REDUCTION OF TERMINAL ORGANYLCHALCOGENO PHOSPHONATES AS A WAY TO PREPARE PRIMARY ORGANYLCHALCOGENO PHOSPHINES

2-Organylseleno(telluro)ethyl phosphines and 4-organylthio(seleno (telluro))butyl phosphines were prepared by reduction of diethyl 2-organylseleno(telluro)ethyl phosphonates and diethyl 4-organylthio(seleno(telluro)) butyl phosphonates with lithium aluminium hydride in diethyl ether. ¹H and ³¹P NMR spectra as well as mass spectra of the resulting phosphines were considered. Their stability in regard to the oxidation by oxygen was discussed.     

Synthese und Reaktivität von 2‐Brom‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol Molekülstruktur von Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl)

Synthesis and Reactivity of 2‐Bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborole Molecular Structure of Bis(1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborol‐2‐yl The reaction of a slurry of calcium hydride in toluene with N,N′‐diethyl‐o‐phenylenediamine ( 1 ) and boron tribromide affords 2‐bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol ( 2 ) as a colorless oil. Compound 2 is converted into 2‐cyano‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 3 ) by treatment with silver cyanide in acetonitrile. Reaction of 2 with an equimolar amount of methyllithium affords 1,3‐diethyl‐2‐methyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 4 ). 1,3,2‐Benzodiazaborole is smoothly reduced by a potassium‐sodium alloy to yield bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl] ( 7 ), which crystallizes from n‐pentane as colorless needles. Compound 7 is also obtained from the reaction of 2 and LiSnMe₃ instead of the expected 2‐trimethylstannyl‐1,3,2‐benzodiazaborole. N,N′‐Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐ yl)‐1,2‐diamino‐ethane ( 6 ) results from the reaction of 2 with Li(en)C≡CH as the only boron containing product. Compounds 2 – 4 , 6 and 7 are characterized by means of elemental analyses and spectroscopy (IR, ¹H‐, ¹¹B{¹H}‐, ¹³C{¹H}‐NMR, MS). The molecular structure of 7 was elucidated by X‐ray diffraction analysis.     

Heterogeneous Parahydrogen-Induced Polarization of Diethyl Ether for Magnetic Resonance Imaging Applications

Magnetic resonance imaging (MRI) with the use of hyperpolarized gases as contrast agents provides valuable information on lungs structure and function. While the technology of ¹²⁹Xe hyperpolarization for clinical MRI research is well developed, it requires the expensive equipment for production and detection of hyperpolarized ¹²⁹Xe. Herein we present the ¹H hyperpolarization of diethyl ether vapor that can be imaged on any clinical MRI scanner. ¹H nuclear spin polarization of up to 1.3 % was achieved using heterogeneous hydrogenation of ethyl vinyl ether with parahydrogen over Rh/TiO₂ catalyst. Liquefaction of diethyl ether vapor proceeds with partial preservation of hyperpolarization and prolongs its lifetime by ≈10 times. The proof-of-principle 2D ¹H MRI of hyperpolarized diethyl ether was demonstrated with 0.1×1.1 mm² spatial and 120 ms temporal resolution. The long history of use of diethyl ether for anesthesia is expected to facilitate the clinical translation of the presented approach.     

EPR study of dithiophosphate,dithiocarbamate, and xanthate complexes of Cr(V), Mo(V), and W(V)

Liquid and frozen solutions of diethyl dithiophosphate, diethyl dithiocarbamate, and butyl xanthate complexes of Cr(V), Mo(V) and W(V) were studied by the EPR method in the temperature range from 293–77dg K. The spin-Hamiltonian parameters were determined. Conclusions were drawn about the structure of these complexes and about the bond character within the complexes. A multiplicity of the hyperfine splitting constants from Cr⁵³, Mo^95,97, and W¹⁸³ to the constant of additional hyperfine splitting from the p³¹ isotope is observed in diethyl phosphate complexes.     

Experimental and Theoretical Studies of Bromination of Diethyl 2,4,6‐Trimethyl‐1,4‐dihydropyridine‐3,5‐dicarboxylate

