Sugars sulfur trioxide

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). 

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 sulfur derivative (87) is 1000 times as sweet as sugar and without the bitter after-taste of saccharin however, it was discovered that N-alkylation of (87) removed the sweetness. On the other hand, in the saccharins (88a)-(88e) containing substituents in the 4-position and 6-position, sweetness was retained after N-alkylation. Many sulfamic acid derivatives are sweet, and there have been numerous studies of structure-taste relationships which have highlighted the importance of molecular shape and stereochemistry (see Chapter 9, p. 162). Two sulfamates which are commercial, non-nutritive sweeteners are cyclamate (85) and acesulfame potassium (86) (Figure 11). Cyclamate (85) is manufactured by refluixing cyclohexylamine either with triethylamine-sulfur trioxide in dichloromethane or with sulfamic acid (see Chapter 9, p. 162). 

A certain number of recognition phenomena involve sugar sulfates. Synthetic examples are found in Chapter 17. Hydrogensulfates are prepared by treating an alcohol dissolved in DMF with sulfur trioxide in the presence of triethylamine (reaction 5.9). 

Similar vinylog -elimination was observed on pyranoid and furanoid sugar derivatives. Perlin and coworkers described a double j8-elimina-tion on 2,3,4,6-tetra-O-acetyl-a-D-mannopyranose by treatment with methyl sulfoxide activated by sulfur trioxide-pyridine-triethylamine. 

Colorless, odorless, viscous oily liquid absorbs moisture from air abstracts water from many organic substances chars sugar and wood bp 338°C (640°F) decomposes at 340°C (644°F) to sulfur trioxide and water anhydrous acid freezes at 10°C (SOT) 98% acid freezes at 3°C (37°F) density 1.84 infinitely soluble in water and alcohol, evolving heat. 

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