Presence Of Me Research Articles

Serum LDL- and HDL-cholesterol determined by ultracentrifugation and HPLC

Simple and precise methods for LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) measurements are essential for assessment of cardiovascular disease (CVD) risks and for lipid and lipoprotein studies. We report here an ultracentrifugation (UC) and HPLC method that requires substantially less specimen volume and provides the necessary reliability and throughput required by large-volume, high-quality research and clinical studies. 2-Mercaptoethanol (ME) was used to dissociate serum lipoprotein [a] (Lp[a]) into apolipoprotein [a] and Lp[a] remnant (Lp[a-]) and eliminated the contamination of Lp[a] in HDL separated by UC. Serum aliquots were centrifuged at a density of 1.006 kg/l for the separation of HDL plus LDL, and in the presence of ME at a density of 1.063 kg/l for the separation of HDL. Cholesterol concentrations of the bottom fractions were analyzed by HPLC. LDL-C and HDL-C determined using this method were equivalent to those with β-quantification and the designated comparison method of the Centers for Disease Control. The total coefficient of variations for LDL-C and HDL-C were 0.65-1.12% and 0.96-2.07%, respectively. This method requires a small amount of specimen and is easy to operate. This method may be used in research or in clinical laboratories where precise and specific lipoprotein cholesterol analysis is needed.

Synthesis–structure–performance correlation for polyaniline–Me–C non-precious metal cathode catalysts for oxygen reduction in fuel cells

In this report, we present the systematic preparation of active and durable non-precious metal catalysts (NPMCs) for the oxygen reduction reaction in polymer electrolyte fuel cells (PEFCs) based on the heat treatment of polyaniline/metal/carbon precursors. Variation of the synthesis steps, heat-treatment temperature, metal loading, and the metal type in the synthesis leads to markedly different catalyst activity, speciation, and morphology. Microscopy studies demonstrate notable differences in the carbon structure as a function of these variables. Balancing the need to increase the catalyst’s degree of graphitization through heat treatment versus the excessive loss of surface area that occurs at higher temperatures is a key to preparing an active catalyst. XPS and XAFS spectra are consistent with the presence of Me–Nx structures in both the Co and Fe versions of the catalyst, which are often proposed to be active sites. The average speciation and coordination environment of nitrogen and metal, however, depends greatly on the choice of Co or Fe. Taken together, the data indicate that better control of the metal-catalyzed transformations of the polymer into new graphitized carbon forms in the heat-treatment step will allow for even further improvement of this class of catalysts.

ChemInform Abstract: Copper-Catalyzed Reactions of Organotitanium Reagents. Highly Selective SN2′-Allylation and Conjugate Addition.

Abstract In the presence of a catalytic amount of CuI·2LiCl, alkyltitanium (RTi(O-i-Pr) 3 ) and titanate reagents (R n Ti(O-i-Pr) 5−n Li) undergo highly selective S N 2′-alkylation reactions with allylic chlorides and allylic diethylphosphates in high yields. The regioselectivity of the reaction is as high as 99.8%. The reaction proceeds with excellent anti -stereoselectivity with respect to the nucleophile and the leaving group, and exhibits high 1,2- anti -diastereoselectivity with a δ-chiral allylic chloride. The catalytic copper reagent is also a mild agent to transfer an alkyl group to an enone in the presence of Me 3 SiCl. The alkyltitanium-based catalytic reagent selectively reacts with an allylic phosphate rather than with an enone, while in the presence of a silicon activator, it reacts preferentially with the enone rather than with the phosphate. 1 H NMR studies on a mixture of Me 2 CuLi and TiCl(O-i-Pr) 3 provided information on reagent composition.

フルボ酸第二鉄錯体とシデロフォアDesferrioxamine Bのリガンド交換速度論に及ぼす二価金属イオンの影響

The effect of divalent cations (Me: Ca2+ and Mg2+) on the ligand-exchange kinetics of Fe (III) -fulvic acid complex and desferrioxamine B (DFOB) was examined by spectrophotometrically measuring the rate of Fe (III) -DFOB complex formation at the various concentrations of Me found in natural water (0-50 mM) . A kinetic model for ligand-exchange incorporating the effects of Me was also developed. The model includes the following two pathways: (1) a disjunctive pathway where Fe (III) -fulvic acid complex initially dissociates followed by complexation of free Fe (III) by DFOB; and (2) an adjunctive pathway where DFOB directly associates with the Fe (III) -fulvic acid complex followed by dissociation of the ternary complex (DFOB-Fe (III) -fulvic acid) to form Fe (III) -DFOB. The ligand-exchange rates of both pathways were accelerated in the presence of Me. The enhanced rates were well explained by considering the ternary complex formation of Me and Fe (III) -fulvic acid complex.

