Dimethylammonium Salt Research Articles

Remarkable Influence of Structures around Rhenium (V) Centers Constructed in Polyoxotungstates for Methanol Dehydrogenation under Visible Light Irradiation

The synthesis and characterization of 1-Dawson-type mono-rhenium (V)-substituted polyoxotungstate, [1-P2W17ReO62] (1), are described. The dimethylammonium salt of 1, [Me2NH2]7[1-P2W17ReO62]·9H2O (Me2NH2-1), was obtained as analytically pure homogeneous black-blue crystals by reacting mono-lacunary 1-Dawson polyoxotungstate with [ReCl6] in CH3COOH/CH3COOLi buffer, followed by crystallization via a vapor diffusion from acetonitrile/ethanol. Characterization was also accomplished by X-ray crystallography, elemental analysis, TG/DTA, FTIR, UV-vis, and solution P NMR spectroscopy; these results showed that the polyoxoanion 1 was a monomeric -Dawson structure, in which the rhenium(V) ion was coordinated to the monovacant site of [1-LiP2W17O61], resulting in an overall C1 symmetry. The polyoxoanion 1, [O{Re(OH)(2-P2W17O61)}2] (2), and [-PW11ReO40] (3) showed the Original Research Article British Journal of Applied Science & Technology, 4(16): 2302-2319, 2014 2303 hydrogen evolution from methanol under visible light irradiation (400nm) in the presence of titanium dioxide. The activities were remarkably depended on the rhenium (V) sites in 1–3; polyoxoanion 2 possessing the dirhenium(V)-oxido-bridged site showed the highest activities among these complexes.

English

Azidation of benzonitrile with dimethylammonium azide yielding 5-phenyltetrazole dimethylammonium salt was performed under microreactor conditions. The kinetics of azidation of benzonitrile in DMF was investigated at the range 80–95 °С. The reaction rate constants were determined: k II ·10 4 (L mol –1 s –1 ): 0.79, 0.97, 1.19, 1.51, at 80, 85, 90, and 95 °С, respectively. It was found that the reaction rate constants obtained in a microreactor are comparable to ones for a batch-type reactor. The thermodynamic parameters of azidation under the microreactor conditions correspond to the mechanism of the 1,3-dipolar cycloaddition of azides to nitriles. It was established that the excessive pressure in the microreactor notably accelerates the process. The alkylation of 5-phenyltetrazole with methyl iodide in microreactor was performed in dichloromethane-aqueous so dium hydroxide system. The accumulation of regioisomers of N1- and N2-met hyl-5-phenyl tetrazole in the microreactor under the conditions of slug flow of the reaction mixture occurs considerably faster than in the batch-type reactor in the conditions of phase-transfer catalysis.

Crystal packing of ammonium salts of arylenebis(phenylphosphinic) acids

It was shown for the first time that the crystal packing mode of the ammonium salt of thiophene-2,5-diylbis(phenylphosphinic acid) substantially differs from that of the dimethyl-ammonium salt of 1,4-phenylenebis(phenylphosphinic acid). The former crystal packing is a three-layer supramolecular sandwich structure consisting of two anionic layers separated by a layer of ammonium cations, whereas the supramolecular organization of the latter salt is based on alternating layers of anions and cations linked by hydrogen bonds.

Tartaric acid and its O-acyl derivatives. 7. Crystal structure of O-p-anisoyl-D-tartaric acid and its dimethylammonium salt trihydrate

Monoacylated derivatives O-p-anisoyl-d-tartaric acid and its N,N-dimethylammonium salt are synthesized by the partial hydrolysis of O,O′-di-p-anisoyl-d-tartaric acid. Crystal and molecular structures of both compounds have been determined and analyzed. In both of them, some strong and moderate strength [O-H…O] hydrogen bonds exist between the carboxylic units. The intermolecular hydrogen bonds link the adjacent fragments forming infinite one-dimensional chains parallel to the X-axis.

ChemInform Abstract: A Direct and Efficient Preparation of 1‐Phenyltetrazol‐5‐yl Sulfides from Alcohols.

