The synthesis and reagent properties of tetrakis-(3,5-dichlorophenyl)borate

Cesium tetrakis(3,5-dichlorophenyl)borate shows similar precipitation and gravimetric properties as tetrakis(m-chlorophenyl)- and tetrakis(p-chlorophenyl)borates. Its overall stability is worse than those of the chloro-substituted borates but it is more stable toward acid attack.     

Studies in the tetraarylborates : The preparation and reagent properties of sodium tetrakis(p-chlorophenyl)borate

Sodium tetrakis(p-chlorophenyl)borate was synthesized. It formed precipitates with K⁺, Rb⁺, Cs⁺, quarternary ammonium and protonated basic nitrogen compounds. The potassium salt was more soluble than potassium tetraphenylborate but flocculated more readily and filtered more easily. The salts formed with nitrogen compounds offer possibilities as derivatives suitable for qualitative analysis.     

Tetraarylborate polymer networks as single-ion conducting solid electrolytes

A new family of solid polymer electrolytes based upon anionic tetrakis(phenyl)borate tetrahedral nodes and linear bis-alkyne linkers is reported. Sonogashira polymerizations using tetrakis(4-iodophenyl)borate, tetrakis(4-iodo-2,3,5,6-tetrafluorophenyl)borate and tetrakis(4-bromo-2,3,5,6-tetrafluorophenyl)borate delivered highly cross-linked polymer networks with both 1,4-diethynylbeznene and a tri(ethylene glycol) substituted derivative. Promising initial conductivity metrics have been observed, including high room temperature conductivities (up to 2.7 × 10^–4 S cm^–1), moderate activation energies (0.25–0.28 eV), and high lithium ion transport numbers (up to t _Li⁺ = 0.93). Initial investigations into the effects of important materials parameters such as bulk morphology, porosity, fluorination, and other chemical modification, provide starting design parameters for further development of this new class of solid electrolytes.     

Towards Reversibility of Ion Transfer Across the Interface between Valinomycin Membranes and Aqueous Electrolyte Solutions

Valinomycin-based potassium-selective membranes doped with potassium tetrakis(4-chlorophenyl)borate (KClTPB) or sodium tetrakis(4-fluorophenyl)borate (NaFTPB) are studied in KCl, NaCl, and CaCl₂ solutions by potentiometric and electrochemical impedance methods. Before contact with KCl, membranes doped with NaFTPB provide Nernstian potentiometric response to Na⁺ ions, which is lost after conditioning the membranes in KCl. The membranes doped with KClTPB even before contact with KCl give no Nernstian response to Na⁺ ions. In CaCl₂ solutions, none of the membranes provide a regular potentiometric response. Despite the difference in potentiometric behavior, the impedance spectra of the membranes are very similar in all solutions regardless of prior conditioning of the membranes. No evidence for a hindrance towards charge transfer processes is observed. The results suggest that the membrane/solution interface is reversible for interfering ions as well as for potassium, and the contamination of solutions with the latter is the sole reason for the lack of Nernstian response in the interfering electrolytes.     

Determination of phosphatidylcitoline in serum with use of a choline-sensitive membrane electrode

A choline-sensitive membrane electrode made with potassium tetrakis(p-chlorophenyl) borate as the exchanger and o-nitrophenyl phenyl ether as membrane solvent in poly (vinyl chloride) was almost insensitive to the surfactant sodium deoxycholate. By using this electrode, choline ( 10^?5 M) formed by the enzymatic hydrolysis of phosphatidylcholine with phospholipase D in the presence of sodium deoxycholate as activator was successfully measured. The method was applied to the determination of phosphatidylcholine in serum.     

Studies in the tetraarylborates: Part 8. The synthesis and reagent properties of tetrathienylborates

The following cesium tetrathienylborates were synthesized and screened for gravimetric reagent properties: tetrakis(2-thienyl), tetrakis(3-thienyl), tetrakis(5-bromo-2-thienyl), tetrakis(5-chloro-2-thienyl),tetrakis(2,5-dimethyl-3-thienyl), tetrakis(5-ethyl-2-thienyl), tetrakis(5-methyl-2-thienyl), and tetrakis(5-t-butyl-2-thienyl). Of these, the tetrakis(5- alkyl-2-thienyl) borates were not sufficiently stable for complete characterization. The following are possible reagents for cesium and quaternary ammonium cations: sodium tetrakis(2-thienyl), tetrakis(3-thienyl), and tetrakis(2,5-dimethyl-3-thienyl)borates.     

