Aliphatic Substituents Research Articles

Efficient oxidative depolymerization of lignite through selective cleavage of cross-linked structures for producing oxygen-containing chemicals

The non-fuel utilization of lignite is of great significance, and mild oxidative depolymerization is a promising approach for producing oxygen-containing chemicals. In this work, Xiaolongtan lignite (XLT) was used to investigate selective oxidation under mild conditions, with the aim of avoiding excessive oxidation and reducing alkali consumption. The results demonstrate that O2 oxidation can efficiently depolymerize XLT into humic acid (HA) in diluted KOH aqueous solution. Under the optimized conditions (XLT/KOH mass ratio = 3, 3 MPa O2, 80 °C, 3 h), the HA yield can reach as high as 65.8%, with only a minimal amount of CO2 (3.1%) generated. In addition, the structure-oxidative depolymerization relationship was further examined through FTIR characterization and the oxidation of model compounds. The cleavage of cross-linked bonds, including methylene and ether bridge bonds as well as hydroaromatic rings, is essential for the depolymerization of lignite by O2 oxidation. The high stability of aliphatic substituents resulted in their enrichment in the oxidized residue (OR). Under mild conditions, the aromatic ring and aromatic carboxylic acids are stable and favors the production of HA. By combining with the oxidation of model compounds, a better understanding of the oxidative depolymerization of XLT to oxygen-containing chemicals is achieved.

Structure and biochemical characterization of an extradiol 3,4-dihydroxyphenylacetate 2,3-dioxygenase from Acinetobacter baumannii

3,4-Dihydroxyphenylacetate (DHPA) 2,3-dioxygenase (EC 1.13.11.15) from Acinetobacter baumannii (AbDHPAO) is an enzyme that catalyzes the 2,3-extradiol ring-cleavage of DHPA in the p-hydroxyphenylacetate (HPA) degradation pathway. While the biochemical reactions of various DHPAOs have been reported, only structures of DHPAO from Brevibacterium fuscum and their homologs are available. Here, we report the X-ray structure and biochemical characterization of an Fe2+-specific AbDHPAO that shares 12% sequence identity to the enzyme from B. fuscum. The 1.8 Å X-ray structure of apo-AbDHPAO was determined with four subunits per asymmetric unit, consistent with a homotetrameric structure. Interestingly, the αβ-sandwiched fold of the AbDHPAO subunit is different from the dual β-barrel-like motif of the well-characterized B. fuscum DHPAO structures; instead, it is similar to the structures of non-DHPA extradiol dioxygenases from Comamonas sp. and Sphingomonas paucimobilis. Similarly, these extradiol dioxygenases share the same chemistry owing to a conserved 2-His-1-carboxylate catalytic motif. Structure analysis and molecular docking suggested that the Fe2+ cofactor and substrate binding sites consist of the conserved residues His12, His57, and Glu238 forming a 2-His-1-carboxylate motif ligating to Fe2+ and DHPA bound with Fe2+ in an octahedral coordination. In addition to DHPA, AbDHPAO can also use other 3,4-dihydroxyphenylacetate derivatives with different aliphatic carboxylic acid substituents as substrates, albeit with low reactivity. Altogether, this report provides a better understanding of the structure and biochemical properties of AbDHPAO and its homologs, which is advancing further modification of DHPAO in future applications.

Stereo‐ and Regiochemical Effect of N,N‐Dialkylamide Extractants on the Speciation of Pu Complexes

AbstractThe relationship between extractant stereochemistry and their extraction performance has only poorly been established. In order to address a part of this concern, we investigated the Pu(IV) liquid‐liquid extraction (LLE) by using the N,N‐di‐(2‐ethylhexyl)butyramide (DEHBA), as well as those of its position isomers. DEHBA (ββ‐isomer) and N‐(2‐ethylhexyl)‐N‐(oct‐3‐yl)butyramide (EHOBA or αβ‐isomer) were synthesized as a mixture of stereoisomer or stereoenriched (R,S)‐ and (S,S)‐diastereoisomers, and were all assessed for PuIV LLE. The results showed that both the position and the stereoisomerism of the aliphatic substituents affect PuIV complexation and extraction. We found that Pu extraction is lowered by factor 2 to 4 when the ethyl branching group is closer to the complexing site. UV‐vis spectroscopy showed that this extraction decrease was affected by steric hindrance inducing a deprivation of Pu inner sphere complex. Effect of stereoisomerism is highlighted for branching closer to the complexing site (α‐position). Enantiopure DEHBA stereoisomers provided similar Pu extraction, whereas a slight decrease could be noticed for the more cluttered stereoenriched (αβ)‐isomers, which was also concomitant with a smaller population of inner sphere complex. In contrast, the stereoisomers mixture led to a strong decrease of Pu extraction because of an antagonistic association in the mixed complexes.

