Modification of interlayer space of kanemite with trimethylsilyl groups: structure and adsorption properties

Interlayer hydroxyl groups of layered silicate kanemite have been modified with trimethylsilyl groups by the reaction between the hydroxyl groups and trimethylchlorosilane. Expansion of the interlayer space by intercalation of dimethyldialkylammonium ions into the silicate layers enables the silylating reagent to access the hydroxyl groups. An increase in specific surface areas was observed with increasing concentration of trimethylsilyl groups. This result suggests that the interlayer space of kanemite can be used as an effective molecular adsorption space by weakening the interaction between the interlayer hydrogen bonds of hydroxyl groups. The modification of kanemite with trimethylsilyl groups restricted the adsorption of water below a monolayer capacity and was favorable for benzene adsorption.     

Bildung und Eigenschaften von Acylphosphinen. II. Verbindungen aus der Reaktion von Tris(trimethylsilyl)phosphin mit Pivaloylchlorid

Syntheses and Properties of Acylphosphines. II. Compounds from the Reaction of Tris(trimethylsilyl)phosphine with Pivaloyl Chloride Tris(trimethylsilyl)phosphine reacts with pivaloyl chloride at +20°C in cyclopentane to form the enol form of pivaloylbis(trimethylsilyl)phosphine. In this compound one trimethylsilyl group is bound to phosphorus, the other to oxygen. As the n.m.r. spectra of the reaction at ?10°C in monoglyme show the thermally instable keto form with two trimethylsilyl groups bound to phosphorus is formed first and rearranges at slightly elevated temperatures. Substitution of the second trimethylsilyl group yields the enol form of dipivaloyltrimethylsilylphosphine. Tripivaloylphosphine with three acyl groups bound to phosphorus and the enol form of tert. butylpivaloyltrimethyl-silylphosphine are produced in side reactions.     

Identification of isomeric structures of phenyl and trimethylsilyl substituted 1-alkenes by gas chromatography

Summary Gas chromatographic retention indices had been measured on two different stationary phases for phenyl and trimethylsilyl substituted 1-alkenes formed during the pyrolysis of a styrene-trimethylvinyl silane copolymer. Retention index differences due to the alteration of trimethylsilyl to phenyl substituent groups at different positions in the molecules of the 1-alkene skeleton were determined. Based on these values the isomeric structure of the pyrolysis products has been identified by determining the position of the trimethylsilyl and phenyl groups in these substituted 1-alkenes. The results correspond to the mechanism of the copolymer's thermal degradation.     

Synthesis of polyacetylenic montiporic acids by means of organosilicon compounds

A straightforward synthesis of polyacetylenic montiporic acids A and B has been developed, based upon the selective and sequential substitution of the two trimethylsilyl groups of the readily available 1,4-bis(trimethylsilyl)-1,3-butadiyne.     

Synthesis of the New Types of N‐Unsubstituted Aminomethylenebisorganophosphorus Acids and Their Derivatives

The interaction of trimethylsilyl esters of trivalent organophosphorus acids containing PH and POSiMe₃ groups with hydrochlorides of ethoxymethylene imines is a convenient method for the synthesis of new trimethylsilyl esters of N‐unsubstituted aminomethylenebisorganophosphorus acids with three and four coordinated phosphorus. Also trimethylsilyl trifluoromethanesulfonate as effective catalyst is used for the similar interaction of hydrochlorides of ethoxymethylene imines with tris(trimethylsilyl)phosphite. The corresponding bisorganophosphorus acids and their derivatives are presented.     

Copolymerisation of maleic anhydride with electron-acceptor monomers

Copolymerisation of maleic anhydride with tert.-butyl methacrylate and trimethylsilyl methacrylate was studied. Both monomers form random copolymers with maleic anhydride and in both cases the acceptor monomer is incorporated preferentially into the copolymer. Maleic anhydride which does not homopolymerise has reactivity ratios of approximately zero. The esters have reactivity ratios of 12.8 for trimethylsilyl methacrylate and 2.95 for tert.-butyl methacrylate. Thermal behavior and molar masses were investigated as a function of composition. Conditions for hydrolysis of the trimethylsilyl ester groups to give free acid groups have been established.     

Synthesis of 4- and 5-substituted 1-hydroxyimidazoles through directed lithiation and metal-halogen exchange.

Electrophiles were introduced regioselectively at the 5-position of 1-(benzyloxy)imidazole by lithiation at C-5 after protection of C-2 with a chloro or a trimethylsilyl group. Subsequent treatment with an electrophile afforded 5-substituted 1-(benzyloxy)-2-chloroimidazoles 8-13 and 5-substituted 1-(benzyloxy)imidazoles 3-5, the 2-(trimethylsilyl) group being lost during workup. Electrophiles were introduced regioselectively at the 4-position of 1-(benzyloxy)imidazole by bromine-lithium exchange of 4-bromo-2-chloro-1-(benzyloxy)imidazoles, protected at C-5 with chloro or trimethylsilyl groups, followed by reaction with an electrophile. The 5-(trimethylsilyl) group was removed via base-catalyzed desilylation. Chlorine at C-2 and O-benzyl groups were removed by palladium-catalyzed hydrogenolysis.     

