Sucrose methylation

Challinor, Haworth and Hirst101 determined the chemical structure of the levan produced by the action of B. mesentericus on sucrose. Methylated levan appeared homogeneous when fractionally precipitated from mixed solvents. Fractional distillation of the hydrolytic products of methylated levan yielded tetramethyl-D-fructofuranose in an amount corresponding to a levan chain length of from ten to twelve fructofuranose units, joined as previously940 shown through the 2- and 6-positions. 

Although dilute aqueous acid hydrolyzed the methyl and benzyl a-D-fructofuranosides approximately 8 and 16 times as rapidly as sucrose, their method of preparation showed them to be unaffected by any of the enzymes active in a fermenting yeast suspension. Purified yeast invertase, proven free of a-D-glucosidases (maltases), could therefore contain no enzyme capable of hydrolyzing the above two a-D-fructo-furanosides, but did contain constituents that readily cleaved the beta isomers and also sucrose. The latter is accordingly a /S-D-fructofuranos-ide. When the evidence is put in this way, the present uncertainties as to whether purified invertase preparations include one or a number of /3-D-fructofuranosidases, and whether or not sucrose, methyl and... 

Later in this text it will be shown that species that are soluble in water are either ionic or polar, like water, as indicated in the rule of thumb "Like dissolves like." Showing that water, sucrose, methyl alcohol, and ethyl alcohol all contain -OH groups will demonstrate their "likeness."... 

The degree of esterification is controlled by the reaction conditions, especially the sucrose methyl ester ratio, and the final product is a mixture of esters (Table 3). The HLB value of a particular product is smaller (more hpophilic) as the degree of esterification increases, as would be expected. 

The results obtained for sucrose methyl laurate, with a methyl group a to the ester bond, and sucrose ethyl laurate, with an ethyl group a to the ester bond, indicated reduced biodegradability of these esters relative to the... 

Collect sections on a drop of 50 50,2.3 M sucrose methyl cellulose. 

The H- and C-n.m.r. spectra of sucrose, methyl a-D-fructofuranoside (20) and methyl P D-fhictofuranoside (21) with single sites of C-substitution at C-1, C-2, C-3-, or C-6 of the furanose moieties have been analysed to assess the conformations of the their furanose rings, and of the glycosidic linkages in aqueous solution. In addition, spin-couplings in 20 and 21 were compared with those of a-(22) and p-D-r/jrco-pentulofuranose (23), respectively, to study the effect of glycosidation and hydroxymethyl substitution on the solution conformations. The conformations of 2-mono- and 2,2 -di-G-substituted a,a-trehalose derivatives 25 have been shown by n.m.r. spectroscopy in combination with molecular mechanics calculations, to differ from that of the 2,2 -unsubstituted disaccharide 24, both in solution and in the solid state. N.O.e. experiments on the 6 -deoxy-, 6 -thio-, and 6 -0-THP derivatives of methyl 2-acetamido-2-deoxy-P-lactoside, potential inhibitors of (2- 6)-a-sialyltransferase, proved that they adopt the same conformation as the parent compound. ... 

Aspartame (L-aspartyl-L-phenylalanine methyl ester [22839-47-0]) is about 200 times sweeter than sucrose. The Acceptable Daily Intake (ADI) has been estabUshed by JECFA as 40 mg/kg/day. Stmcture-taste relationship of peptides has been reviewed (223). Demand for L-phenylalanine and L-aspartic acid as the raw materials for the synthesis of aspartame has been increasing, d-Alanine is one component of a sweetener "Ahtame" (224). 

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. 

Olestra is prepared by a solvenfless transesterification process in which sucrose is treated with methyl ester of fatty acids in the presence of sodium methoxide between 100—180°C for 14 hours (68). The manufacturing process involves removal of the unreacted fatty acid esters by enzymic hydrolysis... 

Aspartame (1) is the primary nonnutritive sweetener used in carbonated soft drinks. It is approximately 200 times sweeter than sucrose. Aspartame is the methyl ester of a dipeptide of T.-phenylalanine and L-aspartic acid. 

Sorbitol is the most important higher polyol used in direct esterification of fatty acids. Esters of sorbitans and sorbitans modified with ethylene oxide are extensively used as surface-active agents. Interesteritication of fatty acid methyl esters with sucrose yields biodegradable detergents, and with starch yields thermoplastic polymers (36). 

The taste properties of the di-O-methylhexopyranosyl derivatives, like those of the corresponding deoxy sugars, are never sweet, and always bitter. As with the deoxy sugars, this is possibly the result of increased lipophilicity of the molecule. In sucrose, however, the presence of two methyl groups on the D-glucopyranosyl or the D-fructofuranosyl group does not seem to cause any marked bitterness (see Table XVIII). 

Structurally related to saccharin are the oxathiazinone dioxides (104). Clauss and coworkers synthesized a series of these compounds, and demonstrated that they possess intense sweetness. Acesulfame-K, the potassium salt of 3,4-dihydro-6-methyl-l,2,3-oxathiazin-4-one 2,2-dioxide (104) has a sweetness intensity 130 times that of sucrose. 

To distinguish between these possibilities, Birch and Mylvaganam studied the effect of the sweetness of sucrose and the bitter-sweetness of methyl a-D-mannopyranoside on the bitterness of quinine sulfate, and the effect of the bitterness of quinine sulfate and methyl a-D-mannopyranoside on the sweetness of sucrose. A significantly diminished sweetness-response... 

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