Trimethylchlorosilane determination

When samples were removed during the course of the reaction, the reaction was terminated by adding to water, or to an alkyllithium, or in some cases to trimethylchlorosilane. The unreacted dichlorides could be determined by direct injection into the gas chromatograph (GC), or by the reaction product with an alkyllithium. 

Greaves et al. [74] used a selected ion-monitoring assay method for the determination of primaquine in plasma and urine using gas chromatography-mass spectrometric method and a deuterated internal standard. After freeze-drying and extraction with trichloroethylene, the sample plus internal standard was reacted with Tri Sil TBT (a 3 3 2 by volume mixture of trimethylsilylimidazole, A/O-bis-(trimethylsilylacetamide and trimethylchlorosilane) and an aliquot injected to the gas chromatograph-mass spectrometer. The gas chromatographic effluent was monitored at m/z 403, and m/z 406, the molecular ions of the bis-tetramethylsilane ethers of primaquine and 6-trideuteromethoxy primaquine. 

Theory This method confirms the presence of TMS derivatives of cyromazine and melamine residues extracted from poultry and red meat tissues from the determinative method. The TMS derivatives are formed by heating the residue with BSTFA (N,0-bis (trimethylsilyl) trifluoroacetamide) in the presence of TMCS (trimethylchlorosilane). 

The GC of halides is considered first. Fluorides react with trialkylchlorosilanes to form volatile trialkylfluorosilanes, which can be analysed by GC. Triethylchlorosilane [571,572] was used as a reagent for the analysis of fluorides in different materials in teeth fluorides were determined after the treatment with trimethylchlorosilane [573], as follows. The sample was dissolved in 0.5 M perchloric acid and 5 jd of the solution were transferred into a polyethylene test-tube containing 50 (A of benzene in which 50 Mg of trimethylchlorosilane and 65 ng of 2-methylbutane (internal standard) had been dissolved. The sample was stirred vigorously at 4°C for 20 min and 6—8 m1 of the benzene layer were analysed (20% of DC-200/50, 80° C). With the use of an FID, less than 1 ng of fluoride could be determined in the sample. 

A GC-MS method was developed for the determination of hyoscyamine and scopolamine in blood semm [91,92]. Extraction was carried out using aqueous basic solution followed by a purification step on an Extrelut column. Derivatization was done with N,0-bis(trimethylsilyl)trifluoroacetamide/trimethylchlorosilane (99 1). GC-MS was performed on a HP-5 MS column (30m x 0.25 mm i.d. with a 0.25 p,m film thickness). The linearity was good between 10 and 5000ng/mL. The limit of detection (LOD) was 5ng/mL for each compound. 

A method for the detection of nerve agent metabolites ba,sed on GC coupled with an atomic emission detector (AED) has been reported (Creasy etal., 1995). The nerve agent degradation products were extracted from spiked water, wipes, and soil samples. The extracted samples were deriva-tized with 1% trimethylchlorosilane in bis-(trimethylsilyl) trifluoroacelamidc. The GC/AED technique was used for separation, detection, and determination of OP nerve agent metabolites. 

The polymerization of D3 was followed by GC/MS. After 36 h, the reaction was quenched by the introduction of trimethylchlorosilane. About 92% of the D3 had been converted, while the amount of unconverted D/ had not changed significantly. Si NMR analyses allowed the determination of the sequence distribution of repeat units, which showed no random copolymerization of D/ and D3 as in the case of diblock copolymers prepared by sequential anionic copolymerization of D3 extended with D/. Because the polymerization of the first monomer could not be carried out to completion (<100% conversion) without increasing the molecular weight distribution, the second monomer (with faster propagation rates) had to be introduced before the equilibration reaction became established. Therefore, unreacted monomer from the first step was still in solution when the second monomer was added. The risk of random copolymerization can be suppressed if the second monomer has far higher reactivity towards polymerization than the first monomer. The block formed in the second step contained only a few methylvinylsiloxane units, i.e. the block purity was very high. 

In a 250 ml three-necked flask fitted with stirrer and internal thermometer 11.04 g (0.078 mol) of 2-chloro-l,4-phenylenediamine are dissolved in 150 ml dry N,N-dimethylacetamide (containing 2 wt% LiCl). 29.5 ml (0.233 mol) of highly pure trimethylchlorosilane (>99%) are dropped into the solution under stirring at 20°C. Then 15.71 g (0.078 mol) of terephthaloyl dichloride are added, whereupon the temperature and the solution viscosity increase immediately. After 2 h opaque, lytropic liquid crystalline solution is obtained. This solution is poured into a beaker and water is slowly added to the solution, whereupon the polyamide precipitates. It is washed with water to remove the salt-containing solvent. Finally, the product is purified by extraction with propane-2-ol. The polymer is dried in a vacuum oven at 100°C. The polyamide is characterized by determination of the solution viscosity at 20°C (1.25 g of polymer in 50 ml Af-methylpyrrolidone with 2 wt% of LiCl). 

Statistical design. Optimum conditions for the prepn. of trimethylvinylsilane from trimethylchlorosilane and vinyl chloride with Na in ether were determined by statistical analysis. Y up to 82.1%. I. Simek and J. Ala6, Ghem. Zvesti 15, 278 (1961). 

The surface of Tospearl 120 can be rendered more hydrophobic by treatment with hexamethyldisilazane (HMDZ) or trimethylchlorosilane (TMSCl) as shown in Table 9. Hydrophobicity is determined by the amount of material that is wetted by the solvent mixture and settles out during centrifugation. 45% of the untreated particles are wetted by a 60/40 methanol/water mixture. After hydrophobizing the surface, less than 5% were wetted (19). 

The compound after treatment with trimethylchlorosilane was determined to be tris(trimethylsilylated) PhyTy-triol using MALDI-TOF MS, Si NMR and X-ray single-crystal analysis. After 40 h of stirring, another product with 1379.47 m/z (calculated 1379.24 m/z) and two Si signals at —76.12 and —78.94 ppm (OsS/Ph) was obtained after trimethylsilylation, which was determined to be tetrakis(trimethylsilylated) PhgTg-tetrol, (68.2% yield). Single-crystal XRD analysis confirmed the double-decker structure of the compound. The crystal of PhgTs-tetrol included two THF molecules. The XRD structure is shown in Fig. 8. 

Hoffman"" has described a procedure (Method 44) for the determination of water in polyesters. In this method, water is allowed to react quickly with a mixture of hexa-methyldisiloxane and trimethylchlorosilane (2 1) in the presence of pyridine to form hexamethyldisiloxane. 

As organic acids are polar, thermally unstable, and have low volatility, it is necessary for GC analysis to convert them into nonpolar, volatile, and thermally stable derivatives. Such derivatization is usually achieved by esterification. The most common method is trimethylsilylation with A,0-bis(trimethylsilyl)trifluoroacet-amide (BSTFA) containing 1% trimethylchlorosilane. However, methylation with diazomethane or methanolic hydrogen chloride/boron trifluoride in methanol is also possible [19,20]. The derivatization to other esters has also been reported, but is rather uncommon in routine analysis [21]. Oxoacids should be stabilized by formation of an oxime prior to the esterification described above. Otherwise, formation of multiple/nonstable derivatives would greatly impair the determination of this class of compounds. The oximes can then react with BSTFA to yield TMS-oxime TMS esters. 

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