Game of Aliphatics: A Density Functional Theory Study of Base-Catalyzed Substrate-Controlled Dimerizations of Aliphatic Alkynones.

The present work focuses on a comprehensive density functional theory (DFT) study of newly discovered base-catalyzed substrate-controlled dimerizations of aliphatic alkynones. In order to understand the origin of selectivity of the cascade assemblies of 6-methylene-5-oxaspiro[2.4]heptanones and 2-alkenylfurans, structural and electronic properties of neutral and deprotonated alkynone molecules, thermodynamic and kinetic characteristics of the deprotonation of alkynones having diverse C-H active substituents at the carbonyl function under the action of a base, and thermodynamic and kinetic characteristics of possible mechanisms of the discussed cascade reactions were theoretically assessed. The obtained computational results have confirmed and clarified an early qualitative assumption on the key role of the nature of the aliphatic substituent. Apart from fully rationalizing the experimental results, the theoretical DFT data give valuable details and data for predicting the outcome of related base-catalyzed reactions between various electrophilic substrates and nucleophilic species formed from C-H active aliphatic alkynones.

Trichosanates A–G and cucurbitacins W–Y, anticomplement monoterpenoids and cucurbitane-type triterpenoids from the pericarps of Trichosanthes kirilowii

The pericarps of Trichosanthes kirilowii are often used to treat cough in traditional Chinese medicine, and its ethanol extract exhibited effective therapeutic effects on acute lung injury (ALI) in vivo caused by H1N1. An anticomplement activity-guided fractionation on the extract resulted in the isolation of ten new terpenoids, including seven monoterpenoids, trichosanates A–G (1–7), and three cucurbitane-type triterpenoids, cucurbitacins W–Y (8–10), as well as eleven known terpenoids (11–21). The new terpenoids’ structures were determined by spectroscopic analysis, X-ray crystallographic analysis (1), electronic circular dichroism (ECD) analysis and calculations (2–10). Twelve monoterpenoids (1–7 and 11–15) and five cucurbitane-type triterpenoids (8–10, 18, and 20) exhibited anticomplement activity in vitro. For the monoterpenoids, the long aliphatic chain substituents might enhance their anticomplement activity. Additionally, two representative anticomplement terpenoids, 8 and 11, obviously attenuated H1N1-induced ALI in vivo by inhibiting complement overactivation and reducing inflammatory responses.

Order-Disorder, Symmetry Breaking, and Crystallographic Phase Transition in a Series of Bis(trans-thiocyanate)iron(II) Spin Crossover Complexes Based on Tetradentate Ligands Containing 1,2,3-Triazoles.

We report herein a series of neutral trans-thiocyanate mononuclear spin crossover (SCO) complexes, [FeIIL(NCS)2] (1-4), based on tetradentate ligands L obtained by reaction of N-substituted 1,2,3-triazolecarbaldehyde with 1,3-propanediamine or 2,2-dimethyl-1,3-diaminopropane [L = N1,N3-bis((1,5-dimethyl-1H-1,2,3-triazol-4-yl)methylene)propane-1,3-diamine/-2,2-dimethylpropane-1,3-diamine, 1/2 and N1,N3-bis((1-ethyl/1-propyl-1H-1,2,3-triazol-4-yl)methylene)-2,2-dimethylpropane-1,3-diamine, 3/4]. The thermal-induced SCO behavior is characterized by abrupt transitions with an average critical temperature (ΔT1/2)/hysteresis loop width (ΔThyst) in the range 190-252/5-14 K, while the photo-generated metastable high-spin (HS) phases are characterized by TLIESST temperatures in the range 44-59 K. Single crystal analysis shows that except 1, all compounds experience reversible symmetry breaking coupled with the thermal SCO. Furthermore, 4 experiences an additional phase transition at ca. 290 K responsible for the coexistence of two HS phases quenched at 10 K through LIESST and TIESST effects. The molecules form hexagonally packed arrays sustained by numerous weak CH···S and C···C/S···C/N···C bonds involving polar coordination cores, while non-polar pendant aliphatic substituents are segregated inside, occupying hexagonal channels. Energy framework analysis of complexes with one step SCO transition (1, 2, and 4) shows a correlation between the cooperativity and the amplitude of changes in the molecule-molecule interactions in the lattice at the SCO transition.