AbstractThe reaction of primary and secondary alcohols with thiol (I) proceeds in the presence of ethylsulfanylmethylene dimethylammonium salt and imidazole.

ChemInform Abstract: Chemistry and Biology of Plant Leaf Movements

The leaves of Mimosa pudica L. are well known for their rapid movement when touched. Recently, we were able to isolate an excitatory substance in small quantities from this plant, which consists of three different components (potassium L-malate, magnesium trans-aconitate, and dimethylammonium salt). Many plants close their leaves in the evening, as if to sleep, and open them early in the morning (nyctinastic leaf movement). This circadian rhythm is known to be controlled by the biological clock of such plants. Extensive studies on other nyctinastic plants led to the isolation of a variety of leaf-opening substances (LOSs) and leaf-closing substances (LCSs). Based on our experiments on these bioactive substances, we found that the circadian rhythmic leaf movement of these plants is initiated by the regulated balance of LOSs and LCSs. The balance of concentration between the two leaf-movement factors (LMFs) is inversed during the day. The glycoside-type LMF is hydrolyzed with β-glucosidase, the activity of which is regulated by the biological clock. The circadian rhythm observed in the leaf movement is introduced by activation of β-glucosidase regulated by the biological clock.

EDTA-Reduction of Water to Molecular Hydrogen Catalyzed by Visible-Light-Response TiO2-Based Materials Sensitized by Dawson- and Keggin-Type Rhenium(V)-Containing Polyoxotungstates

The synthesis and characterization of a Keggin-type mono-rhenium(V)- substituted polyoxotungstate are described. The dimethylammonium salt [Me2NH2]4[PW11ReVO40] was obtained as analytically pure homogeneous black-purple crystals by reacting mono-lacunary Keggin polyoxotungstate with [ReIVCl6]2- in water, followed by crystallization from acetone at ca. 5 °C. Single-crystal X-ray structural analysis of [PW11ReVO40]4- revealed a monomeric structure with overall Td symmetry. Characterization of [Me2NH2]4[PW11ReVO40] was also accomplished by elemental analysis, magnetic susceptibility, TG/DTA, FTIR, UV-vis, diffuse reflectance (DR) UV-vis, and solution 31P-NMR spectroscopy. Furthermore, [PW11ReVO40]4- and the Dawson-type dirhenium(V)-oxido-bridged polyoxotungstate [O{ReV(OH)(α2-P2W17O61)}2]14- were supported onto anatase TiO2 surface by the precipitation methods using CsCl and Pt(NH3)4Cl2. With these materials, hydrogen evolution from water in the presence of EDTA·2Na (ethylenediamine tetraacetic acid disodium salt) under visible light irradiation (≥400 nm) was achieved.

Synthesis and structural investigation of sandwich polyoxotungstates containing cerium (III/IV) and mono-lacunary Keggin tungstophosphate units

The two isostructural anions, [Ce III(α-PW 11O 39) 2] 11− and [Ce IV(α-PW 11O 39) 2] 10−, both composed of Ce III/IV sandwiched by two mono-lacunary Keggin units [α-PW 11O 39] 7−, were isolated as dimethylammonium salts and structurally characterized by single-crystal X-ray diffraction analysis. The structures of the [Ce III/IV(α-PW 11O 39) 2] 11−/10− anions exhibit two enantiomers d- and l-forms due to C 2 (2) symmetry from the square-antiprismatic coordination of the central Ce III/IVO 8 polyhedron. The Ce III compound crystallizes in achiral space group P2 1/ n, while the Ce IV analog in chiral space group P2 1 shows spontaneous resolution without any chiral auxiliaries. The correlation between the ionic radius of the central metal (M) and twist angle of the two mono-lacunary units was studied for a series of [M(α-PW 11O 39) 2] n − (M = Ce III/IV, Eu III, Zr IV, Hf IV) anions and explained in terms of steric repulsion between the O atoms in the mono-lacunary units.

