Deuterium labelling and thermochemical studies of dissociative ionization of methyl substituted monosilacyclobutanes. Ring expansion in the molecular ion of 1,1,3-trimethyl-1-silacyclobutane

Dissociative ionization of 1,1-dimethyl-1-silacyclobutane, 1,1-bis(trideuteromethyl)-1-silacyclobutane, 1,1,3-trimethyl-1-silacyclobutane, 1,1-bis(trideuteromethyl)-3-methyl-1-silacyclobutane and 1,1,2-trimethyl-1-sila-cyclobutane have been studied. Low energy electron impact fragmentation of 1,1-bis(trideuteromethyl)-3-methyl-1-silacyclobutane results mainly in the loss of ethene with the involvement of the C-methyl group from the rearranged molecular ion. No fragment ions indicating rearrangement of the molecular ion have been detected in mass spectra of 1,1-bis(trideuteromethyl)-1-silacyclobutane. The ionization energies for 1,1,3-trimethyl-1-silacyclobutane, 1,1,2-trimethyl-1-silacyclobutane and 1,1-dimethyl-1-silacyclopentane, and also the appearance energies for the [M ? 28]^+˙ and [M ? 42]^+˙ ions, have been measured by photoioniza-tion mass spectrometry. The heats of formation of these ions and of 1,1,3-trimethyl-1-silacyclobutane and 1,1-dimethyl-1-silacyclopentene molecules have been calculated as have the enthalpies of the transformation processes.     

Transsilylation of disilazanes with 1-chloro-1-methyl-1-silacyclobutane and other triorganylchlorosilanes

The first stage of the reaction of hexamethyldisilazane with 1-chloro-1-methyl-1-silacyclotmtane gives 1,3,3,3-tetramethyl-1,1-trimethylenedisilazane, and after that 1,3-dimethyl-1,3-bis(trimethylene)disilazane is formed. The latter reacts with 1-chloro-1-methyl-1-silacyclobutane to give tris[methyl(trimethylene)silyl] amine. From a large number of examples it is shown that transsilylation of disilazanes with chlorosilanes is a general reaction.     

Synthesis and polymerization of 9-carbazolyl-containing 1-silacyclobutane derivatives

Novel 9-carbazolyl-containing 1-silacyclobutane derivatives containing tri-, tetra-, and pentamethylene bridges between the nitrogen and silicon atoms and 1-methyl-1-p-[dimethyl--(9-carbazolylpropyl)silyl]phenyl-1-silacyclobutane have been synthesized. Polymerization (thermally induced and catalytic) of these monomers afforded polysiltrimethylenes having 9-carbazolyl groups in the substituents framing the main chain. The copolymerization of 9-carbazolyl-containing silacyclobutanes with silacyclobutanes of other types has been carried out.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1437–1441, August, 1993.     

Anomalous reaction of sterically hindered grignard reagents with 1-α-naphthyl-1-chloro-1-silacyclobutane

Conclusions In the reaction of sterically hindered Grignard reagents with 1--naphthyl-1-chloro-1-silacyclobutane, the Si-Cl bond is reduced to Si-H with the formation of 1--naphthyl-1-silacyclobutane. When the reaction is conducted in toluene, metallization of the solvent is the basic transformation, resulting in the formation of 1--naphthyl-1-benzyl-1-silacyclobutane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 434–437, February, 1986.     

Synthesis of complexes containing silacyclobutane groupings and variable valence metals

Conclusions On the example of the synthesis of the complexes of 1-methyl-1-(3-pyridyl)-1-silacyclobutane with the cobalt and nickel halides it was shown that it is possible to obtain the complexes of the transition metals with heterocyeles that contain four-member ed silicon-carbon groups.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 135–137, January, 1973.     

Reactions of alkoxy and amino derivatives of silacyclobutane with amino alcohols

2-(N,N-Dimethylamino)ethanol readily replaces the MeO and Et₂N groups in 1-methoxy-1-methyl-, 1,1-dimethoxy-, 1-diethylamino-1-methyl-and 1,1-bis(diethylamino)-1-silacyclobutanes to form dimethylaminoethoxy derivatives. Triethanolamine and N,N-bis(2-hydroxyethyl)glycinamide split the silacyclobutane ring in 1,1-dimethoxy-1-silacyclobutane to form 1-propylsilathrane and 1-propyl-2-azasilathran-3-one, respectively.     