Structure and Surface Behavior of Rh Complexes in Ionic Liquids Studied Using Angle-Resolved X-ray Photoelectron Spectroscopy

We present an ARXPS study on the surface composition and interfacial behavior of commercial [Rh(COD)2][TfO] in [C2C1Im][TfO], [C4C1Im][TfO], [C8C1Im][TfO], and [C2C1Im][EtOSO3]. The complex was found to be non-intact in a solution of these ILs through the loss of COD ligands, accompanied by the depletion of the metal center from the IL/vacuum interface. Increasing the chain length of the aliphatic substituent on the imidazolium cation of the [TfO]−-based ILs led to a more pronounced depletion from the interface, due to the higher surface affinity of the solvent cations with the longer alkyl chains. The loss of COD ligands offered facile in situ ligand substitution with surface-active TPPTS to afford a moderate increase in the surface concentration of Rh. We propose the formation of a Schrock−Osborn-type catalyst [Rh(COD)(TPPTS)2][TfO]. Information on the surface composition and targeted design of the gas/IL interface is highly relevant for applications in IL-based catalytic systems, such as in supported ionic liquid phase (SILP) catalysis.

Acyl Hydrazides and Acyl Hydrazones as High-Performance Chemical Exchange Saturation Transfer MRI Contrast Agents.

Chemical exchange saturation transfer (CEST) MRI is a versatile molecular imaging approach that holds great promise for clinical translation. A number of compounds have been identified as suitable for performing CEST MRI, including paramagnetic CEST (paraCEST) agents and diamagnetic CEST (diaCEST) agents. DiaCEST agents are very attractive because of their excellent biocompatibility and potential for biodegradation, such as glucose, glycogen, glutamate, creatine, nucleic acids, et al. However, the sensitivity of most diaCEST agents is limited because of small chemical shifts (1.0-4.0 ppm) from water. To expand the catalog of diaCEST agents with larger chemical shifts, herein, we have systematically investigated the CEST properties of acyl hydrazides with different substitutions, including aromatic and aliphatic substituents. We have tuned the labile proton chemical shifts from 2.8-5.0 ppm from water while exchange rates varied from ~680 to 2340 s-1 at pH 7.2, which allows strong CEST contrast on scanners down to B0 = 3 T. One acyl hydrazide, adipic acid dihydrazide (ADH), was tested on a mouse model of breast cancer and showed nice contrast in the tumor region. We also prepared a derivative, acyl hydrazone, which showed the furthest shifted labile proton (6.4 ppm from water) and excellent contrast properties. Overall, our study expands the catalog of diaCEST agents and their application in cancer diagnosis.

Effect of alkyloxy substituents on mesomorphic and photophysical properties of star-shaped tristriazolotriazines

ABSTRACTTwo series of tristriazolotriazine (TTT) derivatives with different length of aliphatic substituents have been synthesised in order to study the influence of peripheral substitution on mesomorphism and fluorescent properties of these star-shaped compounds. Homologues with methoxy and alkyloxy substituents (series 1) are non-mesogenic, in contrast to homologues with two alkyloxy substituents (series 2) exhibiting columnar mesophase. The results obtained by quantum-chemical calculations for the monomers and dimers of non-mesogenic TTT series and their comparison with truxenone derivatives having identical substituents made it possible to establish the reasons that deprive series 1 of mesogenity. Compounds of both TTT series possess good solubility in organic solvents and capable of specific interactions with solvents in the ground and excited states. They form fluorescenting floating layers and thin films. An analysis of the fluorescence spectra showed a high potential for their application, in particular, in the field of molecular sensing and precise non-invasive control.

Molecular Orientation of Carboxylate Anions at the Water-Air Interface Studied with Heterodyne-Detected Vibrational Sum-Frequency Generation.

