Carboxybc acids

Band 8, 7-lOy. (1408 cm. ). This is a characteristic carboxybc acid absorption band and it arises from a C—0 vibration coupled with an... 

Amino-3-hydroxyanthraquiQone [117-77-1] (70) is prepared by beating 5-ben2oylben2oxa2olone-2 -carboxybc acid ia sulfuric acid (96). This compound is an iatermediate for Cl Vat Red 10 (166). 

J. Brodeur, R. Goyal, Effect of a Cysteine Prodrug, L-2-Oxothiazobdine-4-carboxybc Acid, on the Metabobsm and Toxicity of Bromobenzene An Acute Study , Can. J. Physiol. Pharmacol. 1987, 65, 816 - 822. 

Carborundum, silver on, 27 10-12 3-Carboxy - 2,2,5,5,- tetramethylpyrrolidin-1-oxy m-nitrophenyl ester, enantiomeric specificity in reactions of cyclohexaamy-lose and cycloheptaamylose on, 23 233 Carboxylate ions, 32 117-118 Carboxybc acids a, 3-unsaturated, 25 109 hydrogenation of, 25 107-115 ketonization of, 24 35-37 Lewis base-promoted ruthenium catalysis, 32 389, 400... 

Commercially, polymeric MDI is trimerized during the manufacture of rigid foam to provide improved thermal stability and flammability performance. Numerous catalysts are known to promote the reaction. Tertiary amines and alkah salts of carboxybc acids are among the most effective. The common step in all catalyzed trimerizations is the activation of the C=N double bond of the isocyanate group. The example (18) highlights the alkoxide assisted formation of the cyclic dimer and the importance of the subsequent intermediates. Similar oligomerization steps have been described previously for other catalysts (61). 

Figure 3.53 shows an addition of a carboxybc acid to isobutene, which takes place via the tert-butyl cation. This reaction is a method for forming ferf-butyl esters. Because the acid shown in Figure 3.53 is a /i-hydroxycarboxylic acid whose alcohol group adds to an additional isobutene molecule, this also shows an addition of a primary alcohol to isobutene, which takes place via the ferf-butyl cation. Because neither an ordinary carboxylic acid nor, of course, an alcohol is sufficiently acidic to protonate the alkene to give a carbenium ion, catalytic amounts of a mineral or sulfonic acid are also required here. 

Base-catalysed ring fission of 3,4-diphenylcyclobut-3-ene-l,2-diones (103) in 50% (v/v) aqueous DMSO proceeds by rapid reversible addition of hydroxide ion followed by rate-determining benzilic acid-type rearrangement to form an intermediate 1-bydroxycyclopropane-l-carboxybc acid wbicb ring opens to tbe corresponding (Z)-2-0X0-3,4-dipbenylbut-3-enoic acid (Scheme 8). This is supported by the value of Hammett p — 3 (for variation of substituents on one or both rings), the kinetic solvent effects, and the three-oxygen enrichment of (107) from reaction of (103) in 50% H2 O-DMSO. 

Table 5 Carbon isotope compositions of CO, CO2, carboxybc acids, dicarboxylic acids, and volatile hydrocarbons in the Murchison (CM2), Tagish Lake (Cl), and Orgueil (CIl) meteorites together with hydrogen isotope...

Formytfuran or funp-l-carboldehyde quanoime-V-carboxybc acid th) 23-dimethytttuophene... 

Breslow (1958JA3719) discussed carbene intermediates on decarboxylation of thiazole-2-carboxybc acid 32 (1948HCA924) which indeed forms thiazol-2-ylidene 33 photochemically starting from the rotamer 32, not 32, via a complex of the NHC 33 and carbon dioxide (Scheme 9) (1997AG1709). 

H Hydroxyl Esterification (formation of an ester) with carboxybc acids oxidation to aldehydes, ketones, and carboxylic acids... 

Many nitrilases have been screened for their abihty to catalyze enantioselective production of valuable carboxybc acid analogs with substitution in the a, p, or y position. For instance, nitrilase selectivity profiles identified a catalyst capable of resolution of racemic mandelonitrile (an a-hydroxynitrile). Strains such as an Alcali-genes sp. [44], Pseudomonas putida, and Microbacterium paraoxydans [45] showed >93% ee when hydrolyzing mandelonitrile to (J )-mandelic acid (Table 14.1). In another example, researchers at Diversa reported on the enantioselective conversion of aromatic aminonitrile compounds for the production of a-amino acids [46]. The authors were successful in achieving a 79.5% yield of the (R)-acid product at an enantiomeric excess of 96.3% from the substrate 4-fluorophenylglydnonitrile. 

Hydrogen bonding between difunctional carboxybc acids can... 

Cacdii, S., Morera, E. and Ortar, G. (1985) Palladium-catalyzed carbonylation of enol triflates. A novel method for one-carbon homologation of ketones to a,P-imsaturated carboxybc acid derivatives. Tetrahedron Letters, 26, 1109—1112. 

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