Reactions of organylhalosilanes with 1,1,3,3-tetra- and hexamethyldisilazane

Organylchlorosilanes, and also SiCl₄, decompose 1,1,3,3-tetra- and hexamethyl-disilazanes with formation of hitherto unknown organylchlorosilazanes of general formulas R_4–nSiCl_n–1NHSiH(CH₃)₂ and R_4–nSiCl_n–1NHSi(CH₃)₃ (n=2–4) in yields of 54–98%. The IR and mass spectra of the prepared compounds were studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1159–1162, May, 1991.     

Tetrakisisopropoxy tantalum(V)O,O′-alkylene dithiophosphate complexes

Summary Tetrakisisopropoxytantalum(V) alkylene dithiophosphato complexes, (G=–CMe₂CMe₂–, –CHMeCHMe–, –CH₂CMe₂CH₂– and –CH₂CEt₂CH₂–) have been prepared from equimolar ratios of tantalum(V) isopropoxide and alkylene dithiophosphoric acids in benzene. These moisture-sensitive compounds, which are soluble in common organic solvents and are monomeric, have been characterized by elemental analysis, molecular weight determinations and by their i.r. and n.m.r. spectra. An octahedral geometry is suggested in which the ligand is bidentate.     

Chromato-mass spectral study of the reactions of organylsiloxanes with metal oxides

A study was carried out on the reaction of 1,1,3,3-tetramethyldisiloxane with metal oxides such as CuO, HgO, and Sb₂O₅ in the presence of compounds containing a siloxane bond such as hexamethyldisiloxane, octamethylcyclotetrasiloxane, and trimethylacetoxysilane, which, at 100–110°C over 0.5–10 h, leads to the formation of linear organyl siloxanes (CH₃-[-Si(CH₃)₂O-]_n-Si(CH₃)₃, CH₃-[-Si(CH₃)₂O-]_n-Si (CH₃)₂H, and H-[-Si(CH₃)₂O-]_n-Si(CH₃)₂H, where n=2–6, and cyclic organylsiloxanes. The reaction does not proceed in the presence of aluminum, bismuth, germanium, and lead oxides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1658–1660, July, 1990.     

On the role of solvent in complexation equilibiria. II. The acid-base chemistry of some sulfhydryl and ammonium-containing amino acids in water—acetonitrile mixed solvents

The macroscopic and microscopic acid-base chemistry of a series of sulfhydryl and ammonium-containing amino acids HS–R–NH₃ [R=–CH₂CH(COOH)–, cysteine (CYS); R=–C(CH₃)₂CH(COOH)–, penicillamine (PEN); R=–CH(COOH)CH₂CH₂CONHCH(–CH₂)CONHCH₂COOH, glutathione (GSH)] was characterized in water and its binary mixtures with acetonitrile (16.3, 34.2, and 53.9 mass % acetonitrile). Macroscopic acid dissociation constants were obtained by potentiometric titration using the glass-calomel electrode pair. Microscopic acid dissociation constants were calculated from ultraviolet absorption measurements at ca. 232 nm where the deprotonated sulfhydryl group absorbs. The macroscopic constants decrease uniformly as the solvent becomes enriched in acetonitrile. The microscopic constants, which characterize the relative concentrations of the two monoprotonated tautomers of the molecules (I and II) reveal that as the solvent becomes enriched in acetonitrile, the fraction of molecules existing as highly charged tautomer I decreases for CYS (0.68–0.40), PEN (0.85–0.34), and GSH (0.61–0.30). These results are related to the decreasing concentration of water as the solvent becomes enriched in acetonitrile.     

Complexes of apatitic layered compound Ca8(HPO4)2(PO4)4·5H2O with dicarboxylates

Octacalcium phosphate(OCP), Ca₈(HPO₄)₂(PO₄)₄·5H₂O, consists of alternative stackings of layers with an apatitic structure and a brushite-like composition. Here we consider whether or not OCP is able to complex with organic substances. The interplanar spacing (d₁₀₀) of OCP prepared in the presence of dicarboxylates (RC₂O₄ ^2–; R=organic group) expanded from the original value of 18.7 Å to 19.2–26.1 Å depending on the length of R. Examples of R were C_nH_2n(n=1–6), CH(CH₃)CH₂, C(CH₃)=CH, CH=CH, CH₂CH=CHCH₂ and C₆H₄. Structural considerations and experimental data suggested that dicarboxylates were incorporated into the OCP structure through the replacement of HPO₄ ^2– by RC₂O₄ ^2–.     

