Mandelic acid structure

Optically pure mandelic acid (see Structure 7.6) can be a useful chiral resolving agent where the compound you are looking at has a basic centre, as it can form an acid-base pair with it, which is a stronger form of association. This compound is of sparing solubility in CDCI3 however and can precipitate out your compound if, as is often the case, its protonated form is of low solubility in CDCI3. 

XRPD can be similarly used to differentiate between the members of a solvatomorphic system. For instance, Fig. 7.12 shows the powder patterns obtained for the anhydrate and monohydrate phases of lactose. The existence of structural similarities in the two forms are suggested in that the main scattering peaks of each form are clustered near 20 degrees 26, but the two solvatomorphs are easily differentiated from an inspection of the patterns. The differentiation could also be rendered more quantitative through the development of a table similar to that developed for the mandelic acid system. 

It is obvious that any factor which prevents tautomerism would hinder racemisation and this happens when the hydrogen atom attached to the asymmetric carbon atom is replaced by some other group. Thus while mandelic acid, C6H5-CH(OH). COOH having the structure resembling lactic acid is racemised by warming with aqueous aodium hydroxide, atrolactic acid C6H5-C (CH3) (OH) COOH is not racemised under the same conditions. 

The degradation of mandelic acid by the bacterium Pseudomonas putida (Chapter 25) is initiated by mandalate racemase, another (a/(3)8-barrel protein.101 X-ray structures of bound inhibitors together with modeling suggest that the side chain of Lys 264 is the catalytic base that abstracts the a-H from S-mandelate (Fig. 13-5) and that the catalytic pair of His 297 and Asp 270 acts as proton donor, or, in the reverse direction, as catalytic... 

In one report, the enantiomers of the racemic compound 73, whose structure resembles ketone 2a, were separated by fractional recrystallization of the optically active mandelic acid salts [43]. Although we tried to optically resolve the optically active mandelic acid salts of the racemic ketone ( )-2a, no satisfying results were obtained. After several trials, the (+)- or (-)-di-p-toluoyl tartrate salt prepared from ketone ( )-2a was effectively fractionally recrystallized and finally provided the optically active ketones (+)-2a and (-)-2a [42]. The chiral ketone (-)-2a was converted to compound 73 via compound 72 by thioacetalization followed by desulfurization using Raney nickel... 

Mravik, A., Bocskei, Zs., Katona, Z., Markovits, I., Pokol, Gy., Menyhard, D.K., and Fogassy, E. A new optical resolution method coordinative resolution of mandelic acid esters. The crystal structure of calcium hydrogen (2R,3R)-0,0 -dibenzoyltartrate-(2i )-methyl mandelate, J. Chem. Soc. Chem. Commun. 1996, 1983. 

The single crystal structure of racemic mandelic acid was originally reported by Cameron and Duffin [11], and then re-determined by Wei and Ward [12]. The compound crystallizes in the orthorhombic Pbca space group, with the unit cell parameters being ... 

Figure 3. Single crystal structures of (a) racemic mandelic acid and (b) (S)-mandelic acid. The figures were adapted from references [12] and [13], respectively.

TA belong to a class of small molecules characterized by a derivatized tropane ring skeleton (8-methyl-8-azabicyclo[3.2.1]octane). Hydroxylated tropane (tropine) is esterified with diverse organic acids often representing structural analogues of, e.g. tropic, benzoic or mandelic acid (Fig. 1). Manifold variations are found either in natural sources or as (semi-) synthetic active pharmaceutical ingredients (API) with individual optimized properties. 

Textual names have the advantage of being machine-readable, but many chemical compound names are derived in the absence of structural information. Common or trivial names were frequently given to compounds based on their properties or methods of extraction (because their structural information was originally an unknown). For example, mandelic acid was extracted from bitter almonds, and its name is derived from Mandel, the German word for almond (Merck 1989). 

Rule-based or systematic nomenclature (e.g., International Union of Pure and Applied Chemistry [IUPAC] or CAS nomenclature) is based on a set of linguistic rules that apply to its structure. For example, the IUPAC and CAS names for mandelic acid are 2-phenyl-2-hydroxyacetic acid and benzeneacetic acid, a-hydroxy-, respectively. The number of possible systematic names is practically endless. A small, but not nearly exhaustive, set of other systematic names includes phenylglycolic acid, phe-nylhydroxyacetic acid, ( )-a-hydroxybenzeneacetic acid, ( )-a-hydroxyphenylacetic acid, ( )-2-hydroxy-2-phenylethanoic acid, ( )-Mandelic acid, (RS)-Mandelic acid, DL-Amygdalicacid,DL-Hydroxy(phenyl)aceticacid,DL-mandelicacid,paramandelic acid, a-hydroxy- a-toluic acid, a-hydroxyphenylacetic acid, a-hydroxybenzeneacetic... 

Structural Isomers. Chromatograms illustrating the separation of ortho, meta and para isomers of cresol (22) and and xylene ( O)on RP columns are shown in Figures 4 and 5. They enable a comparison of the chromatographic properties and selectivities due to <. - and -CD complexation between positional isomers of the above compounds.Similar behaviour was observed for ortho,meta and para isomers of fluoronitrobenzene, chloronitrobenzene, iodoni-trobenzene, nitrophenol, nitroaniline, dinitrobenzene (22), nitrocinnamic acid (22) some mandelic acid derivatives (19,21,34) and ethyltoluene (28). Both [Pg.225]

Nature provides a vast variety of -selective nitrilases that accept aliphatic and aromatic substrates. This disconnection can therefore be applied for the synthesis of many structurally different a-hydroxy acids. Industrially the process is applied on a multi-ton scale, to prepare (R)-mandelic acid and its analogs (Scheme 5.16) [9]. What makes the process particularly interesting from a green point of view, is that no organic solvents are used and the reaction is performed at ambient temperatures. 

The chiral discrimination existing in the diastereomer systems formed by ephedrine and various mandelic acids has been studied in great detail, using a variety of spectroscopic and structural tools. Although significant differences in the solubilities of the n- and p-salts obtained after reaction of ephedrine with mandelic acid were known to exist, both salts were... 

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