Aluminium tricarboxylates

A trivalent cation, for example AF, has the potential to link three chains. Sterically, this is improbable Mehrotra Bohra (1983) assert that simple aluminium tricarboxylates are not known in solution. Nevertheless we consider it probable that a small proportion of AF ions link three chains, in which all three charged ligands are COO". More probable molecular structures would contain one or two F" ions with a single F", an [A1F(H20)3] unit could bridge two polyanion chains, while an [A1F2(H20)2] would have no crosslinking ability. 

In view of the difficulties in the preparation of aluminium tricarboxylates from aqueous systems, the first attempt to prepare a metal carboxylate from its alkoxide appears to have been made in 1932 by McBain and McLatchie from the reaction... 

Formaldehyde condenses with salicylic acid in the presence of nitrite-containing sulphuric acid to give aurin tricarboxylic acid this is converted by ammonia solution into the ammonium salt, which is employed as a reagent for aluminium ( aluminon ) ... 

To examine the cavitational effect of ultrasound on bright-red complex of aluminon adsorbed on Al(OH)3, in our experiments, 25 ml of 0.005 M aluminium sulphate was treated with 5 ml of 1% aluminon (triammonium aurine-tricarboxylate). This adsorption complex was sonicated for 10, 20 and 30 min, while the control sample was agitated for the same duration with a magnetic stirrer. The turbidity in sonicated sample increased, as time of sonication increased compared to the unsonicated condition (Table 9.18 and Fig. 9.4). In sonicated sample, the colour of the adsorption complex was dark compared to the control sample and the settlement of the adsorption complex was also slower due to the smaller size particle of the complex. 

Exudation occurs in response to environmental constraints, especially P deficiency (e.g., Jones 1998 Hinsinger et al. 2003) and differs depending on the P-form (Lambers et al. 2002) and plant species (Nuruzzaman et al. 2006). Banksia grandis exuded citrate, malate, and trans-aconitate when supplied with aluminium-phosphate. It exuded less of these tricarboxylates and dicarboxylates, but instead lactate and acetate, when supplied with iron-phosphate (Lambers et al. 2002). Plant species differ in their abilities to use various P species (van Ray and van Diest 1979), which can be due to differences in their exudation behavior (Nuruzzaman et al. 2006) and acidification of the root zone (Haynes 1992). This can influence the interspecific competition and coexistence of species, as we will discuss later. 

Aurin tricarboxylic acid is of interest as a reagent for detecting aluminium.5... 

A new erythrina alkaloid, erythroculine, from Cocculus laurifolius has been shown to have the structure (167). The ester group may be reduced with lithium aluminium hydride and the acetyl ester of the resulting alcohol on treatment with cyanogen bromide affords the hindered diphenyl (168), with loss of hydrogen bromide and methanol. This on reduction to the secondary base, N-methylation, and successive Hofmann degradations affords an olefin that may be oxidised to the tricarboxylic acid (169).The base represents a novel structure in having the additional carbon atom linked to the ring system. 

The method suggested by Caro 2 for the purification of aurin tricarboxylic acid seems to be unnec sary when the dye is to be used as a test for aluminium. In this /nethod the crude product is dissolved in sodium hydroxide, sodium bisulphite is added until the solution is decolorized, and the addition compound of the free acid is precipitated by adding hydrochloric acid. 

The total synthesis of (+ )-dehydroheliotridine (4), a toxic metabolite of the pyrrolizidine alkaloids (e.g. lasiocarpine and heliotrine), has also been described.2 The pyrrole ring was obtained by reaction of l,6-dihydroxy-2,5-dicyanohexa-l,3,5-triene-l,6-dicarboxylic ester (5) with j3-alanine, which afforded the N-substituted pyrrole ester (6), together with the appropriate amide of oxalic acid. Careful hydrolysis of (6) with dilute alkali afforded the related tricarboxylic acid, which was converted, by Dieckmann cyclization, hydrolysis and decarboxylation, into the keto-acid (7). Esterification of (7) with diazomethane, followed by reduction with lithium aluminium hydride, finally afforded ( )-dehydroheliotridine (4), identical, except in optical rotation, with dehydroheliotridine obtained earlier by Culvenor et al.3... 

Traces of aluminium are of little significance in pharmaceutical analytical work but may be determined by the use of aluminon (ammonium aurine tricarboxylate) which forms a lake with aluminium at a pH of about 4 to 5. Procedures have been suggested by Lampitt and Sylvester, Strafford and Wyatt, Chenery, and Rolfe, Russell and Wilkinson. It is essential that experimental conditions are very carefully controlled in order to obtain a quantitative result. 

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