New infrared spectroscopic observation of 1,1-dimethyl-1-silaethylene in an argon matrix

Conclusions The pyrolysis of 1,1,3-trimethyl-1-silacyclobutane in vacuo gave 1,1-dimethyl-1-silaethylene, which was stabilized in an argon matrix at 10°K, and its most intense IR absorption bands were recorded: 643.0, 825.2, 1003.5 cm^–1, which coincide exactly with the IR spectrum of the same particle when obtained by the pyrolysis of 1,1-dimethyl-1-silacyclobutane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2152–2153, September, 1979.     

Selective on-line deuteration in gas chromatography - mass spectrometry for the investigation of dissociative ionization of silicon-containing compounds

A method for specific gas-phase deuteration of unsaturated silicon-containing compounds over pre-heterogenized Wilkinson's catalyst (a solution of (Ph₃P)₃RhCl in Carbowax 20M coated on Chromaton) in the reaction column connected to the mass spectrometer is described. This method was employed to study the dissociative ionization of the corresponding saturated analogues. With the aid of the mass spectra of the dideutero derivatives thus obtained, the main electron-impact-induced reactions of 1,1-dimethyl-1-silacyclopentane, 1,1,2,2-tetramethyl-1,2-disilacyclohexane, 1-methyl-1-ethyl-1-silacyclobutane and ethyl triethoxysilane were elucidated.     

Complexes of N-derivatives of 1-amino-1-silacyclobutane with aluminum chloride

Conclusions A study was made of the reaction of the N-derivatives of 1-amino-1-silacyclobutane with aluminum chloride, and it was shown that organoaluminum complexes containing silacyclobutane groups can be formed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1364–1366, June, 1973.     

1-烃基-1-硅杂环丁烷的合成及其Si—H键伸缩振动频率与结构关系的研究

硅杂环丁烷在有机硅化学中是一类非常重要的小分子环系化合物。由于硅杂环丁烷和环丁烷的环张力相似,因而显示出较高的反应活性。例如能与某些试剂作用,生成开环产物;在光解或热解条件下,产生具有Si=C结构的高活性中间体,可用以合成多种有机硅化合物。     

Deposition of Silicon Carbide Thin Films from 1,1-Dimethyl-1-Silacyclobutane

1,1-Dimethyl-1-silacyclobutane was used as a single-source precursor to deposit SiC thin films on Si(100) and Si(111) by low-pressure chemical vapor deposition (LPCVD). Polycrystalline β-SiC thin films were grown at temperatures 1100 and 1200°C. At temperatures between 950 and 1100°C, amorphous thin films of silicon carbide were obtained. The films were studied by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and electron diffraction (ED).     

Pyrolysis of 1,1,2-trimethyl-1-silacyclobutane. Site of initial ring cleavage

The gas-phase, flow pyrolysis of 1,1,2-trimethyl-1-silacyclobutane (I) is described. A total of six products, containing two silicon atoms, have been analyzed with respect to relative yields (at 520°, 570°, 620° and 680°) and mechanistic origin. It is concluded that thermolysis of I occurs with predominant initial cleavage of the carboncarbon bond rather than the siliconcarbon bond and that further cleavage affords a silaalkene, Me₂Si=CHCH₃. The pyrolysis of 1,1,3,3-tetramethyl-1,3-disilacyclobutane at 700° leads to silaalkene production as shown through trapping with benzaldehyde.     

1,1-Dimethyl-1-silaethylene : Heat of formation,ionization potential and the energy of the siliconcarbon π-bond

The thermodynamic cycle consisting of thermal decomposition and dissociative ionization processes for 1,1-dimethyl-1-silacyclobutane is calculated. The heat of formation and the ionization potential (IP) for 1,1-dimethyl-1-sila-ethylene (DMSE) have been obtained: ΔH^o_f(DMSE) = 15.5 ± 5 kcal/mol; IP(DMSE) = 7.5 ± 0.3 eV. The siliconcarbon π-bond energy in DMSE is estimated: D_π(SiC)  28 ± 8 kcal/mol.     

