Trimethyloxonium Tetrafluoroborate Research Articles

Synthesis of 5-Amino-3(2H)-furanones via S-Methylation/Intramolecular Cyclization of γ-Sulfanylamides.

The S-methylation/intramolecular cyclization of γ-sulfanylamide is depicted. Different methylating reagents were successfully employed for S-methylation, depending on the substituent pattern of the amide in the starting γ-sulfanylamides; trimethyloxonium tetrafluoroborate was used for N-aryl substituted γ-sulfanylamides, and the combination of methyl iodide and silver(I) tetrafluoroborate was used for N-alkyl substituted γ-sulfanylamides. When the resulting sulfonium salt was treated with DBU, it smoothly underwent intramolecular cyclization to produce a series of N-aryl, N-alkyl, N,N-dialkyl or N-alkyl-N-aryl substituted 5-amino-3(2H)-furanones in 55%-quantitative yields.

Trimethyloxonium-mediated methylation strategies for the rapid and simultaneous analysis of chlorinated phenols in various soils by electron impact gas chromatography–mass spectrometry

The efficient methylation of a panel of five industrial and environmentally-relevant chlorophenols (CPs) employing trimethyloxonium tetrafluoroborate (TMO) for their qualitative detection and identification by electron impact gas chromatography–mass spectrometry (EI-GC–MS) is presented. The protocol’s execution is simple and smoothly converts the phenols into their O-methylated counterparts conveniently at ambient temperature. The efficiency of two versions of the protocol was successfully tested in their ability to simultaneously derivatize five CPs (2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, pentachlorophenol and triclosan) in six distinct, separate soil matrices (Nebraska EPA standard soil, Virginia Type A soil, Ottawa sand, Baker sand, Silt and Georgia EPA standard soil) when present at low levels (~ 10 μgg−1). The first version involves the direct derivatization of the spiked soils with the methylating salt while the second one involves an initial soil extraction step of the CPs followed by methylation. The MDL values for each methylated CP were determined and lower values were found (4.1–13.2 ng.mL−1) for both sand matrices (Ottawa and Baker) as well as for the Georgia EPA standard soil, while larger values (8.2–21.8 ng.mL−1) were found for the Virginia Type soil, Nebraska EPA standard soil and Silt. The presented protocol offers a safer and more practical alternative to the universally employed diazomethane method and can be readily applicable to matrices other than soils. Furthermore, the protocols described herein may find applicability to the methylation of other analytes bearing acidic protons.

Microfluidic Processing of Ligand‐Engineered NiO Nanoparticles for Low‐Temperature Hole‐Transporting Layers in Perovskite Solar Cells

Nickel oxide (NiO) is used as a hole‐transporting layer (HTL) in perovskite solar cells (PSCs) because of its high optical transmittance, intrinsic p‐type doping, and suitable valence band energy level. However, fabricating high‐quality NiO films typically requires high‐temperature annealing, which limits their applicability for low‐temperature, printable PSCs. Herein, the need for such postprocessing steps is circumvented by coupling 4‐hydroxybenzoic acid (HBA) or trimethyloxonium tetrafluoroborate (Me3OBF4) ligand‐modified NiO nanoparticles (NPs) with a Tesla‐valve microfluidic mixer to deposit high‐quality NiO films at a temperature <150 °C. The NP dispersions and the resulting thin films are thoroughly characterized using a combination of optical, structural, thermal, chemical, and electrical methods. While the optical and structural properties of the ligand‐exchanged NiO NPs remain comparable with those possessing the native long‐chained aliphatic ligands, the ligand‐modified NiO thin films exhibit dramatic reductions in surface energy and an increase in hole mobilities. These are correlated with concomitant and significant enhancements in performance and stability factors of PSCs when the ligand‐modified NiO NPs are used as HTL layers within p−i−n device architectures.

