Silicon Moiety Research Articles

Synthesis and spectral study of low dimensional poly-yne polymers containing phthalocyanine silicon and dimethyl silicon in the polymer backbone

A pseudo-one-dimensional poly-yne polymer (I) in which phthalocyanine silicon (PcSi) moieties are bridged by p-diethynylbenzo groups has been obtained by a salt elimination reaction from dichlorophthalocyaninato silicon and the disodium salt of p-diethynylbenzene in tetrahydrofuran (THF) solution. A soluble mixture of short chain oligomers of this polymer was also obtained. For parallel study, an analogous low dimensional poly-yne polymer (III) was synthesized by reaction of dimethyldichlorosilicon with the disodium salt of diethynylbenzene in ether solution. Materials I and III were found to be stable in air and have good thermal stability. These two polymers were characterized by spectral and analytical data.

Metal—silicon bonded compounds: XIV. The electronic spectra of silicon—mercury derivatives

The ultraviolet and visible spectra of compounds of the general formula Hg(SiCl 3- x R x ) 2 where R  Me, Ph are reported. In addition spectra have been obtained on the compounds Hg(GeMe 3) 2, Hg[Si(SiMe 3) 3] 2 and the cyclic compound H gSi(Me 2)CH 2SiMe 2HgSiMe 2CH 2S iMe 2. In cyclohexane all compounds show three characteristic bands, two at ≈4 eV and on at ≈6 eV. Extended Hückel calculations have been used to obtain a qualitative energy level scheme and to make tentative assignments for the transitions. The 4 eV transitions have been assigned to transitions from the ground state, 1A 1, to be 1B 1 and 1A 2 states respectively and the 6 eV transition to a transition to an excited 1A 1 state. The orbitals involved are principally centered on the mercury atom with their energies perturbated by the attached silicon moieties.

Thermal and dielectric properties of styrene and acrylonitrile copolymers with vinyl silanes

Thermal behaviour of copolymers of styrene with 2,6-dimethyl-2,7-octadiene-6-trimethylsilyl ether (linalloxytrimethylsilane, LTMS) and [(2-methacryloyloxy) ethoxy]-trimethylsilane (2-MAETMS) and acrylonitrile-LTMS copolymers has been studied by TGA and DTA. The initial decomposition temperature (IDT) for all the copolymers is less than for polystyrene and polyacrylonitrile irrespective of the nature of the silicon comonomer. However, integral procedural decomposition temperatures (IPDT) and the activation energies for thermal degradation are higher for copolymers. Dielectric measurements have been made at temperatures between 30 and 140° in the frequency range 2.5 × 10 5–10 7 Hz. The higher activation energies of dipolar losses in copolymers are related to the polarity of the silicon moiety in the styrene copolymers.

The redistribution equilibria of silanic hydrogen with chlorine on methylsilicon moieties

The scrambling equilibria of silanic hydrogen with chlorine atoms on various combinations of mono-, di-, and trimethylsilicon moieties have been determined by proton nuclear magnetic resonance. The data have been evaluated in terms of sets of equilibrium constants which show that at equilibrium, the exchangeable hydrogen atoms prefer to be with the silicon moiety bearing the least number of methyl groups.

Dissolution of the toxic parasporal crystals from Bacillus thuringiensis var. pacificus by the gut secretions of the silkworm, Bombyx mori

The mode of action of the fluid secreted by the midgut of the silkworm, Bombyx mori, on the “B.t. δ endotoxin” (crystal toxin) produced by Bacillus thuringiensis var. pacificus was investigated by using selective experimental conditions. Initial dissolution of the proteinaceous, crystalline toxin is accomplished in the insect gut only by action of the nonenzymatic alkaline components (e.g., potassium carbonate). Thereafter the proteolytic enzymes present are capable of attacking and further degrading the crystalline structure. This initial solubilization probably is accomplished by the conversion of the silicon moiety within the parasporal crystals to a soluble salt of silicic acid by the alkaline components of the gut secretions. However, the time during the degradation process when the toxic principle is released is yet to be determined.