Silicon peroxides

Alkyl-substituted silicon peroxides, 78 444 Alkyl sulfates, 23 537 use in cosmetics, 7 849 Alkylsulfones, O-alkylation and, 9 280 Alkyl sulfoxide, micellization of, 24 132t Alkyl tertiary alkyl ethers, 70 575 Alkylthexylboranes, 73 639 Alkyl-thiols, 77 57 4-Alkylthiosemicarbazides, 73 575 Alkyl-tin catalysts, 20 40 Alkyltitanium halides, 25 108—109 Alkyltitaniums, 25 106 higher, 25 116... 

Silicon oxynitride, 22 541 Silicon peroxides, 18 439 Silicon photoconductors, doped,... 

Silanone, disilene oxidation, 821 Silicon peroxides see Silyl peroxides Silicotungstate compound, olefin epoxidation,... 

High Temperature Vulcanized Silicone (Peroxide Cured)... 

Oldhamite, see Calcium sulfide Opal, see Silicon dioxide Orpiment, see Arsenic trisulfide Oxygen powder, see Sodium peroxide... 

Many organic peroxides of metals have been hydrolyzed to alkyl hydroperoxides. The alkylperoxy derivatives of aluminum, antimony, arsenic, boron, cadmium, germanium, lead, magnesium, phosphoms, silicon, tin, and zinc yield alkyl hydroperoxides upon hydrolysis (10,33,60,61). 

Organomineral peroxides of antimony arsenic, boron, magnesium, tin, cadmium, lead, silicon, and 2inc have been prepared by autoxidation and some are Hsted in Table 3 (33,44,60,93,115). For example, dimethyl cadmium reacts with oxygen to form methylperoxy methyl cadmium [69331-62-0] and bis(methylperoxy) cadmium. 

Chromium oxide is mixed with aluminum powder, placed in a refractory-lined vessel, and ignited with barium peroxide and magnesium powder. The reaction is exothermic and self-sustaining. Chromium metal of 97—99% purity is obtained, the chief impurities being aluminum, iron, and silicon (Table 4). Commercial chromium metal may also be produced from the oxide by reduction with silicon in an electric-arc furnace. 

Silicone rubbers are normally cured with peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide and t-butyl perbenzoate being used for the dimethyl-silicones in quantities of 0.5-3%. These materials are stable in the compounds for several months at room temperature but will start to cure at about 70°C. 

The early 1980s saw considerable interest in a new form of silicone materials, namely the liquid silicone mbbers. These may be considered as a development from the addition-cured RTV silicone rubbers but with a better pot life and improved physical properties, including heat stability similar to that of conventional peroxide-cured elastomers. The ability to process such liquid raw materials leads to a number of economic benefits such as lower production costs, increased ouput and reduced capital investment compared with more conventional rubbers. Liquid silicone rubbers are low-viscosity materials which range from a flow consistency to a paste consistency. They are usually supplied as a two-pack system which requires simple blending before use. The materials cure rapidly above 110°C and when injection moulded at high temperatures (200-250°C) cure times as low as a few seconds are possible for small parts. Because of the rapid mould filling, scorch is rarely a problem and, furthermore, post-curing is usually unnecessary. 

A teehnique that is a convenient source of radieals for study by EPR involves photolysis of a mixture of di-t-butyl peroxide, triethylsilane, and the alkyl bromide corresponding to the radieal to be studied. Photolysis of the peroxide gives t-butoxy radieals, whieh selectively abstract hydrogen from the silane. This reactive silicon radieal in turn abstracts bromine, generating the alkyl radieal at a steady-state eoncentration suitable for EPR study. 

Heating with the following solids, their fusions, or vapours (a) oxides, peroxides, hydroxides, nitrates, nitrites, sulphides, cyanides, hexacyano-ferrate(III), and hexacyanoferrate(II) of the alkali and alkaline-earth metals (except oxides and hydroxides of calcium and strontium) (b) molten lead, silver, copper, zinc, bismuth, tin, or gold, or mixtures which form these metals upon reduction (c) phosphorus, arsenic, antimony, or silicon, or mixtures which form these elements upon reduction, particularly phosphates, arsenates,... 

Silicone Good Phenyl-methyl silicones are more stable than are methyl silicones. Platinum cure is superior to peroxide cure full cure during manufacturing can eliminate most postirradiation effects. 

Uses. There are about forty to fifty organic peroxides commercially available in more than seventy formulations designed for specific applications which include (1) initiators for vinyl monomer polymerizations, and copolymerizations of monomers such as vinyl chloride, ethylene, styrene, vinyl acetate, acrylics, fluoroolefms and buta-dienestyrene (2) curing agents for thermoset polyesters, styrenated alkyds and oils, silicone rubbers and poly allyl diglycol carbonates ... 

This excellent method of oxidative cleavage (/) of carbon-silicon bonds requires that the silane carry an electronegative substituent (2), such as alkoxy or fluoro. Either hydrogen peroxide or mcpba may be used as oxidant, and the alcohol is produced with retention of configuration (3). Fluoride ion is normally a mandatory additive in what is believed to be a fluoride ion-assisted rearrangement of a silyl peroxide, as shown below ... 

Poly(hydrosilane)s are stable compounds and can be manipulated in the air only for a short period since they are oxygen-sensitive. The oxidized products obtained from poly(phenylhydrosilane) exposed to the air contain the units 119-122 without the formation of silyl hydroperoxides and peroxides. In particular, units 119,120, and 121+122 were present in the relative percentages of 27,54, and 19%, respectively, which means that more than 70% of the catenated silicons are altered. 

Chidsey and coworkers made pioneering works in preparing covalently bonded monolayer films on silicon surfaces by the radical-initiated reaction of 1-alkenes with the H-Si(lll) surfaces. Reactions were carried out in neat deoxygenated alkenes using thermal decomposition of diacyl peroxides as the... 

The low temperature ALD process for hafnium silicate films using HfCl2[N(SiMe3)2]2 and H2O was modified to improve the film properties by two different methods. With hydrogen peroxide, the silicon content in the film increased to Si/(Hf+Si)=0.2 at 2001 and the impurity levels decreased due to its strong oxidation effect. By introducing TBOS as an additional Si precursor, the silicon content in the film increased to Si/(Hf+Si)=0.5 at 200 °C and the hafiiium silicate films became fully oxidized with O/(Hf+Si)=2.0. 

C03-0008. Write chemical formulas for the following compounds chlorine monofluoride, xenon trioxide, hydrogen bromide, silicon tetrachloride, sulfur dioxide, and hydrogen peroxide. 

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