Effect of Me2SO on Membrane Phase Behavior and Protein Denaturation of Human Pulmonary Endothelial Cells Studied by In Situ FTIR Spectroscopy

Fourier transform infrared spectroscopy (FTIR) provides a unique technique to study membranes and proteins within their native cellular environment. FTIR was used here to study the effects of dimethyl sulfoxide (Me(2)SO) on membranes and proteins in human pulmonary endothelial cells (HPMECs). Temperature-dependent changes in characteristic lipid and protein vibrational bands were identified to reveal the effects of Me(2)SO on membrane phase behavior and protein stability. At Me(2)SO concentrations equal to or below 10% (v/v), Me(2)SO was found to decrease membrane conformational disorder. At higher Me(2)SO concentrations (15% v/v), however, membrane conformational disorder was found to be similar to that of cells in the absence of Me(2)SO. This effect was observed over a wide temperature range from 90 degrees C down to -40 degrees C. Me(2)SO had no clear effects on cellular proteins during freezing. During heating, however, Me(2)SO had a destabilizing effect on cellular proteins. In the absence of Me(2)SO, protein denaturation started at an onset temperature of 46 degrees C, whereas at 15% Me(2)SO the onset temperature of protein denaturation decreased to 32 degrees C. This implies that in the presence of Me(2)SO the onset temperature of protein denaturation is lower than the normal growth temperature of the cells, which could explain the well documented toxic effect of Me(2)SO at physiological temperatures. Me(2)SO destabilizes cellular proteins during heating and decreases membrane conformational disorder over a wide temperature range.

Synthesis, characterization and electrocatalysis of diiron propanediselenolate derivatives as the active site models of [FeFe]-hydrogenases

As an extension of our study on the H-cluster model compounds, a series of diiron propanediselenolate (PDS)-type models have been successfully synthesized. Reaction of diselenol HSe(CH(2))(3)SeH with Fe(3)(CO)(12) in THF (tetrahydrofuran) at reflux gave the parent model compound [micro-Se(CH(2))(3)Se-micro]Fe(2)(CO)(6) (1) in 48% yield. Further reaction of 1 with PPh(3) or PPh(2)H in the presence of Me(3)NO in MeCN at room temperature afforded the phosphine-monosubstituted model compounds [micro-Se(CH(2))(3)Se-micro]Fe(2)(CO)(5)(L) (2, L=PPh(3); 3, L=PPh(2)H) in 76% and 68% yields, respectively. Similarly, the N-heterocyclic carbene I(Mes)-monosubstituted model compound [micro-Se(CH(2))(3)Se-micro]Fe(2)(CO)(5)(I(Mes)) (4) could be prepared in 46% yield by reaction of imidazolium salt I(Mes).HCl with n-BuLi followed by treatment of the resulting I(Mes) ligand with 1 in THF at room temperature. Compounds 1-4 were fully characterized by elemental analysis and various spectroscopic methods. While the structures of 1-4 were further confirmed by X-ray crystallography, the comparative study of 1 and its analog [micro-S(CH(2))(3)S-micro]Fe(2)(CO)(6) demonstrates that 1 is a better catalyst for TsOH proton reduction to hydrogen under electrochemical conditions.

