Trimellitate esters

Derivatives. The dual functionaUty of trimellitic anhydride makes it possible to react either the anhydride group, the acid group, or both. Derivatives of trimellitic anhydride include ester, acid esters, acid chloride, amides, and amide—imides (136). Trimellitate esters are the most important derivatives, and physical properties of more significant esters are Hsted in Table 34. 

There are several widely used trimellitate esters including TOTM (Equation 15.5). 

Trimellitate Esters. These materials are produced by the esterification of a range of alcohols with trimellitic anhydride (TMA), which is similar in structure to phthalic anhydride with the exception of the third functionality (COOH) on the aromatic ring. Consequently, esters are produced in the ratio of three moles of alcohol to one mole of anhydride. Common esters in this family are tris-2-ethyhexyl trimellitate (trioctyl trimellitate, TOTM) L79TM, an ester of mixed semilinear C7 and C9 alcohols and L810TM, an ester of mixed linear Cg and C1Q alcohols. 

DTDP > DIDP > DINP > DOP > DIHP > DBP. Higher molecular weight esters such as trimellitates are even more thermally stable and trimellitate esters find extensive use in the demanding cable specifications which have strict mass loss requirements. 

Plasticizers. Monomeric (mol wt 250—450) plasticizers (qv) are predominantly phthalate, adipate, sebacate, phosphate, or trimellitate esters. Organic phthalate esters like dioctyl phthalate (DOP) are by far the most common plasticizers in flexible PVC. Phthalates are good general-purpose plasticizers which impart good physical and low temperature properties but lack permanence in hot or extractive service conditions and are therefore sometimes called migratory plasticizers. Polymeric plasticizers (mol wt up to 5000 or more) offer an improvement in nonmigratory permanence at a sacrifice in cost, low temperature properties, and processibility examples are ethylene vinyl acetate or nitrile polymers. 

Compressor oils This market sector covers a wide range of compressor types used for a number of different gases. Diesters and phthalates have found their major application in air compressor lubricants and are also used in natural gas compressors. In reciprocating compressors, where oils of rather higher viscosity are preferred, trimellitate esters can be used. Diesters and polyol esters may also be blended with PAOs for use in various compressor types. 

Trimellitates (Trimellitate Esters) with low volatilities, used where high temperatures are involved) ... 

CAS 3319-31-1 EINECS/ELINCS 222-020-0 Synonyms 1,2,4-Benzenetricarboxylic acid, tris (2-ethylhexyl) ester 2-Ethylhexyl trimellitate Tri (ethylhexyl) trimellitate Tri (2-ethylhexyl) trimellitate ester Trimellitate tris (2-eth hexyl) ester Tris (2-ethylhe) ) benzenetricarbor te Tris (2-ethylhe) benzene-1,2,4-tricarbo) te Tris (2-ethylhexyl) ester 1,2,4-benzenetricarboxylic acid Tris (2-ethylhexyl) trimellitate Classification Aromatic ester Empirical C33H54O6 Formula C6H3(COOC8H,7)3... 

Tri (2-ethylhexyl) trimellitate ester. SeeTri-2-ethylhexyl trimellitate Triethyl-2-hydroxypropan-1,2,3-tricarboxylate. See Triethyl citrate Triethylolamine. See Triethanolamine... 

Trimellitic esters, such as tri-(2-ethylhexyl) trimellitate, TOTM, triisooctyl trim-ellitate, TIOTM, triisononyl trimellitate, TNTM... 

In a flexible PVC compound the trimellitates are less volatile and have improved thermal stability over the phthalate and polymeric plasticizers. Their plasticizing effectiveness and compatibility are similar to phthalates. They offer better moisture and water resistance than the phthalates or polymeric plasticizers. Large volumes of trimellitate esters are used in 90°C and 105°C UL rated insulation compounds. Because of their extraction and migration resistance, thermal stability, and low volatility, the trimellitates are used in conjimction with 9IIP and DUP in automotive interior trim applications where windshield fogging is an issue. 

Phthalic anhydride or trimellitic anhydride are converted into esters by reactions with alcohols as shown in Figure 8. Phthalic anhydride is produced cheaply and in large volume from oxidation of ortho-xylene. The largest use of phthalate esters is in the plasticizer market. Only a small fraction of its production is consumed by the synthetic lubricants market. Phthalate esters generally have superior hydrolytic stability than adipic esters because the ortho di-ester groups are electronically less available and sterically more hindered. However, they have lower Vis, 50-70, because of their high polarity and the presence of branched alcohol chains. They are used in special industrial oil applications where VI is not a critical parameter. Trimellitate esters are specialty products and relatively expensive. They are of high viscosity and usually are more resistant to oxidation than adipic esters. 

Trimellitic anhydride is quite a young molecule for Polynt. Its industrial production started in the Scanzorosciate site in Italy in 1994 after a six-year project devoted to develop the technology and catalyst formulation. From 2007 a similar technology and catalyst have been used in Polynt s Changzhou plant in China, where, as in Italy, TMA is further transformed into trimellitate esters, utilized as special plasticizers. 

Trimellitates (esters of 1,2,4-benzenetricarboxylic acid) 8-10-TM-E, mixture of Cl and C9 trimelUtates (plus trace bisphenol-A). 

Because of the lower volatility of DIDP and DPHP relative to other GP plasticizers, these two plasticizers are also sometimes considered low-volatility plasticizers. For automotive interior products the plasticizers DEHP, DINP, DEHTP, DC9CH, citrates, benzoates, as well as many of the phthalate alternatives would fail many interior emission or fogging requirements while DIDP and DPHP, along with trimellitate esters and the linear phthalates L9P and L91P, would pass. 

Figure 24.1 Structures of the phthalate, terephthalate, and trimellitate esters of 2-ethylhexanol.

Trimellitate esters are used as primary plasticizers in those applications where greater permanence is required. Tliese esters, prepared by the esterifica-... 

Palatinol 79TM-I is a high molecular weight trimellitate ester based upon C7 and C9 predominantly linear alcohols. 

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