Studies in the tetraarylborates : Part VII. The preparation and reagent properties of some new nitrogen heterocyclic tetraarylboraees — especially sodium tetrakis(l-imidazolyl) borate,a novel gravimetric reagent for hydrogen ion

Three new tetraarylborates containing nitrogen heterocycles have been synthesized. Sodium tetrakis(1-imidazolyl)borate and sodium tetrakis(1-benzimidazolyl)borate were prepared in very high yield by syntheses which were easy to perform in situ. Interesting analytical properties which are very different from the carbocyclic tetraarylborates were noted in both compounds. Precipitate formation oftetrakis(1-imidazolyl)borate with hydrogen and divalent cations was observed. The feasibility of determination of the hydrogen cation by tetrakis(1-imidazolyl)borate was demonstrated.     

A sodium ion selective optode based on fluorescein octadecyl ether octadecyl ester and application in beverage and urine assay

A fast responsive sodium ion selective fluorescent optode membrane mounted on an optical fiber has been developed. The sensing membrane contained fluorescein octadecyl ether octadecyl ester (FODEE), potassium tetrakis(4-chlorophenyl) borate (KTpClPB) and a calix[4]arene tetraester in a plasticized poly(vinyl chloride) (PVC) matrix. It exhibited a reversible response to Na⁺ in 0.5 mol/l of HCl in the concentration range of 1.0×10⁻⁶ to 0.1 mol/l. The selectivity, response time, reproducibility and lifetime of the optode membrane were discussed. The practical use of this sensor was demonstrated by real sample analysis in complex sample solutions such as beverage and urine samples.     

Synthesis and crystal structure of 4-amino-3-fluorophenylboronic acid

4-Amino-3-fluorophenyl boronic acid has been synthesized from 4-bromo-2-fluoroaniline by protecting the amine group and then carrying out a lithium-bromine exchange, followed by addition of trimethyl borate and then acidic hydrolysis. We obtained a 47% yield. We also measured the X-ray crystal structure. This derivative has a relatively low boronic acid pK_a value of 7.8 when acetylated or attached to acrylamide hydrogels. It also contains a pendant amine which facilitates attachment to polymers, for example. We are using this compound to construct glucose sensing materials that operates at the physiological pH of bodily fluids.     

Activation of hafnocene catalyzed polymerization of 1-hexene with MAO and borate

A study of 1-hexene polymerization with ethylene-bis(9-fluorenyl) hafnium dichloride has been carried out using two different cocatalyst systems, methyl-aluminoxane/trimethylaluminum (MAO/TMA) and tris-isobutyl-aluminum/N,N-dimethylanilinium tetrakis(pentafluorophenyl) borate (TIBA/borate). When MAO/TMA was used, 1-hexene polymerized into a low molar mass poly(1-hexene) with low catalytic activity. Activation with TIBA/borate increased polymerization activity drastically as well as the molar mass of the polymers. In order to analyze differences in the activity profiles, UV-Vis spectroscopy was employed to investigate ligand to metal charge transitions (LMCT) of the hafnocene dichloride during the activation process. The low catalytic activity and the fast chain transfer to the cocatalyst with MAO/TMA may originate from strong bonding between the metallocene cation and the MAO/TMA species thus obstructing monomer coordination and insertion.     

Physicochemical properties of an electroconductive film based on tetrakis(p-aminophenyl)porphine

A strong, optically transparent electroconductive polyporphyrin film is obtained during the electrooxidation of tetrakis(p-aminophenyl)porphine in dichloromethane on the surface of a platinum electrode. Analysis of electronic absorption and IR spectra indicates that tetrakis(p-aminophenyl)porphine is polymerized during electrooxidation via the formation of dihydrophenazine fragments. It is found that the film deposited on the electrode is insoluble in many organic solvents and mineral acids, is thermally stable when heated up to 200°C, and has a homogeneous surface with an even distribution of oligomer globules. It is found through differential scanning calorimetry that the compound deposited on the electrode is a partially crystalline polymer.     

细胞色素c在微-液/液界面上电化学行为的研究

本文采用电化学技术,研究了细胞色素c（Cyt c）在玻璃微米管尖端处形成的微-水/1,2-二氯乙烷（W/DCE）界面上的电化学行为.选用四丁基铵四苯硼（TBAT-PB）、四丁基铵四氯代苯硼（TBATPBCl）以及四丁基铵四氟代苯硼（TBATPBF）三种不同的有机相支持电解质来研究Cyt c在W/DCE界面上的反应.在电势窗较窄的含TBATPB体系中只能够观察到吸附过程;在电势窗较宽的含TBATPBCl和TBATPBF的体系中,可以同时观察到吸附与离子转移过程.当Cyt c浓度较低时,两种过程都可以观察到;当Cyt c浓度较高时,主要是吸附.文中对这些过程的机理进行了探讨.     

