Study on the equilibria in the ZnBr2(CdBr2)?H2O?C2H5OH Systems at 25°C

The solubility isotherms of the three-component systems: ZnBr₂? H₂O? C₂H₅OH and CdBr₂? H₂O? C₂H₅OH at 25°C have been studied. Crystallization fields of the equilibrium coexistence of the salts ZnBr₂ · 2H₂O, ZnBr₂, CdBr₂ · 4H₂O, CdBr₂ and CdBr₂ · 1.5 C₂H₅OH in water-ethanol solvent have been found. The dehydration processes of crystalline hydrates and the probable solvation of Zn²⁺ and Cd²⁺ ions in the saturated solutions have been discussed.     

Selective synthesis of (E)-triethyl(2-arylethenyl)silane derivatives by reaction of aryl bromides with triethyl vinylsilane catalysed by a palladium-tetraphosphine complex

Cis, cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane / 0.5 [PdCl(C₃H₅)]₂ system catalyses the Heck reaction of vinylsilane derivatives with a range of aryl bromides with high ratio substrate/catalyst in good yields. The formation of mixtures of styrene, (E)-triethyl(2-arylethenyl)silane and triethyl(1-arylethenyl)silane derivatives was observed in some cases. Very high selectivities (up to 100%) in favour of the formation of (E)-triethyl(2-arylethenyl)silane derivatives were obtained in the presence of sodium acetate as base. With other bases such as potassium carbonate, the formation of large amounts of styrene derivatives was observed. The reaction tolerates several functions such as fluoro, trifluoromethyl, methoxy, dimethylamino, acetyl, formyl, benzoyl, carboxylate, nitro or nitrile. Moreover, turnover numbers up to 10,000 can be obtained for this reaction.     

Darstellung und Eigenschaften von Organoindiumbromiden

Synthesis and Properties of Organoindium Bromides i-Pr₃In gives with InBr₃ (molar ratio 2:1, toluene, 50°C) i-Pr₂InBr ( 1 ) and (molar ratio 1:2, toluene, 80°C) i-PrInBr₂ ( 2 ). The corresponding reaction of (PhCH₂)₃In and InBr₃ (2:1) gives (PhCH₂)₂InBr ( 3 ), while PhCH₂InBr₂ could be isolated only as ether adduct [PhCH₂InBr₂(OEt₂)_n] ( 4 ). With DME/MeCN and 2 and 4 with THF, respectively, yields the solvate complexes [InBr₃(DME)(MeCN)] ( 5 ), [i-PrInBr₂(THF)₂] ( 6 ) and [PhCH₂InBr₂(THF)₂] ( 7 ). The compounds 1–7 were investigated with NMR-, IR- and MS-techniques. Pyrolysis of the raw material of i-Pr₃In, which contains “MgBrCl” and additional treatment with Et₂O yields the salt [Mg₃Cl_4,65Br_0,35(Et₂O)₆][i-PrInBr_2,7Cl_0,3] ( 8 ). The cation, a trinuclear magnesium complex, possesses local D_3h-symmetric of the Mg₃X₅ backbone (X = Cl, Br).     

Properties of two polymerisable surfactants aqueous solutions: dodecylethylmethacrylatedimethylammonium bromide and hexadecylethylmethacrylatedimethylammonium bromide. II. Partial molar volume and micelle hydration

The partial molar volume and hydration number of two micellised polymerisable surfactants (dodecylethylmethacrylatedimethylammonium bromide (C₁₂PS) and hexadecylethylmethacrylatedimethylammonium bromide (C₁₆PS)) were determined. Results support marginally the annular conformation of the polar head group (N⁺(CH₃)₂-CH₂-CH₂-O-CO-C(CH₃)(=CH₂)) proposed in the literature.     

N-Heterocyclic carbene adducts of cyclopalladated ferrocenylimines: Synthesis,characterization and catalytic activity for the Suzuki–Miyaura reaction

A series of novel air-stable carbene adducts of cyclopalladated ferrocenylimines have been synthesized and characterized. The structures of these complexes were determined by single-crystal X-ray analysis. These adducts have been successfully applied to the Suzuki–Miyaura coupling reaction under aerobic conditions. Good to excellent yields were obtained in short reaction times with a lower loading of the catalyst.     