Defluorination/Fluorination Reaction of BiF3 Nanoparticles Prepared Via Sol–Gel Method for Fluoride Shuttle Battery

Introduction Rechargeable batteries with high energy density have been required for recent applications such as hybrid electric vehicles and large-scale energy storage. Rechargeable batteries based on fluoride shuttle (FSBs) have attracted much attention as a candidate above, owing to their high theoretical energy density by selecting appropriate metal/metal fluoride couples as active materials of negative- and positive-electrode[1-3]. One of the important things of the battery is adoption of the good conductive media for fluoride species, that is, an electrolyte[4]. Another is reversible fluorination/defluorination of active materials at the interface with electrolyte. Previously, we have demonstrated archetypal reversible FSB using a liquid electrolyte containing organic fluoride at room temperature[3]. However, this battery needed to improve the utilization and cyclability of its active material. Since the common metal fluoride shows low electronic- and ionic-conductivity, the active materials should be minified for FSBs. In this study, metal fluoride nanoparticle, e.g. BiF3, was prepared via sol–gel method using a trifluoroacetate precursor for improvement of the charge/discharge reactions in FSB. Bismuth trifluoride having 302 mAh/g in theoretical capacity is considered as a candidate for positive active material[1-6]. Then, we studied reversible defluorination/fluorination reaction of thus prepared BiF3 nanoparticles in a liquid electrolyte of FSB at room temperature, and valence change of bismuth species in the consequent electrode was evaluated using synchrotron ex-situ XANES measurement.Experimental Bismuth trifluoride nanoparticle was prepared from bismuth trifluoroacetate precursor via decarboxylation at 453 K in an oleylamine solution under argon atmosphere. At that time, specific amount of trifluoroacetic acid and/or trifluoroacetic anhydride were added as a supplementary fluorine source. After the nanoparticles were precipitated via addition of toluene and ethanol sequentially, the resulting precipitation was centrifuged and then re-dispersed in toluene containing oleic acid as a dispersant. Finally, nanoparticles were obtained after stripping of ligand using a trimethyloxonium tetrafluoroborate. Size of the resulting nanoparticles can be controlled by precursor concentration, decarboxylation reaction time and its temperature. Electrochemical measurement was carried out using a three-electrode cell with a VSP-300 BioLogic potentiostat/galvanostat in an argon-filled glove box at room temperature. The cell was composed of a carbon cloth as a counter electrode, a silver wire as a quasi-reference electrode, and an ionic liquid containing an organic fluoride as a liquid electrolyte. The liquid electrolyte was prepared by dissolving N-methyl-N-propylpiperidinium fluoride (MPPF) or N,N,N-trimethyl-N-neopentylammonium fluoride (NpF) in N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)amide (TMPA-TFSA) with molar ratio of 1:10. Nanoparticles-supported carbon cloth electrode as a working electrode was prepared by soaking the cloth in BiF3-nanoparticles/acetonitrile dispersion. The prepared nanoparticles via the sol–gel method and the defluorination/fluorination products in electrochemical measurements were evaluated using XRD, XPS, SEM-EDS, and so on in our laboratory. Furthermore, valence change of bismuth species was evaluated using synchrotron ex-situ XANES measurement at SPring-8, Japan.Results and Discussion Thus obtained nanoparticles via above-mentioned procedure had a few tens of nanometers in diameter and showed low crystallinity. Moreover, it was suggested that small amount of oxygen would be doped into the nanoparticles according to elemental analyses. Then, non-doped BiF3 nanoparticles having hexagonal crystalline structure had been acquired after further fluorination-treatment. Consequent BiF3 nanoparticles-supported carbon cloth showed ca. 240 mAh/g (80%) as an initial discharge capacity, and retained ca. 100 mAh/g for more than five cycles at room temperature. Furthermore, in ex-situ bismuth L3-edge XANES spectra, valence of bismuth species changed from trivalent to zero (metal) during the defluorination reaction and similar reverse change was elucidated in fluorination reaction. In this way, the size of the active material was minified by the preparation method, thereby improving the utilization and cyclability in FSB. This method will be also applied for other positive- and negative-active material having high gravitational theoretical capacity.Acknowledgements This work was supported by the “Research and Development Initiative for Scientific Innovation of New Generation Batteries 2 (RISING2)” of the New Energy and Industrial Technology Development Organization (NEDO), Japan.

