Trimellitic acid

See also Trimellitic acid.) [PHTTiALIC ACID AND OTTiERBENZENEPOLYCARBOXYLIC ACIDS] (Vol 18)... 

Of the three benzenetricarboxyhc acids, only trimellitic acid as the anhydride is commercially produced in large volume, by Hquid-phase air oxidation of either pseudocumene or dimethyl benzaldehyde. The pseudocumene oxidation is another variant of the cobalt—manganese—bromine catalyst in acetic acid solvent as described in the terephthaUc acid section. The acid is available as a laboratory chemical (99). The lUPAC name of trimellitic anhydride is 5-isobenzofurancarboxyhc acid (l,3-dihydro-l,3-dioxo). 

Physical and Chemical Properties. Trimellitic acid and trimellitic anhydride are odorless white crystalline soHds in their pure form. The acid is reasonably stable up to the melting point, where dehydration to the anhydride occurs. The anhydride reacts with atmopsheric moisture, even at room temperature, to revert to the acid. Physical properties of the acid and its anhydride are Hsted in Tables 29—31. 

Table 29. Physical Constants of Trimellitic Acid and Trimellitic Anhydride...

The freezing point of trimellitic anhydride, the maximum temperature reached during crystallization of a molten sample, is a measure of the product purity. Impurities and trimellitic acid formed by hydrolysis depress the freezing point. 

Table 34. Properties of Trimellitic Acid Esters and the Chlorocarbonyl Anhydride...

Mitsubishi Gas Chemical Co. in Japan produces pyromellitic dianhydtide in the same unit used for trimellitic anhydtide production (105). This process starts with pseudocumene, which is first carbonylated with carbon monoxide in the presence of boron trifluotide and hydrogen fluotide to form 2,4,5-trimethylbenzaldehyde. The Hquid-phase oxidation of the trimethylbenzaldehyde to pyromellitic acid and subsequent processing steps ate much the same as described for the Mitsubishi Gas Chemical process in the trimellitic acid section. The production of pyromellitic anhydtide is in conjunction with a joint venture agreement with Du Pont. 

TrikotfUrberei, /. dyeing of knitted goods. Tr lt,..n. ( Jzpl.) "trilit" (trinitrotoluene). Trimellit(h)saure,/. trimellitic acid. Trimesinsaure, /. trimeaic acid. ... 

Tri-(2-hydroxyethyl)amine, t266 1,2,6-Trihydroxyhexane, h63 1,2,3-Trihydroxypropane, gl9 Triiodomethane, i33 Trimellitic acid, b30... 

There is an interesting technique which makes it possible to introduce carboxylic acid groups into a copper phthalocyanine structure by an economical route. Carrying out the phthalic anhydride/urea process in the presence of a small amount of trimellitic acid or another benzene polycarboxylic acid will afford a car-boxylated pigment. 

Lastly, we show in Scheme 18.2 what would be two logical reaction products of the alkyl radical which is produced. The hydrogen abstraction was already proposed [11, 25] by others on the basis of spectroscopic evidence for an aldehyde but it has not been confirmed that the species was an aliphatic aldehyde being produced as opposed to an aromatic one and so is ambiguous. Hydrolysis of the top product of this section of the scheme would produce formic acid, which has been reported [11], However, more reasonable sources of formic acid exist in Schemes 18.3 and 18.4 (see below). The other product that one would expect to see would result in trimellitic acid being observed in the hydrolysate of the degraded polyester. This has, to our knowledge, not been reported as yet. 

A review by Galli et al. describes several buffer-absorbing chromophores as co-ions. These include phthalate, PDG (2,6-pyridinedicarboxylic acid), PMA (1,2,4,5-benzenetetra-carboxylic acid or pyromellitic acid), TMA (trimellitic acid), MES, 2,4-dihydrobenzoic acid with s-aminocaproic acid, p-hydroxybenzoate, p-anisate, 3,5-dinitrobenzoic acid, salicylic acid with TRIS, benzoic acid with tris (hydroxymethyl)aminomethane (TRIS), and many others. On the other hand, some inorganic chromophores such as chromate (Figure 9) or molybdate may be added to a buffer. A BGE-containing chromate should have a pH above 8, because it precipitates below this value. The advantage of a TRIS buffer or buffers at around pH 6 is that carbonate will not interfere with the separation because it is not soluble in TRIS or at lower pHs. 

