Compounds hydroxycarboxylic acid

Many natural and synthetic organic compounds are hydroxy dicarboxyhc acids (see also Hydroxycarboxylic acids). This article discusses mainly malic and tartaric acids thiomalic acid is included because of its stmctural similarity to malic acid. 

Oxy-aldehyd, n, hydroxy aldehyde, -ammo-niak, n, oxyammonia (hydroxylamine), -azoverbindung, /. hydroxyazo compound, -benzol, n, hydroxybenzene (phenol), -bem-steinsaure. /, hydroxysuccinic acid (malic acid). -biazol, n. oxadiazole, oxdiazole. -bitumen, n, oxidized bitumen, -carbon-s ure, /, hydroxycarboxylic acid, -chlnoltn, n. hydroxyquinoline, -clunon, n. hydroxy-quinone. -chlorid, n. oxychloride, -chlor-kupfer, n. copper oxychloride, -cyan, n. oxycyanogen. 

Dochnahl M, Fu GC (2009) Catalytic asymmetric cycloaddition of ketenes and nitroso compounds enantioselective synthesis of a-hydroxycarboxylic acid derivatives. Angew Chem Int Ed 48 2391-2393... 

Stereoselechve follow-up reactions of non-racemic cyanohydrins enable the synthesis of many other classes of important compounds with one or more stereogenic centers, such as 2-hydroxycarboxylic acids, 2-amino acids, etc. (Scheme 3). ... 

A concerted mechanism is also possible for a-hydroxycarboxylic acids, and these compounds readily undergo oxidative decarboxylation to ketones.281... 

The addition of doubly deprotonated HYTRA to achiral4 5 as well as to enantiomerically pure aldehydes enables one to obtain non-racemic (3-hydroxycarboxylic acids. Thus, the method provides a practical solution for the stereoselective aldoi addition of a-unsubstituted enolates, a long-standing synthetic problem.7 As opposed to some other chiral acetate reagents,7 both enantiomers of HYTRA are readily available. Furthermore, the chiral auxiliary reagent, 1,1,2-triphenyl-1,2-ethanediol, can be recovered easily. Aldol additions of HYTRA have been used in syntheses of natural products and biological active compounds, and some of those applications are given in Table I. (The chiral center, introduced by a stereoselective aldol addition with HYTRA, is marked by an asterisk.)... 

Condensation polymerizations (polycondensations) are stepwise reactions between bifunctional or polyfunctional components, with elimination of small molecules such as water, alcohol, or hydrogen and the formation of macromo-lecular substances. For the preparation of linear condensation polymers from bifunctional compounds (the same considerations apply to polyfunctional compounds which then lead to branched, hyperbranched, or crosslinked condensation polymers) there are basically two possibilities. One either starts from a monomer which has two unlike groups suitable for polycondensation (AB type), or one starts from two different monomers, each possessing a pair of identical reactive groups that can react with each other (AABB type). An example of the AB type is the polycondensation of hydroxycarboxylic acids ... 

Most of the carbonyl compounds discussed in this section are either pyran-2- or -4-ones but a small number of pyran-3-ones and chroman-3-ones are known <77HC(31)193>. Tetrahy-dropyran-2-ones are lactones of 5- (or S-) hydroxycarboxylic acids and are not discussed in detail. 

Cleansing compounds -glycobic acid m [HYDROXYCARBOXYLIC ACIDS] (Vol 13)... 

Toda, F., Sano, A., Nassimbeni, L. R., and Niven, M. L. (1991) Optical Resolution of Amino Acid and Hydroxycarboxylic Acid Esters by Complexation with Optically Active Host Compounds a Crystallographic Result, J. Chem. Soc., Perkin Trans. 2, 1971-1975. 

Combination of the coordinating ability of metal ions for hydroxy group containing compounds with the before mentioned exceptional behaviours of DBTA in chiral recognation processes gave us a new possibility for direct resolution of a-alkoxycarboxylic acids, a-hydroxycarboxylic acid esters and series of racemic alcohols... 

To construct such a porphyrin-based positive allosteric system, we chose a cerium(iv) bis(porphyrinate) double decker compound 184-861 namely the tetrakis(4-pyridyl)porphyrin derivative 38.[871 This molecule satisfies the aforementioned requirements firstly, slow rotation of the two porphyrin planes with respect to one another should be possible at room temperature,1881 in analogy to similar cerium(iv) bis(diarylporphyrin) and bis(tetraarylporphyrin) complexes studied by Aida et al/861 Secondly, tilting of two porphyrin planes is more difficult than in 37, and thirdly, four pairs of 4-pyridyl groups are available as hydrogen bond acceptor sites for diols, hydroxycarboxylic acids, and dicarboxylic acids. Compound 39, which has only one pair of pyridyl groups, was used as a reference. 

Unlike ethylene glycol, a-hydroxycarboxylic acids, and p-mercaptoethanol, ligands such as ethanolamine, ethylenediamine, amino acids, and 2-aminoethanethiol do not form V2L2 complexes with vanadate [46], However, weakly formed products of VL stoichiometry (—546 ppm, —556 ppm) are observed with a number of a-amino acids [47], Because the amine functionality in amino acids is not suitable for formation of the cyclic [VN]2 core expected for a dimer, then one or the other of these VL compounds may correspond to the monomeric precursor to such a dimeric product. Certainly, with the a-hydroxycarboxylic acids, the monomeric complex can be a major component in solution. Similar VL complexes have not been reported for the amino alcohols. Perusal of the available reports suggests that the amine derivatives were studied under conditions where the nitrogen functionality was protonated, so the results may be somewhat misleading. 

Roots modify their environment quite extensively in many ways. The most important of these are pH change, exudation and microbiological activity in the rhizosphere. Root exudates contain compounds such as hydroxycarboxylic acids and amino acids and these are capable of complexing trace metals. Bowling (1976), Farago (1986) and Streit and Stumm (1993) have discussed the theories of mineral uptake by plant roots the first suggests that there are four links in the uptake chain movement of ions or complexes in the soil to the roots uptake into the root transport across the root to the vascular system and movement to the shoot. 

The chemistry of silicon oxygen compounds with SiOs and SiC>6 skeletons in aqueous solution is of special interest. It has been speculated that such Si(IV) complexes with ligands derived from organic hydroxy compounds (such as pyrocatechol derivatives, hydroxycarboxylic acids, and carbohydrates) may play a significant role in silicon biochemistry by controlling the transport of silicon. 

Tacke and his coworkers have recently reported the synthesis and structural characterization of a series of pentacoordinated anionic germanium complexes based on the Ge04C ligand framework340-344. The route to these compounds involves the reaction of (chloromethyl)trimethoxygermane with a secondary amine in the presence of triethy-lamine, followed by an exchange with two equivalents of bidentate ligands, such as aromatic 1,2-diols or a-hydroxycarboxylic acids, as shown for the synthesis of 114340 (equations 22 and 23). 

An aldol addition involves the addition of the a-C atom of a carbonyl compound, a carboxylic acid, a carboxylic ester, or a carboxylic amide to the C=0 double bond of an aldehyde or a ketone. The products of aldol additions are /3-hydroxylcarbonyl compounds (aldols), /i-hydroxycarboxylic acids, /Thydroxycarboxylic esters, or j3-hydroxycarboxylic amides. 

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