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Saccharin functions

The reducing-end units (see Fig. 8) are highly labile in alkaline solutions. After an initial attack by hydroxide ions at the hemiacetal function, C-1, a series of enoHzations and rearrangements leads to deoxy acids, ie, saccharinic acids, and fragmentation. Substituents on one or more hydroxyl groups influence the direction, rate, and products of reaction. [Pg.261]

Benzisothiazoles also suffer N—S bond cleavage, following attack at sulfur, but 1,2-benzisothiazole 1,1-dioxides are cleaved at the C—N bond. Saccharin derivatives are attacked at the carbonyl function. In cases where N—S bond cleavage occurs, recyclization can sometimes occur, often producing thiophene compounds. [Pg.146]

Moncrief summarized the work of Cohn and the information in the early literature. As early as 1923, it was known that rupture of the heterocyclic ring, as well as substitution of the imino hydrogen atom, results in the loss of sweetness. Thus, o-carboxybenzenesulfonamide and N-alkyl derivatives of saccharin are tasteless. This loss of sweetness would be expected, as the NH group is the only proton-donor function available in the molecule. [Pg.298]

Andersen et a/.," with a saccharine-particle method, found a weak positive association between tracheobronchial clearance and nasal clearance. A strong positive correlation would have indicated that information about the tracheobronchial clearance rate can be derived by studying clearance rates in the nose, which is more accessible. The saccharine method was shown to be a useful clinical tool for evaluating the status of the nasal mucociliary function in human subjects exposed to ambient pollutants or to controlled concentrations of specific pollutant gases or aerosols. [Pg.297]

Saccharinic acid formation has been studied for several years. The four-step reaction proceeds rapidly in alkaline solution because of basic catalysis, particularly in the last two steps. Initially formed is an enediol that can undergo j8-elimination of a functional group, usually a hydroxyl group. The final two steps involve tautomerization to an a,j8-dicarbonyl intermediate followed by a benzilic acid rearrangement. This sequence is shown in Scheme 6 for the formation of the a- and j8 -xylometasac-charinic acids (30) by way of 3-deoxy-D-g/ycero-pentos-2-ulose (29). [Pg.281]

The standard means for preparing oxicams 285, initially developed by Lombardino, is through the base-promoted rearrangement reaction of isothiazole dioxides 286, which in turn are prepared from saccharin derivatives such as 287 (Scheme 40) <1981AHC(28)73>. The oxicam core can be further derivatized by N-alkylation of oxicam 285 and amidation of the C-3 ester functionality of 288 to form the common drug scaffold 289. [Pg.556]

Anand and Filler123 demonstrated that pyridine reacted with xenon difluoride forming 2-fluoro-, 3-fluoro- and 2,6-difluoropyridine and 8-hydroxyquinoline was converted to 5-fluoro 8-hydroxyquinoline, while nitrogen functionalization was observed by reaction of phthalimide and saccharin in benzene124. A-Fluoroimides were formed in good yields by reactions of xenon difluoride with imides of perfluorinated succinic and glutaric acids125 (Scheme 52). [Pg.854]

We are going to do a little more than simply give the reactions that eventually made up the synthesis of dofetilide. We are going to put ourselves in the place of the chemists who invented the synthesis and try to see what led them to the reactions they chose. First, we should inspect the structure of the molecule. There are two sulfonamides, one at each end. We have seen how to make sulfonamides earlier in this chapter when saccharin was being discussed. The usual way is to react the amine with a sulfonyl chloride. In this case we shall need to react methane sulfonyl chloride (MeS02Cl or MsCl) with the aromatic amines. This is a well-known reaction and should work well here. The other functional groups—tertiary amine and alkyl aryl ether—should not interfere so no protection is needed. [Pg.659]

These results will be used to construct a standard response curve for caffeine, saccharin, and benzoate. Since precision is a function of the volume... [Pg.392]

