Mellite

Colourless solid m.p. 79 - C. Forms a quinone, duroquinone, a phenol, durenol and a carboxylic acid, durylic acid. Oxidized to pyro-mellitic dianhydride. 

C]2Hi50]2. Colourless needles m.pr. 286-288°C. When heated it decomposes into pyro mellitic anhydride, water and CO2. Occurs as the aluminium salt (honeystone) in some lignite beds. Prepared by oxidation of charcoal with concentrated nitric acid. 

See also Mellitic acid.) [PHTHALIC ACID AND OTHERBENZENEPOLYCARBOXYLIC ACIDS] (Vol 18)... 

Neither benzenepentacarboxylic acid nor mellitic acid are manufactured commercially, but synthetic mellitic acid can be purchased as a laboratory chemical (99). Both can be synthesized by oxidizing the corresponding methylbenzenes or other substituted benzenes, and both are present in trace amounts after oxidation of coal or coal-like substances. 

The composition varies with the heat treatment and the end point according to x-ray diffraction studies it is a form of carbon that reconverts to weU-ordered graphite on heating to 1800°C. Before the use of x-rays, chemists used the Brodie reaction to differentiate between graphitic carbons and turbostratic carbons. Turbostratic carbons yield a brown solution of humic acids, whereas further oxidation of graphite oxide produces mellitic acid (benzenehexacarboxyhc acid) [517-60-2] ... 

When the original reaction between the 1-methylpyrrole and dimethyl acetylenedicarboxylate was carried out on a larger scale with inadequate cooling, an exothermic reaction took place and none of the dihydroindole (48) could be detected among the products. However these included the mellitic ester (49) and the pyrrole (50), indicating that some of the dihydroindole (48) had formed and had combined with more of the acetylenic ester as already described. A decomposition product of the dihydroindole as yet unidentified, tetramethyl l-methylindole-2,3,6,7-tetracarboxylate (52), and tetramethyl prehnit-... 

Honig-harnruhr, f. diabetes mellitus. -klee, m. sweet clover, melilot. -saft, m. nectar, -silure, /. Pharm.) oxymel mellitic acid, -acheibe, /. honeycomb, -aeim, m. liquid honey. -stein, m. honeystone, mellite. -steinsilure, /. mellitic acid, honigsliss, a. honey-sweet. 

Sigmoid curves, attributable to nucleation and growth reactions, were observed for the decompositions of cobalt phthalate and silver mellitate these are marked in Table 16. The decomposition of nickel terephthalate [88] obeys the Avrami—Erofe ev equation [eqn. (6)], for which n is 1.0— 1.5 and E = 226 8 kJ mole-1. Decompositions of Co—Ni mixed mellitates are discussed in Sect. 7. 

Pyrolyses of formates, oxalates and mellitates yield CO and C02 (H2, H20 etc.) as the predominant volatile products and metal or oxide as residue. It is sometimes possible to predict the initial compositions from thermodynamic considerations [94], though secondary reactions, perhaps catalyzed by the solids present, may result in a final product mixture that is very different. The complex mixtures of products (hydrocarbons, aldehydes, ketones, acids and acid anhydrides) given [1109] by reactants containing larger organic groupings makes the collection of meaningful kinetic data more difficult, and this is one reason why there are relatively few rate studies available for the decompositions of these substances. 

Fig. 19. The rate of decomposition of a 1 1 Ni—Co mixed mellitate at 663 K was appreciably greater than that expected from the sum of the contributions from the pure individual components. (Reproduced, with permission, from the Journal of the Chemical Society.)...

Decomposition rates of (Ni,Co) mellitates [1110] increase with increase in nickel content. The a—time curves for the pure components and the mixed mellitates were deceleratory throughout and there was no discontinuity in shape with changes in composition. Rates of decomposition of the solid solutions were appreciably greater than those expected from the decomposition of the individual components present (Fig. 19). The values of E determined for the initial stages of the decomposition of mixtures were close to that found for the nickel salt (184 kJ mole 1) and in the latter stages tended to increase towards that for cobalt mellitate (251 kJ mole-1). Values of A showed a systematic decrease with increase in cobalt content. 

Copper(II) oxide and cobalt(II) hydroxide form cements with solutions of many multifunctional organic acids propanetricarboxylic acid, tartaric acid, malic acid, pyruvic acid, mellitic acid, gallic acid, tannic acid and phytic acid (Allen et al., 1984 Prosser et al., 1986). These have been used mainly in cement devices for the sustained release of copper and cobalt (Manston et al., 1985 Mansion Gleed, 1985). Little is known about... 

Oxidation of the durene derivative to benzenehexacarboxylic acid (mellitic acid) in an autoclave is normally effected in stages, initially by heating at 80-104°C with the vent open to allow escape of the evolved gases. Subsequent heating to a higher temperature with the vent closed completes the reaction. On one occasion omission of the first vented heating phase led to explosive rupture of the autoclave at 80° C. 

Mellitic acid can be decarboxylated to yield pyromellitic acid, either by the action of heat alone 4 or in the presence of sulfuric acid.5... 

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