Of hydroxy carboxylic acids

Polymers of hydroxy carboxylic acids as a rheologic additive [1298]... 

H. Muller, S. Podubrin, C. P. Herold, and A. Heidbreder. Dispersions containing homopolymers or copolymers of hydroxy carboxylic acids... 

RCHiCOOH - RCH=C—0.i Mukaiyama s reagent has been used for macro-lactonization of -hydroxy carboxylic acids (14,117-118). However, reaction of the substrate 2 with 1 and N(C2H5)3 in refluxing CH3CN does not lead to the expected... 

For much of the last century, scientists attempted to make useful plastics from hydroxy adds such as glycolic and lactic acids. Poly(glycolic acid) was first prepared in 1954, but was not commercially developed because of its poor thermal stability and ease of hydrolysis. It did not seem like a useful polymer. Approximately 20 years later it found use in medicine as the first synthetic suture material, useful because of its tendency to undergo hydrolysis. After the suture has served its function, the polymer biodegrades and the products are assimilated (Li and Vert 1995). Since then, suture materials, prosthetics, artificial skin, dental implants, and other surgical devices made from polymers and copolymers of hydroxy carboxylic acids have been commercialized (Edlund and Albertsson 2002). 

When formed on cellulose [thin-layer-chromatography (TLC) plates], the colored forms of 6-nitro-8-methoxyBIPS and of trimethylindolinospironaphthoxa-zine are stabilized against thermal or photoerasure by interaction with nickel or zinc salts of hydroxy carboxylic acids or dicarboxylic acids. The zinc salts of 1-hydroxy-... 

Decarboxylative dehydration of -hydroxy carboxylic acids (9, 504). Study of the stereochemistry of this reaction indicates that syn-P-hydroxy carboxylic acids are usually converted into (E)-alkenes (equation I), in contrast, the anti-isomers are converted... 

The reagent has been used successfully for conversion of hydroxy carboxylic acid esters into the corresponding chloro esters.4 Bromo esters are obtained if CBr4 is used. The replacement occurs with inversion. The method is applicable to hindered a-hydroxy esters. Hooz and Gilani5 state that the reaction is more rapid if tri-n-octylphosphine is used in place of triphenylphosphine. 

Octel Chemicals have patented a process to decompose the diazonium at nearly room temperature using a copper salt of hydroxy carboxylic acid, allowing them to use conventional glass lined reactors, but with poor productivity and problems of copper effluent in aqueous. 

Konigs-Knorr synthesis (1, 1005 4, 67). The Konigs-Knorr synthesis of )3-glucosides is improved with respect to reaction conditions and to yield by use of silver salts of dicarboxylic acids e.g., oxalic acid) or of hydroxy carboxylic acids (e.g., 4-hydroxyvaleric acid). Use of the silver salt of a polymeric reagent offers the further advantages of other polymeric reagents. ... 

Lactones - Cyclic esters of hydroxy carboxylic acids, containing a l-oxacycloalkan-2-one structure, or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. [5]... 

DCC-DMAP has been used in the synthesis of depsipeptides. Macrocyclic lactones have been prepared by cyclization of hydroxy carboxylic acids with DCC-DMAP. The presence of salts of DMAP, such as its trifluoroacetate, is beneficial in such cyclizations, as shown for the synthesis of a (9. -dihydroerythronolide. Other macrolactonizations have been achieved using 2,4,6-Trichlorobenzoyl Chloride and DMAP in Triethylamine at rt or Di-2-pyridyl Carbonate (6 equiv) with 2 equiv of DMAP at 73 °C. ... 

The Use of 2-Quinoxal Chloride for Precolumn Derivatizution in the Separation of Hydroxy Carboxylic Acids Enantiomers... 

Rontani and Aubert [47] studied the El mass spectral fragmentation of hydroxy carboxylic acids and trimethylsilyl derivatives of oxocarboxylic acids. Some fragmentations appeared to be specific to characterize and... 

Electrolysis of -hydroxy carboxylic acid (90) gave ketone (91) as the main product, which was converted to dl-muscone (Scheme 34) [113]. The migratory aptitude of alkyl substituents at the 6-position in the intermediate 6-hydroxy carbenium ion was scrutinized to show that vinyl, cyclopropyl, and benzyl groups rearrange predominantly. 

Alen R, Sjostrom E, Suominen S. Application of ion-exclusion chromatography to alkaline pulping liquors, separation of hydroxy carboxylic acids from inorganic solids. J Chem Tech Biotechnol 1990 51 225-33. 

Alen R, Oasmaa A. Thermochemical conversion of hydroxy carboxylic acids in the liquid phase. 

The reduced form of mevalonic acid, compound CXXIX, has been found to be more active than the two dehydrated isomers of this acid, namely, CXXX and CXXXI, respectively [320]. The j8-y-unsaturated acid has been reported to reduce serum and liver concentration of cholesterol in the rat at a dose of 300 mg per kg/day [321]. The homolog of this acid, substance CXXXII, was found to be twice as active when tested under the same conditions [322]. The lower homolog of acid CXXXI, 2-methyl-2-butenecarboxyhc acid (CXXXIII) has been reported not only to decrease serum cholesterol levels but also to prevent the development of atherosclerotic lesions in rats receiving an atherogenic diet [323]. Amides of hydroxy carboxylic acids, e.g. the unsubstituted amide and the iV-phenylethylamide of y-hydroxybutyric acid (CXXXI V), have been reported in the patent literature to be useful hypocholesterolemic agents [324,325]. 

Under the conditions of hydrocarboxylation good yields of hydroxy carboxylic acids and their derivatives can be obtained. Thus, formaldehyde reacts with carbon monoxide and water to give glycolic acid [556]. 

Maximum concentrations of the species were obtained when the reaction was carried out at low pressure with removal of the water formed in the course of the reaction. In this way the Cr species stabilized by ethylene glycol was stable at room temperature for several days. When the reaction was studied in dioxan, a variety of hydroxy-carboxylic acids were shown to give rise to Cr signals whereas oxalic acid and mercapto-carboxylic acids do not. The kinetics of the oxidation of a-hydroxybutyric and other a-hydroxy-acids in water have been investigated,with no evidence for intermediate complex formation. Failure to detect any reduction of HgCl2 has been attributed to the absence of free radicals, the authors considering the rate-determining process to involve the formation of a carbonium ion which yields the ketone product by release of a proton. 

---