Reaction of esters,ortho esters,acetals, thioacetals and epoxides with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (Lawesson reagent)

2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide,LR, reacted with ethyl formate, triethoxymethane, 1,1,1-triethoxyethane and tetraethoxymethane to give2a and3. 1,1-diethoxymethylbenzene when treated withLR produced2a,3,7,8, and9b. Triethoxymethylbenzene when heated withLR gave2a,8 and11. The reaction of benzyl formate, tris(benzyloxy)methane and 1,1-dibenzyloxy-N,N-dimethylmethanamine withLR afforded2b. Bis(methylthio)methane, tris(ethylthio)methane and 1,1-bis(butylthio)ethane withLR gave9. 1,1-Bis(2,2-dimethylpropoxy)-N,N-dimethylmethanamine withLR yielded2c and17. The reaction of 1,2-epoxyethylbenzene withLR gave20, while 1,2-epoxypropane or 1,2-epoxybutane withLR afforded23 a,b.

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Reaktionen von Estern, Orthoestern, Acetalen, Thioacetalen und Epoxiden mit 2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetan-2,4-disulfid (Lawesson Reagens)

Zusammenfassung Lawesson-Reagens (LR) reagiert mit einer Vielzahl von Verbindungen zu entsprechenden Derivaten. Es wurden folgende Reaktionspartner fürLR eingesetzt: Ethylformiat, Triethoxymethan, 1,1,1-Triethoxyethan, Tetraethoxymethan, 1,1-Diethoxymethylbenzol, Triethoxymethylbenzol, Benzylformiat, Tris(benzyloxy)methan, 1,1-Dibenzyloxy-N,N-dimethylmethanamin, Bis(methylthio)methan, Tris(ethylthio)methan, 1,1-Bis(butylthio)ethan, 1,1-Bis(2,2-dimethylpropoxy)-N,N-dimethylmethanamin, 1,2-epoxyethylbenzol, 1,2-epoxypropan und 1,2-Epoxybutan. Die entstandenen Produkte wurden mittels MS und¹³C- bzw.¹H-Spektroskopie charakterisiert.

     

Synthesis of Mixed Thiuram Disulfides

Abstract

Tris(aminomethyl)phosphines and their oxides form triacidic salts that, unlike the free bases, are air-stable and non-hygroscopic. The salts of the unsubstituted compounds, (NH₃ ⁺CH₂)₃ P(O)_n 3X^?(3b: n = O, X = Br; 4a-c: n = 1, X = Cl, Br, or I), may be prepared directly from 1,3,5-triaza-7-phosphaadamantane (1) or its oxide (2) or from tris(N-carbomethoxylaminomethyl)phosphine oxide (9) by hydrolysis with the appropriate acid. The behaviour of the compounds towards acids and nucleophilic reagents is discussed.     

Enantioselective fluorescent recognition of mandelate by substituted BINOL in aqueous solutions

The fluorescent photo-induced electron transfer chemosensors (R)-1, (R)-2, (S)-1 and (S)-2 based on the 3,3′-positions of 1,1′-bi-2-naphthol were designed for their recognition of mandelate. The binding properties for mandelate were examined by the fluorescence spectra. The high fluorescence sensitivity and enantioselectivity make compound (R)-2 a practically useful sensor for the recognition of mandelate in CH₃OH/H₂O system (1:1, 0.01 M Tris–HCl buffer, pH 7.4).     

Beiträge zur Chemie der Kohlensäurederivate, 3. Mitt.: Neue Synthesen von Tris(trimethylsilyl) cyanurat,N-Chlorsulfinylimid und Chlorcyan

Tris(trimethylsilyl)cyanurate (I) has been prepared in high yields by silylation of cyanuric acid with trimethylsilyl cyanide, as well as by the reaction of trichloroisocyanuric acid with trimethylsilyl cyanide or trimethylsilylsulfinylimide. The latter reactions, yielding Cl–CN and Cl–NSO resp. as the only by-products, are convenient methods for synthesizing these pseudohalogen-chloride compounds in a very pure state. Starting fromN-chlorocarbonyl isocyanateI is formed in high yields by a complex reaction with trimethylsilylsulfinylimide too. Based on IR, Raman and¹H-NMR data the O-silyl structure ofI was confirmed. The formation of products with N-silyl or N,O-silyl structure was never observed.