A reaction of diethyl 2,4,6‐trimethyl‐1,4‐dihydropyridine‐3,5‐dicarboxylate with 1, 2, and more equivalents of N‐bromosuccinimide (NBS) in methanol was investigated by NMR spectroscopy at a temperature interval ranging from 25 to 40°C. The reaction was found to proceed through several steps. The structures of the intermediates diethyl 3‐bromo‐2,4,6‐trimethyl‐3,4‐dihydropyridine‐3,5‐dicarboxylate, diethyl 3‐bromo‐2‐methoxy‐2,4,6‐trimethyl‐1,2,3,4‐tetrahydropyridine‐3,5‐dicarboxylate, and diethyl 3,5‐dibromo‐2‐methoxy‐2,4,6‐trimethyl‐2,3,4,5‐tetrahydropyridine‐3,5‐dicarboxylate were identified by multinuclear (¹H, ¹³C, and ¹⁵N) NMR spectral data. The optimal structures of all species participating in the reaction as well as changes in their relative energies along with the proposed pathway of the reaction were analyzed by quantum‐chemical calculations. The mechanism of bromination of diethyl 2,4,6‐trimethyl‐1,4‐dihydropyridine‐3,5‐dicarboxylate with NBS in methanol was found to favor the bromination in the 2,6‐methyl side chains as the only products in full agreement with experimental observations.     

Addition of Secondary Amines to Alkynephosphonates

Addition of secondary amines to diethyl alkynephosphonates, catalyzed by Cu(I) salts, proceeds regio- and stereospecifically and yields diethyl (E)-2-diethylaminooalkenephosphonates. The E configuration was established by analysis of the vicinal coupling constants between the phosphorus and carbon nuclei in the ¹³C NMR spectra of the reaction products and model compounds: ³ JPC is 6-10 Hz at the cis arrangement of the coupled nuclei and 16 Hz or higher at the trans arrangement. In all the diethyl diethylaminoalkenephosphonates obtained, ³ JPC is about 5 Hz, suggesting cis addition.     

Electroanalytical study of diethyl and dibutyl phthalate in micellar and oil-in-water emulsified media

A polarographic study was carried out of the reduction processes of diethyl and dibutyl phthalate in micellar solutions with the cationic surfactant Hyamine 1622, and in an emulsified medium from aliquots of the phthalates dissolved in a diethyl ether: ethyl acetate (1:9) mixture and Hyamine 1622 as emulsifying agent. The characteristics of the reduction processes in both media were established. The number of electrons involved was higher for the base form of the electroactive species. Using dpp at E=–50 mV, the detection limits obtained in the emulsified medium were 6.7×10^–8 and 7.4×10^–7 moll^–1 for diethyl phthalate and dibutyl phthalate, respectively. Interferences between the two phthalates were studied, and the possibility of carrying out the overall determination of both phthalates was demonstrated. Good results were obtained when applying the polarographic method developed in the emulsified medium to determine diethyl phthalate by dpp in spiked milk after extraction of the analyte with diethyl ether: ethyl acetate (1:9).     

Application of low energy CID in the determination of structures of [M – halogen]+ ions obtained from diethyl halosuccinates under electron impact

Low energy collision induced dissociation (CID) spectra indicate that m/z 173 ions formed by the loss of a halogen atom from diethyl chloro- and bromo-succinate under electron impact are mixtures of O-protonated diethyl maleate (>90%) and fumarate (<10 %). Hydrogen migration precedes the C-halogen bond cleavage in these cases. The low energy CID spectrum of the m/z 173 [M? I]⁺ ion obtained from diethyl iodosuccinate shows that only a small fraction of the [M? I]⁺ ions are the O-protonated species formed by hydrogen migration. The results of this study demonstrate the potential of low energy CID in the determination of structure (including configuration) of gas phase ions.     

Dialkyl phosphates determination by gas chromatography: Evaluation of a microwave‐assisted derivatization†

Dialkyl phosphates are organophosphate insecticide metabolites and their urinary analysis is useful for assessing human exposure to these compounds. This study presents a sample preparation method with microwave‐assisted derivatization for two dialkyl phosphates to make the process faster before gas chromatographic analysis. The optimized conditions for derivatization procedure were: 250 μL of 2,3,4,5,6‐pentafluorobenzyl bromide 3% in acetonitrile for derivative; microwave for 5 min with intensity of 160 W. The electron ionization mass spectrometric analysis was performed using a gas chromatography with mass spectrometry QP‐2010 from the Shimadzu^® equipped with RTx^®‐5MS capillary column. Ions were monitored at selected‐ion monitoring mode at m/z 350 for diethyl thiophosphate and m/z 366 for diethyl dithiophosphate. The developed method was linear for both metabolites. The intra‐assay precision was the values ranged between 1.1 and 9.1%, for diethyl thiophosphate, and between 4.06 and 6.9%, for diethyl dithiophosphate. The interassay precision showed relative standard deviation between 10.3 and 15.1%, for diethyl thiophosphate and between 4.9 and 11.9%, for diethyl dithiophosphate. The results obtained suggests that derivatization assisted by microwave, before gas chromatography with mass spectrometry analysis, can be applied to monitoring of exposure to organophosphates once is fast, sensible, and precise method to determinate dialkyl phosphates.     

