Phenyl silicone

Chlorine Ammonia, acetylene, alcohols, alkanes, benzene, butadiene, carbon disulflde, dibutyl phthalate, ethers, fluorine, glycerol, hydrocarbons, hydrogen, sodium carbide, flnely divided metals, metal acetylides and carbides, nitrogen compounds, nonmetals, nonmetal hydrides, phosphorus compounds, polychlorobi-phenyl, silicones, steel, sulfldes, synthetic rubber, turpentine... 

Although aimed at the introductory class, this simple experiment provides a nice demonstration of the use of GG for a qualitative analysis. Students obtain chromatograms for several possible accelerants using headspace sampling and then analyze the headspace over a sealed sample of charred wood to determine the accelerant used in burning the wood. Separations are carried out using a wide-bore capillary column with a stationary phase of methyl 50% phenyl silicone and a flame ionization detector. 

The principle of headspace sampling is introduced in this experiment using a mixture of methanol, chloroform, 1,2-dichloroethane, 1,1,1-trichloroethane, benzene, toluene, and p-xylene. Directions are given for evaluating the distribution coefficient for the partitioning of a volatile species between the liquid and vapor phase and for its quantitative analysis in the liquid phase. Both packed (OV-101) and capillary (5% phenyl silicone) columns were used. The GG is equipped with a flame ionization detector. 

The most widely used method of analysis for methylene chloride is gas chromatography. A capillary column medium that does a very good job in separating most chlorinated hydrocarbons is methyl silicone or methyl (5% phenyl) silicone. The detector of choice is a flame ionization detector. Typical molar response factors for the chlorinated methanes ate methyl chloride, 2.05 methylene chloride, 2.2 chloroform, 2.8 and carbon tetrachloride, 3.1, where methane is defined as having a molar response factor of 2.00. Most two-carbon chlorinated hydrocarbons have a molar response factor of about 1.0 on the same basis. 

The diacetate was judged to be virtually pure by the submitters on the basis of a gas chromatographic analysis carried out at 150° using a glass column packed with 3% OV 17 (1 1 methyl-phenyl silicone) supported on 70-80 mesh Chromosorb W. 

Polybutadiene is produced by solution polymerisation, and one important feature governing the performance of the resultant polymer is the cis 1,4, and 1, 2 vinyl contents. High cis 1,4 polymers (>90%) have a Tg around -90 °C, and hence exhibit excellent low temperature flexibility only exceeded by the phenyl silicones. They also exhibit excellent resilience and abrasion resistance unfortunately the high resilience gives poor wet grip in tyre treads, and hence this rubber finds limited use as the sole base for such compounds. 

The CGC analysis of the volatile degradation products were performed using a Perkin-Elmer Sigma 2000 capillary gas chromatograph. The column used was either a fused silica 0.25 micron, bonded methyl silicone (10 m, 0.25 mm I.D.) or a methyl/5% phenyl silicone (15 m 0.25 mm I.D.) bonded phase. The carrier gas was helium and the capillary column head pressure was maintained at 20 psi. The make-up gas for the pulsed electron capture detector (ECD) was 95% Ar/5% methane supplied at a flow rate of 60 ml/min. 

Perkin-Elmer Sigma 2000,15m,methyl/5% phenyl silicone column... 

Some other silicon elastomers include vinyl silicone elastomers, phenyl silicon elastomers, nitrile silicone elastomers, and fluorosilicone elastomers. 

The sample thus obtained is 94-97% pure by capillary GC analysis using a 25-m 5% methyl phenyl silicone capillary column. This material gave the following elemental analysis Anal. Calcd for Ci2 15 0 C, 76.15 H, 7.99 N, 7.40. Found C, 75.49 H, 8.15 N, 7.31. 

Silicone. Silicone elastomers have a siloxy backbone with methyl, vinyl, and phenyl groups attached. The elastomers are designated by their chemical composition, as follows methyl silicone (MQ), methyl vinyl silicone (VMQ), methyl phenyl silicone (PMQ), methyl phenyl vinyl silicone (PVMQ), and fluorovinyl methyl silicone (FVMQ). 

A gas chromatograph of the Hewlett-Packard 5890 series with a HP 7673A injector and a flame ionisation detector can be used. A capillary free fatty acid phase (Hewlett-Packard FFAP 19091F-105) column (50 m x 0.20 mm x 0.33 pm) is cut into two equal 25-m lengths, which are used for the separation, provided that a capillary pre-column (J W Scientific Altech 93493) with a 50% phenyl silicone DB 17 coating (1.35 m of a 15 mx0.25 mmx0.25 pm column) is installed. 

Aliphatic organofunctional silanes recommended as coupling agents for glass-reinforced polyesters, epoxies, or phenolics have heat stabilities of typical aliphatic organic chemicals and are not at all comparable to the methyl or phenyl silicones found in silicone polymers and resins. 

The presence of residual THF in the final product is easily detected by the characteristic NMR signals at 6 1.85 (4 H) and 3.75 (4 H). The checkers found GLC to be more convenient than 1H NMR for analysis at this point. Either a 6 x 2 mm glass column of 3% 0V-101 on MHP 80/100 with 30 nt/min He or a 15 m x 0.25 mm fused silica capillary column of DB-5 (cross-linked phenyl silicone) with 1 mL/min H2 proved sufficient to resolve butane, trimethylsilylacetylene, butyltrimethylsilane, THF, 1-chlorobutane, and b1s trimethylsilyl)acetylene. 

