Oxalic acid, 290 Table

As in fruits, the major organic acids in vegetables are malic and citric acids, followed by oxalic acid (Table 10.5). The content of free titratable acids in vegetables is 0.2-0.4g/100g of fresh tissue, an amount that is low in comparison to fruits. Oxalic acid occurs in larger amonnts in some vegetables. 

Spinach and rhubarb contain oxalic acid (Table 14.7). Individuals prone to kidney stones composed of highly insoluble calcium oxalate must limit their intake of foods containing oxalic acid. 

One series of Ni/Al binary hydroxide coprecipitates was prepared with an initial atomic ratio of 1 1 Ni/Al with nickel equilibrated with anionic agents acetic acid or- citric acid or EDTA in a molecular ratio 1 1 and mixed with the initially precipitated A1 hydroxide. In this system sequestration of the Ni in solution occurred until a pH of 10-12 was attained precluding a staged coprecipitation in an acid regime. A second series of Nl/Al binary hydroxide coprecipitates using a lower Initial atomic ratio of 0.5 for Nl/Al was prepared In the presence of a 1 1 molecular ratio of citric acid or oxalic acid. (Table 1.). In this case Ni loadings in the range of 4.0-4.3 wt.% were obtained at pH values of 10.0 and 7.5 respectively but no Improvement in the state of dispersion as Indicated by the BET areas of the precipitates calcined at 350° C was obtained. 

A series of sequential coprecipitations was conducted also with Cu/Al in an initial atomic ratio of 1 1 and with a molecular ratio of 1 1 with citric acid or oxalic acid (Table 1). In these systems Cu loadings in the range of 3.9-5.8 wt.% were obtained at pH values of 4.0 and 7.4 respectively. In this sequence the presence of citric acid resulted in a decreased state of dispersion as indicated by the BET area of the coprecipitate calcined at 350° C when compared with the reference system with no anionic present. On the other hand the system prepared with the oxalic acid present preadsorbed on the initially precipitated A1 hydroxide provided an order of magnitude increase in the dispersion as indicated by the BET area of the calcined oxide. 

Table 1. Physical and Thermochemical Properties of Oxalic Acid and its Dihydrate...

Anhydrous Oxalic Acid. The anhydrous form of oxaUc acid is odorless and colorless. It exists in two crystal forms, ie, the rhombic or a-form and the monoclinic or P-form (3). The rhombic crystal is thermodynamically stable at room temperature, but the monoclinic form is metastable or slightly stable. The main difference between the rhombic and monoclinic forms exists in the melting points which are 189.5 and 182°C, respectively (Table 1)-... 

Table 2. Specific Gravities of Various Aqueous Solutions of Oxalic Acid Dihydrate...

Table 4. Supply and Demand of Oxalic Acid in tbe World Market in 1992, tons...

Uses of oxalic acid ia each region are summarized in Table 5 (58). The demand for agrochemical/pharmaceutical production and for separation/recovery of rare-earth elements in each region has been increasing. The use for marble polishing in western Europe is unique to the region. 

The austenitic irons are also useful in some circumstances for handling organic acids such as dilute acetic, formic and oxalic acids, fatty acids and tar acids. They are more resistant to organic acids than unalloyed cast irons, e.g. in acetic acid the austenitic irons show corrosion rates 20-40 times lower than the ferritic iron (Table 3.51). 

Table 9 contains six values of K lying between 10-6 and 10-4. One of these (oxalic acid) belongs to class IV, three belong to class III, and the remaining two arc the values of Kb just discussed. The fact that these six values of K lie between 10-4 and 10 means that the values of J do not differ by more than 20 per cent. Since J — (Jnm + J,i), a given value of J may arise from moderate values of / and J,i, or from a larger value of / combined with a smaller J,t, or from a smaller. / ... 

Conceptual Flowsheet for the Extraction of Actinides from HLLW. Figure 5 shows a conceptual flowsheet for the extraction of all the actinides (U, Np, Pu, Am, and Cm) from HLLW using 0.4 M 0< >D[IB]CMP0 in DEB. The CMPO compound was selected for this process because of the high D m values attainable with a small concentration of extractant and because of the absence of macro-concentrations of uranyl ion. Distribution ratios relevant to the flowsheet are shown in previous tables, IV, V, VI, and VII and figures 1 and 2. One of the key features of the flowsheet is that plutonium is extracted from the feed solution and stripped from the organic phase without the addition of any nitric acid or use of ferrous sulfamate. However, oxalic acid is added to complex Zr and Mo (see Table IV). The presence of oxalic acid reduces any Np(VI) to Np(IV) (15). The presence of ferrous ion, which is... 