Synthesis, structure and reactivity of tetranuclear square-type complexes of rhenium and manganese bearing pyrimidine-2-thiolate (pymS) ligands: versatile and efficient precursors for mono- and polynuclear compounds containing M(CO)3 (M = Re, Mn) fragments

Reactions of M(2)(CO)(10) (M = Re, Mn) with pyrimidine-2-thiol (pymSH) in the presence of Me(3)NO afford the tetranuclear square-type complexes [M(4)(CO)(12)(micro-kappa(3)-pymS)(4)] (, M = Re; , M = Mn). Both consist of four M(CO)(3) (M = Re, Mn) units, pairs of which are joined by tridentate pyrimidine-2-thiolate ligands. Treatment of with a variety of donor ligands results in cleavage of the square to afford mononuclear species with either a mono- or bidentate pyrimidine-2-thiolate ligand. Triphenylphosphine reacts with to give [Mn(CO)(3)(PPh(3))(kappa(2)-pymS)] () in which the pyrimidine-2-thiolate coordinates in a bidentate fashion. With diamines [M(CO)(3)(kappa(2)-L)(kappa(1)-pymS)] () (M = Re, Mn; L = 2,2'- bipy, 1,10-phen, en) result in which the pyrimidine-2-thiolate binds in a monodentate fashion through sulfur. With diphosphines, complexes with different stoichiometries and pyrimidine-2-thiolate binding modes are obtained depending on the nature of the metal and diphosphine. With dppm and dppe, gives [Re(CO)(2)(kappa(1)-pymS)(kappa(2)-dppm)] () and [Re(CO)(2)(kappa(2)-pymS)(kappa(1)-dppe)(2)] (), respectively, whereas affords [Mn(CO)(2)(kappa(2)-pymS)(kappa(1)-dppm)(2)] () and [Mn(CO)(2)(kappa(2)-pyS)(kappa(2)-dppe)] () under similar conditions. Reactions of with [Os(3)(CO)(10)(NCMe)(2)] affords mixed-metal butterfly clusters [MOs(3)(CO)(13)(micro(3)-kappa(2)-pymS)] () in which the group 7 metal occupies a wing-tip position and the pyrimidine-2-thiolate ligand caps a triangular Os(2)M face. With Ru(3)(CO)(12), carbon-sulfur bond cleavage occurs to give the tetranuclear clusters [MRu(3)(CO)(14)(micro(4)-S)(micro-kappa(1):eta(1)-pym)] () bearing both the extruded sulfur and the heterocyclic ring. The molecular structures of , and have been established by X-ray diffraction allowing the binding mode of the pyrimidine-2-thiolate ligands to be probed.

Effect of divalent cations on the kinetics of Fe(III) complexation by organic ligands in natural waters

We have investigated the kinetics of Fe(III) complexation by several organic ligands including fulvic acid, citrate and ethylenediaminetetraacetic acid (EDTA). Particular attention was given to examination of the effect of competitive divalent cations (Me: Ca 2+ and Mg 2+) at concentrations typical of seawater on the complexation rate. All experiments were conducted in 0.5 M NaCl solution buffered with 2 mM bicarbonate at pH 8.0 in the absence and presence of Me (25 μM–250 mM). The rate constants of complex formation determined by using the competitive ligand (5-sulfosalicylic acid) method combined with visible spectrophotometry ranged from 3.3 × 10 4 to 3.2 × 10 6 M −1 s −1. The mechanism of complexation was then examined based on a kinetic model. When EDTA was used as a ligand, Me at concentrations comparable to the ligand markedly retarded the rate of iron complex formation due to the predominance of an adjunctive pathway (where iron–ligand complex is formed via direct association of iron to Me–ligand complex). In contrast, the competing effect of Me on iron complexation by citrate and fulvic acid was observed only when the Me concentration was in excess of the ligand by more than a factor of 10–1000. The kinetic model suggests that iron complexation by fulvic acid occurs predominantly via a disjunctive pathway (where iron complexation by ligand occurs after dissociation of Me from Me–ligand complex) at concentrations of divalent cations and natural organic matter typical of natural waters including seawater and freshwater.

Performance of unsupported Ni(Co,Fe)/MoS2 catalysts in hydrotreating reactions

Abstract The catalytic performance of unsupported Me/MoS2 catalysts (where Me = Co, Ni, Fe) in the hydrotreating reactions of furfurylamine (FA) and dibenzothiophene (DBT) in a dynamic micro-reactor was reported. The Me/MoS2 samples were synthesized by the impregnated thiosalt decomposition (ITD) method and sulfided under a mixture H2S/H2 (20% v/v), at 400 °C for 4 h. In all samples the Me/(Me + Mo) atomic ratio was of 0.85. The samples were characterized by Chemical analysis by EDS, N2 adsorption–desorption, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The Ni/MoS2 sample showed higher catalytic activity in the hydrotreating reactions of FA and DBT in comparison with the Co/MoS2 and Fe/MoS2 samples. The selectivity in both FA and DBT reactions depends strongly on the presence of Me (Ni, Co or Fe). We found two interesting correlations between the catalytic activity of both FA and DBT reactions with the fraction sulfided of Me and Mo species and with the total sulfidation degree of the samples.