Relation among the 2:2-, 1:1- and 1:2-type complexes of hafnium(IV)/zirconium(IV) with mono-lacunary α 2-Dawson polyoxometalate ligands: Synthesis and structure of the 2:2-type complexes [{α 2-P 2W 17O 61M(μ-OH)(H 2O)} 2] 14− (M = Hf, Zr)

The synthesis and characterization of di-nuclear Hf IV and Zr IV complexes (the Dawson 2:2-type complexes) sandwiched between 2 mono-lacunary α 2-Dawson polyoxometalate (POM) ligands, i.e., (Me 2NH 2) 14[{α 2-P 2W 17O 61Hf(μ-OH)(H 2O)} 2]·17H 2O (Me 2NH 2- 1) and (Me 2NH 2) 14[{α 2-P 2W 17O 61Zr(μ-OH)(H 2O)} 2]·16H 2O (Me 2NH 2- 2) are described. [ Note: the moieties of their polyoxoanions are abbreviated simply as 1 and 2, respectively.] A pair of Hf IV- and Zr IV-containing POMs belonging to the same family were herein isolated as dimethylammonium salts and were unambiguously characterized by complete elemental analysis, in addition to potassium analysis, TG/DTA, FTIR, single-crystal X-ray structure analysis, and solid-state ( 31P CPMAS) and solution ( 31P and 183W) NMR spectroscopy. Polyoxoanions 1 and 2 were isostructural with each other. The central [M 2(μ-OH) 2(H 2O) 2] 6+ (M = Hf, Zr) cation unit was composed of 2 polyhedral M units, which were linked through 2 μ-OH groups and contained 1 water molecule coordinated to each metal center. Since the mono-lacunary Dawson POM acts as an oxygen-donor quadridentate ligand, the Hf and Zr centers are 7-coordinate. The Dawson 2:2-type complexes were converted to the Dawson 1:2-type complexes [M(α 2-P 2W 17O 61) 2] 16− (M = Hf, Zr), or vice versa, in solution under appropriate conditions. Also, the Dawson 2:2-type complex can be reversibly converted to the 1:1-type complex under the pH-dependent conditions. The Dawson 2:2-type POMs 1 and 2 can be compared with the recently reported, Keggin 2:2-type POMs, i.e., [M 2(μ-OH) 2(H 2O) 2] 6+ (M = Hf, Zr) complexes sandwiched between 2 mono-lacunary α-Keggin POM ligands.

Tetra-hafnium(IV) cluster cation sandwiched between 2 di-lacunary Dawson polyoxotungstate anions: Synthesis and structure of [Hf4(μ3-O)2(μ-OH)2(H2O)4(P2W16O59)2]14−

Abstract The title polyoxometalate (POM) 1 was obtained by a 1:2 molar-ratio reaction of tri-lacunary Dawson POM [B-α-P2W15O56]12− with Hf(SO4)2 or HfCl4 in an aqueous solution, and isolated as dimethylammonium salt (Me2NH2-1) and, also, as sodium salt (Na-1). These compounds were unambiguously characterized by complete elemental analysis, including sodium and oxygen analyses, TG/DTA, FTIR, single-crystal X-ray structure analysis, (solid-state and solution) 31P NMR and solution 183W NMR spectroscopy. X-ray crystallography revealed that 1 with Ci symmetry was composed of a tetra-HfIV cluster cation species [Hf4(μ3-O)2(μ-OH)2(H2O)4]10+ sandwiched between 2 di-lacunary Dawson polyoxometalates (POMs), [P2W16O59]12−, and it was isostructural with the previously reported Zr4 analogue. Thus, a pair of Hf- and Zr-containing POMs belonging to the same structure-family was built up.

Solid‐state linear viscoelastic properties of intercalated poly(L‐lactide)/organo‐modified montmorillonite hybrids

AbstractHybrids of poly(L‐lactide)/organophilic clay (PLACHs) have been prepared by a melt‐compounding process using poly(L‐lactide) (PLLA) and different contents of surface‐treated montmorillonite modified with a dimethyl dioctadecyl ammonium salt. The dispersion structures of clay particles in PLACHs were investigated using wide‐angle X‐ray diffraction and transmission electron microscopy. The solid‐state linear viscoelastic properties for these PLACHs were examined as functions of temperature and frequency. The incorporation of organo‐modified silicate into PLLA matrix enhanced significantly both storage moduli (E′) and loss moduli (E″). The strong enhancement observed in dynamic moduli of PLACHs could be attributed to uniformly dispersed state of the clay particles with high aspect ratio (= length/thickness of clay) and the intercalation of the PLLA chains between silicate layers. Copyright © 2006 Society of Chemical Industry

