A. I. Mikaya

Ring-opening polymerization of cycloolefins by tungsten(VI) chloride—acetylene catalyst systems

Abstract The ring-opening polymerization of various cycloolefins was carried out using catalytic systems for metathesis that did not contain any organometallic co-cotalysts. They were formed by the interaction of equimolar amounts of tungsten(VI) halides (WCl 6 or WOCl 4 ) with monosubstituted acetylenic hydrocarbons (phenyl-, n-butyl- or trimethylsilylacetylene). It was possible to enhance the activity of these systems by adding small amounts of oxygen-containing substances. The use of WCl 4 -phenyl-acetylene catalyst clarified the question of polymerizability of methyl-substituted cyclopentenes. It was shown that a mixture of 3-methyl- and 4-methylcyclopentenes gave polymers having a polymethylpentenamer structure. The thermodynamic parameters of this polymerization, which has an equilibrium character, were evaluated. Reactions occurring during the interaction of WCl 6 with phenylacetylene were studied by GC-MS. The data obtained indicated that the first step in the interaction is insertion of an acetylene molecule into the WCl bond. Some considerations are suggested concerning the possible pathways for formation of metal-carbene active centres. 13 C NMR study of the copolymers obtained from phenylacetylene and cyclopentene or norbornene showed that their chains included sequences with random distributions of co-monomer units. The implications of this fact for the mechanistic interrelation between the cycloolefin metathesis polymerization and the addition polymerization of acetylene are discussed.

Effective gas-phase deoxygenation of alcohols and ketones on iron catalyst

Abstract A method of gas-phase deoxygenation of alcohols and ketones into hydrocarbons on iron catalyst at 600 K and 1–2·105 Pa is discussed.

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

Abstract A method for specific gas-phase deuteration of unsaturated silicon-containing compounds over pre-heterogenized Wilkinsons catalyst (a solution of (Ph 3 P) 3 RhCl 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.

Mechanism of gas-phase hydrogenation of alicyclic ketones on iron catalyst: effective experimental method on the basis of reaction gas chromatography/mass spectrometry

Abstract The mechanism of gas-phase deuterium addition to cyclopentanone and cyclohexanone over fused iron catalyst has been studied by reaction gas chromatography/mass spectrometry ( GC MS ) which involves the on-line deuteriogenation and on-column silylation of reaction products. It has been found that in the temperature range of 50–210 °C cyclanone hydrogenation proceeds both via ketonic and enolic mechanisms. Also, it has been shown that the method developed can be used for the determination of enolic forms of carbonyl compounds in the gas phase.

Iron carbonyl complexes containing an azomethylene moiety III. Mass-spectrometric study of diiron hexacarbonyl complexes from azomethynes and azines

Abstract The electron impact mass spectra of diironhexacarbonyl complexes prepared from benzylidene- and α-naphthylidene-anilines, benzalazine and ketazines of acetophenone, p-bromoacetophenone and benzophenone are studied. The main fragmentation of the ligands occurs only after complete decarbonylation of the molecular ions and involves rupture of metal-ligand bonds, elimination of a part of the central ligand in the form of HCN and RCN, elimination of a neutral aromatic fragment or elimination of a part of the ligand.

Cycloorganosilyl derivatives for the determination of alcohols and carboxylic acids by gas chromatography/mass spectrometry

New silylating agents—methyl(trimethylene-, tetramethylene-, pentamethylene)silyl chlorides, ethyl(tetramethylene-, pentamethylene)silyl chlorides and chloromethyl(pentamethylene)silyl chlorides—are suggested for the investigation of alcohols and carboxylic acids by gas chromatography/mass spectrometry (GC/MS). It is shown that corresponding derivatives may easily be prepared by solution reactions and by on-column silylation. All the derivatives appeared to be less mobile in GC than trimethylsilyl derivatives. Under electron impact (EI), all the derivatives [except chloromethyl(pentamethylene)silyl derivatives] of primary alcohols form pronounced molecular ions. For all kinds of derivatives obtained from secondary alcohols, the most characteristic fragmentation is due to cleavage of a C–C bond near to the silyloxy group. The mass spectra of trimethylene- and tetramethylenesilyl ethers derived from isomeric straight-chain and branched alcohols differ quantitatively. Main fragmentation reactions of the latter derivatives under EI conditions are elucidated with the aid of D-analogues. The mass spectra of cycloorganosilyl esters of alkanoic acids are less characteristic and are due mainly to the loss of an alkyl radical from the silicon atom or to a cleavage of the silacycloalkane ring in molecular ions.