Rapid, easy copper-free Sonogashira couplings using aryl iodides and activated aryl bromides

We present here an easy, rapid copper-free methodology for the Sonogashira coupling reaction. It works well for a range of aryl iodides and activated aryl bromides.     

Estimated ionicB-coefficients from NMR measurements in aqueous electrolyte solutions

¹⁷O-NMR spin-lattice relaxation timesT ₁ of D₂O molecules were measured at 5–85°C in D₂O solutions of alkali metal halides (LiClCsCl, KBr, and KI), DCl, KOD, Ph₄PCl, NaPh₄B, and tetraalkylammonium bromides (Me₄NBrAm₄NBr) in the concentration range 0.1–1.4 mol-kg^–1 TheB-coefficients of the electrolytes obtained from the concentration dependence of relaxation ratesR ₁=1/T₁ were divided into the ionicB-coefficients by three methods: (i) the assumption ofB (K⁺)=B(Cl^–), (ii) the assumption ofB(Ph₄P⁺)=B(Ph₄B^–), and (iii) the use ofB(Br^–) obtained from a series ofB(R₄NBr). It was found that Methods (ii) and (iii) resulted in an abnormal temperature dependence of theB-coefficients of alkali metal ions and a negative values of rotational correlation times _c at lower temperatures for hydroxide and halide ions. These results suggest that the methods based on the van der Waals volume are not adequate for the ionic separation of NMRB-coefficients. From the analysis using the assumption ofB(K⁺)=B(Cl^–), it was found that D₃O⁺, OD^–, and Me₄N⁺ ions are the intermediates between structure makers and breakers, and that the hydrophobicity of phenyl groups is weaker than that of alkyl groups due to the interactions between water molecules and -electrons in phenyl groups.     

Copper-free PdCl2/PPh3-catalyzed Sonogashira coupling reaction of aryl bromides with terminal alkynes in water

A simple, copper-free and efficient catalytic system for the Sonogashira coupling reaction of aryl bromides with terminal alkynes in pure water has been developed. The use of PdCl₂/PPh₃ in the presence of pyrrolidine allows the coupling reaction to proceed at 120 °C in moderate to excellent yields.     

Reaction of aryl di-, tri-, or tetrabromides with arylboronic acids or alkenes in the presence of a palladium-tetraphosphine catalyst

cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C₃H₅)]₂ system catalyses the Suzuki and Heck reactions of aryl di-, tri-, or tetrabromides with a range of arylboronic acids or alkenes with moderate to high ratio substrate/catalyst in good yields. Aryl polybromides such as dibromobenzenes, 1,3,5-tribromobenzene, 1,2,4,5-tetrabromobenzene, dibromopyridines or a dibromothiophene have been successfully used. Convenient synthesis of a variety of di- and triarylated or vinylated compounds and even a 1,2,4,5-tetraarylated compound were prepared by use of this reaction.     

Influence of additives on the clouding behavior of amphiphilic drug solutions

The present work focuses on the clouding phenomenon in an amphiphilic drug [amitriptyline (AMT), which is a tricyclic antidepressant] solution. A 50-mM AMT solution prepared in 10 mM of sodium phosphate (SP) buffer was taken where the cloud point (CP) was found to decrease with increasing pH. The same CP decreasing trend (with pH increase) followed in the presence of a fixed concentration (50 mM) of added salts [NaBr, and tetra-n-butylammonium bromide (TBuAB)]. The addition of increasing amounts of quaternary bromides (tetramethylammonium bromide, tetraethylammonium bromide, tetra-n-propylammonium bromide, TBuAB, and tetra-n-pentylammonium bromide) to 50 mM of AMT solution (prepared in 10 mM of SP buffer) caused continuous increase in CP, which was found to be dependent upon the alkyl chain length of that particular salt. The similar type of CP increase was also observed in the presence of conventional (cetyltrimethylammonium bromide and tetradecyltrimethylammonium bromide) and gemini surfactants [bis(hexadecyldimethylammonium)hexane, bis(hexadecyldimethylammonium)pentane, and bis(hexadecyldimethylammonium)butane]. The overall behavior was discussed in terms of electrostatic interactions, micellar growth, and mixed micelle formation.