Raman and Infrared Spectra, Ab Initio Calculations, Normal Coordinate Analysis, and Conformational Stability of 2-Methoxypropene

The Raman (3500–40 cm^–1) and infrared (3500–70 cm^–1) spectra of gaseous and solid 2-methoxypropene, CH₃O(CH₃)C=CH₂, and the isotopomers, CD₃O(CH₃)C=CH₂ and CH₃O(CD₃)C=CD₂ have been recorded. In addition, the Raman spectra of the liquids have been recorded with qualitative depolarization measurements. All of these data indicate that only one conformer is present in the fluid phases at ambient temperature and this form is the cis conformer, which remains in the solid. Assignments are provided for the fundamentals of all three isotopomers for the cis conformer with C_s symmetry. The far-infrared spectra of all three isotopic species have been recorded at a resolution of 0.1 cm^–1 in the gas and 1.0 cm^–1 in the solid. The parameters of the potential function governing the asymmetric torsion are determined to be V₃ = 1485 ± 9 cm^–1 and V₆ = –55 ± 4 cm^–1 for the d₀ compound, where only two terms were determined, since a second conformer was not evident. The barrier to internal rotation for the methyl group attached to the oxygen atom is 1370 ± 8 cm^–1 and the C—CH₃ barrier is 772 ± 5 cm^–1. Ab initio calculations with full electron correlation have been carried out by the perturbation method to second order to obtain the equilibrium structural parameters, harmonic force constants, fundamental frequencies, infrared intensities, Raman activities, depolarization values, and conformational stability. The predicted values have been compared to the experimental values where appropriate.     

O,O′-dialkyl and alkylene dithiophosphate derivatives of silver(I). X-ray crystal structure of [Ag{S2POCH2CMe2CH2O} PPh3]2 · 2H2O

Silver(I) dialkyl/alkylene dithiophosphates of the types [Ag{S₂P(OR)₂}] and [Ag{S₂P(OGO)}] (where R = –Pr ⁿ ; G = –CMe₂CH₂CHMe–, –CH₂CMe₂CH₂–, –CMe₂CMe₂– or –CH₂CH₂CHMe–) have been prepared by treating an aqueous solution of AgNO₃ with ammonia salts of the respective dithiophosphoric acid. The derivatives form 1:1 adducts readily with 2,2-bipyridine or Ph₃P in CH₂Cl₂ solution. These novel complexes have been characterized by elemental analyses, molecular weight measurements and spectral (i.r., ¹H- and ³¹P-n.m.r.) studies. The crystal structure of [Ag{S₂POCH₂CMe₂CH₂O · PPh₃]₂ · 2H₂O exhibits an unsymmetrical attachment of the silver(I) to the ligand moiety.     

2-(Trialkoxysilylalkylthio)ethyl vinyl sulfides

Conclusions Trialkoxysilylalkanethiols (CH₃O)₃Si(CH₂)_nSH (n=1–3) react with divinyl sulfide at 100–110° to give 2-(trialkoxysilylalkylthio)ethyl vinyl sulfides (CH₃O)₃Si(CH₂)_nS (CH₂)₂SCH=CH₂ in high yield. The reactivity of the trialkoxysilylalkanethiols decreases with increase in the number of CH₂ groups between the S and Si atoms. A second molecule of the organosilicon thiol acids adds with difficulty to divinyl sulfide to give the diadduct.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 197–199, January, 1977.     

Manganese Complexes with Octaphenyltetraazaporphine: Acid–Base Interactions and Kinetic Stability in Proton-Donor Solvents

Complexes of manganese(III) and manganese(V) with octaphenyltetraazaporphine (H₂OPTAP) were synthesized. Acid–base interactions of these complexes in the CH₂Cl₂–CF₃COOH system and kinetics of their dissociation in concentrated sulfuric acid, as well as kinetics of octaphenyltetraazaporphine destruction in sulfuric acid solutions were studied by spectrophotometric methods. Acid–base interactions in CH₂Cl₂–CF₃COOH were shown to involve two macrocyclic meso-nitrogen atoms in succession. Concentration stability constants of the acid forms obtained pK ₁ = 0.29 ± 0.01 and pK ₂ = –0.62 ± 0.08 for (chlorine)manganese(III)octaphenyltetraazaporphine ((Cl)MnOPTAP); pK ₁ = 0.99 ± 0.02 and pK ₂ = – 0.70 ± 0.03 for (nitrido)manganese(V)octaphenyltetraazaporphine ((N)MnOPTAP). The rate of dissociation of the complexes in 94–98% H₂SO₄ does not depend on the acid concentration. The manganese(V) complex is three times as stable as the manganese(III) complex.     