Mass spectrometry in structural and stereochemical problems–CLXXXIX: Electron-impact induced fragmentations and rearrangements of alkoxycyclohexanol trimethylsilyl ethers and alkoxycyclohexyl trimethylsilanes

In view of the current interest in the electron-impact induced rearrangements of both trimethylsilyl derivatives and bifunctionalized cyclohexanes, the mass spectral properties of several alkoxycyclohexanol trimethylsilyl ethers and alkoxycyclohexyl trimethylsilanes have been investigated. Using deuterium labeling, the basic fragmentation modes incurred upon electron-impact of ethanol trimethylsilyl ether were elucidated. The major peaks in the spectrum of this simple ether occur also in those of the title compounds, the latter fragments having been formed by interaction of the two functional groups. Thus the initial rearrangement ion of mass 103 (e) from electron bombardment of 4-ethoxycyclohexanol trimethylsilyl ether and 2-ethoxycyclohexyl trimethylsilane corresponds to the [M ? CH₃] ion from ethanol trimethylsilyl ether. Its further fragmentation has been studied using high resolution and metastable ion measurements, and the scope of the interaction between the alkoxy and trimethylsilyl groups, when silicon is attached both to oxygen and to carbon, has been determined. In addition, the origin of every ‘characteristic’ fragment ion has been elucidated on the basis of each corresponding peak in the spectra of several derivatives labeled specifically with deuterium. Peaks derived from initial ionization of both functionalities in each compound have been observed, although the majority of ions in the spectra of both series seem to be directed by fragmentations associated with the trimethylsilyl ether moiety.     

Formation of trimethylsilylated open-cage oligomeric azidophenylsilsesquioxanes

Formation of open-cage oligomeric azidophenylsilsesquioxane was surprisingly discovered in the successive reduction and azidation reactions starting from octa(nitrophenyl)octasilsesquioxane. The mixture of oligomeric products was characterized after end-capping with trimethylsilyl groups. The IR spectra confirmed the introduction of azide function to aromatic moiety, and trimethylsilyl group on silsesquioxane framework. Together with the GPC result, NMR analysis revealed the introduction of different number of trimethylsilyl groups in the structure. Some of them maintained the cage-like silsesquioxane structure characterized by XRD analysis. Their TGA profiles gave a unique pattern with clear two-step mass loss with the first mass loss of about 8-10 wt% from 180 to 225 °C corresponding to a thermal decomposition of azide groups.     

Stereoselective total synthesis of (S)-Virol C and (S)-1-dehydroxyvirol A

A stereoselective total synthesis of (S)-Virol C and (S)-1-dehydroxyvirol A has been developed, based upon the selective and sequential substitution of the two trimethylsilyl groups of readily available 1,4-bis(trimethylsilyl)-1,3-butadiyne.     

Reactions of Tris(acetonitrile)tricarbonylchromium with Trimethylsilylarenes

The reactions of tris(acetonitrile)tricarbonylchromium 1 with trimethylsilyl derivatives 2–5 of phenalene, indene, 1,2-dihydronaphthalene and trans-β-methylstyrene gave products 10-13, respectively, containing no trimethylsilyl groups. The reactions of 1 with trimethylsilyl derivatives 6–8 of benzene, toluene and cycloheptatriene gave products 14–16, respectively, containing trimethylsilyl groups. The reaction of 1 with 1,2-bis(trimethylsily-1,2-dihydro)naphthalene 9 gave product 17 in which only trimethylsilyl at the allylic position was cleaved. Compound 10 crystallizes in the orthorhombic system, space group Pbca, with a = 12.228(4), b = 14.288(1), c = 15.128(3) Å, Z = 8, R_F= 0.046, and R_w = 0.047. X-ray crystallographic data confirm that the Cr(CO)₃ moiety is bonded to phenalene in a η⁶-mold.     

Synthesis of new α-aminonitriles containing organosilicon groups via three component Strecker reactions

A three-component efficient procedure is described for the synthesis of α-aminonitriles containing bis(trimethylsilyl)ethenyl groups from 4-[2,2-bis(trimethylsilyl)ethenyl]benzaldehyde (1), aromatic amines and trimethylsilyl cyanide (TMSCN). Reactions have been studied in the presence of various Lewis acids as catalysts or in ionic liquids under mild conditions. Compound (1) was obtained via Peterson olefination of terephthaldehyde with tris(trimethylsilyl)methyllithium, (Me₃Si)₃CLi, in THF at 0 °C.     

Mass spectra of trimethylsilyl derivatives of naturally occurring flavonoid aglycones and chalcones

Electron impact mass spectra of the trimethylsilyl derivatives of a series of flavonoid aglycones and chalcones are reported. The spectra show prominent ions arising from fragmentation of the trimethylsilyl (TMS) groups. Inter-actions between adjacent TMS groups, and between TMS groups in the 3- or 5-position (6′-position for the chalcones) and the C-ring carbonyl, yield structurally significant ions. Few fragments associated with the retro-Diels-Alder cleavage of the C-ring characteristic of the underivatized compounds, are observed. The TMS derivatives thus provide complementary information for the identification of flavonoid aglycones and chalcones in biological systems.     

