Hydroxy compounds, with Sugars

Glycoside Acetals derived from hydroxy compounds and sugars Halogenation Combination of Cl, Br, I, or F with a compound Humic Acid An acid-insoluble component of humic material, with molecular weight greater than fulvic acid... 

As with the flexible foams there has been a shift to the use of polyethers. These are largely adducts based either on trifunctional hydroxy compounds, on tetrafunctional materials such as pentaerythritol or a hexafunctional material such as sorbitol. Ethylene diamine and, it is understood, domestic sugar are also employed. Where trifunctional materials are used these are of lower molecular weight (-500) than with the polyethers for flexible foams in order to reduce the distance between hydroxyl groups and hence increase the degree of cross-linking. 

Compounds with hydroxy groups, such as flavonoids, sugars, or hydroxy acids, often react with 1% diphenyl boric acid (3-aminoethylester in methanol or ethanol. Various colors are formed by many natural products Neu reagent). 

However, most asymmetric 1,3-dipolar cycloaddition reactions of nitrile oxides with alkenes are carried out without Lewis acids as catalysts using either chiral alkenes or chiral auxiliary compounds (with achiral alkenes). Diverse chiral alkenes are in use, such as camphor-derived chiral N-acryloylhydrazide (195), C2-symmetric l,3-diacryloyl-2,2-dimethyl-4,5-diphenylimidazolidine, chiral 3-acryloyl-2,2-dimethyl-4-phenyloxazolidine (196, 197), sugar-based ethenyl ethers (198), acrylic esters (199, 200), C-bonded vinyl-substituted sugar (201), chirally modified vinylboronic ester derived from D-( + )-mannitol (202), (l/ )-menthyl vinyl ether (203), chiral derivatives of vinylacetic acid (204), ( )-l-ethoxy-3-fluoroalkyl-3-hydroxy-4-(4-methylphenylsulfinyl)but-1 -enes (205), enantiopure Y-oxygenated-a,P-unsaturated phenyl sulfones (206), chiral (a-oxyallyl)silanes (207), and (S )-but-3-ene-1,2-diol derivatives (208). As a chiral auxiliary, diisopropyl (i ,i )-tartrate (209, 210) has been very popular. 

Fibrous Materials. Contact with moist cloth, paper, or wood often causes ignition.4 Hydrogen Sulfide. Gas ignites immediately on contact with solid peroxide.7 Hydroxy Compounds. Mixture with ethanol, glycerol, sugar, or acetic acid usually results in fire or explosion.8... 

The sweetener aspartame was discovered in 1965 and approved by the FDA in 1981. It is the methyl ester of a dipeptide formed from the amino acids aspartic acid and phenylalanine. Because both of these amino acids occur naturally and arc part of nearly every protein, there is much less reason to be concerned about the health effects of this compound. Nevertheless, it has been extensively tested. Aspartame is about 180 times sweeter than sucrose, so the amount that is needed to sweeten a can of a soft drink, for example, is so small that it contributes only negligible calories to the diet. In addition, the taste profile of aspartame is much closer to sugar than is that of saccharin. Aspartame, sold under the brand name NutraSweet, has been an enormous financial success. Sucralose (Splenda) is prepared from sucrose by replacing some of the hydroxy groups with chlorines. Its taste closely resembles sucrose, but it is about 600 times sweeter. Acesulfame K (Sunett, Sweet One) is about 200 times sweeter than sucrose. It is quite stable to heat, so it is potentially very useful in baked goods. 

The most dramatic results obtained so far with gold catalysts have been with the liquid phase processes. They are conducted with oxygen or air, often using water as solvent, and are therefore felt to be environmentally benign. Particular success has been obtained with reducing sugars (Section 8.3.2) and other aldehydes (Section 8.3.3), and with alcohols and other hydroxy-compounds (Sections 8.3.4-8.3.7). Reactions that use soluble gold complexes to catalyse selective oxidation are reported in Chapter 12. 

The precipitation of aluminium hydroxide by solutions of sodium hydroxide and ammonia does not take place in the presence of tartaric acid, citric acid, sulphosalicylic acid, malic acid, sugars, and other organic hydroxy compounds, because of the formation of soluble complex salts. These organic substances must therefore be decomposed by gentle ignition or by evaporating with concentrated sulphuric or nitric acid before aluminium can be precipitated in the ordinary course of qualitative analysis. 

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