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2. Mitt.:E. Nachbaur, Mh. Chem.97, 361 (1966).     

PEG-400 mediated an efficient eco-friendly synthesis of new isoxazolyl pyrido[2,3-d]pyrimidines and their anti-inflammatory and analgesic activity

Abstract

Polyethylene glycol-400 (PEG-400) has been developed as an efficient and eco-friendly reaction medium for the synthesis of new isoxazolyl pyrido[2,3-d]pyrimidine derivatives 11 from isoxazolyl cyanoacetamide synthon 7. Compound 7 was employed with various aromatic aldehydes 8 and malononitrile 9 in the presence of triethylamine (Et₃N) to afford the corresponding (E)-6-amino-1-(3-methyl-5-styrylisoxazol-4-yl)-2-oxo-4-phenyl-1,2-dihydro- pyridine-3,5-dicarbonitrile 10 at room temperature by using PEG-400 as a solvent medium as well as catalyst. The intermediate 10 on treatment with thiourea in the presence of PEG-400 at 90?°C to give the target compounds isoxazolyl pyrido[2,3-d]pyrimidines 11 in good to excellent yields. The newly synthesized compounds 10 and 11 were characterized by IR, ¹H NMR, ¹³C NMR, and HRMS analysis. The target compounds 11a-x was screened for their anti-inflammatory and analgesic activities. Among the tested compounds, the compounds 11s, 11t, 11u, 11v, 11w, and 11x showed significant anti-inflammatory and potent analgesic activities as that of reference drugs. The advantages of this protocol are operational simplicity, catalyst free, environmental safety, wide substrate scope, good yields, and PEG-400 can be recovered and reused. Most significant of all, this protocol is green.     

Modellrechnungen zu den Schwingungsspektren von Tris(trimethylsilyl)phosphan und Tris(triphenylsilyl)phosphan

The vibrational spectra of Tris(trimethylsilyl)phosphane-d ₀ and -d ₂₇ as well as Tris(triphenylsilyl)phosphane are reported and assigned. A normal coordinate analysis has been performed. The resulting SiP valence force constants (190 and 200 N/m) are compared with the force constants of other silylphosphanes.

     

Synthesis of Novel Thioethers and Sulfoxide Compounds

Abstract

Thiosubstituted butadiene and butenyne compounds were synthesized from the reactions of 1,1,3,3,4,4-hexachloro-1-butene or 1,1,2,4,4-pentachlorobuta-1,3-diene with different thiols in EtOH/H₂O solution of NaOH. Tris(thio)substituted butadiene compound was treated with potassium tert-butoxide to obtain tris(thio)substituted butatrienyl halide compound. The novel sulfoxide compounds were synthesized from the reactions of polyhalobutadiene compounds with aliphatic thiols in CHCl₃ with m-CPBA at 0°C. The structures of the novel compounds were characterized by micro analysis, FT-IR, ¹H-NMR, ¹³C-NMR, and MS.     