The carboxylate anion group plays an important role in many (bio)chemical systems and polymeric materials. In this work, we study the orientation of carboxylate anions with various aliphatic and aromatic substituents at the water-air interface by probing the carboxylate stretch vibrations with heterodyne-detected vibrational sum-frequency generation spectroscopy in different polarization configurations. We find that carboxylate groups with small aliphatic substituents show a large tilt angle with respect to the surface normal and that this angle decreases with increasing size of the substituent. We further use the information about the orientation of the carboxylate group to determine the hyperpolarizability components of this group.

Changes in the Structure of Asphaltene Molecules in the Process of Initiated Cracking of Tars

The results of a study of asphaltenes isolated from the liquid products of tar cracking performed at a temperature of 500°C in the presence of didodecanoyl peroxide are presented. The reactions rate constants of the thermal transformations of asphaltenes in the studied tars were calculated. It was found that the reaction rate of asphaltene condensation into solid compaction products depends not only on the initial asphaltene content of tars but also on the molecular structure. Changes in the structural group parameters of tar asphaltenes in the course of initiated cracking were established. It was shown that the destruction of structural blocks without changes in their number in the molecular composition is a distinctive feature of asphaltene cracking in the presence of didodecanoyl peroxide. Averaged asphaltene molecules became more compact due to the destruction of aliphatic substituents and naphthenic rings, and the fraction of condensed aromatic structures in their composition increased significantly.

Study of the reaction of olefins with acetic acid

The purpose of this work is to study the esterification of liquid olefins with acetic acid in the presence of catalysts and to study the structure and properties of the synthesized saturated esters. 1-Hexene, 2-methyl-1-pentene, 2-ethyl-1-pentene, 3-methyl-1-pentene, and 3-methyl-2-pentene were used as liquid olefins and acid catalysts were used as catalysts for the esterification reaction: H2SO4 and HCl. The influence of various factors (the nature of the catalysts, the relative activity of olefins and temperature a) on the rate of the esterification reaction was studied. It has been shown that the reaction rate is much higher in the presence of sulfuric acid than in HCl. It has been established that in the esterification of olefins with acetic acid, with an increase in the length of the side aliphatic substituent of 2-methyl-1-pentene olefins on 2-ethyl-1-pentene, the rate of the ester formation reaction decreases. The mechanisms of esterification reactions are presented. A basic technological scheme for the production of esters was proposed.

Efficient Antibacterial/Antifungal Activities: Synthesis, Molecular Docking, Molecular Dynamics, Pharmacokinetic, and Binding Free Energy of Galactopyranoside Derivatives.

The chemistry and biochemistry of carbohydrate esters are essential parts of biochemical and medicinal research. A group of methyl β-d-galactopyranoside (β-MGP, 1) derivatives was acylated with 3-bromobenzoyl chloride and 4-bromobenzoyl chloride in anhydrous N,N-dimethylformamide/triethylamine to obtain 6-O-substitution products, which were subsequently converted into 2,3,4-tri-O-acyl derivatives with different aliphatic and aromatic substituents. Spectroscopic and elemental data exploration of these derivatives confirmed their chemical structures. In vitro biological experiments against five bacteria and two fungi and the prediction of activity spectra for substances (PASS) revealed ascending antifungal and antibacterial activities compared with their antiviral activities. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) experiments were performed for two derivatives, 3 and 9, based on their antibacterial activities. Most of these derivatives showed >780% inhibition of fungal mycelial growth. Density functional theory (DFT) was used to calculate the chemical descriptors and thermodynamic properties, whereas molecular docking was performed against antibacterial drug targets, including PDB: 4QDI, 5A5E, 7D27, 1ZJI, 3K8E, and 2MRW, and antifungal drug targets, such as PDB: 1EA1 and 1AI9, to identify potential drug candidates for microbial pathogens. A 100 ns molecular dynamics simulation study revealed stable conformation and binding patterns in a stimulating environment by their uniform RMSD, RMSF, SASA, H-bond, and RoG profiles. In silico pharmacokinetic and quantitative structure-activity relationship (QSAR) calculations (pIC50 values 3.67~8.15) suggested that all the designed β-MGP derivatives exhibited promising results due to their improved kinetic properties with low aquatic and non-aquatic toxicities. These biological, structure-activity relationship (SAR) [lauroyl-(CH3(CH2)10CO-) group was found to have potential], and in silico computational studies revealed that the newly synthesized MGP derivatives are potential antibacterial/antifungal candidates and can serve as therapeutic targets for human and plant pathogens.