Evaluation of the optimum composition of neutral-carrier membrane electrodes with incorporated cation-exchanger sites

Selectivities were measured for membrane electrodes containing a given amount of a neutral carrier (ETH 1692) and varying amounts of the additive potassium tetrakis(p-chlorophenyl)borate. The pronounced selectivity changes induced by the additive agreed with a theoretical model. Both theory and experiment confirmed that an optimum composition of the membrane exists. Ideally, sensors for monovalent cations should contain only small amounts of the additive, whereas sensors for divalent cations should contain a molar ratio of additive/carrier of about 0.7 (for 1:2 cation/carrier complexes). Also described are the new desk-computer programs used for the reduction, evaluation, and graphical presentation of ion-selective electrode data.     

Stepwise determination of quaternary ammonium salts and aromatic amines in pharmaceuticals by ion association titration.

A stepwise titrimetric method has been developed for the simultaneous determination of pharmaceutical quaternary ammonium salts (R4N+) and aromatic amines (R3N). The method is based on the solvent extraction of R4N+ and R3NH+ with an ion association reagent. Sodium tetrakis(4-fluorophenyl)borate and sodium tetraphenylborate were used as titrants and potassium tetrabromophenolphthalein ethyl ester (TBPE) was used as an indicator. The ion associate which formed between R4N+ ion and TBPE made a blue color in 1,2-dichloroethane, while the ion associate formed between R3NH+ and TBPE showed a red-violet one. Sample solutions containing quaternary ammonium and/or amine compounds were titrated with sodium tetrakis(4-fluorophenyl)borate or sodium tetraphenylborate. When one drop of excess titrant was added, the color of the organic phase turned from blue or red-violet to yellow at the equivalence point. On the other hand, in the mixture of R4N+ and R3N, the color changed from blue to red-violet at the first equivalence point, and then its color turned to yellow at the second equivalence point. The quaternary ammonium compound and aromatic amine in pharmaceuticals could be simultaneously and successfully determined by the proposed titration method.     

A PVC-based 1,8-diaminonaphthalen electrode for selective determination of vanadyl ion

A PVC membrane vanadyl (VO²⁺) ion-selective electrode was constructed using 1,8-diaminonaphthalen (DAN) as a neutral carrier. The electrode shows good Nernstian response for VO²⁺ ions over a wide concentration range (1.0×10⁻¹-1.0×10⁻⁵ M). The optimum composition of the membrane was 55 wt.% poly(vinylchloride), 35 wt.% 2-nitrophenyl octyl ether (NPOE), 5 wt.% ionophore, and 5 wt.% potassium tetrakis(p-chlorophenyl)borate (KTpClPB). It has relatively fast response time and can be used at least for 5 weeks without any considerable divergence in potentials. The proposed electrode revealed relatively good selectivity for VO²⁺ over wide variety of other metal ions. The electrode was used for the potentiometric titration of VO²⁺ ions with EDTA.     

Development of a new fluorimetric bulk optode membrane based on 2,5-thiophenylbis(5-tert-butyl-1,3-benzexazole) for nickel(II) ions

A highly sensitive and selective fluorimetric optode membrane for the determination of ultra trace amounts of Ni²⁺ ions was prepared. The plasticized PVC-membrane incorporating potassium tetrakis(p-chlorophenyl)borate (KTpClPB) and 2,5-thiophenylbis(5-tert-butyl-1,3-benzexazole) (TTBB), as a highly fluorescent chromoionophore, displays a calibration response for Ni²⁺ ions over a wide concentration range of 1.0×10⁻³ to 1.0×10⁻⁸ M. It has a relatively fast response of <40 s. In addition to high stability and reproducibility, and relatively long working lifetime, the sensor possesses good selectivity for nickel ions over several common diverse ions. The fluorescence signal of the optode membrane can be easily recovered by immersion in EDTA solution. The optode was applied successfully to the determination of traces of Ni²⁺ ion in edible oil and a wastewater sample from nickel electroplating industries.     