The oxidation by Mn(lII) chloride involves three complexes and the kinetic data of Taube " are summarised in Table 15. The greater thermal stability of the /m-complex is considered to result from the lowering of the free energy relative to the transition state as compared with bis- and mono-complexes. The study of MnC204 was based on the Mn(III)-catalysed chlorine oxidation of oxalic acid. ... 

Add about 1.0 g of oxalic acid to the flask and measure its mass again. Record the mass of the flask and acid in Data Table 1. 

Ito et al.40 examined the electrochemical reduction of C02 in dimethylsulfoxide (DMSO) with tetraalkylammonium salts at Pb, In, Zn, and Sn under high C02 pressures. At a Pb electrode, the main product was oxalic acid with additional products such as tartaric, malonic, glycolic, propionic, and n-butyric acids, while at In, Zn, and Sn electrodes, the yields of these products were very low (Table 3), and carbon monoxide was verified to be the main product even at a Pt electrode, CO was mainly produced in nonaqueous solvents such as acetonitrile and DMF.41 Also, the products in propylene carbonate42 were oxalic acid at Pb, CO at Sn and In, and substantial amounts of oxalic acid, glyoxylic acid, and CO at Zn, indicating again that the reduction products of C02 depend on the electrode materials used. 

The reagent scheme used in the pilot plant included oxalic acid-acidified silicate Na2SiF6 gangue depressant system and collector composed of a mixture of phosphoric esters and alkyl sulphate modified with mineral oil. The metallurgical results obtained are presented in Table 23.5. 

The reagent scheme developed for the White Mountain titanium ore is shown in Table 25.15. Gangue depressants H2SiF6, oxalic acid and DAX1 were used. Depressant DAX2 is a mixture of low-molecular-weight acrylic acids designed specifically to depress calcite. 

The kinetic parameters for the oxidation of a series of alcohols by ALD are shown in Table 4.1 (74). Methanol and ethylene glycol are toxic because of their oxidation products (formaldehyde and formic acid for methanol and a series of intermediates leading to oxalic acid for ethylene glycol), and the fact that their affinity for ALD is lower than that for ethanol can be used for the treatment of ingestion of these agents. Treatment of such patients with ethanol inhibits the oxidation of methanol and ethylene glycol (competitive inhibition) and shifts more of the clearance to renal clearance thus decreasing toxicity. ALD is also inhibited by 4-methylpyrazole. 

Inactive metals in the wastes, such as Fe(III), Mo(VI), and Zr(IV), are retained in the aqueous feed by addition of suitable quantities of oxalic acid. As with CMPO, some Ru is extracted. Currently, the extraction of Pd, Tc, Np and their poor stripping remain a problem for which process modifications are necessary. The flow sheet in Fig. 12.13 and Table 12.11 has... 

Table 1 Catalysts used for the dehydration of polysaccharides Organic acids Oxalic acid, levulinic acid, maleic acid, p-toluenesulfonic acid Inorganic acids Phosphoric acid, sulfuric acid, hydrochloric acid, iodine, or hydroiodic acid generated in situ...

In some cases, the product depends on the nature of the acylating agent. Acylation of 182 with 2,2-difluoro-4-pentenoic acid anhydride leads to acylation at C, whereas acylation with 2,2-difluoro-4-pentenoic acid choride yields the 5-acyloxyoxazole 185 as the major compound. The 5-acyloxyoxazole can be rearranged to the 5(47/)-oxazolone 183 upon treatment with 4-(dimethylamino)pyridme. Treatement of 183 with anhydrous oxalic acid promotes decarbonylation to give fluorinated a-amino ketones 184 (Scheme 7.55). Selected examples of 4-acyl-5(4//)-oxazolones are shown in Table 7.20 (Fig. 7.22). 

Since the values in this table are taken from analytical experience, Thomson in effect is predicting the composition of the superacid by the rationale of the atomic theory, but he offers no evidence that the predicted compositions are confirmed by analysis. Early in the next year, however, Thomson delivered a paper on oxalic acid to the Royal Society. The oxalate of potash, he noted, combines with an excess of acid, and forms a superoxalate. The acid contained in this salt is very nearly double of what is contained in oxalate of potash. Suppose 100 part of potash if the weight of acid necessary to convert this quantity into oxalate be x, then xx will convert it into superoxalate. Later he notes that there are two oxalates of... 

Among the chelates active for the reduction of oxygen mentioned in Section 4.1, there is only one compound capable of catalyzing anodic reactions too. This is CoTAA, which, as Table 7 shows, is very active in acid solutions for the reaction of formic acid, oxalic acid and hydrazine, but less active for the reaction of formaldehyde and carbon monoxide 10>. 

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