Insights into the structure evolution of sewage sludge during hydrothermal carbonization under different temperatures

In this paper, hydrothermal carbonization (HTC) of sewage sludge (SS) under different temperatures was investigated, and the effect of the HTC temperature on the structure evolution and properties of the hydrochar was studied. Here, BET, XPS, Raman and the peak separation and fitting of FTIR were used to analyze the chemical structures of hydrochar during HTC comprehensively. The results indicated that the specific surface area of the hydrochar increased and then decreased with the temperature increasing, and the highest specific surface area was got for hydrochar obtained at 200 ℃, which was 18.30 m2/g. Furthermore, the results showed that raising the temperature could decrease the O/C and H/C ratio of the hydrochars, and the decrease of O/C was mainly attributed to the reduction of CO and COOR rather than C-O during the HTC process. Interestingly, the results also showed that the short chain aliphatic or aromatic substituents ring in SS began to breakage at 160 ℃ and the longer aliphatic chain broke when the temperature was higher than 200 ℃. Increasing the temperature could promote the transformation of the relatively small aromatic ring system to the larger aromatic ring system in hydrochar. The results also showed that the aliphatic carbon content decreased and the degree of aromatization increased with temperature increasing. This work may provide comprehensive structural information of SS during the HTC process, and provide a theoretical basis for the application of SS and its hydrochars.

Study of Hypoglycemic Activity of Novel 9-N-alkyltetrahydroberberine Derivatives.

Novel 9-N-alkyltetrahydroberberine derivatives were synthesized, among which, based on the results of OGTT, one compound containing the longest aliphatic substituent was selected for study in mice C57BL/6Ay, which demonstrate obesity, impaired glucose tolerance, and concomitant liver non-alcoholic fatty disease. Administration of this substance at a dose of 15 mg/kg for four weeks improved the insulin sensitivity of mice, which resulted in a decrease in fasting glucose levels and improved the tolerance of mice to OGTT glucose loading. A decrease in the level of lactate in the blood and a decrease in the amount of glucokinase in the liver were also found. The introduction of compound 3c did not have a toxic effect on animals based on biochemical data, histological analysis, and measurements of general parameters such as body weight and feed intake. Thus, the 9-N-heptyltetrahydroberberine derivative showed prominent hypoglycemic effects, which makes it promising to obtain and study other derivatives with longer substituents.

Tri(3‐alkoxyl‐3‐oxopropyl) phosphine oxides derived from PH3 tail gas as a novel phosphorus‐containing plasticizer for polylactide

AbstractPreparing a polylactide (PLA)/plasticizer system has been regarded as an effective solution to improve the ductility of brittle PLA. In this reach, a novel type of alkyl phosphine oxides consisting of three aliphatic ester substituents was prepared from PH3 tail gas, and its potential to be employed as a PLA plasticizer was studied. Differential scanning calorimeter tests confirmed that the newly‐prepared plasticizer decreased the Tg of PLA (28 wt% plasticizer) from 52°C (neat PLA) to 11°C, and increased the elongation at break from 11% (neat PLA) to 271% (plasticized PLA). X‐ray diffraction results showed that the crystallization degree of PLA (28 wt% plasticizer) increased from 0.12% of neat PLA to 14.04%, while Young's modulus of PLA remained as high as 121.3 MPa, which was much higher than that of the PLA/citrate ester systems with same plasticizer content. These novel phosphorus‐containing plasticizers exhibited excellent thermal stability and a weight‐loss of the system no more than 2.5% at 180°C; therefore, no unpleasant volatiles were released during processing. In contrast, the weight loss of the PLA/citrate system was as high as 10.8% at 180°C, forming heavy fog with an unpleasant smell during thermal mixing. Scanning electron microscopy was employed to observe the microstructure of the PLA/plasticizer systems, which indicated that the carboxylic butyl ester‐containing phosphine oxides was compatible with PLA matrix.

Ring opening in epoxidized SIS block copolymer with thiolated nucleophiles and their antioxidant activity

The functionalization of poly(styrene-b-isoprene-b-styrene) block copolymer by full epoxidation of polyisoprene block and its subsequent epoxy rings opening with thiolated nucleophiles was studied. The optimal ring-opening conditions were microwave heating at 110 °C for 3 h in tetrahydrofuran as a solvent, using sodium benzylthiolate as a model system. Afterwards, this methodology was successfully extended to thiolated nucleophiles with aliphatic and heterocyclic substituents. The new derivatives were characterized by size exclusion chromatography, spectroscopic techniques (FTIR-ATR, 1H and 13C NMR), thermal methods (TGA and DSC), and scanning electron microscopy to study morphology. The antioxidant activity of new block copolymers was examined by 1,1-diphenyl-2-picrylhydrazyl test. The polymer films showed an efficient DPPH radical inhibition activity.