Chlorotrimethylsilane‐Mediated Synthesis of Functionalized Fused Pyridines: Reaction of 3‐Formylchromones with Electron‐Rich Aminoheterocycles.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Chlorotrimethylsilane-Mediated Synthesis of Functionalized Fused Pyridines: Reaction of 3-Formylchromones with Electron-Rich Aminoheterocycles

The reaction of 3-formylchromones with aminoheterocycles was investigated. A simple and flexible general procedure for annulation of 5-(2-hydroxybenzoyl)pyridines was proposed. The best reaction conditions were found to be heating the reaction mixture in DMF in the presence of Me 3 SiCl as a promoter and water as scavenger.

Adsorption of Me–HEDP complexes onto γ-Al 2O 3

This work studies the adsorption of Me–1-hydroxiethane-(1,1-diphosphonic acid) (HEDP) complex onto alumina in the pH range from 5.0 to 9.5. The extent of HEDP adsorption is not significatively affected by the presence of Me(II), while, HEDP has an interesting effect on Me(II) adsorption. At high surface covering, Cu(II) adsorption is enhanced at low pH reaching a maximum of 57% at pH nearly 6, however, at pH > 6 a decrease about 20% in the amount of Cu(II) adsorbed takes place by the presence of HEDP. The model predicts a ternary surface complex ( AlLCu −) to justify the increase of Cu(II) adsorbed at lower pH. At the lower pH and at high Zn(II) concentration the presence of equimolar concentration of HEDP also causes a discernible increase in the amount of Zn(II) adsorbed. At pH 5, the percentage of Zn(II) complexed with HEDP increased from negligible to 40% as the HEDP concentration increased. However, in this case the HEDP does not have a suppressor effect on the Zn(II) adsorption at the higher pH. Again, the presence of anionic-type complexation is here postulated to reach a good fit with the experimental results. The effect of HEDP over Zn(II) adsorption becomes less pronounced with the excess of surface sites. Cd(II)–HEDP solution complexes are weaker than those corresponding to Cu(II) and Zn(II), so competitive effects between surface and solution are much less significant in comparison to Cu(II)–HEDP and Zn(II)–HEDP alumina systems. So, the effect of HEDP on the Cd adsorption at low concentration and low pH is more stressed than in the case of Cu(II) and Zn(II). Overall, results indicate that the presence of HEDP in the aquatic systems could have a significant impact on the mobility and distribution of Cu(II), Zn(II) and Cd(II) in the environment.

Nickel(0)‐Catalyzed Disilylative and Silastannylative Cyclizations of 1,3‐Diene and Tethered Aldehyde.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Bi 2V 1− xMe xO 5.5− δ (Me = Ta, Ni) membranes for selective oxidation of C 1–C 3 alkanes in a catalytic dense membrane reactor

Pure and Me-doped γ-Bi 2V 1− x Me x O 5.5− δ (BIMEVOX) (Me = Ta, Ni) materials exhibit a transient behaviour during the oxidation of C 1–C 3 alkanes when shaped as dense membranes separating two compartments fed with diluted hydrocarbon and with air, respectively (catalytic dense membrane reactor). Alkenes are first produced at low conversion and CO and H 2 follow at higher conversion. The H 2/CO ratio increases up to values close to the stoichiometric ones and continues to increase after a peak of activity during which coke builds up. The same transient phenomena as initially observed happen after burning the coke by replacing diluted hydrocarbon by air. The fact that the membrane can be in situ regenerated means that the structure and integrity of the membranes have not been modified, as indeed shown by physicochemical analyses (XRD, SEM and XPS). The catalytic properties are mainly related to the presence of ME which affects the electronic conductivity of the materials. At variance with quite neutral BITAVOX, the behaviour of BINIVOX is close to that of BICOVOX which is also a p-type semiconductor. Only BINIVOX is able to oxidise methane quite steadily (conversion ca. 22–25 mol%) to syngas at low temperature (650 °C).