Methylation protocol for the retrospective detection of isopropyl-, pinacolyl- and cyclohexylmethylphosphonic acids, indicative markers for the nerve agents sarin, soman and cyclosarin, at low levels in soils using EI-GC–MS

A practical and efficient protocol for the derivatization and detection by GC-EI-MS of isopropyl-, pinacolyl- and cyclohexylmethylphosphonic acids, key diagnostic degradation products of the nerve agents sarin, soman and cyclosarin respectively, in six different types of soil matrices is presented. The method involves the in situ conversion of the phosphonic acids to their respective methyl esters using trimethyloxonium tetrafluoroborate when present in the soils at low levels (10 μg g−1) without any prior extractions or soil preparation. The soils employed in our study were Nebraska EPA soil, Georgia soil, silt, Virginia type A soil, regular sand and Ottawa sand and were chosen for their vast differences in composition and physical features. Appealing attributes of the protocol include its rapidity (t < 30 min), mildness (ambient temperature), and practicality that includes the production of the phosphonic methyl esters that can be easily detected by GC-EI–MS and corroborated with the instrument's internal NIST spectral library or the Organisation for the Prohibition of Chemical Weapons (OPCW) central analytical database (OCAD v.21_2019). The overall efficacy of the protocol was then tested on a soil sample featured in the 44th OPCW PT that our laboratory participated in. After preparing the soil so as to give pinacolyl methylphosphonic acid at a 5 μg g−1 concentration, the acid was successfully methylated and detected by GC-EI-MS. The protocol's performance mirrors that of the universally employed diazomethane protocol but accomplishes this without any of the explosive hazards and time consuming reagent preparation commonly associated with it.

Efficient derivatization of methylphosphonic and aminoethylsulfonic acids related to nerve agents simultaneously in soils using trimethyloxonium tetrafluoroborate for their enhanced, qualitative detection and identification by EI-GC–MS and GC–FPD

Trimethyloxonium tetrafluoroborate (TMO·BF4) has been used in the simultaneous derivatization of phosphonic and 2-aminoethylsulfonic acids related to nerve agents in different soils for their enhanced detection and identification by electron ionization gas chromatography-mass spectrometry (EI-GC–MS). The panel of acids consisted of five Schedule 2 phosphonic acids (methyl methylphosphonic acid, ethyl methylphosphonic acid, isopropyl methylphosphonic acid, pinacolyl methylphosphonic acid and cyclohexyl methylphosphonic acid) along with two sulfonic acids, N,N-diethyl-2-aminoethylsulfonic acid and N,N-diisopropyl-2-aminoethylsulfonic acid. The acids were converted to their corresponding methyl esters at ambient temperature when present at a 10μgg−1 concentration in three separate soils: Virginia type A soil, Ottawa sand and Nebraska EPA soil. The concentration of the acids reflects values typically encountered during proficiency tests (PTs) administered annually by the Organisation for the Prohibition of Chemical Weapons (OPCW). Derivatization times to yield detectable signals for the methyl ester products for all the acids was found to vary among all three soil samples, however, it was found that generally the most optimal time across all the matrices involved was 3h after the addition of TMO·BF4. Concomitantly, the analysis of the samples was complemented using GC coupled to flame photometric detection (GC–FPD). The inclusion of GC–FPD in the analysis yielded stronger signals for all seven methylated analytes making their detection after merely 3h possible relative to the ones initially obtained with EI-GC–MS. Regarding the three soils employed in our study, a greater methylating efficiency was found in the Virginia type A soil and Ottawa sand yielding results that were significantly larger in magnitude to those found during the same time points for the Nebraska EPA soil sample. Prolonged reaction times (up to 72h) were explored to find the time for the highest yield of methyl ester production were found instead to be deleterious to the process showcasing the importance of the fast yielding nature of the process specifically in situations where time-sensitive analysis is crucial (e.g. OPCW-PT).

A novel fast method for aqueous derivatization of THC, OH-THC and THC-COOH in human whole blood and urine samples for routine forensic analyses.

