines toward oxidants was tested in the laboratory with cerium(IV) ammonium nitrate and ozone. Simazine, atrazine and terbutylazine were tested. The oxidative N-dealkylation occurred both with cerium ammonium nitrate and with ozone at acidic pH. The N-de-ethylation was invariably preferred to the N-dealkylation reaction. A degradation pathway for triazine herbicides is suggested. The kinetics of the oxidation of these triazines with ozone at pH 3 and the kinetics of the saturation of the solution with ozone have been evaluated. These data may be useful for the prediction of the persistency of these compounds in the environment.

Comparative metabolism of clinically important precursors of N- desmethyldiazepam using phenobarbitone-pretreated rat liver microsomes

Phenobarbitone-pretreated male Sprague-Dawley rat liver microsomes were used to examine C 3-hydroxylation and N-dealkylation of four clinically important benzodiazepines: diazepam (DZP), prazepam (PZP), pinazepam (PIN) and halazepam (HZP). These substrates differ only in the nature of the N-substituent of the B ring and N-desmethyldiazepam (DMD) is the N-dealkylation product in each case. C 3-Hydroxylation was accordingly also studied with DMD as substrate. All monooxygenations were studied with substrates at a concentration of 10 μM, in the absence of solubilizing agents, and under conditions where the production of secondary metabolites was minimized. A 20-fold variation in the rate of C 3-hydroxylation was recorded across the five substrates with HZP showing the highest rate and DMD showing the lowest rate. An almost equally large range of variation was shown for the N-dealkylation reaction, with PZP undergoing this biotransformation more than 17 times faster than DZP. Log P values (a measure of lipophilicity) for the five substrates were determined using an HPLC method and a remarkable lack of correspondence between this substrate parameter and either of the monooxygenations was noted. This suggests that multiple substrate determinants govern the relative rates of these monooxygenations. It was, however, notable that the additive rate of metabolism of these substrates by both monooxygenase routes did show an excellent correlation with substrate lipophilicity.

Transition metal complexes of a functionalised triazamacrocycle

The imidazole- and pyrazole-functionalised macrocyclic ligands 1,4,7-tris(1-methylimidazol-2-ylmethyl)-1,4,7-triazacyclononane, L1, and 1,4,7-tris(pyrazol-1-ylmethyl)-1,4,7-triazacyclononane, L2, form stable complexes with some 3d metal cations of formula [ML]Y2(M = Fe, L = L1 or L2, Y = BPh4; M = Co, L = L1, Y = ClO4; L = L2, Y = BPh4; M = Ni, L = L1, Y = BPh4 or ClO4; L = L2, Y = BPh4; M = Cu, L = L1, Y = BPh4; L = L2, Y = ClO4; M = Zn, L = L2, Y = BPh4). The complexes have been isolated in the solid state and characterised by standard physicochemical methods. The complex [NiL2][BPh4]2 affords by slow recrystallisation from an acetonitrile—ethanol solution the new compound [Ni(CH3CN)L3][BPh4]2 where L3 is the new ligand 1,4-bis(pyrazol-1-ylmethyl)-1,4,7-triazacyclononane formed from L2 by a N-dealkylation reaction and loss of a pendant arm. Its crystal structure has been determined by X-ray diffraction: space group P21/c, a= 18.544(12), b= 12.460(5), c= 23.400(9)A, β= 90.49(4)°; R 0.069 for 3025 observed reflections. The nickel atom is in a six-co-ordinate environment formed by the five nitrogen atoms provided by the L3 ligand and by the acetonitrile N atom. All Ni–N distances are in the range 2.00–2.11 A, those formed by the macrocycle nitrogens spanning the upper half of this interval.

A novel N-dealkylation reaction of n,N-dialkylarylcarboxamides promoted by electron transfer from alkali metals

Reactions of some N,N-dialkylarylcarboxamides with either lithium or sodium metals in dry tetrahydrofuran (THF) promoted by ultrasound waves afforded the corresponding N-monoalkylarylcarboxamides in good yields. In the cases of N,N-diethylarylcarboxamides the products obtained were derived from coupling reactions rather than from N-dealkylation reactions.

Spectroscopic Characterization of Secondary Amine Mono-oxygenase: Comparison to Cytochrome P-450 and Myoglobin

Abstract Secondary amine mono-oxygenase from Pseudomonas aminovorans catalyzes the NAD(P)H- and dioxygen-dependent N-dealkylation of secondary amines to yield a primary amine and an aldehyde. Heme iron, flavin, and non-heme iron prosthetic groups are known to be present in the oligomeric enzyme. The N-dealkylation reaction is also catalyzed by the only other heme-containing mono-oxygenase, cytochrome P-450. In order to identify the heme iron axial ligands of secondary amine mono-oxygenase so as to better define the structural requirements for oxygen activation by heme enzymes, we have investigated the spectroscopic properties of the enzyme. The application of three different spectroscopic techniques, UV-visible absorption, magnetic circular dichroism and electron paramagnetic resonance, to study eight separate enzyme derivatives has provided extensive and convincing evidence for the presence of a proximal histidine ligand. This conclusion is based primarily on comparisons of the spectral properties of the enzyme with those of parallel derivatives of myoglobin (histidine proximal ligand) and P-450 (cysteinate proximal ligand). Spectral studies of ferric secondary amine mono-oxygenase as a function of pH have led to the proposal that the distal ligand is water. Deprotonation of the distal water ligand occurs upon either raising the pH to 9.0 or substrate (dimethylamine) binding. In contrast, the deoxyferrous enzyme appears to have a weakly bound nitrogen donor distal ligand. Initial spectroscopic studies of the iron-sulfur units in the enzyme are interpreted in terms of a pair of Fe2S2 clusters. Secondary amine mono-oxygenase is unique in its ability to function as cytochrome P-450 in activating molecular oxygen but to do so with a myoglobin-like active site. As such, it provides an important system with which to probe structure-function relations in heme-containing oxygenases.

A novel P-450 model system for the N-dealkylation reaction

A novel P-450 model system for the N-dealkylation reaction

Hepatic microsomal N-dealkylation reaction. Molecular oxygen as the source of the oxygen atom

Hepatic microsomal N-dealkylation reaction. Molecular oxygen as the source of the oxygen atom

2-Oxazolidinones from an N-dealkylation reaction of phosgene with dialkylaminoalkanols. Isolation and reactivities of an N-acyl quaternary ammonium intermediate

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT2-Oxazolidinones from an N-dealkylation reaction of phosgene with dialkylaminoalkanols. Isolation and reactivities of an N-acyl quaternary ammonium intermediateKeith C. MurdockCite this: J. Org. Chem. 1968, 33, 4, 1367–1371Publication Date (Print):April 1, 1968Publication History Published online1 May 2002Published inissue 1 April 1968https://doi.org/10.1021/jo01268a014RIGHTS & PERMISSIONSArticle Views264Altmetric-Citations22LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (650 KB) Get e-Alerts Get e-Alerts