Cyclodimerization of the Stevens Rearrangement Products from 4-Alkoxy-2-butynyl(alkoxycarbonylmethyl)dimethyl-ammonium Salts into Cyclohexene Derivatives

4-Alkoxy-2-butynyl(alkoxycarbonyl)dimethylammonium salts undergo 3,2-Stevens rearrangement by the action of the corresponding sodium alkoxides. Hydrolysis of the rearrangement products with dilute hydrochloric acid gives 3-alkoxy-2-oxo-3-pentenoic acid esters which are converted into 3-methylene-2-oxo-4-pentenoates via 1,4-elimination of alcohol. [2 + 4]-Cyclodimerization of 3-methylene-2-oxo-4-pentenoates leads to 1,4-bis(alkoxalyl)-4-vinylcyclohexenes.

Synthesis and structure of supramolecular polyoxothiometalate nanocluster containing 52 metal atoms [{Mo3S4(H2O)5}4(γ-SiW10O36)4]16–

The polyoxothiometalate complex [{Mo3S4(H2O)5}4(γ-SiW10O36)4]16– was prepared by the reaction of the cationic triangular molybdenum aqua complex [Mo3S4(H2O)9]4+ (electrophile) with the lacunary polyoxotungstate complex [γ-SiW10O36]8– (nucleophile). According to the results of single-crystal X-ray diffraction analysis of the dimethylammonium salt, the anionic nanocluster contains 52 molybdenum and tungsten atoms and has a cyclic porphyrin-like structure.

Trisubstituted 1,3,5-Triazines. 5. Reaction of 2,4,6-Tris[di(tert-butoxycarbonyl)nitromethyl]-1,3,5-triazine with Nucleophiles

The reaction of 2,4,6-tris[di(tert-butoxycarbonyl)nitromethyl]-1,3,5-triazine with ammonia, amines, and hydrazine has been studied. It was possible to substitute one of the di(tert-butoxycarbonyl)nitromethyl groups in this compound in the presence of ammonia, primary aliphatic amines, dimethylamine, and morpholine. The reaction with hydrazine leads to both mono- and disubstituted products. A double dealkoxylation occurs in the presence of diethylamine to give the bis(dimethylammonium) salt of 2,4-bis(tert-butoxycarbonylnitromethyl)-6-[di(tert-butoxycarbonyl)nitromethyl]-1,3,5-triazine.

Crystal structure of (1-hydroxy-l-phosphono-pentyl)-phosphonic acid dimethyl ammonium salt, C7H21NO7P2, and of (1,8-dihydroxy-1,8,8-trisphosphono- octyl)-phosphonic acid bis-dimethylammonium salt tetrahydrate, C12H36N2O14P4 · 4H2O, evidence for trapped alcaline species by bisphosphonic and tetraphosphonic acids in the crystalline state

Article Crystal structure of (1-hydroxy-l-phosphono-pentyl)-phosphonic acid dimethyl ammonium salt, C7H21NO7P2, and of (1,8-dihydroxy-1,8,8-trisphosphono- octyl)-phosphonic acid bis-dimethylammonium salt tetrahydrate, C12H36N2O14P4 · 4H2O, evidence for trapped alcaline species by bisphosphonic and tetraphosphonic acids in the crystalline state was published on December 1, 2002 in the journal Zeitschrift für Kristallographie - New Crystal Structures (volume 217, issue JG).