Fawcett IW, Taylor AJN, Pepys J Asthma due to inhaled chemical agents—Epoxy resin systems containing phthalic acid anhydride, trimellitic acid anhydride and triethylene tetramine. Clin Allergy 7 1-14, 1977... 

Trimellitic acid [528-44-9] M 210.1, m 218-220°. Crystd from acetic acid or aqueous EtOH. 

Aromatic hydrocarbons which have methyl side chains mainly behave like toluene and form aldehydes, while combustion is stimulated and selective oxidation of the nucleus is repressed. The oxidation of methyl-naphthalene, for example, exhibits a low selectivity with respect to phtha-lic anhydride formation, combustion and maleic acid formation being the dominating reactions. Durene is a special case because it resembles o-xy-lene. The oxidation of durene over a V—W—O catalyst at 420° C is reported to produce pyromellitic dianhydride, phthalic and maleic anhydride, although combustion dominates (Geiman et al. [122]). 1,2,4-Trimethyl-benzene yields dimethylbenzene and trimellitic acid if oxidized on a Sn— V—O catalyst. Kinetic data have been measured by Balsubramanian and Viswanath [37]. 

Pseudocumene 200 Trimellitic acid, 23 Methylphthalic acid, 39 Dimethylbenzoic acid, 14... 

Trimellitic acid, b29 Trimesic acid, b30 Trimesoyl chloride, b32 Trimethylacetaldehyde, d596... 

Also, when benzene polycarboxylic acid compounds (31-35) were used, a 3 1 complex (39) of trimellitic acid (34) with 1, and a 2 1 complex (40) of pyromel-litic acid (35) with 1 were obtained (Table 4). Although the inclusion complexes were not obtained with the other similarly structured compounds (31-33), it was shown that as the number of carboxyl groups of the host increases, the inclusion complexation becomes easier. 

The analysis of aliphatic acids was performed using a P/ACE MDQ capillary electrophoresis instrument equipped with a 60 cm x 50 pm id fused silica capillary (Beckman Coulter, Fullerton, CA). The samples were filtered through a 0.45-gm cellulose acetate filter (Whatman, Maidstone, UK) prior to hydrodynamic injection at 15 psi for 4 s. The voltage was set to 20 kV at reversed polarity. The electrolyte, composed of 5.0 mM trimellitic acid, 50 mM tris(hydroxymethyl)-aminomethane, 1.0 mM tetradecyl-trimethylammoniumbromide, and 0.5 mM calcium chloride, had a pH of 9.8. Before use, it was filtered through a 0.2-gm cellulose nitrate filter and degassed withhelium. Detection was performedby indirect UV absorption at 220 nm. Succinic acid was used as internal standard. 

SYNS ANHYDROTRIMELLIC ACID 1,2,4-BENZ-ENETRICARBOXYLIC ACID ANHYDRIDE 1,2,4-BENZENETRICARBOXYLIC ACID, CYCLIC 1,2-ANHYDRIDE 1,2,4-BENZENETRICARBOXYLIC ANHYDRIDE 4-CARBOXYPHTHALIC ANHYDRIDE l,3-DIHYDRO-l,3-DIOXO-5-ISOBENZOFURANCARBOX-YXIC ACID l,3-DIOXO-5-PHTHAL. NCARBOXYLIC ACID DIPHENYLMETHANE-4,4 -DIISOCYANATE-TRIMELLIC ANHYDRIDE-ETHOMID HT POLYMER NCI-C56633 TMA TMAN TRIMELLIC ACID ANHYDRIDE TRIMELLIC ACID-1,2-ANHYDRIDE TRIMELLITIC ACID CYCLIC-1,2-ANHYDRIDE... 

Probes currently employed in the indirect UV detection of amino acids include p-aminosalicylic acid, benzoic acid, phthalic acid, sodium chromate, 4-(N,N -dimethylamino)benzoic acid, 1,2,4,-benzenetricar-boxylic acid (trimellitic acid), 1,2,4,5-benzenetetracar-boxylic acid (pyromellitic acid), and quinine sulfate. Several of these probes are employed in combination with metal cations and cationic surfactants, which are incorporated into the electrolyte solution as modifiers of the electro-osmotic flow. 

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