Sucrose, resonance assignment

Acetates. Because of the significant interest in selective acetylation reactions of sucrose, the need for a convenient and unambiguous method of identification has been recognized (34,35). The position of an acetyl group in a partially acetylated sucrose derivative can be ascertained by comparison of its H-nmr acetyl methyl proton resonances after per-deuterioacetylation with those of the assigned octaacetate spectmm. The synthesis of partially acetylated sucroses has generally been achieved either by way of selectively protected derivatives such as trityl ethers and cychc acetals or by direct selective acetylation and deacetylation reactions. 

Benzoates. The selective debenzoylation of sucrose octabenzoate [2425-84-5] using isopropylamine in the absence of solvents caused deacylation in the furanose ring to give 2,3,4,6,1/3/6 -hepta- and 2,3,4,6,1/6 -hexa-O-benzoyl-sucroses in 24.1 and 25.4% after 21 and 80 hours, respectively (54). The unambiguous assignment of partially benzoylated sucrose derivatives was accompHshed by specific isotopic labeling techniques (54). Identification of any benzoylated sucrose derivative can thus be achieved by comparison of its C-nmr carbonyl carbon resonances with those of the assigned octabenzoate derivative after benzoylation with 10 atom % benzoyl—carbonyl chloride in pyridine. 

Bilia et al. reported the efficiency of two-dimensional homonuclear H- H correlated spectroscopy and two-dimensional reverse heteronuclear shift correlation spectroscopy in evaluating the composition of phloroglucinols, flavonols and naphthodianthrones in a dried extract of St John s wort. They successfully assigned carbon resonances for these three classes of compounds and also identified shikimic and chlorogenic acids, sucrose, lipid, polyphenols and traces of solvent (methanol) during the extraction process. This rapid technique is an alternative to HPLC, TLC or capillary GC for the analysis of St John s wort preparations. Another report utilized near-infrared reflectance spectroscopy (NIRS) for the... 

Fig. 8.—The Partial, H Nuclear Magnetic Resonance Spectrum of Sucrose Octaacetate (8) in Solution in Acetone-rid, With a Diagrammatic Representation of the First-order Assignment of the n-Glucose Protons is Shown in A. [The set of INDOR traces (B, C, D, and E) was obtained by sequentially monitoring transitions 1, 8, 5, and 3.]...

ID and 2D) of long-chain N-alkyl lactosylamines has been reported. All H- and C-resonances of potassium sucrose octasulfate have been assigned with the help of 2D and deuterium-induced differential-isotope-shift (DIDIS) n.m.r. methods. A H-n.m.r. study in D2O showed that 3 -ketolactose (11) crystallized from methanol as the hemiacetal 12 with an equatorial methoxy group. A 500 MHz H-n.m.r. investigation of methyl fl-cellobioside confirmed the presence of an intramolecular hydrogen bond between HO-3 and 0-5 in DMSO, but not in DjO or CDjOD. ... 

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