Synthesis and structure of diethyl (1-benzyloxycarbonylamino-1-carboranyl-3,3,3-trifluoropropyl)phosphonate

A reaction of C-carboranylmethylmagnesium bromide with diethyl (N-benzyloxycarbonyl-2,2,2-trifluoroethaneimidoyl)phosphonate gave P- and N-protected aminophosphonic acid, an organophosphorus analog of alanine. The phosphonate was characterized by ¹H, ¹⁹F, and ³¹P NMR spectroscopy. X-ray diffraction analysis of diethyl (1-benzyloxycarbonylamino-1-carboranyl-3,3,3-trifluoropropyl)phosphonate showed that the molecules form dimers in crystals due to the intermolecular hydrogen bond.     

Determination of diethyl ether and methyl iodide in dimethylcadmium using headspace analysis

The possibility of direct gas-chromatographic analysis of dimethylcadmium was demonstrated. A procedure for determining impurities of diethyl ether and methyl iodide using headspace analysis was developed. The limits of detection for diethyl ether and methyl iodide were 3 x 10^-4 and 2 x 10^-3 mol %, respectively.     

β-Carbolines as agonistic or antagonistic benzodiazepine receptor ligands. 1. Synthesis of some 5-, 6- and 7-amino derivatives of 3-methoxycarbonyl-β-carboline (β-CCM) and of 3-ethoxycarbonyl-β-carboline (β-CCE)

Condensation of diethyl formylamino- or diethyl acetylaminomalonate with 4-, 5- or 6-nitrogramine 1 afforded the diethyl formylamino- or the diethyl acetylamino[(nitroindol)-3-ylmethyl]malonates 2 ; reduction of the nitro group followed by N-formylation or acetylation of the resulting amino compounds 3 , led to the 4-, 5-and 6-acylamino derivatives 4 . Cyclization of 4 in the presence of polyphosphoric esters gave the 3,3-bis(ethoxycarbonyl)-3,4-dihydro-β-carbolines 5 , which underwent lithium chloride/water catalyzed monodeethoxycarbonylation to the corresponding 5-, 6- and 7-acylamino-3-ethoxycarbonyl-β-carbolines 6 , whose acidic hydrolysis led finally to the 5-, 6- and 7-amino-3-ethoxycarbonyl-β-carbolines 9 . The 6-amino compounds 9b-e were obtained also by direct nitration of 3-methoxycarbonyl-β-carboline 7a and of 3-ethoxycarbonyl-β-carboline 7c , followed by the nitro group reduction of the resulting nitro carbolines 8 . Preliminary studies of the binding to rabbit brain benzodiazepine receptor sites indicate compounds 9b and 9c to inhibit the ³H-diazepam binding at 10^?8 M concentrations.     

Structural studies of organometallic compounds in solution: I. Magnesium iodide in diethyl ether and tetrahydrofuran

The structure of 2.8 M MgI₂ in diethyl ether solution and that of 1.7 M MgI₂ in tetrahydrofuran solution have been determined by large angle X-ray scattering measurements. The measurement on the diethyl ether solution was performed at 44°C, on a phase crystallizing at approximately 30°C. In diethyl ether a dimeric structure is found, arranged in a square-planar fashion. The bond lengths are: MgI 2.652(2), II (diagonal) 3.75(2) and II (linear) 5.30 Å. Three diethyl ether molecules are probably coordinated to each magnesium to complete an octahedral arrangement. In tetrahydrofuran the ion MgI⁺ from a dissociated complex predominates. In the MgI₂ complex a tetrahedral arrangement is found. In both the MgI⁺ and MgI₂ complexes the MgI distance is 2.56(2) Å. In the MgI₂ complex the II distance is 4.44(4) Å. In both solutions the MgO and MgC distances were kept fixed at 2.10 and 3.48 Å, respectively. The solubility of MgI₂ in diethyl ether has been shown to be strongly dependent on the water content of the ether; 0.2 M was the highest concentration obtained in anhydrous diethyl ether.     

Microwave assisted synthesis and Anti-microbial activity of new Diethyl ((dialkoxyphosphoryl) (2-hydroxyphenyl) methyl) phosphoramidates

The synthesis of new α-aminophosphonates 4a-j (diethyl((dialkoxyphosphoryl)(phenyl)methyl)phosphoramidates) were achieved through a one pot simple and efficient method from the three-component condensation reaction (Kabachnik-Fields reaction) of diethyl phosphoramidate, aryl salicylaldehydes, and dialkyl phosphite by using microwave irradiation under solvent-free and catalyst-free conditions in good to excellent yields and short reaction times. The structures of the novel products were established by IR, ¹H, ¹³C & ³¹P-NMR and Mass spectroscopy. All the synthesized compounds were screened their antimicrobial activity.     

