A- -Tartaric acid

For each of the following polyprotic acids, state which species (H2A, HA, or A2 of the diprotic acid or H3A, H,A, HA2, or A for triprotic acids) you expect to be the form present in highest concentration in aqueous solution at pH = 5.0 (a) tartaric acid (b) hydrosulfuric acid (c) phosphoric acid. 

Methods for reducing peak absorption of americium after inhalation or oral exposure have not been described. Topical applications of saline containing DTP A, tartaric acid, or citric acid (e.g., Schubert s solution) have been used to remove americium from the skin and wounds after accidental dermal exposures (Breitenstein 1983). These agents form stable, water soluble complexes with americium. 

Figure 5. Dependence of rate of dissolution of 5pM Y-FeOOH in pH 4.0, 0.01M NaCl on concentration of a) tartaric acid, and b) salicylic acid. Fitted parameters obtained for rectangular hyperbolic model are given. Light source mercury arc lamp with 365nm band-pass filtering.

Chiral titanium catalysts have generally been derived from chiral diols. Narasaka and colleagues251 developed an efficient catalyst, 406, prepared from TiCl2(OPr- )2 and a (+)-tartaric acid derived 1,4-diol. These authors found that Af-crotonyl-l,3-oxazolidin-2-one (404) reacted with cyclopentadiene in the presence of 10 mol% of 406 to give cycloadduct 405 with up to 91% ee (equation 120)252. 

Saito et al. (32) developed a tartaric acid derived chiral nitrone 18. In the reaction of 18 with methyl crotonate 19, the 1,3-dipolar cycloaddition product 20 was obtained in an endo/exo ratio of 10 1 and with high diastereofacial induction to give the endo-isomer (Scheme 12.9). 

Enantioselective epoxidation of allylic alcohols using hydrogen peroxide and chiral catalysts was first reported for molybdenum 7B) and vanadium 79) complexe. In 1980, Sharpless 80) reported a titanium system. Using a tartaric acid derivative as chiral auxiliary it achieves almost total stereoselection in this reaction. 

The development of a large scale manufacturing route to Esomeprazole is described by Federsel and Larsson ° using the titanium catalyst originally described by Kagan and Luukas. Employment of a tartaric acid derived chiral auxiliary, with the addition of a base such as diisopropylethylamine to the reaction mixture, resulted in a full-scale catalytic process capable of delivering multi-ton quantities of product with optical yields well above 90 %, a figure which could be raised to 99.5 % ee by recrystallization from methyl isobutyl ketone. 

Powders with a tartaric acid basis are tested for as follows About 20 grams of the powdered bread are treated with water in a flask of about 200 c.c. capacity on a water-bath, the liquid being concentrated to about 50 c.c., transferred to a separating funnd, acidified with sulphuric add and extracted with ether. The ethereal solution is evaporated in a porcelain dish and the residue heated with a few crystals of resorcinol and one or two drops of concentrated sulphuric acid until white fumes appear the formation of a violet-red coloration indicates the presence of tartaric add. 

Di-isobutylaluminium hydride reduction33 of aldehyde-derived O-TBDMS cyanohydrins, followed by hydrolysis with a tartaric acid buffer, gives the corresponding O-protected 2-hydroxyaldehydes. Related methodology has been employed in a diastereo-selective synthesis34 of a potential precursor of taxol . 

High enantioselectivities (up to 94%) are obtained in the sodium borohydride reduction of aliphatic ketones using a tartaric acid-derived boronic ester (TarB-N02) as a chiral catalyst. A mechanism (Scheme 14) involving an acyloxyborohydride intermediate has been postulated.319... 

Recently, complex formation reactions of (A,A)-tartaric acid (TA) and its 0,0 -dibenzoyl derivative (DBTA) with a series of chiral alcohols (26, 27, 8 and 28, Scheme 11) were investigated in our laboratory using Toda s suspension method. [35] As an example, resolution of 28 is outlined in Scheme 12. 

A new chiral acyloxyborohydride has been prepared by combining sodium borohy-dride with a tartaric acid-based reagent. This reagent effects the reduction of aromatic ketones to provide the product alcohols in ees of 93-98%. Several aliphatic ketones were also reduced with moderate to excellent enantioselectivity. A mechanism has been provided with supporting calculations for the proposed active species and tran- sition state.262... 