Preparation of 6,13-bis(trimethylsilyl)pentacene and formation of second-ring Diels-Alder adduct of pentacene

6,13-Bis(trimethylsilyl)pentacene was synthesized by a coupling reaction of bicyclic dilithiobutadiene with diiodonaphthalene followed by aromatization. Diels-Alder reaction of 6,13-bis(trimethylsilyl)pentacene with dienophiles afforded the corresponding second-ring adducts. Elimination of two silyl groups gave the second-ring Diels-Alder adducts of parent pentacene.     

The mass spectra of the trimethylsilyl derivatives of some alkyl and aminoalkyl phosphonates

The mass spectra of the trimethylsilyl derivatives of a series of alkyl and aminoalkyl phosphonates were investigated with the aid of deuterium labeling and high resolution mass measurements. The spectra contained several prominent ions characteristic of the phosphonate system and a number of ions produced by inter and intra molecular migration and interaction of trimethylsilyl groups.     

Tris(trimethylsilyl)silylamin und seine lithiierten und silylierten Derivate — Kristallstruktur des dimeren Lithium-trimethylsilyl-[tris(trimethylsilyl)silyl]amids

Tris(trimethylsilyl)silylamine and the lithiated and silylated Derivatives — X-Ray Structure of the dimeric Lithium Trimethylsilyl-[tris(trimethylsilyl)silyl]amide The ammonolysis of the chlor, brom or trifluormethanesulfonyl tris(trimethylsilyl)silane yields the colorless tris(trimethylsilyl)silylamine, destillable at 51°C and 0.02 Torr. The subsequent lithiation, reaction with chlor trimethylsilane and repeated lithiation lead to the formation of lithium tris(trimethylsilyl)silylamide, trimethylsilyl-[tris(trimethylsilyl)silyl]amine and finally lithium trimethylsilyl-[tris(trimethylsilyl)silyl]amide, which crystallizes in the monoclinic space group P2₁/n with a = 1 386.7(2); b = 2 040.2(3); c = 1 609.6(2) pm; β = 96.95(1)° and Z = 4 dimeric molecules. The cyclic Li₂N₂ moiety with Li? N bond distances displays a short transannular Li …? Li contact of 229 pm. The dimeric molecule shows nearly C₂-symmetry, so that one lithium atom forms agostic bonds to both the trimethylsilyl groups, the other one to the tris(trimethylsilyl)silyl substituents. However, the ⁷Li{¹H}-NMR spectrum displays a high field shifted singlet at —1.71 ppm. The lithiation of trimethylsilyl-[tris(trimethylsilyl)silyl]amine leads to a high field shift of the ²⁹Si{¹H} resonance of about 12 ppm for the Me₃SiN group, whereas the parameters of the tris(trimethylsilyl)silyl ligand remain nearly unaffected.     

Preparation and constitution of the Crystalline Silicic Acid Trimethylsilyl Ester [(CH3)3Si]6Si6O15

A new crystalline compound has been synthesized by trimethylsilylation of tetraethylammonium silicate which was identified by means of gas chromatography, mass spectrometry, ²⁹Si NMR and X-ray analysis to be a eage-like double three-ring silicic acid trimethylsilyl ester containing six inequivalent SiO₄ tetrahedra and trimethylsilyl groups.     

Systematic Studies on Homo- and Heteronuclear Doubly Bonded Compounds of Heavier Group 15 Elements

The first stable phosphabismuthene (R 1 --P=Bi--R 2 ) and stibabismuthene (R 1 --Sb=Bi--R 2 ) were successfully synthesized by taking advantage of efficient steric protection groups, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt), 2,6-bis[bis(trimethylsilyl)-methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt), and 2,4,6-tri- t -butylphenyl (Mes*). Their spectroscopic properties and structural parameters were systematically compared with those of previously reported stable, homonuclear, doubly bonded systems, such as diphosphene, diarsene, distibene, and dibismuthene.     

The GLC Separation of Hydroxyl-Substituted Amines of Biological Importance Including the Catecholamines. Preparation of Derivatives for Electron Capture Detection

Abstract

The catecholamines and related biological amines have been converted to trimethylsilyl ether-amide derivatives through a two-step reaction sequence. All hydroxyl groups (phenolic and alcohol) were converted to TMSi ethers by reaction with TSIM. N-acylimidazole was added to the reaction mixture to effect the acylation of primary and secondary amines. TMSi-Ac (trimethylsilyl ether-acetyl) and TMSi-HFB (trimethylsilyl ether-heptafluorobutyryl) derivatives were studied. The HFB derivatives had excellent GLC properties. It is proposed to compare the sensitivity of detection of these and related compounds by flame ionization and by electron capture detection systems.     

Interaction of trimethylsilyl ions with nitrates of the estrane series in the gas phase

The interaction of trimethylsilyl ions with nitrates of the estrane series affords the adducts [M + SiMe₃]⁺, whose fragmentation proceeds through the elimination of the functional groups either along with the trimethylsilyl residue, or in the form of molecules containing no SiMe₃.