New water-soluble and film-forming aminocellulose tosylates as enzyme support matrices with Cu<Superscript>2+</Superscript>-chelating properties

Within the framework of our studies on enzyme-compatible support matrix structures, we succeeded in making further derivatives of the new aminocellulose type P–CH₂–NH–(X)–NH₂ (P = cellulose); (X) = –(CH₂)₂– (EDA), –(CH₂)₂–NH–(CH₂)₂– (DETA), –(CH₂)₃–NH–(CH₂)₃– (DPTA), –(CH₂)₂–NH–(CH₂)₂–NH–(CH₂)₂– (TETA) accessible by nucleophilic substitution reaction with ethylenediamine (EDA) and selected oligoamines starting from 6(2)-O-tosylcellulose tosylate (DS_tosylate = 0.8). The ¹³C-NMR data show that the EDA and oligoamine residues are at C6 of the anhydroglucose unit (AGU) and that OH and tosylate are also (partially) present at C6. OH and partially tosylate are at C2/C3. All the synthesized aminocellulose tosylates were soluble in water and formed transparent films from their solutions. The aminocellulose tosylate solutions and the films prepared from them formed blue-coloured chelate complexes with Cu²⁺ ions, whose absorption maxima at wavelengths in the VIS region were located similarly to those of the Cu²⁺ chelate complexes with EDA and with the oligoamines. AFM investigations have shown that the aminocellulose films, depending on structural and environment-induced factors influencing e.g. SiO₂ polymer films, exhibit flat topographies (<1 nm), and on protonated NH₂ polymer films, such as aminopropyl-functionalized polysiloxane films, nanostructured topographies of derivative-dependent shape and nanostructure size as film supports in the form of nanotubes. The aminocellulose films could be covalently coupled with glucose oxidase enzyme by various known and novel bifunctional reactions via NH₂-reactive compounds. In this connection, it was confirmed again that the immobilized enzyme parameters, such as enzyme activity/area and K_M value, can be changed by the interplay of aminocellulose film, coupling structure and enzyme protein in the sense of an application-relevant optimization.     

Tin(IV) complexes ofSchiff bases derived from salicylaldehyde and aminoalcohols

11 and 12 molar reactions of tin(IV) chloride with theSchiff bases, HO–C₆H₄CHNROH [where R=–(CH₂)₂–, –CH₂–, –CH(CH₃)–, –(CH₂)₃–, and –CH(C₂H₅)CH₂–] have been studied in different stoichiometric ratios and derivatives of the type SnCl₄(SBH₂) and SnCl₄(SBH₂)₂ (whereSBH₂ represents theSchiff base molecule) have been isolated. These have been characterised by elemental analysis, conductivity measurements and I.R. spectral studies.     

Reaction of α,α,ω-trichloro- and α,α,α,ω-tetrachloroalkanes with alkali metal acylates in aprotic solvents

Polychloroalkanes and -alkenes R(CH₂)_nCl (R=CHCl₂CH₂, CCl₂=CH, n=1, 3) in dipolar aprotic solvents — dimethylformamide (DMF), dimethylsulfoxide (DMSO), hexamethylphosphoramide (HMPA) — at 130–150°C react selectively at the CH₂Cl group with salts of carboxylic acids RCO₂K(Na) to form dichloroesters RCO₂· (CH₂)_nR (R=CHCl₂CH₂, CCl₂=CH). In tetrachloroalkanes CCl₃CH₂(CH₂)_nCl (n = 1, 3, 5) under the same conditions the selectivity of the CCl₃ and CH₂Cl groups relative to the nucleophile RCO₂K(Na) is altered — unsaturated esters RCO₂(CH₂)_nCH=CCl₂ are formed in one stage with yields of 75–90%. Under the selected conditions, high conversion of polychloroalkanes to esters is attained 3 to 5 times more rapidly than in acid media. The structure of the ester obtained has been confirmed by their PMR spectra.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2790–2793, December, 1990.     