A novel aqueous in situ derivatization procedure with propyl chloroformate (PCF) for the simultaneous, quantitative analysis of Δ9 -tetrahydrocannabinol (THC), 11-hydroxy-Δ9 -tetrahydrocannabinol (OH-THC) and 11-nor-Δ9 -tetrahydrocannabinol-carboxylic acid (THC-COOH) in human blood and urine is proposed. Unlike current methods based on the silylating agent [N,O-bis(trimethylsilyl)trifluoroacetamide] added in an anhydrous environment, this new proposed method allows the addition of the derivatizing agent (propyl chloroformate, PCF) directly to the deproteinized blood and recovery of the derivatives by liquid-liquid extraction. This novel method can be also used for hydrolyzed urine samples. It is faster than the traditional method involving a derivatization with trimethyloxonium tetrafluoroborate. The analytes are separated, detected and quantified by gas chromatography-mass spectrometry in selected ion monitoring mode (SIM). The method was validated in terms of selectivity, capacity of identification, limits of detection (LOD) and quantification (LOQ), carryover, linearity, intra-assay precision, inter-assay precision and accuracy. The LOD and LOQ in hydrolyzed urine were 0.5 and 1.3 ng/mL for THC and 1.2 and 2.6 ng/mL for THC-COOH, respectively. In blood, the LOD and LOQ were 0.2 and 0.5 ng/mL for THC, 0.2 and 0.6 ng/mL for OH-THC, and 0.9 and 2.4 ng/mL for THC-COOH, respectively. This method was applied to 35 urine samples and 50 blood samples resulting to be equivalent to the previously used ones with the advantage of a simpler method and faster sample processing time. We believe that this method will be a more convenient option for the routine analysis of cannabinoids in toxicological and forensic laboratories.

Effective methylation of phosphonic acids related to chemical warfare agents mediated by trimethyloxonium tetrafluoroborate for their qualitative detection and identification by gas chromatography-mass spectrometry

The effective methylation of phosphonic acids related to chemical warfare agents (CWAs) employing trimethyloxonium tetrafluoroborate (TMO·BF4) for their qualitative detection and identification by gas chromatography-mass spectrometry (GC-MS) is presented. The methylation occurs in rapid fashion (1 h) and can be conveniently carried out at ambient temperature, thus providing a safer alternative to the universally employed diazomethane-based methylation protocols. Optimization of the methylation parameters led us to conclude that methylene chloride was the ideal solvent to carry out the derivatization, and that even though methylated products can be observed surfacing after only 1 h, additional time was not found to be detrimental but beneficial to the process particularly when dealing with analytes at low concentrations (∼10 μg mL−1). Due to its insolubility in methylene chloride, TMO·BF4 conveniently settles to the bottom during the reaction and does not produce additional interfering by-products that may further complicate the GC-MS analysis. The method was demonstrated to successfully methylate a variety of Schedule 2 phosphonic acids, including their half esters, resulting in derivatives that were readily detected and identified using the instrument's spectral library. Most importantly, the method was shown to simultaneously methylate a mixture of the organophosphorus-based nerve agent hydrolysis products: pinacolyl methylphosphonate (PMPA), cyclohexyl methylphosphonate (CyMPA) and ethyl methylphosphonate (EMPA) (at a 10 μg mL−1 concentration each) in a fatty acid ester-rich organic matrix (OPCW-PT-O3) featured in the 38th Organisation for the Prohibition of Chemical Weapons (OPCW) Proficiency Test. In addition, the protocol was found to effectively methylate N,N-diethylamino ethanesulfonic acid and N,N-diisopropylamino ethanesulfonic acid that are products arising from the oxidative degradation of the V-series agents VR and VX respectively. The work described herein represents the first report on the use of TMO·BF4 as a viable, stable and safe agent for the methylation of phosphonic acids and their half esters and within the context of an OPCW Proficiency Test sample analysis.

