Triester Compounds

Ink compositions with triester compounds can be widely used in inkjet inks, paints, textile printing, paper manufacturing, cosmetics manufacturing, or the ceramic industry (36). 

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The addition of triester compounds improves the waterfastness of printed images and dry and wet rub fastness to have good colorfastness on the paper (36). An example is shown in Figure 3.19. 

Asymmetrical triesters of phosphoric acid of the general formula ROPO (OR,)2 (R = C8 i4 alkyl R, = C, 3 alkyl) were obtained in approximately 70% yield by treatment of a higher fatty alcohol and a Ci 3 alcohol with P0C13 in hexane or pyridine at <0°C. The products were soluble in nonpolar organic solvents and partially soluble in polar organic solvents and water. But the foamforming ability and foam stability of the compounds in water were low [11]. 

The neutral surfactant is measured after fixing of the ionic substances on a combined anionic/cationic ion exchange column. Volatile substances in the eluate are determined by gas chromatography and nonvolatile substances are measured gravimetrically. In the bulk of the neutral compounds phosphoric acid triesters may be present. This part is additionally determined by atom emission spectroscopy. 

A gel of diesel or crude oil can be produced using a phosphate diester or an aluminum compound with phosphate diester [740]. The metal phosphate diester may be prepared by reacting a triester with phosphorous pentoxide to produce a polyphosphate, which is then reacted with an alcohol (usually hexanol) to produce a phosphate diester [870]. The latter diester is then added to the organic liquid along with a nonaqueous source of aluminum, such as aluminum isopropoxide (aluminum-triisopropylate) in diesel oil, to produce the metal phosphate diester. The conditions in the previous reaction steps are controlled to provide a gel with good viscosity versus temperature and time characteristics. All the reagents are substantially free of water and will not affect the pH. 

How the aliphatic monomers are incorporated into the suberin polymer is not known. Presumably, activated co-hydroxy acids and dicarboxylic acids are ester-ified to the hydroxyl groups as found in cutin biosynthesis. The long chain fatty alcohols might be incorporated into suberin via esterification with phenylpro-panoic acids such as ferulic acid, followed by peroxidase-catalyzed polymerization of the phenolic derivative. This suggestion is based on the finding that ferulic acid esters of very long chain fatty alcohols are frequently found in sub-erin-associated waxes. The recently cloned hydroxycinnamoyl-CoA tyramine N-(hydroxycinnamoyl) transferase [77] may produce a tyramide derivative of the phenolic compound that may then be incorporated into the polymer by a peroxidase. The glycerol triester composed of a fatty acid, caffeic acid and a>-hydroxy acid found in the suberin associated wax [40] may also be incorporated into the polymer by a peroxidase. 

The low reactivity of the triesters [101] allowed the plot shown in Fig. 19 to be extended to better leaving groups, and in this case, uniquely, there is some evidence that the bond-lengthening effect may reach a limit. As shown by Fig. 20, the P-OX bond lengths of the three most reactive compounds, with pXHox < 6, are identical within experimental error. The significance of this interesting but isolated observation is not clear (Jones et al., 1985). 

Methyl 2-substituted 4-hydroxyquinoline-3-carboxylates (564) were prepared in 41 -54% yields by heating diazo derivatives (562) in boiling toluene for 0.5-9 hr, via aminomethylenemalonates (563). H-NMR investigation revealed the formation of a 52 48 mixture of aminomethylenemalonate (563, R = COPh) and quinolinecarboxylate (564, R = COPh) when the diazo compound (562, R = COPh) was heated in toluene for 4 hr. A better yield was achieved when the triester (562, R = COOMe) was heated in boiling 1,2-dichlorobenzene (80T1821). 

Phosphatases are numerous and important enzymes (see also Chapt. 2). They are classified as phosphoric monoester hydrolases (phosphatases, EC 3.1.3), phosphoric diester hydrolases (phosphodiesterases, EC 3.1.4), triphosphoric monoester hydrolases (EC 3.1.5), diphosphoric monoester hydrolases (pyrophosphatases, EC 3.1.7), and phosphoric triester hydrolases (EC 3.1.8) [21] [63]. Most of these enzymes have a narrow substrate specificity restricted to endogenous compounds. However, some of these enzymes are active toward xenobiotic organophosphorus compounds, e.g., alkaline phosphatase (EC 3.1.3.1), acid phosphatase (EC 3.1.3.2), aryldialkylphosphatase (para-oxonase (PON1), EC 3.1.8.1) and diisopropyl-fluorophosphatase (tabunase, somanase, EC 3.1.8.2) [64 - 70]. However, such a classification is far from definitive and will evolve with further biochemical findings. Thus, a good correlation has been found in human blood samples between somanase and sarinase activities on the one hand, and paraoxonase (PON1) type Q isozyme concentrations on the other [71]. 

This section is concerned mostly with the enzymatic hydrolysis of substrates classified as phosphoric acid mono-, di-, and triesters, phosphonates, phosphoro(di)thioates, phosphonodithioates, and P-halide compounds. 

Whereas there are relatively few phosphoric acid diesters of medicinal or toxicological interest, phosphoric acid triesters are of greater significance. Such compounds occur mainly as prodrugs, as discussed in the present section, or plasticizers and insecticides (see next section). 

A variety of industrial compounds are also phosphoric acid triesters of interest in xenobiotic metabolism and molecular toxicology. First, we examine here a few triesters used for example as plasticizers, hydraulic fluids, and flame retardants. In the second part of the section, insecticides of the phosphoric acid triester class will be discussed. 

At higher temperatures retro-Diels-Alder reaction may also occur in the opposite sense to addition, as in the reaction of methyl pyrrole-1-carhoxylate with dimethyl acetylenedicarboxylate at 200°, which affords acetylene and the pyrrole triester (56). The decomposition of the suspected intermediate Diels-Alder adduct (11) at 170° has been separately established. Compounds 19 and 20 are intermediates in similar addition-elimination reactions leading to pyrrole-l,3,4-triesters, in which removal of acetylene from the system makes the reaction sequence effectively irreversible. 

Parathion is one of a class of phosphorothionate triesters widely used as insecticides. These compounds exert their toxic effects in insects and mammals by inhibiting the enzyme acetylcholinesterase. The phosphorothionates, in general, are relatively poor inhibitors of acetylcholinesterase but are converted by the cytochrome P-450-containing monooxygenase enzyme systems in insects and mammals to the corresponding phosphate triesters that are potent inhibitors of this enzyme. 

Contents Low-molecular-weight organosulfur compounds in nature / Eric Block—Chemical mechanisms of the cytochrome P-450 monooxygenase-catalyzed metabolism of phosphorothionate triesters / R. A. Neal —Sulfur in propesticide action / T. R. Fukuto and M. A. H. Fahmy—[etc.]... 

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