Crystal structure of (1-hydroxy-l-phosphono-pentyl)-phosphonic acid dimethyl ammonium salt, C7H21NO7P2, and of (1,8-dihydroxy-1,8,8-trisphosphono- octyl)-phosphonic acid bis-dimethylammonium salt tetrahydrate, C12H36N2O14P4 · 4H2O, evidence for trapped alcaline species by bisphosphonic and tetraphosphonic acids in the crystalline state

Crystal structure of (1-hydroxy-l-phosphono-pentyl)-phosphonic acid dimethyl ammonium salt, C7H21NO7P2, and of (1,8-dihydroxy-1,8,8-trisphosphono- octyl)-phosphonic acid bis-dimethylammonium salt tetrahydrate, C12H36N2O14P4 · 4H2O, evidence for trapped alcaline species by bisphosphonic and tetraphosphonic acids in the crystalline state

Diversity Oriented Synthesis of Chiral Hexacoordinated Phosphate Anions

Novel hexacoordinated phosphate anions consisting of a central phosphorus(v) atom and at least one tetrachloropyrocatechol ligand can be simply prepared in modest to decent yields (37-71%) as their dimethylammonium salts following a one-pot process and with simple, usually commercially available, starting materials. A variety of symmetrical diones (α-diketones or ortho-quinones) can be used in this protocol and the structurally-diverse products are chemically stable when two tetrachloropyrocatechol ligands surround the P atom.

Contribution of Neutron Diffraction to the Crystal Structure Determination of 1-Hydroxy-1-Phosphono-Pentyl-Phosphonic Acid Dimethyl Ammonium Salt

The crystal structure of 1-hydroxy-1-phosphono-pentyl-phosphonic acid dimethylammonium salt has been determined by neutron diffraction measurements on single crystals at room temperature (triclinic, space group P-1, a=11.419(23) Å, b=10.447(18) Å, c=6.211(9) Å, α=92.041(2)°, β=95.870 (3)°, γ=110.408(2)°, V=689(2) Å 3). Refinements of the structure using 1195 observed structure factors converged to the final R=0.068. Results have put in evidence that acids of the hydroxybisphosphonic family can protonate volatile alkaline species like dimethylamine to give particularly stable crystals. The hydrogen bonds formed by the dimethylammonium cation link columns of hydroxybisphosphonate groups parallel to the [010] direction. The structure is built up by alternated hydrophobic/polar layers parallel to the (100) plane.

Contribution of Neutron Diffraction to the Crystal Structure Determination of 1-Hydroxy-1-Phosphono-Pentyl-Phosphonic Acid Dimethyl Ammonium Salt

The crystal structure of 1-hydroxy-1-phosphono-pentyl-phosphonic acid dimethylammonium salt has been determined by neutron diffraction measurements on single crystals at room temperature (triclinic, space group P -1, a =11.419(23) Å, b =10.447(18) Å, c =6.211(9) Å, α =92.041(2)°, β =95.870 (3)°, γ =110.408(2)°, V =689(2) Å 3 ). Refinements of the structure using 1195 observed structure factors converged to the final R =0.068. Results have put in evidence that acids of the hydroxybisphosphonic family can protonate volatile alkaline species like dimethylamine to give particularly stable crystals. The hydrogen bonds formed by the dimethylammonium cation link columns of hydroxybisphosphonate groups parallel to the [010] direction. The structure is built up by alternated hydrophobic/polar layers parallel to the (100) plane.

Asymmetric Synthesis and Configurational Stability of C2-Symmetric Hexacoordinated Phosphate Anions (TARPHATs) with Predetermined Chirality from Tartrate Esters

C2-Symmetric TARPHAT anions 5 made of a central PV atom, one tartrato (=dialkyl 2,3-di(hydroxy-KO)butanedioato(2-)), and two tetrachloropyrocatecholato (=3,4,5,6-tetrachlorobenzene-1,2-diolato(2-)-KO,KO) ligands can be easily prepared in decent to high yields (50-86%) as their dimethylammonium salt by using a one-pot process and simple commercially available starting materials. The presence of the chiral tartrato ligands (usually (2R,3R)) leads to the formation of diastereoisomeric anions ((?,2R,3R)/(?,2R,3R)). Decent to good control by the chiral ligands - under equilibration conditions - over the ? or ? configuration of the adducts was observed (d.r. 84 : 16 in CHCl3 for the di(tert-butyl) tartrate derivative), the selectivity depending on the nature of the ester chains as well as on the solvent.