Experimental study on the optimization of general conditions for a free‐flow electrophoresis device with a thermoelectric cooler†

With a given free‐flow electrophoresis device, reasonable conditions (electric field strength, carrier buffer conductivity, and flow rate) are crucial for an optimized separation. However, there has been no experimental study on how to choose reasonable general conditions for a free‐flow electrophoresis device with a thermoelectric cooler in view of Joule heat generation. Herein, comparative experiments were carried out to propose the selection procedure of general conditions in this study. The experimental results demonstrated that appropriate conditions were (i) <67 V/cm electric field strength; (ii) lower than 1.3 mS/cm carrier buffer conductivity (Tris‐HCl: 20 mM Tris was titrated by HCl to pH 8.0); and (iii) higher than 3.6 mL/min carrier buffer flow rate. Furthermore, under inappropriate conditions (e.g. 400 V voltage and 40 mM Tris‐HCl carrier buffer), the free‐flow electrophoresis separation would be destroyed by bubbles caused by more Joule heating. Additionally, a series of applications under the appropriate conditions were performed with samples of model dyes, proteins (bovine serum albumin, myoglobin, and cytochrome c), and cells (Escherichia coli, Streptococcus thermophilus, and Saccharomyces cerevisiae). The separation results showed that under the appropriate conditions, separation efficiency was obviously better than that in the previous experiments with randomly or empirically selected conditions.     

Reactions of Tris(diethylamino)phosphine with Some Quinones

Abstract

Tris(diethylamino)phosphine reacts with chloranil and 2,3-dichloro-4,5-dicyanoquinone to give products of addition to carbon with loss of chloride ion.     

Study on Chemiluminescence Assay of Surfactant PEG-400 Using Luminol–Hydrogen Peroxide System

Abstract

Based on the fact that nonionic surfactant polyethylene glycol-400 (PEG-400) catalyzed the chemiluminescence of luminol-H₂O₂ system, a novel and simple chemiluminescence method has been developed for the determination of PEG-400. Under the optimal conditions, the standard curve was Y = 198835X–2091.8, where the correlation coefficient (R) was 0.9999. The detection limit was 4 × 10^?5 g·ml^?1 PEG-400 and the linear range was 1.0 × 10^?4–4.0 × 10^?2g·ml^?1. The relative standard deviation was 3.2% at 2.0 × 10^?3 g·ml^?1 PEG-400 (n = 7). This method has been applied to the determination of PEG-400 in cosmetic samples with satisfactory results. Furthermore, the dynamics characteristic curve of PEG-400 in luminol-H₂O₂ system was compared to typical metallic ion and other surfactants. Moreover, the mechanism of the luminol-H₂O₂-PEG-400 chemiluminescence system was studied, assisted by fluorescence spectra and UV spectra.     

Synthesis,spectroscopic characterization,and X-ray crystal structure of tris(trimethylsilyl)cyanurate

Tris(trimethylsilyl)cyanurate, C₁₂H₂₇N₃O₃Si₃ (1), has been synthesized and characterized by elemental analysis, IR, Raman, ¹³C and ²⁹Si NMR, and thermogravimetric methods. The molecular and crystal structure has been determined by single crystal X-ray diffraction. This compound crystallized in space group P6₃/m (176), Z = 2 with a = 11.017(2), b = 11.017(2), c = 9.676(3) Å; α = 90°, β = 90°, γ = 120°. The geometry of the molecule is compared with tris(trimethylsilyl)cyamelurate.     

Cis- undtrans-α,β-dialkylsubstituierte Phenylazo-alkene

Zusammenfassung Bei der Umsetzung aliphatischer Keto-phenylhydrazone (1) mit J₂ in Pyridin wird ein H-Atom einer -ständigen Methyloder Methylengruppe durch den Pyridinium-Substituenten ersetzt, so daß die -Phenylhydrazonoalkyl-pyridiniumjodide2 bzw.3 entstehen. Aus3 werden durch Alkalieinwirkung unter 1,4-Eliminierung von Pyridin·HJ die orangefarbenen s-trans-(E, E)-Phenylazo-alkene5 und—in der offenkettigen Reihe—die s-trans(E,Z)-Phenylazo-alkene6 erhalten. Die Strukturen von5 und6 werden durch spektroskopische Daten (EA,¹H-NMR) gestützt.