Amination of isomeric bromo-1-methylnitropyrazoles

A method was developed for the synthesis of 5-bromo-1-methyl-4-nitropyrazole from 1-methylpyrazole. In the reaction with 25% aqueous ammonia at 180–190 °C, 5-bromo-1-methyl-4-nitropyrazole is readily converted to 5-amino-1-methyl-4-nitropyrazole; the production of 4-amino-1-methyl-5-nitropyrazole from 4-bromo-1-methyl-5-nitropyrazole requires the presence of a copper catalyst; under the same conditions in the amination of 4-bromo-1-methyl-3-nitropyrazole, 4-amino-1-methyl-3-nitro- and 1-methyl-3-nitropyrazoles are formed in a 23 ratio.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1672–1675, December, 1983.     

Studies on the mechanism of decomposition of 1-methyl-1-(1-naphthyl)ethyl hydroperoxides to 2-(1-naphthyloxy)propenes

Abstract  

Thermal decomposition of 1-methyl-1-(4-methyl-1-naphthyl)ethyl hydroperoxide under gas chromatography-mass spectroscopy (GC–MS) conditions gives 2-((4-methyl-1-naphthyl)oxy)propene as the main product (50.5%), without any detectable traces of the isomeric 2-((5-methyl-1-naphthyl)oxy)propene. This finding excludes the rearrangement pathway of 1-methyl-1-(1-naphthyl)ethyl hydroperoxides to the corresponding 2-(1-naphthyloxy)propenes, which involves formation of a naphthofuran derivative as an intermediate and transfer of the isopropenyloxy group to the 8 position. This result, as well as our previous density functional theory (DFT) calculations, points to the rearrangement pathway involving an oxirane-type intermediate as the most plausible pathway to 2-(1-naphthyloxy)propenes. This rearrangement is responsible for the unusual inhibition effects of 1-methyl-1-(1-naphthyl)ethyl hydroperoxide on the liquid-phase oxidation of isopropylarenes with oxygen.     

Amidrazones 11. Rearrangement of 1-allyl-substituted-4,5-dihydro-1-methyl-1H-pyrazolium bromides

1-Methyl-2-(2-propenyl)-3-pyrazolidinimine ( 5 ) was obtained by treatment of 3-amino-4,5-dihydro-1-methyl- 1-(2-propenyl)-1H-pyrazolium bromide ( 4 ) with ethanolic sodium ethoxide. Similar treatment of the analogous 2-(2-butenyl) and 2-(3-phenyl-2-propenyl)-substituted salts 12 and 15 gave 1-methyl-2-(1-methyl-2-propenyl)-3- pyrazolidinimine ( 13 ) and 1-methyl-2-(1-phenyl-1-propenyl)-3-pyrazolidinimine ( 16 ) respectively.     

Oxidation of 1-methyl-1H-imidazole-2-thiol with chlorine dioxide

Oxidation of 1-methyl-1H-imidazole-2-thiol with chlorine dioxide was performed for the first time, and the results were shown to depend on the oxidation conditions. Optimal conditions were found for the preparation of 1-methylimidazole-2-sulfonic acid, 2,2′-disulfanediylbis(1-methylimidazole) hydrochlorite, and 1-methyl-3-sulfo-3H-imidazolium chloride. A new salt, 4-methylanilinium 1-methyl-1H-imidazole-2-sulfonate, was isolated.     

Benzazoles: II. Synthesis and arenesulfonylation of 1-methyl-1H-benzimidazol-2-amine

The reaction of 1-methyl-1H-benzimidazol-2-amine with arenesulfonyl chlorides in the presence of triethylamine afforded 1-arenesulfonyl-3-methyl-2,3-dihydro-1H-benzimidazol-2-imines instead of expected N-(1-methyl-1H-benzimidazol 2-yl)arenesulfonamides.     

Planar silicon-carbon heterocycle in dinaphthylsilacyclobutane

Conclusions As a result of an x-ray structure study of 1,1-di--naphthyl-1-silacyclobutane, a planar structure has been established for the first time for a four-membered silicon-carbon heterocycle.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2060–2065, September, 1982.