Synthesis of di(Imdazolium) and di(Pyrazolium) Salts as Precursors for N-heterocyclic Dicarbene Complexes

Alpha,omega-bis(pyrazol-1-yl)alkanes and alpha,omega-bis(imidazol-1-yl)alkanes with spacers consisting of four to ten methylene groups have been prepared from pyrazole, 3,5-dimethylpyrazole or imidazole and corresponding dibromoalkanes in a superbasic medium KOH-DMSO. The proposed method of synthesis allowed the preparation of new flexible bidentate ligands without the need to use toxic solvents and tedious workup procedures. Bis(pyrazol-1-yl)alkanes were further functionalized for their use as precursors for “non-classical” mesoionic N-heterocyclic carbene ligands. One the first step, iodine atoms were introduced to positions 4 of pyrazole rings by oxidative iodination using I2-HIO3 system. On the next step, nitrogen atoms in positions 2 of pyrazole rings were alkylated using several agents. Reaction with methyliodide unexpectedly led to the formation of only mono-alkylated products even after 7 days of refluxing in a neat alkyliodide. Methylation by trimethyloxonium tetrafluoroborate or methyltriflate led to dimethylated products in high yields. Bis(imidazol-1-yl)alkanes were easily alkylated by methyliodide to give di(imidazolium) salts – precursors to “classic” N-heterocyclic dicarbenes.

ChemInform Abstract: Efficacious N‐Protection of O‐Aryl Sulfamates with 2,4‐Dimethoxybenzyl Groups.

AbstractThe protection‐deprotection strategy comprises reaction of phenols (I) with sulfonylbis(methylimidazole) (II) to provide aryl imidazole sulfonates (III), which are activated by reaction with trimethyloxonium tetrafluoroborate, before further reaction with the methoxy‐substituted dibenzylamine (IV) or (VII).

Photoinduced Ligand Exchange and Covalent DNA Binding by Two New Dirhodium Bis-Amidato Complexes

Two new dirhodium complexes, the head-to-tail (H,T) and head-to-head (H,H) isomers of cis-[Rh(2)(HNOCCH(3))(2)(CH(3)CN)(6)](2+), were synthesized, separated, and characterized following the reaction of Rh(2)(HNOCCH(3))(4) with trimethyloxonium tetrafluoroborate in CH(3)CN. The products were characterized by (1)H NMR spectroscopy, mass spectrometry, elemental analysis, and single crystal X-ray diffraction. Each bis-amidato isomer has a total of six CH(3)CN ligands, two along the internuclear Rh-Rh axis, CH(3)CN(ax), two in equatorial positions trans to the oxygen atoms of the bridging amidato groups, CH(3)CN(eq)(O), and two in equatorial positions trans to the amidato nitrogen atoms, CH(3)CN(eq)(N). When aqueous solutions of the complexes are irradiated with low energy light (λ(irr) ≥ 495 nm, 60 min), both types of CH(3)CN(eq) ligands undergo efficient ligand exchange with solvent H(2)O molecules to form monoaqua, followed by bis-aqua, adducts, releasing two CH(3)CN(eq) ligands in the process. The quantum yields, Φ(400nm), for the H,T and H,H isomers to form monoaqua adducts are 0.43 and 0.38, respectively, which are substantially greater than the 0.13 yield observed for cis-[Rh(2)(O(2)CCH(3))(2)(CH(3)CN)(6)](2+); importantly, no ligand exchange is observed when the complexes are kept in the dark. Finally, low energy excitation (λ(irr) ≥ 610 nm, 30 min) of the H,T isomer was shown to generate photoproducts that covalently bind to linearized DNA, making 2 a potential agent for photochemotherapy that does not require the formation of (1)O(2), as is typical of organic photodynamic therapy (PDT) agents.

Pd-catalyzed modifiable silanol-directed aromatic C-H oxygenation.

Pd-catalyzed modifiable silanol-directed aromatic C-H oxygenation.

ChemInform Abstract: N‐Alkylation of N‐Arylsulfonyl‐α‐amino Acid Methyl Esters by Trialkyloxonium Tetrafluoroborates.