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Cis- and trans-,-dialkylated Phenylazo-alkenes

Phenylhydrazones of aliphatic ketones1 react with I₂ in pyridine replacing one hydrogen atom of a methyl or methylene group at the -position of the functional group by the N-pyridinium substituent to give1-(2-phenylhydrazonoalkyl)-pyridinium iodides2 and3 respectively. Upon alkali induced 1.4-elimination of pyridine·HI from3 the orange s-trans(E, E)-phenylazo-alkenes5 and—in the acyclic series—s-trans(E,Z)-phenylazo-alkenes6 are obtained. Their structures are derived from their spectroscopic properties (ea and¹H-nmr).

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Oxidationsprodukte von Arylhydrazon-Verbindungen, 7. Mitt. (6. Mitt.)     

Synthesis,structure, and DNA-binding properties of manganese(II) and zinc(II) complexes with tris(<Emphasis Type="Italic">N</Emphasis>-methylbenzimidazol-2-ylmethyl)amine ligand

Tris(N-methylbenzimidazol-2-ylmethyl)amine (Mentb) and its two complexes, [Mn(Mentb)(DMF)(H₂O)](pic)₂ 1 and [Zn(Mentb)(pic)](pic) 2 (pic = picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single crystal X-ray diffraction revealed that the two complexes have different structures. In complex 1, the coordination sphere around Mn(II) is distorted octahedral, whereas in complex 2 the coordination sphere around Zn(II) is distorted trigonal bipyramidal. The DNA-binding properties of the free ligand and its two complexes have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that the ligand and its two complexes bind to DNA via an intercalation binding mode, and their binding affinity for DNA follows the order 1 > 2 > ligand.     

Correlation between Thermodynamic Behavior and Structure in the Complexation of Modified β-Cyclodextrins and Bile Salts

Complex stability constants (K _S), standard molar enthalpy changes (ΔH ⁰) and entropy changes (ΔS ⁰) for the inclusion complexation of two cyclodextrin dimers, 6,6′-{2,2′-diselenobis[2-(benzoylamino)ethylamino]}-bridged bis(β-cyclodextrin) (1) and o-phenylenediseleno bridged bis(β-cyclodextrin)s (3), and their monomer analogs, 6-deoxy-6-{[2-(2,3-dihydro-3-oxo-1,2-benzisoselenazol-2-yl)ethyl]amino}-β-cyclodextrin (2) and mono[6-(phenylseleno)-6-deoxy]-β-cyclodextrin (4), with two bile salt guests, sodium cholate (CA) and sodium deoxycholate (DCA), were determined at 25°C in Tris buffer solutions (pH 7.4) at 298.15?K by means of isothermal titration microcalorimetry (ITC). The interactions and binding modes between the host cyclodextrins and the guest bile salts were further studied by ROESY spectroscopy. The thermodynamic parameters obtained, together with the ROESY spectra, were used to examine the correlations between thermodynamic behavior and binding modes of the host–guest complexation. The results indicate that the length, structure and conformation of the tethers linked to the cyclodextrins determine the binding modes and the binding abilities between hosts and guests to a great extent, leading to a reversion in binding ability when comparing the corresponding dimer and its monomer analog.     

Rhodamine-linked pyridyl thiourea as a receptor for selective recognition of F–, Al3+ and Ag+ under different conditions

A new rhodamine-labelled pyridyl thiourea-based compound 1 has been designed and synthesised. While the receptor selectively recognises F^– and Al³⁺ ions in CH₃CN, Al³⁺ and Ag⁺ ions are selectively screened from other cations in CH₃CN/water (4/1, v/v; 10 μM Tris–HCl buffer, pH 6.8) by observing different emission characteristics and colour changes. While Ag⁺ is sensed through an increase in emission at 416 nm, Al³⁺ is detected by a ratiometric change in emission of 1 with a band at 585 nm. The receptor shows in vitro detection of both the ions in human cervical cancer (HeLa) cells.     