Carbonylation of aliphatic and cyclic alcohols by carbon monoxide in the presence of complexes of BF3 with acetic,propionic, or monochloroacetic acid

Conclusions The complexes BF₃-2CH₃CH₂COOH and BF₃·2CH₃COOH and the system 3BF₃·2CH₂ClCOOH-BF₃·2CH₃-COOH are active and stable catalysts of the carbonylation reaction (80–100°, p_CO=100 atm) of tertiary and secondary alcohols of aliphatic and cyclic structure with formation of carboxylic acids in high yields and can be used repeatedly without a decrease in the initial activity.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 817–825, April, 1977.Deceased.     

Improvement on multiparameter equations of state for dimethylsiloxanes by adopting more accurate ideal-gas isobaric heat capacities: Supplementary to P. Colonna, N.R. Nannan, A. Guardone, E.W. Lemmon, Fluid Phase Equilib. 244, 193 (2006)

A recent paper by the authors reports ideal-gas isobaric heat capacities () for several siloxanes. These values were determined using ad hoc speed-of-sound measurements and ab initio calculations. Thermodynamic models for some siloxanes documented in an earlier work by the same authors adopted less accurate estimations for . This note reports coefficients for the substance-specific Aly–Lee correlations for which ensure higher accuracy when used with the multiparameter equations of state for fluids [(CH₃)₂–Si–O]₄ (D₄, octamethylcyclotetrasiloxane), [(CH₃)₂–Si–O]₅ (D₅, decamethylcyclopentasiloxane), (CH₃)₃–Si–O–Si–(CH₃)₃ (MM, hexamethyldisiloxane), and (CH₃)₃–Si–O–[(CH₃)₂–Si–O]₄–Si–(CH₃)₃ (MD₄M, tetradecamethylhexasiloxane), as described in Colonna et al. [P. Colonna, N.R. Nannan, A. Guardone, E.W. Lemmon, Multiparameter equations of state for selected siloxanes, Fluid Phase Equilib. 244 (2) (2006) 193–211].     

Novel properties of molecular assemblies of isoprenoid surfactants

Unlike micelles of straight hydrocarbon chain-surfactants, isoprenoid surfactants, CH₃ [CH(CH₃)CH₂CH₂CH₂]₃ CH(CH₃)CH₂–R (R=CH₂N⁺ (CH₃)₃ Br^–, CH₂OPO₃H^– Na⁺, CH₂OSO ₃ ^– Na⁺, CO ₂ ^– Na⁺), gave large globular and cellular assemblies in water which could be observed directly by transmission electron microscopy; critical micelle concentration of 0.31.4×10^–3 M at 20°C, aggregation number of 215×10⁴, and diameter of 200–2000 Å. A basic structure of the assemblies was a thin layer with a thickness (about 30 Å) which was close to the molecular length of the surfactants. The assemblies were decomposed during gel column chromatography; viz., they were not as stable as the liposomes of lecithins. The morphology was discussed in conjunction with a steric effect of the isoprenoid chain.     

Liquid chromatography with and of platinum complexes

Summary Reversed-phase, high-performance liquid chromatography (HPLC) on chemically bonded C₁₈-phases with acetonitrile-water mobile phases, contianing platinum complexes like Zeise's salt C₂H₄PtCl₃, the amine derivative C₂H₄–PtCl₂–NH₂–CH(CH₃)–C₆H₅ or the amino acid compound C₂H₄–PtCl–OOC–CH(N(CH₃)₂)–C₆H₅ by analogy with argentation chromatography, was used to increase selectivity for the separation of various types of olefins, amines and heterocyclic compounds. On the other hand, normal-phase adsorption chromatography on silica with n-heptane, dichloromethane and n-propanol mobile phases proves to be an ideal tool for the analytical and preparative separation of diastereomeric platinum complexes of olefins, introduced by Gil-Av, that can be easily preparedin vitro, by the reaction of C₂H₄–PtCl–OOC–CH(N(CH₃)₂)–C₆H₅ with optically active olefins in CH₂Cl₂. The preparation of the intitial complex as well as its application to the separation of several interesting types of enantiomeric olefins is described and discussed. The number and amount of separable diastereomers formed by the above reaction is strongly influenced by sterical effects. By comparison of the chromatographic pattern of either racemic or partly racemic mixtures, it is possible to decide, which peaks belong to one or the other enantiomeric form of the olefin.     