Ten-Vertex Iron−Monocarbollide Complexes: Synthesis and Reactivity of the Anion [4,9-{Fe(CO)4}-9,9,9-(CO)3-arachno-9,6-FeCB8H11]-

The reagent [arachno-4-CB8H14] reacts with [Fe3(CO)12] in tetrahydrofuran (THF) at reflux temperatures, followed by addition of [N(PPh3)2]Cl, to afford [N(PPh3)2][4,9-{Fe(CO)4}-9,9,9-(CO)3-arachno-9,6-FeCB8H11] (3). In the anion of 3, one iron atom is part of the open CBBFeBB face of a 10-vertex {arachno-9,6-FeCB8} cage, to which the second iron atom is attached via an Fe-Fe bond and an additional exo-polyhedral Fe-B sigma bond. Upon heating 3 in refluxing toluene, the closed 10-vertex species [N(PPh3)2][2,2,2-(CO)3-closo-2,1-FeCB8H9] (4) is obtained, whereas the isomeric compound [N(PPh3)2][6,6,6-(CO)3-closo-6,1-FeCB8H9] (5) is isolated upon heating [closo-4-CB8H9]- and [Fe3(CO)12] in refluxing THF with subsequent addition of [N(PPh3)2]Cl. Protonation of 3 using CF3SO3H in CH2Cl2 gives the charge-compensated compound [4,9-{Fe(CO)4}-4-(mu-H)-9,9,9-(CO)3-arachno-9,6-FeCB8H11] (6), in which the B-Fe sigma bond of the precursor has been converted to a B-H right harpoon-up Fe linkage. In contrast, 3 with {M(PPh3)}+ gives the trimetallic species [1,3,4,9-{MFe(CO)4(PPh3)}-1,3-(mu-H)2-9,9,9-(CO)3-arachno-9,6-FeCB8H9] (M = Cu (7), Ag 8) in which the three metal centers form a V-shaped M-Fe-Fe unit. Compound 6 reacts with PEt3 in the presence of Me(3)NO to yield [4,9-(PEt3)2-9,9-(CO)2-nido-9,6-FeCB8H10] (9). In the latter, the formerly exo-polyhedral {Fe(CO)4} fragment has been replaced by a PEt3 ligand, with a second PEt3 substituting one CO group at the remaining cluster iron vertex. The novel structural features of compounds 3-9 have been confirmed by single-crystal X-ray diffraction studies.

Synthesis of Nickel−Monocarbollide Complexes by Oxidative Insertion

Treatment of the 11-vertex carborane anion [closo-2-CB(10)H(11)](-) with Ni(0) reagents in tetrahydrofuran (THF) affords-via oxidative insertion reactions-12-vertex Ni(II) complexes, isolated as the salts [N(PPh(3))(2)][2,2-L(2)-closo-2,1-NiCB(10)H(11)] (L = CO (1a), CNBu(t) (1b), and CNXyl (1c; Xyl = C(6)H(3)Me(2)-2,6); L(2) = cod (1d; cod = 1,2:5,6-eta-cyclo-octa-1,5-diene)). One CO ligand in 1a is readily replaced by donors L' in the presence of Me(3)NO to give the species [N(PPh(3))(2)][2-CO-2-L'-closo-2,1-NiCB(10)H(11)] (L' = PEt(3) (1e), PPh(3) (1f), CNBu(t) (1g), and CNXyl (1h)). The anionic complexes themselves readily react with hydride abstracting reagents in the presence of donor ligands to yield zwitterionic complexes in which boron vertexes bear substituents that are bound through C, N, or O atoms. Thus, for example, 1c with H(+) and CNXyl gives [2,2,7-(CNXyl)(3)-closo-2,1-NiCB(10)H(10)] (2b), while 1f with Me(+) in the presence of OEt(2) affords [2-CO-2,11-{mu-PPh(2)(C(6)H(4)-o)}-7-OEt(2)-closo-2,1-NiCB(10)H(9)] (4), in which an additional cycloboronation of one phosphine phenyl ring has occurred. In contrast, 1f with Me(+) in the presence of NCMe gives a mixture of the isomers [2-CO-2-PPh(3)-7-{(X)-N(Me)=C(H)Me}-closo-2,1-NiCB(10)H(10)] (X identical with E (5c) and Z (5d)). X-ray diffraction analyses of compounds 1a, 2b, 4, and 5c confirmed their important structural features.

