The presence of acetate and pyruvate groups in Klebsiella capsular polysaccharides may be demonstrated and estimated quantitatively by running the proton magnetic resonance spectrum of the polysaccharide (as sodium salt) in deuterium oxide at 95 C. Such spectra also permit an assessment to be made of the number of a-and a-linkages in the repeat unit of the polysaccharide structure.

De,u(~rtit~e/~t of Clle~?!i~t~:\., The L'ni~,er.sit?. oj'Bt.iti~h Col~rn~bin, Vu~~c.orr\-ei. 8, British Col~rr?lbia Received July 13. 1972.The configuration (D or L) of a sugar may be determined conveniently by c i r c~~l a r dichroism measurements at 213 nm on alditol acetates, or their niethylared derivatives, where the acetoxy group acts as a chron~ophcre. Only milligram quantities of niaterial are required and the method is well suited to a n a l y~-Ing fractions obtained by gas-liquid chromatography. Structural information which ]nay be derived from he c.d. spectra is briefly discussed.La configtlration ( D or L) d'un sucre peut Ctre etabiie par le dicl-iroisme circulaire 8 213 nm soit des alditol acetates soit de l e~i r de~ives methyles, oh le gro~ipelnent acetate jcue le i6le de chromophore. O n ne necessite que de tres petites y~~a n t i t e s de substance et la n~ethode s'adapte tres bien a l'analyse des fractions obten~ies par chromatographie en phase gaseuse. On discute brievement des renseignn~ents structuraux que fournissent les spectres d.c.( a n . J . Cheni.. 51. 32-1 (1971)

No abstract

Del~(rrt1~~nt o l ' C h e~n i s t r~~. Tlre U~l i r e r s i t~of British Colrr~tlbia, Va~tcolcrer 8 . British Colrrmbia Received July 24, 1972 P.m.r. spectroscopy at 60 MHz of trimethylsilyl ethers and esters, prepared from hydroxy acids, gives well resolved sharp singlets in the range T 9.8-9.9. These signals may be used to determine the ratio of hydroxyl to carboxyl groups in a molecule. Measurements may be made directly on fractions isolated by gas-liquid chromatography. The influence of the solvent on the resolution is demonstrated.La spectroscopie r.m.n. (60 MHz) des ethers et esters trimCthylsilyl, derives des acides hydroxyies, donne des pics bien resolus (T 9.8--9.9). On peut utiliser ces signaux pour determiner le rapport entre les groupements hydroxyles et carboxyles dans une molCcule. On peut faire les mesures directement sur les fractions isolees par chromatographie en phase gaseuse. L'influence du solvant sur la rCsolution des pics est demontree.Canadian Journal of Chemistry, 50. 3913 (1971) Trimethylsilyl derivatives have been prepared from many different types of compounds and the silylation reaction has been reviewed (1). These derivatives are commonly prepared mainly for the purpose of separations by gasliquid chromatography and also for mass spectrometry (1). In contrast to the wealth of literature available on these two applications of trimethylsilyl derivatives much less has been reported on the physical properties of such compounds and, in particular, their uses in p.m.r. spectroscopy.We have shown recently that the protons of the -OSi(CH,), group in trimethylsilyl ethers give a sharp singlet in the range T 9.8 and that non-equivalent ethers have distinct chemical shifts (2). Thus, the trimethylsilyl ether of glycerol gives two such singlets (integral ratio 1 : 2), and the derivatives of methyl a-D-galactopyranoside and of a-D-glucopyranose give four and five well resolved signals of equal magnitude, respectively. Carboxylic acids readily form trimethylsilyl esters and thus hydroxy acids give derivatives which are both trimethylsilyl ethers and esters. The present note shows how p.m.r. spectroscopy of these derivatives may be used to determine the relative numbers of carboxyl and hydroxyl groups per molecule and, in certain cases, the absolute number.Trimethylsilyl (TMS) derivatives were prepared by reaction of the hydroxy acid in pyridine with hexamethyldisilazane (HMDS) alone or For personal use only.

4-O-β-D-Galactopyranosyl-L-rhamnopyranose has been synthesized in 60% yield by condensation of 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide with methyl 2,3-O-isopropylidene-α-L-rhamnopyranoside using mercuric cyanide in acetonitrile (Helferich reaction). The disaccharide is a syrup but the derived alditol and alditol peracetate are crystalline compounds.