Fused silica capillary columns give better separation than packed columns. Columns having inside diameters of 0.25, 0.32, and 0.53 mm and film thickness between 0.25 and 1 pm have found use in herbicides analysis. The stationary phase is generally made out of phenyl silicone, methyl silicone, and cyanopropyl phenyl silicone in varying compositions. Some common columns are DB-5, DB-1701, DB-608, SPB-5, SPB-608, SPB-1701, Rtx-5, AT-1701, HP-608, BP-608, or equivalent. Use helium as carrier gas flow rate 30 cm/s on narrowbore columns with 0.25 or 0.32 mm ID and 7 mL/min for megabore 0.53 ID columns. 

Conventional high pressure NICI spectra were obtained using a Hewlett-Packard 5985B quadrupole GC/MS, as described previously (1). Methane was used as the Cl reagent gas and was maintained in the source at 0.2-0.4 torr as measured through the direct inlet with a thermocouple gauge. A 200 eV electron beam was used to ionize the Cl gas, and the entire source was maintained at a temperature of 200° C. Samples were introduced into the spectrometer via the gas chromatograph which was equipped with a 25 meter fused silica capillary column directly interfaced with the ion source. For all experiments, a column coated with bonded 5% methyl phenyl silicon stationary phase, (Quadrex, Inc.) was used and helium was employed as the carrier gas at a head pressure of 20 lbs. Molecular sieve/silica gel traps were used to remove water and impurities from the carrier gas. 

A few other miscellaneous reactions may be noted. Vinylsilicon-metal compounds in entries 4 and 30 undergo addition of HBr in an anti-Markownikoff sense to give 2-bromoethyl derivatives in some other related systems, HBr induces cleavage (see Section III,B,2). Also, the phenyl group in a phenyl-silicon-metal compound can undergo hexahapto interaction with a Cr(CO)3 group (entry 39). 

There have been many investigations to determine the best chemical structures to provide for resistance to moisture and hydrolysis. Attempts have been made to synthesize epoxy adhesives with improved water resistance by replacing some hydrogen atoms by fluorine.50 However, the cost of processing of such materials has restricted commercial development. For electronic sealants, it is highly desirable to keep moisture from penetrating into critical areas. Hydrophobic polymers have been developed to accomplish this task. They are siloxyimides, fluorosilicones, fluoroacrylics, phenylated silicone, and silastyrene. 

Pare compound 179 can be i solated by gas chromatography (100 °C, phenyl silicon oil type 0 S 26.14 (PE) on Sterchamol, 6 m column, 1 atm helium). By a study of the nmr, i.r. and mass spectra, compound 179 is identified, and compared with that produced by a different synthesis S4 The yield was 30%. As the following possibilities for a hydrosilylation exist, this low yield is not surprising ... 

Models were applied to the results obtained in the first collector, since the extract obtained in the second collector was made up of water and some volatiles that can not be separated. A Hewlett Packard 5890 Series II fitted with a flame ionisation detector was used to analyse the extract obtained in the first collector. A capillary column HP5 (cross linked phenyl silicone gum phase) was used. The separation was carried out with nitrogen as carrier gas using a detector at 523 K. Terpineol was the major component of the precipitated matter ( 65 % w/w). 

Modification of the properties of the phenyl silicones is possible through chlorination of the aromatic nucleus.43 One or more chlorine atoms may be substituted for hydrogen in each ring, as by chlorination of the phenylchlorosilane with iron powder as a carrier. The chloro-phenylchlorosilane is then hydrolyzed, and the resulting silicols are condensed by heat, just as is done with unsubstituted phenylchloro-silanes. The product is a brittle fusible resin, but it melts at a higher temperature than phenyl silicone and is less flammable. If an average of three chlorine atoms has been introduced into each phenyl nucleus, the product will not bum at all. 

Other aryl silicones have been prepared in considerable variety, and they all resemble phenyl silicone rather than the higher alkyl... 

Ethyl phenyl silicone is another alkyl-aryl silicone which may be made either from ethylphenyldichlorosilane41 or by cocondensation of mixed ethyl and phenyl chlorosilanes. The cross-linked ethyl phenyl silicone resins have good dielectric and mechanical properties, but their maximum service temperatures in air are somewhat lower than those for methyl phenyl silicone, being limited to about 250° C. for... 

If equation 11 is set up for the production of phenyl silicone in place of methyl, the combining weights become ... 

The net changes involved in this direct method for preparing phenyl silicone can be represented by the following series of equations ... 

As was pointed out in the discussion of the Grignard method, a larger part of the chlorobenzene molecule appears in the finished silicone product than is true of the methyl chloride molecule. At the same price per pound for raw materials, the basic material cost for phenyl silicone therefore would be less than that for methyl silicone. The difference is accentuated by the fact that chlorobenzene is produced in very large volume at low cost, so that it becomes an inexpensive source of phenyl groups for phenyl silicone. On the other hand, the factors which act to increase the relative cost of phenyl silicone by the direct method are (1) the cost of recovering the silver catalyst, and (2) the possible uneconomical disposition of the hydrochloric acid, which cannot easily be recirculated in the process. 

The different operating conditions for the methyl and phenyl reactions make it desirable to employ two separate flow sheets to illustrate the production of methyl and phenyl silicones by the direct process. Fig. 2 shows the flow of materials for the production of methyl silicone via the methanol process, and Fig. 3 depicts the production of phenyl silicone from benzene. 

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