Synthesis of Methyldopa-Tin Complexes and Their Applicability as Photostabilizers for the Protection of Polyvinyl Chloride against Photolysis.

Polyvinyl chloride (PVC) is a ubiquitous thermoplastic that is produced on an enormous industrial scale to meet growing global demand. PVC has many favorable properties and is used in various applications. However, photodecomposition occurs when harsh conditions, such as high temperatures in the presence of oxygen and moisture, are encountered. Thus, PVC is blended with additives to increase its resistance to deterioration caused by exposure to ultraviolet light. In the current research, five methyldopa-tin complexes were synthesized and characterized. The methyldopa-tin complexes were mixed with PVC at a concentration of 0.5% by weight, and thin films were produced. The capability of the complexes to protect PVC from irradiation was shown by a reduction in the formation of small residues containing alcohols, ketones, and alkenes, as well as in weight loss and in the molecular weight of irradiated polymeric blends. In addition, the use of the new additives significantly reduced the roughness factor of the irradiated films. The additives containing aromatic substituents (phenyl rings) were more effective compared to those comprising aliphatic substituents (butyl and methyl groups). Methyldopa-tin complexes have the ability to absorb radiation, coordinate with polymeric chains, and act as radical, peroxide, and hydrogen chloride scavengers.

Multi-spectroscopic characterization of bitumen and its polarity-based fractions

• Insights on H/C-ratio, aromatic systems and average molecular sizes are obtained. • NMR reveals varying chain lengths of aliphatic substituents throughout the fractions. • Characteristic NMR shifts in the resins suggest presence of some esters or amides. • 31 P NMR after derivatization, shows minor amounts of alcohols and carboxylic acids. Bitumen contains a complex mixture of molecules, ranging from simple linear alkanes to complex polyaromatic systems. Used in road construction, those structures are permanently influenced by atmospheric processes, which result in oxidation, degradation, loss of volatiles and structural rearrangements. In order to understand those molecular changes, a profound description of the unaltered system is needed. In this study, structural and chemical peculiarities of bitumen and its polarity-based fractions were analysed using nuclear magnetic resonance (NMR) techniques in combination with infrared/fluorescence spectroscopy and elemental analysis. The bitumen sample was separated into saturates, aromatics, resins and asphaltenes. Elemental analysis provided insights into variations of heteroatom content and hydrogen-carbon ratio among the fractions. Fluorescence spectroscopy showed an increase in the aromatic condensation degree with rising polarity. The combination of heteronuclear single quantum coherence (HSQC) and elemental analysis facilitated the assessment of length and branching extent of aliphatic side chains, throughout the fractions. Another 2D NMR technique, heteronuclear multiple bond coherence (HMBC) found evidence for minor contributions of carboxylic esters or amides within the resins. Hydroxyl and amino groups were analysed by 31 P NMR after derivatization, revealing minor amounts of alcohols, amides and carboxylic acids in the most polar fractions. Additionally, diffusion ordered spectroscopy was carried out to obtain estimations on average molecular sizes and weights. Applying in-depth NMR analysis to bitumen and combining it with complementary analytical techniques, this study provides a unique basis for future ageing studies and demonstrates how multi-spectroscopy can give new insights into bitumen structure and chemistry.

Synthesis of 1,2,3-Triazine Derivatives by Deoxygenation of 1,2,3-Triazine 1-Oxides.

A convenient, efficient, and inexpensive method has been developed for the synthesis of 1,2,3-triazine derivatives via deoxygenation of 1,2,3-triazine 1-oxide using trialkyl phosphites. Triethyl phosphite is more reactive than trimethyl phosphite, and both phosphites form their corresponding phosphates in these reactions. This procedure provides a range of aromatic and aliphatic substituted 1,2,3-triazine-4-carboxylate derivatives cleanly in high yields. Unexpected 1,2,4-triazine derivatives were also obtained as minor products during deoxygenation of 1,2,3-triazine-4-carboxylate 1-oxides having an aliphatic substituent at the 5-position.