Extraction Properties of Oligodentate Carbamoylmethylphosphine Oxides and β-Aminophosphine Oxides Toward Lanthanides and Rhenium(VII)

Abstract

The extraction properties of a series of carbamoylmethylphosphine oxides and β-aminophosphine oxides with lanthanide metal ions is presented. Tris[bis(2-diphenyl- phosphorylethyl)-aminoethyl]amine is shown to be highly effective for extraction of Re(VII).     

Oxidative Dissolution of Silver Nanoparticles by Dioxygen: A Kinetic and Mechanistic Study

We have recently reported a kinetic and mechanistic study on oxidative dissolution of silver nanoparticles (AgNPs) by H₂O₂. In the present study, the parameters that govern the dissolution of AgNPs by O₂ were revealed by using UV/Vis spectrophotometry. Under the same reaction conditions (Tris‐HOAc, pH 8.5, I=0.1 M at 25 °C) the apparent dissolution rate (k_app) of AgNPs (10±2.8 nm) by O₂ is about 100‐fold slower than that of H₂O₂. The reaction rate is first‐order with respect to [Ag⁰], [O₂], and [Tris]_T, and inverse first‐order with respect to [Ag⁺] (where [Ag⁰]=total concentration of Ag metal and [Tris]_T=total concentration of Tris). The rate constant is dependent on the size of AgNPs. No free superoxide (O₂⁻) and hydroxyl radical (⋅OH) were detected by trapping experiments. On the basis of kinetic and trapping experiments, an amine‐activated pathway for the oxidation of AgNPs by O₂ is proposed.     

Separation of the Proteins of Locust Neurosecretory Endings with HPLC

Abstract

High performance liquid chromatography on gel permeation columns was use to analyse the protein and peptide content of the neurosecretory corpora cardiaca of the locust (Locusta migratoria). A variety of extraction conditions and mobile phase compositions were tested for their separation efficiency.

A good resolution, showing 12 peaks distributed within 5 distinct groups, could be achieved in 32 min with the fresh homogenate from only two corpora cardiaca (0.5 M Tris buffer, 0.3 NaCl, 0.1 % SDS, pH = 7.4; flow rate: 0.5 ml/min). Similar HPLC patterns were obtained with three fractions previously separated on a Sephadex G-100 column as well as with isolated neurosecretory vesicles.

HPLC then appears as a promising technique in the field of insect neurohormone isolation.     

Supramolecular isomerism of Cu(I) and 3,5-di-2-pyridyl-1,2,4-triazolate via in situ solvothermal ligand reaction: meso-helix and luminescence

The sixth supramolecular isomer of Cu(I) and 3,5-di-2-pyridyl-1,2,4-triazolate (2-pytz), [Cu₂(2-pytz)₂] _n (1), via in situ solvothermal ligand reaction, has been synthesized and characterized as a rare meso-helical chain. Complex 1 exhibits high thermal stability (until 400°C) confirmed by thermogravimetric analysis and has potential applications as an optical material. This research makes the maximum number of genuine supramolecular isomers with structural characterization, found for coordination polymers, six.     

Viscosity Molecular Weight Determination of Polyadenylic Acid

Abstract

In this study viscosity measurements of polyadenylic acid (PolyA) in aqueous solution were carried out under different conditions. In the absence of any additives, the polymer degraded during flow through the capillary of a viscometer or when standing still. Degradation during the former was more severe. The degradation of polyadenylic acid can be prevented by addition of an electrolyte such as KCl to increase the ionic strength. However, in this case the deviation from linearity was still considerable at most ionic strength values. The best fit to the Huggins and Kraemer equations was obtained using a Tris–EDTA buffer solution with a final pH of 7.65. Estimation from intrinsic viscosity and weight-average molecular weight values gave k and α as 2.04 × 10^?5 and 0.89 from the equation η = kM ^α. The difference between Huggins (k ₁) and Kraemer (k ₁′) constants was close to 0.50 for all measurements.