Oxalic acid structure

Because of the structural requirements of the bielectrophile, fully aromatized heterocycles are usually not readily available by this procedure. The dithiocarbamate (159) reacted with oxalyl chloride to give the substituted thiazolidine-4,5-dione (160) (see Chapter 4.19), and the same reagent reacted with iV-alkylbenzamidine (161) at 100-140 °C to give the 1 -alkyl-2-phenylimidazole-4,5-dione (162) (see Chapter 4.08). Iminochlorides of oxalic acid also react with iV,iV-disubstituted thioureas in this case the 2-dialkylaminothiazolidine-2,4-dione bis-imides are obtained. Thiobenzamide generally forms linear adducts, but 2-thiazolines will form under suitable conditions (70TL3781). Phenyliminooxalic acid dichloride, prepared from oxalic acid, phosphorus pentachloride and aniline in benzene, likewise yielded thiazolidine derivatives on reaction with thioureas (71KGS471). 

Hydrocarbon A has the formula C Hg- It absorbs 8 equivalents of H2 on catalytic reduction over a palladium catalyst. On ozonolysis, only two products are formed oxalic acid (H02CC02H) and succinic acid (H02CCH2CH2C02H). Write the reactions, and propose a structure for A. 

Osmium tetroxide, reaction with alkenes, 235-236 toxicity of, 235 Oxalic add, structure of, 753 Oxaloacetic acid, structure of, 753 Oxetane, reaction with Grignard reagents, 680 Oxidation, 233, 348 alcohols, 623-626 aldehydes, 700-701 aldoses, 992-994 alkenes, 233-236 biological, 625-626 phenols, 631 sulfides, 670 thiols, 668... 

Oxalic acid, H2C204, is a poisonous compound found in rhubarb leaves. Draw the Lewis structure for oxalic acid. There is a single bond between the two carbon atoms, each hydrogen atom is bonded to an oxygen atom, and each carbon is bonded to two oxygen atoms. 

Write the structural formula of two units of the polymer formed from (a) the reaction of oxalic acid (ethanedioic acid), HOOCCOOH, with 1,4-diaminobutane, H2NCH2CH2CH2CH2NFI2 (b) the polymerization of the amino acid alanine (2-aminopropanoic acid). 

Write the condensed structural formulas of the principal products of the reaction that takes place when (a) ethylene glycol, 1,2-ethanediol, is heated with stearic acid, CH,(CH2)i6COOH (b) ethanol is heated with oxalic acid, HOOCCOOH (c) 1-butanol is heated with propanoic acid. 

The 2 1 reaction of 9-BBN with a series of dicarboxylic acids, namely oxalic acid, malonic acid, 2,2-dimethylmalonic acid, and succinic acid, in dimeth-oxyethane gives in some cases dimeric and in other cases macrocyclic (acyloxy)diorganoboranes. This has been proved by IR spectroscopy (all C = O groups are bidentate), B-NMR 5 = 10 ppm) and X-ray crystallography [47]. With oxalic acid two structures are possible (IV and V), of which the first with a five-membered boron heterocycle instead of a four-membered one is the more probable formulation (Fig. 13). 

Fig. 13. Possible structures for (acyloxy)boranes formed from the reaction of 9-BBN with oxalic acid and solid state structure of the complex with 2,2-dimethylmalonic acid 30...

Del Nozal, M. J., Bernal, J. L., Gomez, L. A., Higes, M., and Meana, A. (2003b). Determination of oxalic acid and other organic acids in honey and in some anatomic structures of bees. Apidologie 34,181-188. 

Langer and coworkers constructed diverse O- and N-heterocydic scaffolds, such as y-alkylidene-a-hydroxybutenolides and pyrrolo[3,2-b]pyrrol-2,5-diones, exploiting the well-established cyclization strategy of bisnucleophiles with oxalic acid derivatives [163], while Stockman s research group reported in this context on a novel oxime formation/Michael addition providing the structural core of the alkaloid perhydrohistrionicotoxin [164]. 

The structure of the levan synthesized by the action of B. subtilis on sucrose was determined by Hibbert and Brauns.89 Levan, in a yield of 60-65% calculated on the D-fructose part of the sucrose, was obtained by precipitation of the concentrated culture into methanol, and purified by reprecipitation and electrodialysis. Hydrolysis of purified levan with 0.5% aqueous oxalic acid for one hour at 100° gave a 99% yield of crystalline D-fructose. Triacetyllevan was prepared by treatment with acetic anhydride in pyridine, and deacetylation with alcoholic alkali yielded material identical with the original levan.940... 