Acyloxyboranes. Yamamoto et a/.1 have used the known reactivity of borane with carboxylic acids to activate acrylic acids for Diels-Alder reactions. Thus addition of BH3-THF to acrylic acids at 0° furnishes an acyloxyborane formulated as 1, which undergoes cycloaddition (equations I and II). The reaction proceeds satisfactorily even when borane is used in catalytic amounts. A chiral acyloxyborane, BL, prepared from a tartaric acid derivative, can serve as a catalyst for an asymmetric Diels-Alder reaction (equation III). 

A simple and rapid FI-HG-AAS method was developed and optimized for the determination of Pb in beer and other beverages by Cabrera et al. [65]. Beer samples were degassed in an ultrasonic bath prior to analysis in order to improve the precision of the determinations. Then they were acidified, introduced into a microwave oven and cooled in an ice bath to reduce the amount of water vapour. The Pb content in beer was found to be 41 +1 fig f1. Lead was also determined in beer by HG-ICP-AES and the effects of four acid oxidant mixtures on PbH4 generation were evaluated [44]. Beer samples were treated with HNO3 and H202 and evaporated to dryness before addition of tartaric acid. Lead HG was performed with 85 percent efficiency in a tartaric acid medium. Concentrations of 115 + 5 and 101 + 5 p,g U1 Pb in white and dark beers, respectively, were reported. 

A better accessible chiral mediator is the (acyloxy)borane (CAB) 2-64 prepared in situ from a tartaric acid derivative and arylboronic acid at room temperature. Hetero Diels-Alder reaction of benzaldehyde and Danishefsky s diene 2-10 in the presence of 2-64 gave the corresponding pyrone after acidic work up with 52 - 95 % ee depending on R. The best results were obtained with R = 2,4,6-Me3Ph and 2,4,6-iPr3Ph. Similarly, with 2-60 the pyrone 2-61 with up to 97% ee was found [107]. 

The synthesis of y-lactones from acetals derived from a tartaric acid dithioester was recently reported552. Quenching the readily obtained lithium dienolate (analyzed as its bis-silylketen acetal, Scheme 111, bottom structure) with a series of aldehydes gave only one diastereomeric lactone, generally in ca 60% yield, along with a variable amount of oxidized diester depending on steric factors (Scheme 111). An intramolecular complexa-tion of the lithium atom is assumed to favor the C2-symmetric Z,Z non-planar chelated... 

Arsenates and silicates with ammonium molybdate yield the ammonium salts of arsenomolybdic, H3[AsMo12O40] or H3[As(Mo3O10)4], and silico-molybdic, H4[SiMo12O40] or H4[Si(Mo3O10)4], acids respectively these complex acids and their salts react similarly with benzidine. However, phosphates may be detected in the presence of arsenates and silicates by preventing the formation of the corresponding molybdo-acids by the use of a tartaric acid-ammonium molybdate reagent which does not react with arsenic and silicic acids but does react with phosphoric acid when the reaction is carried out on filter paper. 

Several arylboronic acids have been examined in place of borane-THF to improve the Lewis acidity of 2 and the stereoselectivity [49b]. The boron substituent of 2 has a large effect on the chemical yield and the enantiomeric excess of the allylation adduct, and 3,5-bistrifluoromethylbenzeneboronic acid results in the greatest reactivity— when a complex which is easily prepared from a tartaric acid derivative and 3,5-bistri-fluoromethylbenzeneboronic acid in propionitrile at room temperature is used, the reactivity is improved without reducing the enantioselectivity. For instance, the reaction of l-trimethylsilyl-2-methyl-2-propene with benzaldehyde in the presence of only 10 mol % 2 proceeds to give 99 % yield and 88 % ee (Fig. 19). 

Polymethacrylate and polyvinyl resins play only a secondary role in the manufacture of cation exchangers. Presently, the only polymethacrylate-based cation exchanger is offered by Sykam (Gauting, Germany) under the trade name LCA K02. This column differs from its PS/DVB analogue (see Table 3-24) only in the particle size (5 pm) and exchange capacity (0.4 mequiv/g). With a tartaric acid eluent, this phase is preferred for the analysis of heavy and transition metals. 

Yamamoto has documented the use of boryl complexes prepared with a tartaric acid-derived ligand class [106]. The modified tartrate ligands are conven-... 

An acyloxyborane catalyst (7) made from a tartaric acid derivative promotes cyclocondensation of Danishefsky s diene and aldehydes to construct substituted di-hydropyran-4-ones. ... 

The total synthesis of zaragozic acid C (1) by Evans [7] is shown in Schemes 11 and 12. Evans identified a tartaric acid unit in the C3-C4 partial structure of zaragozic acid. Accordingly, his synthesis commences from a tartaric acid derivative (Scheme 11). The... 

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