Oxalic acid pyrolysis

This method can also be used in the determination of the DA of chitin based on reactive pyrolysis gas chromatography in the presence of oxalic acid aqueous solution. The DA could be determined from chromatography of the characteristic products of thermal decomposition of chitin in the absence of oxygen. 

The Naval Ammunition Depot (NAD) at Crane, Indiana has developed improved fire-retardant phenolic foams containing blends of boric/oxalic acids as catalysts, as described above. The resultant foams were found to be extremely efficient fire barriers due to their high heat absorptivity, the amount of carbon and/or coke produced during pyrolysis, and the adhesion of the char to the burned materials. Other advantages of the foam during flaming and nonflaming pyrolysis are its low smoke emissions and lack of toxic fumes other than carbon monoxide. It takes one hour to reach 230°F (110°C) when a 13 Ib/tf (208 kg/m ) phenolic foam specimen 2.9 inches (7.4 cm) is exposed to a fully developed fire (41). 

Scheme 6 Transformation of Carvone (71) to methyl ketone (74) was achieved by the use of known reagents. It was converted to a mixture of diasteromers(75) and separarated. Hydration of each isomer with dilute methanolic oxalic acid yielded the corresponding lactone (76), each of which was converted into the same lactone (77). Epoxidation followed by reduction gave a mixture of epimeric diols whose diacetate was subjected to pyrolysis to phytuberin (55).

Co-precipitation method, sol-gel method, freeze drying method, spray pyrolysis method and combustion method are usually used to prepare powders. Powders prepared by the combustion method have small size, high purity and good chemical stability. Urea, glycine, carbohydrazide, citric acid and so on were used as the fiiel in this paper. According to the previous report, Gd203 powders have a monoclinic structure when citric acid was used as the fiiel. While we used the citric acid and EDTA as combination fuel, the Gd203 powders prepared had the cubic structure in this paper. As comparison, oxalic acid co-precipitation was also used to prepare the powders. 

H. Sato, S.-I. Mizutani, S. Tsuge, H. Ohtani, K. Aoi, A. Takasu, et al., Determination of the degree of acetylation of chitin/chitosan by pyrolysis-gas chromatography in the presence of oxalic acid, Anal. Chem. 70 (1998) 7-12. 

Finely divided oxide may be obtained by pyrolysis of cadmium salts of carboxylic acids, such as cadmium formate or oxalate ... 

Ceda-based oxides can be obtained by the decomposition of some compound precursor, such as hydroxide, nitrate, halides, sulfates, carbonates, formates, oxalates, acetates, and citrates.For example, nanosize or porous cerium oxide particles have been prepared at low temperatures by pyrolysis of amorphous citrate," which is prepared by the evaporation of the solvent from the aqueous solution containing cerium nitrate (or oxalate) and citric acid. In the case of mixed oxides, the precursor containing some cations in the same solid salts is prepared. In the same manner of ceria particles, the precursors complexing some cations with citrates are useful to synthsize ceria-zirconia mixed oxides and their derivatives. Also. Ce02-Ln203 solid solutions, where Ln = La. Pr, Sm. Gd. and Tb, have been synthesized from the precursors obtained by the evaporation of nitrate solutions at 353 K in air from an intimate mixture of their respective metal nitrates. The precursors are dried and then heated at 673 K to remove niU ates, followed by calcination at 1073 K for 12h. 

Coffee brewed from roasted beans and those prepared from instant powder, including the caffeine-free type, all display mutagenic activity. Apart from natural mutagens such as caffeic acid and its precursors chlorogenic and neochlorogenic acids, these drinks contain mutagenic products of pyrolysis methylglyoxal and less active gly-oxal and diacetyl (Ames, 1986) ... 

Furfuraldehyde (furan), when reacted with NaOH, forms furfuryl alcohol, which can be polymerized by applying heat in the presence of an acid catalyst (e.g. oxalic add or maleic anhydride) to initiate the reaction. Once started, the reaction becomes exothermic and can be controlled, or stopped by cooling. The process initially forms difurfuryl alcohol and finally a highly crosslinked resin with a yield, when pyrolyzed at 950°C, of some 50-60% carbon with a density of about 1.55 gcm and a linear shrinkage of around 20%. In the process, H2O, CH4, CO2, CO and H2 are evolved [39] and above 450°C, the water evolved in this process actually takes part in the latter stages of the pyrolysis. 

---