Abstract In this work we present the results obtained for the N-alkylation of a series of N -arylsulfonyl-α-amino acid methyl esters bearing different substituents at the 4-position of the sulfonamide aromatic ring. In particular, we compare the reactivity of these species with diazomethane and trimethyloxonium tetrafluoroborate in N-methylation processes. Diazomethylation is unsuccessful for N -arylsulfonamide derivatives containing electron-releasing groups on the aromatic ring. In these cases trimethyloxonium tetrafluoroborate is the reagent of choice for the direct and quantitative N-methylation. Further we extend our evaluation to the use of triethyloxonium tetrafluoroborate. This reagent shows to be very efficient in order to prepare N -ethyl derivatives of N -arylsulfonyl-α-amino acid methyl esters. An experimental protocol similar to that used for N-methylation with trimethyloxonium tetrafluoroborate is applied for the N-ethylation.

Efficacious N-protection of O-aryl sulfamates with 2,4-dimethoxybenzyl groups

Sulfamates are important functional groups in certain areas of current medicinal chemistry and drug development. Alcohols and phenols are generally converted into the corresponding primary sulfamates (ROSO(2)NH(2) and ArOSO(2)NH(2), respectively) by reaction with sulfamoyl chloride (H(2)NSO(2)Cl). The lability of the O-sulfamate group, especially to basic conditions, usually restricts this method to a later stage of a synthesis. To enable a more flexible approach to the synthesis of phenolic O-sulfamates, a protecting group strategy for sulfamates has been developed. Both sulfamate NH protons were replaced with either 4-methoxybenzyl or 2,4-dimethoxybenzyl. These N-protected sulfamates were stable to oxidising and reducing agents, as well as bases and nucleophiles, thus rendering such masked sulfamates suitable for multi-step synthesis. The protected sulfamates were synthesised by microwave heating of 1,1'-sulfonylbis(2-methyl-1H-imidazole) with a substituted phenol to give an aryl 2-methyl-1H-imidazole-1-sulfonate. This imidazole-sulfonate was N-methylated by reaction with trimethyloxonium tetrafluoroborate, which enabled subsequent displacement of 1,2-dimethylimidazole by a dibenzylamine (e.g. bis-2,4-dimethoxybenzylamine). The resulting N-diprotected, ring-substituted phenol O-sulfamates were further manipulated through reactions at the aryl substituent and finally deprotected with trifluoroacetic acid to afford a phenol O-sulfamate. The use of 2,4-dimethoxybenzyl was particularly attractive because deprotection occurred quantitatively within 2 h at room temperature with 10% trifluoroacetic acid in dichloromethane. The four key steps in the protocol described [reaction of 1,1'-sulfonylbis(2-methyl-1H-imidazole) with a phenol, methylation, displacement with a dibenzylamine and deprotection] all proceeded in very high yields.

Correlation of spectroscopically determined ligand donor strength and nucleophilicity of substituted pyrazoles

The relative ligand donor strengths of 10 pyrazole-derived ligands has been determined with great accuracy, making use of the interdependence between the donor strength of the co-ligand and the (13)C NMR chemical shift of the (i)Pr(2)-bimy carbene signal in trans-[PdBr(2)((i)Pr(2)-bimy)L] complexes ((i)Pr(2)-bimy = 1,3-diisopropylbenzimidazolin-2-ylidene; L = pyrazole-derived ligand). Even subtle variations in the substitution pattern of the pyrazole backbone up to three bonds away from the coordinating nitrogen could be detected reliably using this methodology. Alkylation experiments conducted on the pyrazoles using electrophiles of varied reactivity (ethyl bromide, ethyl iodide, and trimethyloxonium tetrafluoroborate) served as a benchmark to rank the pyrazoles in three groups of gradually increasing nucleophilicity, which correlated well with their determined donor strength.

