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Silyl derivatives other than TMS

Some of the properties of TBDMS derivatives have already been alluded to above in the general discussion of the use of silyl derivatives other than TMS in synthetic studies. The early promise of TBDMS derivatives is now being fulfilled through their routine application in the analytical field. [Pg.75]

The development of N-t-butyldimethylsilyl-N-methyl-trifluoroacetamide (MTBSTFA) [288], its analytical application [50] and its subsequent commercial availability proved to be a major advance in the routine application of tert-butyldimethylsilylation in analytical chemistry. [Pg.76]

The advantages of using MTBSTFA rather than TBDMSIM and TBDMCS include (i) enhanced reactivity, including its ability to silylate carboxyls, hydroxyls, thiols and primary and secondary amines (ii) short reaction times, often at room temperature, and (iii) simplified work-up owing to derivatization by-products being neutral and largely volatile, so providing the possibility for direct injection of the reaction mixture for GC analysis. [Pg.76]

4 Applications of t-butyldimethyl-silylation to the GC analysis of organic compounds [Pg.76]

1 Short-chain organic acids and related compounds [Pg.76]


PREPARATION OF SILYL DERIVATIVES 4.3 Silyl derivatives other than TMS 75... [Pg.51]

Table 1 lists the common names, abbreviations and structures of silyl derivatives used in chromatography. I here has been a substantial expansion in the range of silyl reagents that have been considered for use in GC analysis since the late 1970 s [1,7]. Many of the derivatives have not, however, found routine application, and TMS derivatives have maintained their popularity. The following section describes the general properties of the most commonly used reagents for trimethylsilylation. Subsequent sections will then deal with the preparation and applications of silyl derivatives other than TMS. [Pg.55]

Of other silyl derivatives, trialkylsilyl derivatives [93], particularly for GC-MS, and dimethylsilyl derivatives [94] have been described. They are prepared by similar methods to TMS derivatives. DMS derivatives are more volatile and have shorter retention times than TMS derivatives (see Table 4.11), but they are less stable they are suitable for com-... [Pg.73]

CH3OH (1 1) at 60°C in DMF) 91 In addition, this reaction does not require any special precautions other than use of a well-ventilated hood since the generation a high concentration of the hazardous free HN3 is avoided. 9,9. The initial product is a mixture of 4 and its O-silylated derivative (O-TMS-4). The latter is converted to 4 upon treatment of the mixture with HCI in ethanol affording 4 in over 85% yield. [Pg.196]

TMS derivatives of amino acids were also combined with other procedures and some difficulties were thus avoided. N-TMS-methyl and -ethyl esters of most protein amino acids were prepared by the action of TMSDEA on alkyl esters of amino acids and were chromatographed on methylsilicone stationary phases [246], Their retention times were found to be 15—20% lower than those of the corresponding TMS derivatives. Despite having an additional step in comparison with direct silylation, the procedure was applied by Hardy and Kerrin [259] to the GC analysis of twenty protein amino acids, including Hypro and CysH. Amino acids were esterified with a 3 N HC1 solution in n-butanol at 150°C for 15 min with subsequent silylation with BSTFA for 90 min at the same temperature. Acetonitrile and methylene chloride were used as solvents for the silylation. In the former solvent double derivatives of Gly and Lys (bis- and tris-) were produced, whereas in the latter the less silylated form only was produced. As Arg, in contrast to direct silylation, also leads to one peak in this instance, methylene chloride is recommended as the silylation solvent. The separation of all twenty amino acids was achieved on a simple column with 2% of OV-7 on GLC-110 textured glass beads (100—120 mesh). [Pg.139]

This procedure is reputedly more suitable than silylation with BSTFA under the same conditions or with BSA—pyridine at room temperature. Other workers [272] accomplished the silylation of thiohydantoins with the aid of BSTFA-pyridine (1 1) at 50°C for 10 min. Gly and Thr, however, provide two products which are not stable. A good separation of silylated 2-thiohydantoins was obtained on a 4 ft. X 2 mm I.D. column packed with 10% of SP-400 on Chromosorb W HP with temperature programming (145— 260°C). The analysis was also performed on 1% of Dexsil 300 GC and 5% of OV-17 with identification by means of mass spectrometry. A number of mass spectra of thiodantoins and their TMS derivatives have been published [271]. [Pg.142]

Acylation is the most common method as amides are preferred over other kinds of derivatives. Their basicity is significantly less than that of amines and, hence, the pH of samples indicates that the influence is not as strong as on initial amines. Schiff bases and especially iV-trimethyl-silyl (TMS) derivatives are sensitive to postreaction hydrolysis. [Pg.52]


See other pages where Silyl derivatives other than TMS is mentioned: [Pg.55]    [Pg.75]    [Pg.75]    [Pg.55]    [Pg.75]    [Pg.75]    [Pg.52]    [Pg.52]    [Pg.612]    [Pg.646]    [Pg.247]    [Pg.137]    [Pg.75]    [Pg.363]    [Pg.70]    [Pg.223]    [Pg.549]    [Pg.7]    [Pg.92]    [Pg.121]    [Pg.653]   


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Silyl derivatives

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