Saccharin methylation

Soil. In unsterilized soils, 58% of C-labeled sulfometuron-methyl degraded after 24 wk. Metabolites identified were 2,3-dihydro-3-oxobenzisosulfonazole (saccharin), methyl-2-(amino-sulfonyl) benzoate, 2-aminosulfonyl benzoic acid, 2-(((aminocarbonyl)amino)sulfonyl) benzoate, and [ C]carbon dioxide. The rate of degradation in aerobic soils was primarily dependent upon pH and soil type (Anderson and Dulka, 1985). The reported half-life in soil was approximately 4 wk (Hartley and Kidd, 1987). 

Acryhc stmctural adhesives have been modified by elastomers in order to obtain a phase-separated, toughened system. A significant contribution in this technology has been made in which acryhc adhesives were modified by the addition of chlorosulfonated polyethylene to obtain a phase-separated stmctural adhesive (11). Such adhesives also contain methyl methacrylate, glacial methacrylic acid, and cross-linkers such as ethylene glycol dimethacrylate [97-90-5]. The polymerization initiation system, which includes cumene hydroperoxide, N,1S7-dimethyl- -toluidine, and saccharin, can be apphed to the adherend surface as a primer, or it can be formulated as the second part of a two-part adhesive. Modification of cyanoacrylates using elastomers has also been attempted copolymers of acrylonitrile, butadiene, and styrene ethylene copolymers with methylacrylate or copolymers of methacrylates with butadiene and styrene have been used. However, because of the extreme reactivity of the monomer, modification of cyanoacrylate adhesives is very difficult and material purity is essential in order to be able to modify the cyanoacrylate without causing premature reaction. 

Acesulfame-K. Acesulfame-K [55589-62-3] (4), the potassium salt of acesulfame [33665-90-6] (6-methyl-l,2,3-oxathiaziQ-4(3ff)-one 2,2-dioxide), is a sweetener that resembles saccharin in stmcture and taste profile. 5,6-Dimethyl-l,2,3-oxathiazine-4(3ff)-one 2,2-dioxide, the first of many sweet compounds belonging to the dihydrooxathia2inone dioxide class, was discovered accidentally in 1967 (63). From these many sweet compounds, acesulfame was chosen for commercialisation. To improve water solubiUty, the potassium salt was made. Acesulfame-K (trade name Sunette) was approved for dry product use in the United States in 1988 and in Canada in October, 1994. Later, it was approved by the FDA for additional food categories such as yogurts, frosen and refrigerated desserts, and baked goods. 

Saccharin, 2-methyl-reduction, 6, 152 Saccharin, 6-nitro-reduction, 6, 154 Saccharin, thio-hydrolysis, 6, 161 methylation, 6, 160 Safranines applications, 3, 196 Safrole derivatives toxicity, 1, 139-140 occurrence, 6, 781 Safrole, 1-hydroxy-toxicity, 1, 140 Salazosulfapyridine... 

For example, if saccharin (33) is methylated in benzene suspension, then only iV-methylsaccharin is isolated. If an ethereal saccharin solution is added to a concentrated solution of diazomethane in excess, then 10% of 0-methylsaecharin (34) can be detected in addition to the A"-raethy] derivative. Finally, if the diazomethane solution is gradually added to a saturated ethereal solution of saccharin, the proportion of 0-methylation increases to 24%. " ... 

For high diazomethane concentrations, the Sn2 reaction, Eq. (7), and thus A—methylation occurs, whereas 0-methylation is favored by lower diazomethane concentrations, Eq, (6) (for an interpretation of this effect, according to Arndt, see references 33 and 42). The extent of this effect is limited by the constitution of the lactam in question. The fact that the addition of the sodium salt of saccharin to the reaction mixture leads to increased A -mcthylation for saccharin can be taken as supporting the foregoing interpretation. 

When diazomethane is slowly added to excess lactam, the anions formed can interact with unreacted lactam by means of hydrogen bonds to form ion pairs similar to those formed by acetic acid-tri-ethylamine mixtures in nonpolar solvents. The methyldiazonium ion is then involved in an ion association wdth the mono-anion of a dimeric lactam which is naturally less reactive than a free lactam anion. The velocity of the Sn2 reaction, Eq. (7), is thus decreased. However, the decomposition velocity of the methyldiazonium ion, Eq. (6a), is constant and, hence, the S l character of the reaction is increased which favors 0-methylation. It is possible that this effect is also involved in kinetic dependence investigations have shown that with higher saccharin concentrations more 0-methylsaccharin is formed. 

The effect of solvents on the reactions of lactams with diazomethane can be pronounced saccharin gives only A -methyl derivative in benzene solution, but in ethereal solution up to 24% of 0-methyl saccharin is formed in the still more strongly polar solvent di-... 

Methyl groups attached to benzene rings can be reacted with oxygen to produce aromatic carboxylic acids. Benzoic acid, the parent aromatic acid, finds wide use as a food preservative and in metal corrosion inhibitors. Aspirin and saccharin are derivatives of benzoic acid. 

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. 

