Carbohydrates trimethylsilyl derivatives

Structural Identification of Isomeric O-Trimethylsilyl Derivatives of Some Hexuronic Acids, J. F. Kennedy, S. M. Robertson, and M. Stacey, Carbohydr. Res., 57 (1977) 205-214. 

First attempts to combine pyrolysis with in situ HMDS silylation of organic art materials were reported by Chiavari et al., who were successful in obtaining trimethylsilyl derivatives of fatty acids [52], amino acids [53] and carbohydrates [54]. The same authors also applied pyrolysis-silylation to the analysis of different kinds of natural resins and for each of them diagnostic silylated compounds were identified, even if many were difficult to assign precise structures [55],... 

The volatility of the trimethylsilyl derivatives of the aldonolactones and related carbohydrates has made these derivatives suitable for use in mass spectrometry.161,162 Petersson and coworkers161,162 reported the mass spectra of a variety of trimethylsilyl derivatives of aldonolactones, including the spectrum of 54. 

Despite the many advantages of converting free sugars into their O-trimethylsilyl derivatives, the formation of anomeric and isomeric derivatives (see Section IV, p. 38) may constitute a problem, especially with complex mixtures. Much effort has, therefore, been expended in seeking carbohydrate derivatives, suitable for analysis, in which the anomeric center has been eliminated. This may conveniently be accomplished by oxidation to the acid or lactone, by... 

Brobst, K. 1972. Gas liquid chromatography of trimethylsilyl derivations. In Methods in Carbohydrate Chemistry, Vol. 6, pp. 3-8. Academic Press, New York. 

As can be seen from Figures 12.3.1 and 12.3.2 and from Table 12.3.1, the carbohydrate moiety is not detected because furfural, acetol, and other typical pyrolysis products from sugars are absent. However, in these pyrograms only the more volatile components can be seen. Several less volatile components can be seen in a GC analysis only after the pyrolysate is derivatized, for example, to generate trimethylsilyl derivatives (TMS). The chromatogram of the silylated pyrolysate (pyrolysis done at 510° C) from egg albumin is shown in Figure 12.3.3, and that from bovine serum albumin in Figure 12.3.4... 

Honda et al. [266] described the GC determination of conjugated aldehydes in the products of periodate oxidation of pyranose sugars as diethyl dithioacetals. The component dialdehyde in dialdehyde compounds formed on periodate oxidation of carbohydrates can be determined by treating the dialdehyde with ethanethiol and trifluoro-acetic acid to convert the component aldehydes into diethyldithioacetals, which can be determined directly on OV-1 columns as their trimethylsilyl derivatives. 

Determination of carbohydrates in biological materials by GC was reviewed by Clamp et al. [400] who present extensive tables of the previously published applications as well as the retention characteristics of various carbohydrate derivatives. The survey of applications strongly indicates that the use of trimethylsilyl derivatives is by far the most popular. The other very common procedures are acetylation and methylation. Because of the procedural simplicity, these main derivatives continue to be most commonly used. 

Modzeleski, J.E., Laurie, W.A. and Nagy, B., 1971. Carbohydrates from Santa Barbara Basin sediments Gas chromatographic—mass spectrometric analysis of trimethylsilyl derivatives. Geochim. Cosmochim. Acta, 34 825—838. 

Much of our knowledge on the fragmentation patterns of carbohydrate derivatives arises from studies on methylated monosaccharides, but in structural investigations, such compounds are seldom subjected to mass spectrometry. On the other hand, the molecular weight of a permethylated oligosaccharide is significantly less than that of the per(trimethylsilyl) derivative. For this reason, the mass spectra of disaccharides as -their permethylated alditols have been determined by Chizhov and coworkers, Karkkainen, and Krone and Beckey. Trisaccharides have also been studied by Karkkainen, either as permethylated glycosides or as alditols. ... 

A modified method for the analysis of sugars as the 6>-trimethylsilyl derivatives of methyl glycosides has been used to give reproducible fingerprints of the carbohydrates of Streptococcus mutans ... 

Silyluronic acid derivatives—Trimethylsilyl derivatives of carbohydrates s. 16,174 ... 

Gas liquid chromatography (GLC) has found only limited application in lichen chemistry because most lichen substances are very polar and have low volatility. To overcome this problem, more volatile derivatives are used. Nishikawa et al. (1973) analyzed the low molecular weight carbohydrates of eight lichen species as their acetyl, trifluoroacetyl and trimethylsilyl derivatives by GLC under the following conditions Hj,... 

Table 16. Relative retention times of the acetyl, trifluoroacetyl and trimethylsilyl derivates of some low molecular weight carbohydrates from lichens...

Petersson, G. (1974), Gas-chromatographic analysis of sugars and related hydroxy acids as acyclic oxime and ester trimethylsilyl derivatives. Carbohydr. Res., 33,47. 

Petersson, G. (1977), Retention data in GLC analysis Carbohydrate related hydroxy carboxylic and dicarboxylic acids as trimethylsilyl derivatives./. Chromatogr. ScL, 15, 245. 

The most stable protected alcohol derivatives are the methyl ethers. These are often employed in carbohydrate chemistry and can be made with dimethyl sulfate in the presence of aqueous sodium or barium hydroxides in DMF or DMSO. Simple ethers may be cleaved by treatment with BCI3 or BBr, but generally methyl ethers are too stable to be used for routine protection of alcohols. They are more useful as volatile derivatives in gas-chromatographic and mass-spectrometric analyses. So the most labile (trimethylsilyl ether) and the most stable (methyl ether) alcohol derivatives are useful in analysis, but in synthesis they can be used only in exceptional cases. In synthesis, easily accessible intermediates of medium stability are most helpful. 

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