The interaction of water with sulfonium ions and the effects of hydration on the energetics of methyl group transfer: An ab initio molecular orbital study of the hydration of (CH3)3S+ and (CH3)2S+CH2CO2 −

The interactions of the sulfonium ions (CH₃)₃S⁺, (CH₃)₂S⁺CH₂CO₂ ^–, and (CH₃)₂S⁺-CH₂CH₂CO₂ ^– with up to four water molecules have been studied by ab initio molecular orbital methods. Complexes of (CH₃)₃S⁺ with one to three water molecules involve strong electrostatic sulfur-oxygen interactions; in contrast, the sulfide (CH₃)₂S interacts with water molecules via weak S-H hydrogen bonds, suggesting that methyl-group transfer from (CH₃)₃S⁺ in aqueous solution involves a significant alteration of the hydration pattern around the sulfur atom. Two conformers of (CH₃)₂S⁺CH₂CO₂ ^– were found that display sulfur-oxygen distances which are approximately 0.3 å less than the sum of the sulfur and oxygen van der Waals radii, indicating a strong intramolecular electrostatic interaction. For the complexes (CH₃)₂S⁺CH₂CO₂ ^–·nH₂O(n =1–4), water interacts primarily with the carboxylate group via hydrogen bonds, rather than electrostatically with the sulfur atom, although in complexes with the three- and four-water complexes, the proximity of the positively charged sulfur atom to the carboxylate group significantly alters the hydration pattern compared to that in the corresponding of complexes CH₃SCH₂CO₂ ^–· Thus, methyl transfer from (CH₃)₂S⁺CH₂CO₂ ^– to an acceptor in aqueous solution also involves substantial changes in the hydration pattern around the carboxylate group.     

Co-hydrolysis products of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions: Part 2 [1]

²⁹Si NMR peaks due to species with the double four-membered ring siloxane backbone composed of both Si(O^–)_4/2 and CH₃Si(O^–)_3/2 units, (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=1–3), formed by co-hydrolysis of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions in methanol have been assigned. It has been found that ²⁹Si NMR peaks due to Si(OSi)₃(O^–) units shift to lower frequencies by replacement of the adjacent Si(O^–)_4/2 units by CH₃Si(O^–)_3/2 units, in other words, with increasing m value in Si[OSi(O^–)₃]_{3 – m} [OSi(CH₃) (O^–)₂] _m (O^–) (m=0–2). Peaks from CH₃ Si(OSi)₃ units in the species have also appeared as separated due to the kind of neighbor structural units. On the basis of the assignments, positions of CH₃Si(O^–)_3/2 units in the cubic octameric siloxane framework of (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=2, 3), for both of which three isomers are present, have been estimated.     

The structures of HCOO−, CH3COO−, C2H5COO− and CH3O− in gas phase and in crystal structure by ab initio and resonance theory

The purpose of this report is to quantitatively find the cause for the elongation of the R-C bond in R-COO^– (R = H, CH₃ and C₂H₅) and the shortening of the C-O bond in CH₃-O^– upon deprotonation in the gas phase. These elongations and shortenings result from the contributions of R^–---CO₂ and H^–---CH₂=O as resonance structures to the systems. Because these structures must make only a small contribution in the crystal, the R-C bond lengths of R-COO^– (R= H and CH₃) in the crystal structure are shorter than those in the gas phase.     

Solid-state chlorodecarboxylation of mono- and dicarboxylic acids with the Pb(OAc)<Subscript>4</Subscript>-MCl system

Solid state reactions of acids RCOOH (R = n-C₇H₁₅, BuC(Et)H, n-C₉H₁₉, PhCH₂, PhCH₂CH₂, H₂C=CH(CH₂)₈, or MeOOC(CH₂)₃) with Pb(OAc)₄ combined with KCl, NaCl, CdCl₂, or NH₄Cl in the absence of a solvent and without mechanical activation afford chlorohydrocarbons RCl. The corresponding reactions of acids HOOC(CH₂)_nCOOH (n = 3–6) give dichloroalkanes Cl(CH₂)_nCl and γ-butyrolactone (n = 3).__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2105–2109, October, 2004.