Synthesis, characterization, and complexation of tetraarylborates with aromatic cations and their use in chemical sensors

Five aromatic borate anions, namely tetrakis(4-phenoxyphenyl)borate (1), tetrakis(biphenyl)borate (2), tetrakis(2-naphthyl)borate (3), tetrakis(4-phenylphenol)borate (4), and tetrakis(4-phenoxy)borate (5), have been prepared and tested as ion-recognition sites in chemical sensors for certain aromatic cations and metal ions. To gain further insight into the complexation of the cations, some complexes have been prepared and structurally characterized. The complexation behavior of 1 and 2 towards N-methylpyridinium (6), 1-ethyl-4-(methoxycarbonyl)pyridinium (7), tropylium (8), imidazolium (9), and 1-methylimidazolium (10) cations has been studied, and the stability constants of the complexes of 1 with cations 6 and 8 have been measured to compare them with the values for the previously studied complexes of tetraphenylborate. The structures of the borate anions and their complexes have been characterized by NMR and mass spectrometric methods. X-ray crystal structures have been determined for potassium tetrakis(4-phenoxyphenyl)borate (K(+)1), N-methylpyridinium tetrakis(4-phenoxyphenyl)borate (61), 1-ethyl-4-(methoxycarbonyl)pyridinium tetrakis(4-phenoxyphenyl)borate (71), tropylium tetrakis(4-phenoxyphenyl)borate (81), and imidazolium tetrakis(biphenyl)borate (92). The results show that borate derivatives are potential candidates for a completely new family of charged carriers for use in cation-selective electrodes.     

1-( p -Fluorophenyl)-2-(2′-pyridyl)ethanol and 1-( p -fluorophenyl)-2-(2′-pyridyl)ethene obtained from the condensation reaction of 2-picoline and p -fluorophenylaldehyde under catalyst-and solvent-free conditions

The novel intermediate 1-(p-fluorophenyl)-2-(2′-pyridyl)ethanol or 2-[2′-(1-hydroxy-1-(p-fluorophenyl)ethyl]pyridine and the corresponding novel dehydration compound 1-(p-fluorophenyl)-2-(2′-pyridyl)ethene or 2-[p-fluorophenylvinyl]pyridine were obtained from the condensation reaction of p-fluorophenylaldehyde and 2-picoline under catalyst-and solvent-free conditions. The intermediate 1-(p-fluorophenyl)-2-(2′-pyridyl)ethanol was obtained at 42 h reaction time and temperature of 120°C, respectively. ¹H-NMR, IR spectroscopic data of the 1-(p-fluorophenyl)-2-(2-pyridyl)ethanol clearly showed the presence of the-CH₂-CHOH-group. The compound was obtained as a white powder with m.p. 121–122°C and a yield of 8%. For 1-(p-fluorophenyl)-2-(2-pyridyl)ethene, the reaction conditions were similar, but the reaction temperature was increased to yield the double bond in the 1-(p-fluorophenyl)-2-(2′-pyridyl)ethene. At the reaction temperature of 140°C, the compound was a slightly brown powder with a m.p. of 78°C and yield of 18%. ¹H-NMR, IR spectroscopic data for the 1-(p-fluorophenyl)-2-(2′-pyridyl)ethene showed the presence of a double bond in trans configuration (-CH=CH-), characteristic of a styrylpyridine.     

Microwave-assisted and conventional synthesis of new phthalocyanines containing 4-(p-fluorophenyl)-3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one moieties

New metal-free and metal (Zn, Ni, Cu and Co) phthalocyanines containing 4-(p-fluorophenyl)-3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one moiety have been prepared from 1-(3,4-dicyanophenyl)-4-(p-fluorophenyl)-3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one by both conventional and microwave-assisted methods. All of these compounds are soluble in CHCl₃, DMF and DMSO. The new compounds have been characterized by elemental analysis, IR, NMR, UV-Vis spectroscopies. The crystal structures of compounds I and II were also determined by the single crystal diffraction technique.     

Synthesis and Rearrangement of Mono and Bis-(p-Fluorophenyl)Hydrazones of Dehydro-L-Ascorbic Acid

Abstract

The mono- and bis-(p-fluorophenyl)hydrazones of dehydro-L-ascorbic acid were prepared. Oxidation of the bis(hydrazone) afforded 3,6-anhydro-3-C-(p-fluorophenylazo) L-xylo-2-hexul osono-1,4-1 actone-2-(p-fluorophenyl)hydrazone. Rearrangement of the bis(hydrazone) gave T-(p-fluorophenyl)-3-(L-threo-glycerol-1-yl)-pyrazoli n-4,5-di one-4-(p-fluorophenyl)hydrazone, whose periodate oxidation gave 3-formyl-1-(p-fluorophenyl pyrazol in-4.5-dione-3-4-(p-fluorophenyl)hydrazone that upon reduction gave 1-(p-fluorophenyl)-3-hydroxymethyl pyrazol in-4,5-dione-4-(p-fluorophenyl)hydrazone. The compounds were characterized as their acetates and benzoates.