Carboxylic acid thermal degradation

Many impurities are present in commercial caprolactam which pass into the liquid wastes from PCA manufacture from which caprolactam monomer may be recovered. Also, the products of die thermal degradation of PCA, dyes, lubricants, and other PCA fillers may be contained in the regenerated CL. Identification of die contaminants by IR spectroscopy has led to the detection of lower carboxylic acids, secondary amines, ketones, and esters. Aldehydes and hydroperoxides have been identified by polarography and thin-layer chromatography. 

Some relevant substituents are displayed in Table XV. Hydrolysis of esters or nitriles followed by thermal decarboxylation of 2-, 5-, 6-, and 7-carboxylic acids is often used for degradation reactions (61CPB883, 61JCS3046 64UP1). 5-Amino-l,2,4-triazole-3-carboxylic acid is decarbox-ylated in situ by condensation to TP (83S44) TP-5-amideoxime is cyclized to the 5-( 1,2,4-oxadiazol-3-yl) derivative (90EGP282009). 

The vinyl groups can be retained in many of the degradations of chlorophylls thus 3-vinylpheoporphyrin a5 (106) and 3-vinylrhodoporphyrin-XV (107) can be obtained. Both chlorin e6 and rhodin gy can be re-converted by treatment with methoxide or, better, with butoxide (8OJOC2218) into pheophorbides a or b, respectively. Of the three carboxylic acid groups in chlorin e6, those at the methine and 13-positions can be removed thermally to give chlorin e4 (108) and isochlorin e4 (109), together with phyllochlorin (110). 

One of the first non-formaldehyde fluorescent dye carrier systems for polyolefins was based on the reaction of polyfunctional amines with polyfunctional carboxylic acids to form relatively short chain polyamides [5].These linear thermoplastic resins showed good solubility and friability making them suitable for the incorporation of dyes, which offered increased protection from thermal and UV degradation. This fluorescent resin showed a dramatic increase in color retention upwards of 288°C, even after a 10 minute hold period at this temperature. Due to its non-ide-alized polymeric nature, the polyamide chemistry suffered from preferential plating out or migration of polar oligomeric species not incorporated into the polymer chains. 

At temperatures greater than a 100°C, thermal degradation of carboxylic acids produces methane and carbon dioxide (Surdam et ai, 1984). As the carboxylic acid anions are consumed due to increasing temperature, the carbonate system becomes internally buffered, and thus the pH may decrease due to increased in the system, leading to carbonate dissolution and the enhancement of secondary porosity (Surdam et ai, 1984). Factors influencing the thermal destruction rate of organic acids include coupled sulphate reduction and hydrocarbon oxidation, and the mineralogy of host sediments (Bell, 1991) the presence of hematite causes rapid rates of acetic acid decomposition. 

Thermal oxidative degradation of PE and PE nanocomposites has been extensively studied over the past decades [26-30], It has been reported that the main oxidation products of PE are aldehydes, ketons, carboxylic acids, esters and lactones [26, 27], According to Lacoste and Carlsson [28], P-scission plays an important role in thermal oxidation of UHMWPE. Notably, the feasibility of intra-molecular hydrogen abstraction by the peroxy radicals for polyethylene has been questioned in frames of a thermal oxidation mechanism proposed by Gugumus [29, 30],... 

Destruction of Carboxylic Acid Anions. Destruction of CAA has been postulated to occur by two processes bacterial degradation at low temperature and thermal decarboxylation at higher temperature (JJ). Little is known about the distribution of CAA substrate bacteria in formation waters, so their affect upon the distribution and concentration of CAA in formation waters is difficult to effectively model. However, bacterial degradation is important in many formation waters (7.43.45). Although they don t coexist, both anaerobic and aerobic bacteria have been reported in different petroliferous environments at temperatures in excess of 90 C (60.61) it should be noted that at temperatures in excess of about 45 °C they are metabolically inactive (2). At surface conditions, CAA are so readily metabolized by aerobic bacteria, produced formation water samples require immediate preservation at the time of sampling (35.45). 

A scheme for the formation of guaiacols from ferulic acid has also been proposed by Manley et al. (1974). The biosynthesis of various phenolic acids from p-coumaric acid (H.84) was studied by Friedrich (1976). Formation pathways for simple phenols in food flavors have been reviewed (Maga, 1978a). The two primary pathways could be the decarboxylation of phenolic carboxylic acids and the thermal degradation of lignin. Secondary pathways include bacterial, fungal, yeast enzymic and glycosidic reactions. 

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