Physico-Chemical Characterization of Watermelon Urease upon Immobilization in Alginate Beads

Watermelon (Citrullus vulgaris) urease was immobilized in 3.5% alginate leading to 72% immobilization. There was no leaching of the enzyme over a period of 15 days at 4°C. It continued to hydrolyse urea at a faster rate upto 90 min of incubation. The immobilized urease exhibited a shift of apparent pH optimum by one unit towards acidic side (from pH 8.0 to 7.0). The Km was found to be 13.3 mM; 1.17 times higher than the soluble enzyme (11.4 mM). The beads were fairly stable upto 50°C and exhibited activity even at −10°C. The enzyme was significantly activated by ME and it exhibited two peaks of activation; one at lower concentration and another at higher concentration. Time-dependent ureolysis in presence of ME progressed at a much elevated rate. Unlike soluble enzyme, which was inhibited at 200 mM urea, the immobilized enzyme was inhibited at 600 mM of urea and above, and about 47% activity was retained at 2000 mM urea. Moreover, the inhibition caused by high urea concentration was partially abolished by ME. The significance of the observations is discussed.

Cyclodextrin-Mediated Drug Release from Liposomes Dispersed Within a Bioadhesive Gel

The aim of the present study was to design a new mucosal drug delivery system composed of liposomes dispersed within a bioadhesive hydrogel containing methyl-beta-cyclodextrin (Me(beta)CD) for controlled drug release. A hydrophilic model molecule, inulin, was encapsulated within positively charged and PEG-ylated liposomes and its release was measured in the presence of Me(beta)CD after vesicle dispersion within the bioadhesive Carbopol 974P gel. Freeze-fracture electron microscopy (FFEM) was used to follow liposome morphological changes when dispersed within the hydrogel. Liposome-Me(beta)CD interactions were investigated by turbidity monitoring during continuous addition of Me(beta)CD to liposomes and by FFEM. Inulin diffusion within the gel was influenced by Carbopol 974P concentration since no gel erosion occurred. When dispersed within the gel, positively charged liposomes displayed a higher stability than PEG-ylated vesicles. In the presence of Me(beta)CD, higher amounts of free inulin were released from liposomes, especially in Carbopol-free system. Me(beta)CD appeared to diffuse towards lipid vesicles and permeabilized their bilayer allowing inulin leakage. Indeed, freeze-fracture experiments and liposome turbidity monitoring have shown that Me(beta)CD behaved as a detergent behavior, resulting in lipid vesicle solubilization. is able to mediate, within a bioadhesive hydrogel, the release of a liposome-encapsulated molecule allowing further application of this delivery system for mucosal administration.

Samarium Diiodide-Catalyzed Diastereoselective Pinacol Couplings

A complex of samarium diiodide (SmI(2)) with tetraglyme catalyzes the intermolecular pinacol coupling of aromatic or aliphatic aldehydes at loadings of 10 mol % in the presence of Me(2)SiCl(2) and Mg. Diastereoselectivity of up to 95/5 (+/-/meso) has been achieved for aliphatic aldehydes and up to 19/81 (+/-/meso) for aromatic aldehydes. De values of up to 99% have been achieved in intramolecular pinacol coupling reactions using the SmI(2)/tetraglyme/Mg/Me(2)SiCl(2) catalytic system.

3‐Formylchromones in Guareschi Synthesis of 5‐(2‐Hydroxybenzoyl)‐2‐pyridones.

A set of 5-(2-hydroxybenzoyl)-pyrid-2-ones, which are analogous to cardiotonic drugs such as milrinone, has been prepared in high yield by recyclization of 3-formylchromones with acetic acid amides having at the α-position an electron-withdrawing group. The best reaction conditions were found to be heating in DMF in the presence of Me 3 SiCl as a promoter and water scavenger.