D-glucose and its lactone from 2,3,6-trimethyl-D-glucose provided conclusive proof that the ring system was not of the hexylene oxide type.142 188 The final evidence necessary to characterize the tetramethylglucose in question as a furanose derivative was provided by Haworth, Hirst and Miller,176 who demonstrated that oxidation of the tetramethylglucose with bromine water and of the resulting lactone with nitric acid yielded dimethoxysuccinic acid and oxalic acid, but not i-zyZo-trimethoxyglutaric acid, the absence of which ruled out a pyranose structure. 

Working first with Polanyi, Weissenberg, and Brill, and later as the leader of the Textile Chemistry Section, Mark successively published papers on the crystal structures of hexamethylenetetramine, pentaerythritol, zinc salts, tin, urea, tin salts, triphenylmethane, bismuth, graphite, sulfur, oxalic acid, acetaldehyde, ammonia, ethane, diborane, carbon dioxide, and some aluminum silicates. Each paper showed his and the laboratory s increasing sophistication in the technique of X-ray diffraction. Their work over the period broadened to include contributions to the theories of atomic and molecular structure and X-ray scattering theory. A number of his papers were particularly notable including his work with Polanyi on the structure of white tin ( 3, 4 ), E. Wigner on the structure of rhombic sulfur (5), and E. Pohland on the low temperature crystal structure of ammonia and carbon dioxide (6, 7). The Mark-Szilard effect, a classical component of X-ray physics, was a result of his collaboration with Leo Szilard (8). And his work with E. A. Hauser (9, 10, 11) on rubber and J. R. 

Mitrovic and Knezic (1979) also prepared ultrafiltration and reverse osmosis membranes by this technique. Their membranes were etched in 5% oxalic acid. The membranes had pores of the order of 100 nm, but only about 1.5 nm in the residual barrier layer (layer AB in Figure 2.15). The pores in the barrier layer were unstable in water and the permeability decreased during the experiments. Complete dehydration of alumina or phase transformation to a-alumina was necessary to stabilize the pore structure. The resulting membranes were found unsuitable for reverse osmosis but suitable for ultrafiltration after removing the barrier layer. Beside reverse osmosis and ultrafiltration measurements, some gas permeability data have also been reported on this type of membranes (Itaya et al. 1984). The water flux through a 50/im thick membrane is about 0.2mL/cm -h with a N2 flow about 6cmVcm -min-bar. The gas transport through the membrane was due to Knudsen diffusion mechanism, which is inversely proportional to the square root of molecular mass. 

Polymers of D-fructose are important carbohydrate reserves in a number of plants. Inulins and levans are two major types that differ in structure. D-Fructans require only relatively mild conditions for their hydrolysis, for example, levan was qualitatively hydrolyzed by hot, dilute, aqueous oxalic acid. Permethylated fructans could be hydrolyzed with 2 M CF3CO2H for 30 min at 60°. Fructan oligosaccharides were hydrolyzed in dilute sulfuric acid (pH 2) at 70 (see Ref. 53) or 95° (0.1 M). D-Fructans from timothy haplocorm (where they comprise 63% of the water-soluble carbohydrates) could be hydrolyzed with 0.01 M hydrochloric acid at 98°. 

The feasibility of benzenic ring amines, benzenic ring structures and aliphatic acids oxidation by means of Fenton chemistiy was tested in synthetic, acidic wastewaters by Fenton s reagent electrogenerated at a reticulated vitreous carbon cathode using the flow-cell. The organic molecules considered were phenol (Ph), cresol (Cr), aniline (An) hydroquinone (HQ), catechol (Cat), parabenzoquinone (pBQ) and oxalic acid (OxAc). Their initial... 

With 2,4-D, neither the trimethylsilyl ester nor the free acid was found among the reaction products. The dominant chromatographic peaks in the mixture represent the TMS derivatives of glycolic acid, oxalic acid, and several four-carbon oxidation products. Some of the latter have been tentatively identified, and the work needed to confirm choices between alternative structures is continuing. Some smaller chromatographic peaks probably represent derivatives of structures containing five or more carbon atoms. The nature of... 

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