Sulfones, of sugars

Gas — liquid chromatography has proved a useful analytical technique in carbohydrate chemistry, particularly for methyl ethers and acetic esters. By forming trimethylsilyl ethers of relatively nonvolatile sulfonates of sugars, gas — liquid chromatography can be performed. 

Cyclamate is about 30 times (8% sucrose solution sweetness equivalence) more potent than sugar. Its bitter aftertaste is minor compared to saccharin and acesulfame-K. The mixture of cyclamate and saccharin, especially in a 10 1 ratio, imparts both a more rounded taste and a 10—20% synergy. Cyclamate (6) is manufactured by sulfonation of cyclohexylamine (7). Many reagents can be used, including sulfamic acid, salts of sulfamic acid, and sulfur trioxide (74—77). 

The displacement is effected preferentially by a nucleophilic group already in the molecule. Thus, in the above reaction there is no evidence that OTs- is displaced by the external ion, OMe-, under the conditions used, nor is there ahy displacement of OTs- of a sugar sulfonate by OAc-, Buch as was found to occur when the sulfonate of a monohydric aliphatic alcohol was treated with potassium acetate.11... 

Bimolecular, nucleophilic-displacement reactions of sugar sulfonates have been reviewed in this Series.58,59 The value of these reactions in the preparation of deoxyhalo sugars has been emphasized by Hanessian.92... 

In saccharides sodium amalgam has been used for regeneration of sugars from their sulfonates but in low yields only [702],... 

Stilbenes, photocyclization of, 30, 1 StiUe reaction, 50, 1 Stobbe condensation, 6, 1 Substitution reactions using organocopper reagents, 22, 2 41, 2 Sugars, synthesis by glycosylation with sulfoxides and sulfinates, 64, 2 Sulfide reduction of nitroarenes, 20, 4 Sulfonation of aromatic hydrocarbons and aryl halides, 3, 4 Swem oxidation, 39, 3 53, 1... 

Incomplete carbonization of sugar, starch or cellulose followed by sulfonation produces stable and very active catalysts [25]. These materials, denoted sugar catalysts , not only show higher activity than other solid acids in the esterification of waste oils, but also maintain more than 90% of their original activity even after 50 cycles and they are stable up to 275 °C [26]. 

The structures of four sulfur derivatives of sugars have thus far been solved. Two are sulfides, the third is a C-sulfonate, and the fourth is a sulfoxide. Sinigrin, from the seeds of black mustard,... 

Vanilla flavour is not only determined and characterised by the vanillin molecule, but also by many more phenolic compounds and vanillin derivatives. Two examples of molecules that recently obtained FEMA-GRAS status are vanillyl ethyl ether and vanillin 2,3-butanediol acetal (Scheme 13.11). Vanillin can be hydrogenated to form vanillyl alcohol, which is also used in vanilla flavours. Vanillyl alcohol can be reacted with ethanol to form vanillyl ethyl ether. Vanillin can also form an acetal with 2,3-butanediol (obtained by fermentation of sugars) catalysed byp-toluene sulfonic acid in toluene. 

Mannitol hexanitrate is obtained by nitration of mannitol with mixed nitric and sulfuric acids. Similarly, nitration of sorbitol using mixed acid produces the hexanitrate when the reaction is conducted at 0—3°C and at —10 to —75°C, the main product is sorbitol pentanitrate (117). Xylitol, ribitol, and L-arabinitol are converted to the pentanitrates by fuming nitric acid and acetic anhydride (118). Phosphate esters of sugar alcohols are obtained by the action of phosphorus oxychloride (119) and by alcoholysis of organic phosphates (120). The 1,6-dibenzene sulfonate of D-mannitol is obtained by the action of benzene sulfonyl chloride in pyridine at 0°C (121). To obtain 1,6-dimethanesulfonyl-D-mannitol free from anhydrides and other by-products, after similar sulfonation with methane sulfonyl chloride and pyridine the remaining hydroxyl groups are acetylated with acetic anhydride and the insoluble acetyl derivative is separated, followed by deacetylation with hydrogen chloride in methanol (122). Alkyl sulfate esters of polyhydric alcohols result from the action of sulfur trioxide—trialkyl phosphates as in the reaction of sorbitol at 34—40°C with sulfur trioxide—triethyl phosphate to form sorbitol hexa(ethylsulfate) (123). 

The importance of sugar sulfonates as synthetic intermediates has been widely recognized.77,78 Selective methanesulfonylation and p-toluenesulfonylation of maltose and its derivatives has been studied. Umezawa and coworkers used sequential p-toluenesulfonylation and acetylation to obtain crystalline l,2,3,2, 3, 4 -hexa-0-acetyl-6,6 -di-0-p-tolylsulfonyl-/3-maltose in 45% yield.79 Dimolar methanesulfonylation of methyl /3-maltoside followed by acetylation afforded crystalline methyl 2,3,2, 3, 4 -penta-0-acetyl-6,6 -di-0-(methylsulfonyl)-/3-maltoside. The mother liquor also yielded a small proportion of a... 

The foregoing method of preparation of sugar thiocyanates109,110 by Sn2 displacement of a sulfonyloxy group has been reported by many workers.111 143 Displacement of sugar sulfonate groups by various nucleo-... 

It appears that the initial lack of interest in sulfonic esters of carbohydrates can be attributed to the fact that sugar chemists were so accustomed to thinking of sugar esters in terms of carboxylic esters (particularly, acetates and benzoates) that they overlooked an earlier... 

Studies on sulfonic esters of sugar alcohols have revealed that sulfonic... 

Despite the immediate application of unimolar sulfonylation for the preparation of many w-sulfonic esters of sugar derivatives, a kinetic study of the reaction was not made until 1942 Hockett and Downing136 then found that, with p-toluenesulfonyl chloride-pyridine at 23° 2°, the time to half-esterification for a mole of l,2 3,4-di-0-isopropylidene-D-galactose (with a primary hydroxyl group) is 0.272 hours (see Fig. 2), whereas for l,2 5,6-di-0-isopropylidene-D-glucose (with a secondary hydroxyl group) it is 20.2 hours (see Fig. 3). That is, after about 120 minutes, nearly all of the compound with the free primary hydroxyl group... 

In purifying, and assessing the purity of, sulfonic esters of sugars, a knowledge of some of their general physical properties is helpful. 

Many sulfonic esters of monosaccharides and their derivatives crystallize with comparative ease, thereby affording a means of purification. As a consequence, little attention has been paid to application of other methods of purification. A few sulfonic esters of sugars have been purified chromatographically.148161 -3181... 

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