The sulfonyl urea sulfometuron methyl is stable at neutral or alkaline pH values, but is hydrolyzed at pH 5 to methyl 2-aminosulfonylbenzoate that is cyclized to saccharin (Figure 1.21) (Harvey et al. 1985). The original compound is completely degraded to CO2 by photolysis. 

Figure 11.5 Formation of methylated saccharinic acids from glucose and cellulose, and methylated deoxyglucaric acid from glucuronic acid [66,681...

C. Schwarzinger, Identification of methylated saccharinolactones and partially methylated saccharinic acids in the thermally assisted hydrolysis and methylation of carbohydrates, J. Anal. Appl. Pyrol., 71, 501 514 (2004). 

There is a recent trend towards simultaneous CE separations of several classes of food additives. This has so far been applied to soft drinks and preserved fruits, but could also be used for other food products. An MEKC method was published (Lin et al., 2000) for simultaneous separation of intense sweeteners (dulcin, aspartame, saccharin and acesulfame K) and some preservatives (sorbic and benzoic acids, sodium dehydroacetate, methyl-, ethyl-, propyl- and isopropyl- p-hydroxybenzoates) in preserved fruits. Ion pair extraction and SPE cleanup were used prior to CE analysis. The average recovery of these various additives was 90% with good within-laboratory reproducibility of results. Another procedure was described by Frazier et al. (2000b) for separation of intense sweeteners, preservatives and colours as well as caffeine and caramel in soft drinks. Using the MEKC mode, separation was obtained in 15 min. The aqueous phase was 20 mM carbonate buffer at pH 9.5 and the micellar phase was 62 mM sodium dodecyl sulphate. A diode array detector was used for quantification in the range 190-600 nm, and limits of quantification of 0.01 mg/1 per analyte were reported. The authors observed that their procedure requires further validation for quantitative analysis. 

Chemical/Physical Sulfometuron-methyl is stable in water at pH values of 7 to 9 but is rapidly hydrolyzed at pH 5.0 forming methyl-2-(aminosulfonyl) benzoate and saccharin. When sulfometuron-methyl in an aqueous solution was exposed to UV light (k = 300-400 nm), it degraded to the intermediate methyl benzoate which then mineralized to carbon dioxide (Harvey et ah, 1985). 

Xyloisosaccharinic acid [2,4-dihydroxy-2-(hydroxymethyl)butanoic acid] is one of the major, alkaline-degradation products of wood xylan, in particular, that of birch. The disaccharide, 2-O-D-xylopyranosyl-L-arabinose, which was isolated as a hydrolysis product of corn-cob hemicellulose, is readily degraded at 100° in 15 mM Ca(OH)2 to acidic products, primarily saccharinic acids. Xylan oligosaccharides from corn-cob hemicellulose produced 2,4-dihydroxy-2-(hydroxymethyl)buta-noic acid when exposed to 0.02 M Ca(OH)2 at 25°. However, it was noted that the xylan, itself, was stable at 100° in Af NaOH. The major acidic component of the hemicellulose fraction of slash pine Pinus el-liotti) after acid hydrolysis was identified as 4-O-methyl-D-glucuronic... 

Methyl ethyl ketone Methyl methacrylate Naphthalene Saccharin and salts Thiourea Toluene... 

Piroxicam Piroxicam, 1,1 -dioxid-4-hydroxy-2-methyl-iV-2-pyradyl-2//-1,2-benzothiazine-3-carboxamide (3.2.78), is synthesized from saccharin (3.2.70). Two methods for saccharin synthesis are described. It usually comes from toluene, which is sulfonated by chlorosulfonic acid, forming isomeric 4- and 2-toluenesulfonyl chlorides. The isomeric products are separated by freezing (chilling). The liquid part, 2-toluenesulfonyl chloride (3.2.68) is separated from the crystallized 4-toluenesulfochloride and reacted with ammonia, giving 2-toluenesul-fonylamide (3.2.69). Oxidation of the product with sodium permanganate or chromium (VI) oxide in sulfuric acid gives saccharin—o-sulfobenzoic acid imide (3.2.70) [123-126]. 

The reaction of saccharin with sodium hydroxide results in substitution of the imide hydrogen atom of saccharin with sodium, giving a sodium salt (3.2.75). The resulting product is reacted with methyl chloroacetate, giving the saccharin-substituted acetic acid methyl ester (3.2.76). Upon reaction with sodium methoxide in dimethylsuhoxide, the product undergoes... 

In the carbohydrate series, the acids encountered are aldonic, aldaric, uronic, or saccharinic acids. Often, these acids are readily transformed into their lactones or methyl esters, and it is as derivatives of these that they are commonly studied. Table VIII (see p. 136) records examples in which derivatives of such acids and lactones have been subjected to gas-liquid chromatography. 

All of the 4-carbon saccharinic acids possible have been prepared and characterized.132 The 4-carbon metasaccharinic acid has been encountered frequently,1,133-137 and a racemic mixture of the 2-methyl-glyceric acids (2,3-dihydroxy-2-methylpropanoic acids) was obtained from 4-O-methyl-D-threose.136... 

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