Pyrolysis of silicon-containing cyclic polysulphides

Abstract Thermal decomposition of silicon-containing monocyclic polysulphides 1-methyl-3-trimethylsilyl-2,5-dithiacyclopentane (I), 1,4-bis(trimethylsilyl)-2,3,6,7-tetrathiacyclooctane (II) and 1-trimethylsilyl-2,3,4,5,6-pentathiacycloheptane (III)) has been studied at temperatures from 400 to 600° C using the pulse pyrolytic GC/MS method. The major decomposition of the compounds leads to trimethylvinylsilane, carbon disulphide, silicon disulphide, thiophene and its homologues as well as lower hydrocarbons and trimethylsilyl-substituted thiophenes. No similarity has been found between the electron-impact induced and thermal processes.

Mass spectrometric investigation of silicon-containing cyclic polysulphides

Abstract The electron impact-induced decomposition of cyclic polysuphides prepared by the cycloaddition reaction between Sx and trimethylvinylsilane (1-trimethylsilyl- 2,3,4,5,6-pentathiacycloheptane (I), 1-methyl-3-trimethylsilyl-2,5-dithiacyclopentane (II), 1,4-di(trimethylsilyl)-2,3,6-trithiacycloheptane (III), 1,4-di(trimethylsilyl)- 2,3,6,7-tetrathiacyclooctane (IV) and 1,1-dimethyl-1-silacyclopentene (8,8-dimethyl 8-sila-2,3,4,5-tetrathiabicyclo[4.3.0] nonane (V), 6,6,13,13-tetramethyl-6,13-disila- 2,3,9,10-tetrathiatricyclo[9.3.0.04,8]tetradecane (VI) and 7,7,14,14-tetramethyl-7,14- disila-2,3,4,10,11-pentathiatricyclo[10.3.0.05,9]pentadecane (VII) has been studied. The major fragmentation pathway of the compounds I–IV, containing a silicon atom in the side chain trimethylsilyl group, results in the formation of the [(CH3)3SiCHCH2S]+ ions. Skeletal rearrangements associated with the migration of sulphur atoms to silicon and the loss of C4H6 appeared to be characteristic of polysulphides V–VII which contain silicon atom in annelated cycle. The [CH3)2 SiS2+ and [(CH32Si=s]+ ions are the final products of the rearrangements

Reductive Dimerization and Oligomerization of Alcohols, Ketones, and Aldehydes to Hydrocarbons on a Promoted, Fused Iron Catalyst

A new reductive dimerization and oligomerization reaction of (C5 and C6) cycloalkanols and cycloalkanones, benzaldehyde, and benzyl alcohol to hydrocarbons containing as many, or more, carbon atoms as the reactant oxygenated compound on a promoted, fused iron catalyst proceeds at a temperature of 250–350°C, a hydrogen pressure of 0.1–1 MPa, a specific feed rate of oxygenated reagent of 80–320 g h−1kg−1Ct, and a hydrogen space velocity of 1 × 103 to 20 × 103 h−1. Possible reaction mechanisms have been considered.

Alkylation of 4-methoxyphenol with styrene in the presence of alumoxane compounds

The catalytic properties of alumoxane compounds in the alkylation of 4-methoxyphenol with styrene were studied. Structures and yields of aikylation products depend on the amount of catalyst, the phenol: olefin ratio, and the reaction time. Phenoxyalumoxanes are effectiveortho-directing catalysts with respect to the hydroxy group. Under optimum conditions, 2-(α-methylbenzyl)-4-methoxyphenol and 2,5-di-(α-methylbenzyl)-4-methoxyphenol were obtained in 94 % and 84–86 % yields, respectively.