True 3-imino-2,3-dihydrobenz[d]isothiazole-l,1-dioxides (82) are capable of existence provided they bear an alkyl or aryl substituent in 2-position as in saccharin anils (23). The free imino compound (82a R = Me, R =H) is obtained from isomerization of o-cyano-V-methyl-phenylsulfonamide in the presence of methylamine,256 or more generally preparation of 82 may start from o-cyanophenylsulfonyl chloride together with an excess of amine.3, 256 A straightforward approach uses cyclization of an o-sulfamylbenzamide monosubstituted at each amide function, like o-(iV-phenylsulfamyl)benzanilide (83)257 with phosphorus pentoxide, phosphorus pentachloride, or preferably phosphorus oxychloride.135,257 Similarly, 2-chlorocarbonylbenzene sulfonyl chloride... [Pg.269]

Moskowitz and Arabic (1970) found that the taste intensity (sweetness, sourness, saltiness, and bitterness) was related to the apparent viscosity of carboxymethylcel-lulose solutions by a power function with a negative slope. Pangbom et al. (1973) observed that the influence of different hydrocolloids on the perception of some basic taste intensities (saltiness, bitterness, sourness) appeared to be more dependent on the nature of the hydrocolloid and the taste of the substance than on the viscosity level. In contrast, sweetness imparted by sucrose was found to be highly dependent on viscosity, that is, the hydrocolloid concentration above a certain viscosity threshold, it was shown that the sweetness intensity of sucrose was significantly depressed. Saltiness was the taste attribute less affected, sourness, imparted by citric acid, was significantly reduced by all hydrocolloids tested, and for the other taste substances, the presence of a hydrocolloid generally enhanced the taste intensity of saccharin and depressed that of sucrose and caffeine (bitterness). [Pg.415]

Promoters appear to have a relatively high tissue specificity. Thus, phenobarbital functions as a promoter for rodent liver neoplasia but not urinary bladder neoplasia. Saccharin, on the other hand, promotes urinary bladder neoplasia but not liver neoplasia in the rat. Similarly, 12-o-tetradecano-ylphorbol-13-acetate (phorbol ester) is a potent skin and forestomach neoplasm promoter in the laboratory rodent but has no appreciable activity in the liver. Other agents, such as the antioxidants 3-t-butyl-4-methoxyphenol and 2,6-di-t-butyl-4-met-hoxyphenol, may act as promoters in one organ and antipromoters in another and have no effect in a third organ. Thus, the practical definition of a promoter must include the designation of the susceptible tissue. [Pg.459]

Aromatic halogen substitution increases bitterness and is a function of the atomic weight of the halogen (see e.g., halogenated saccharins)... [Pg.852]

The definition is not, perhaps, entirely satisfactory. It is arbitrary and formal. It does not include those acids of formula C H2 0 which contain a quaternary carbon atom, because the hydroxy-aldehyde of like general formula required by the definition is structurally impossible. In other words, such acids could not be formed by the imaginary reaction which is the basis for the defintion and they would, therefore, not be called saccharinic acids. On the other hand, the definition does have the advantage of perfect clarity. Furthermore, it establishes a connection between the saccharinic acids and the aldoses. Finally, it escapes the drawback of a functional definition, because it depends, not on an actual, but on a theoretically possible, number of isomers. The term saccharinic acid will be used in this article to denote only those compounds encompassed by the Glattfeld-Sherman definition. [Pg.170]


See other pages where Saccharin functions is mentioned: [Pg.1]    [Pg.839]    [Pg.73]    [Pg.328]    [Pg.341]    [Pg.827]    [Pg.392]    [Pg.291]    [Pg.163]    [Pg.488]    [Pg.1082]    [Pg.987]    [Pg.497]    [Pg.530]    [Pg.196]    [Pg.987]    [Pg.164]    [Pg.668]    [Pg.1825]    [Pg.548]    [Pg.619]    [Pg.998]    [Pg.1185]    [Pg.57]    [Pg.11]    [Pg.222]    [Pg.201]    [Pg.208]    [Pg.226]    [Pg.219]    [Pg.121]    [Pg.180]    [Pg.169]    [Pg.463]   
See also in sourсe #XX -- [ Pg.477 ]




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