New class of diethyl substituted phosphoramidimidates and phosphonimidates: synthesis,spectral characterization and antimicrobial activity

Abstract

A series of new class of diethyl N-2-hydroxyethyl-N'-substituted phosphoramidimidates 6(a–e) and diethyl P-morpholino-N-substituted phosphonimidates 6(f–j) was synthesized. The precursor intermediates, diethyl substituted phosphoramidites 3(a–b) were prepared initially by a reaction of various amines 1(a–b) and diethyl phosphorochloridite (2) and then they were treated by in situ with aromatic/alkyl azides through Staudinger reaction to accomplish title products. Structures of all the synthesized compounds were characterized by spectroscopic data such as IR, NMR (¹H, 13C, ³¹P), mass, and elemental analyses. The synthesized compounds were screened for their in vitro antimicrobial activity to understand their biological potency. The biological screening results disclosed that compounds 6b, 6c, 6e, 6g, 6h and 6j having potent antimicrobial activity against all the tested pathogens.     

Absolute rate constants for the coordination of olefins to a transient coordinatively unsaturated cobalt complex

Absolute second-order rate constants for the coordination of diethyl phenylphosphonite and various olefins to a transient coordinatively unsaturated cobalt complex, i.e. hydridotris(diethyl phenylphosphonite)cobalt(I), have been measured in cyclohexane at 23° C using laser flash photolysis techniques. The rate constants have been found to depend markedly on the structures of the olefins, e.g. 1.2 × 10⁸ and 6.5 × 10⁴M^?1 s^?1 for 1-hexene and tetramethylethylene, respectively. The mechanism of photochemical double-bond migration catalyzed by the transient is discussed on the basis of these rate constants.     

Novel aziridination of α-halo ketones: an efficient nucleophile-induced cyclization of phosphoramidates to functionalized aziridines

A novel and efficient aziridination of α-halo ketones is reported. The reaction of α-halo ketones with diethyl N-arylphosphoramidates affords diethyl N-aryl-N-(2-oxoalkyl)phosphoramidates which undergo reductive (H⁻-induced) cyclization with sodium borohydride followed by sodium hydride to give 1,2-disubstituted and 1,2,3-trisubstituted aziridines. The cyclization induced by NCS⁻ or PhS⁻ affords substituted aziridines functionalized at C-2. The reactions give excellent yields and are highly diastereoselective in favour of cis aziridines.     

Surface tension of diethyl carbonate, 1,2-dimethoxyethane and diethyl adipate

The surface tension was investigated with a differential capillary rise method in the temperature range from 273 to 373 K for diethyl carbonate, 278 to 373 K for 1,2-dimethoxyethane, and 293 to 373 K for diethyl adipate, respectively. The uncertainties of the temperature and surface tension were estimated to be within ±10 mK and ±0.2 mN m⁻¹, respectively. A surface tension correlation was developed as a function of temperature with the experimental data, and the average absolute deviations were 0.04, 0.07 and 0.09 mN m⁻¹ for diethyl carbonate, 1,2-dimethoxyethane and diethyl adipate, respectively.     

Theoretical studies on the interaction of anionic collectors with Cu+, Cu2+, Zn2+ and Pb2+ ions

 The influence of collector structure on interaction with metal cations was modelled by computational ab initio methods. The interaction energies were calculated between metal ions (Cu⁺, Cu²⁺, Zn²⁺ and Pb²⁺) and selected collector anions: ethyl xanthate, ethyl trithiocarbonate, dithiobutyric acid, ethyl dithiocarbamate, diethyl dithiocarbamate, diethylphosphinecarbodithioic acid and diethoxyphosphinecar bodithioic acid. The strongest interaction was found with diethyl dithiocarbamate. The results give qualitative information on the effect of the collector structure on the initial adsorption steps on sulphide mineral flotation. Received: 25 September / Accepted: 11 October 2001 / Published online: 22 March 2002     

Li- and P NMR spectra of cyclopentanone lithium enolate in ethereal solvents: identification of the HMPA-coordinated aggregate structures

The structures of cyclopentanone lithium enolate under HMPA titration in 0.04-0.8 M diethyl ether and dimethyl ether solvents have been investigated using the low-temperature ⁷Li, ³¹P, and ¹³C NMR. The progressive solvation by HMPA occurs for the tetra- and dimeric enolates, and upon addition of >2 equiv. of HMPA, the lithium enolate has been converged on a mixture of tetra-HMPA coordinated tetramer and bis-HMPA coordinated dimer with the ratio of 5:95 and <1:99 in diethyl ether and dimethyl ether, respectively. Neither monomeric nor trimeric enolate is detectable under such HMPA titration.