N-Alkylation of N-arylsulfonyl-α-amino acid methyl esters by trialkyloxonium tetrafluoroborates

In this work we present the results obtained for the N-alkylation of a series of N-arylsulfonyl-α-amino acid methyl esters bearing different substituents at the 4-position of the sulfonamide aromatic ring. In particular, we compare the reactivity of these species with diazomethane and trimethyloxonium tetrafluoroborate in N-methylation processes. Diazomethylation is unsuccessful for N-arylsulfonamide derivatives containing electron-releasing groups on the aromatic ring. In these cases trimethyloxonium tetrafluoroborate is the reagent of choice for the direct and quantitative N-methylation. Further we extend our evaluation to the use of triethyloxonium tetrafluoroborate. This reagent shows to be very efficient in order to prepare N-ethyl derivatives of N-arylsulfonyl-α-amino acid methyl esters. An experimental protocol similar to that used for N-methylation with trimethyloxonium tetrafluoroborate is applied for the N-ethylation.

Novel Method for Simultaneous Aqueous in Situ Derivatization of THC and THC-COOH in Human Urine Samples: Validation and Application to Real Samples

The present work describes the validation of a novel aqueous in situ derivatization procedure with trimethyloxonium tetrafluoroborate (TMO) as methylating agent for the simultaneous, quantitative analysis of Δ(9)-tetrahydrocannabinol (THC) and 11-nor-Δ(9)-tetrahydrocannabinol carboxylic acid (THC-COOH) in human urine. The derivatizing agent is directly added to the urine sample and the methyl-derivatives are then recovered by liquid-liquid extraction procedure. Gas chromatography-mass spectrometry was used to detect the derivatives in selected ion monitoring mode. The limits of detection were 0.7 ng/mL for THC and 0.5 ng/mL for THC-COOH, whereas the limits of quantification were 1.9 and 0.9 ng/mL, respectively. The method has been applied to 60 real samples both positive and negative to immunochemical screening test resulting to be very useful and reliable in routine analysis of THC-COOH in human urine for toxicological and forensic purposes.

1,2‐Diphosphaacenaphthene 1,2‐Dications: Synthetic, Stereochemical and Computational Study of the Stabilising Role of Naphthalene‐1,8‐diyl Backbone

Syntheses and full characterisation data (including single crystal diffraction) of three 1,2-diphosphonium dicationic species with the naphthalene-1,8-diyl (Nap) backbone are reported. The oxidation of Nap[P(NMe(2))(2)](2) with P(2)I(4) to its 1,2-dication was achieved. meso- and rac-forms of "all carbon" 1,2-diphosphonium dications were obtained in good yields and purity by double alkylation of the parent diphosphine (1,2-diphenyl-1,2-diphosphaacenaphthene) with methyl triflate or trimethyloxonium tetrafluoroborate. Each methylating reagent produces one of the rac- or meso-forms of the dication diastereospecifically. Structural parameters of the new dications are discussed with respect to other phosphorus 1,2-dications. DFT (B3LYP) computations revealed the significant role of the naphthalene backbone in stabilisation of the dicationic motif and helped to assess the energy cost of the steric clash of a variety of groups attached to the peri-positions of naphthalene. The synthesis and single crystal X-ray data of the extremely crowded Nap[P(Se)(OiPr)(2)](2) are discussed, and are contrasted with the unsuccessful synthesis of Nap(PtBu(2))(2) from NapLi(2) and ClPtBu(2).

ChemInform Abstract: Detailed Procedures for the Preparation of Dimethoxycarbenium and Trimethyloxonium Tetrafluoroborate.

ChemInform Abstract: Detailed Procedures for the Preparation of Dimethoxycarbenium and Trimethyloxonium Tetrafluoroborate.

Triethyloxonium Tetrafluoroborate/1,2-Dimethoxyethane – a Versatile Substitute for Trimethyloxonium Tetrafluoroborate in O-Methylation Reactions

The triethyloxonium tetrafluoroborate/1,2-dimethoxyethane (TEO/DME) mixture is a versatile and cheap substitute for trimethyloxonium tetrafluoroborate in O-methylations of pyrrolin-2-ones, quinolones, acridones, and 1-oxo-β -carbolines. Undesired O-ethylation can be avoided by preincubation of triethyloxonium tetrafluoroborate and 1,2-dimethoxyethane for 1 h, prior to addition of the substrate. In the course of these investigations it was found that the structures assigned to the alkaloids taraxacine A and B are erroneous.