Hydroxy Acetate Research Articles

Kinetics of in situ Epoxidation of Natural Unsaturated Triglycerides Catalyzed by Acidic Ion Exchange Resin

The kinetics of the epoxidation of nonedible oil (mahua oil) by peroxyacetic acid, formed in situ by the reaction of aqueous hydrogen peroxide and acetic acid, in the presence of an acidic ion exchange resin (AIER) as the catalyst, was studied. The influence of some relevant process variables such as stirring speed, hydrogen peroxide to ethylenic unsaturation molar ratio, acetic acid to ethylenic unsaturation molar ratio, temperature, and catalytic loading of AIER on the epoxidation rate as well as on the oxirane ring stability and iodine value of the epoxidized Mahua oil (EMO) was examined. The proposed kinetic model takes into consideration two side reactions, namely, epoxy ring opening involving the formation of hydroxy acetate and a hydroxyl group and the reactions of the peroxyacid and epoxy group. Kinetic parameters were estimated by fitting experimental data using a nonlinear regression method. From the estimated kinetic constants, the apparent activation energy for the epoxidation reaction was fou...

Thermal Degradation of Acetate-Intercalated Hydroxy Double and Layered Hydroxy Salts

Two hydroxy double salts (HDSs), zinc copper hydroxy acetate (ZCA) and zinc nickel hydroxy acetate (ZNA), and an analogous layered compound, zinc hydroxy acetate (ZHA), have been prepared by a coprecipitation method. The thermal degradation of these materials was characterized via thermogravimetric analysis (TGA), differential thermal analysis (DTA), and TGA coupled with Fourier transform infrared spectroscopy of gas-phase products, TGA-FTIR. Loss of physisorbed and interlayer H2O was observed between 50 and 150 degrees C for all compounds. Acetic acid, acetone, water, and CO2 were released at high temperatures with relative acetone yields found to be dependent on precursor identity, with very little formed from ZCA compared with ZHA and ZNA. Combined FTIR and XRD analysis of solid residues extracted at different points in the heating profile suggests that ketonization occurs via dissociative adsorption of acetic acid on ZnO surfaces. Nanometer-sized ZnO particles were formed from ZHA, showing slight preferential growth in the ZnO (002) lattice direction, while the presence of a second metal, Ni or Cu, served to retard ZnO crystallite growth at temperatures below 600 degrees C and eliminate preferential growth. ZCA leads to the formation of reduced copper species (metallic copper and Cu2O) when heated to 250 degrees C.

Nonlinear Optical Activity and High Thermal Stability of a New 3DOpen‐Framework with Interconnected 24‐, 16‐, and 8‐Atom Channels: (NH4)Zn[O3PCH(OH)CO2

AbstractHydrothermal reaction of hydroxy(phosphono)acetic acid, H2O3PCH(OH)CO2H, with zinc(II) acetate resulted in a new ammonium zinc hydroxy(phosphonato)acetate, (NH4)Zn[O3PCH(OH)CO2] (1). The structure of 1 contains a 3D open‐framework consisting of interconnected 24‐, 16‐, and 8‐atom channels. TGA and XRD reveal that the framework is stable up to 350 °C in air. Its powder SHG intensity is about 0.8 times that of potassium dihydrogen phosphate KDP. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Synthesis and Crystal Structure of (9s)-N-methyl-3-azabicyclo[3.3.1] nonan-9-yl (cyclopentyl)(hydroxy)(2-thienyl)Acetate Hydrochloride

(9s)-N-methyl-3-azabicyclo[3.3.1]nonan-9-yl (cyclopentyl)(hydroxy)(2-thienyl)acetate hydrochloride, a more effective muscarinic receptor antagonist, was synthesised and its crystal structure elucidated by X-ray crystallography.

Hydroxy Double Salt Anion Exchange Kinetics: Effects of Precursor Structure and Anion Size

(1)H NMR spectroscopy and powder X-ray diffraction have been used to explore the details of anion exchange reactions of two layered hydroxy double salts (HDSs), zinc copper hydroxy acetate (ZCA), nickel zinc hydroxy acetate (NZA), and a related layered material, zinc hydroxy acetate (ZHA), at room temperature (21-22 degrees C). Reactions that followed Avrami-Erofe'ev kinetics with respect to temporal profiles for acetate release, ZCA with butyrate (k = 1.7 x 10(-3) s(-1)), and octanoate (k = 0.79 x 10(-3) s(-1)) anions, as well as ZHA with octanoate (k = 2.6 x 10(-3) s(-1)), demonstrate that rate constants for acetate release are influenced by the exchange anion relative size as well as by the solid precursor structure/composition. The reaction of NZA with octanoate deviated from expected Avrami-Erofe'ev behavior, with evidence for an intermediate species in the solid phase that may influence the rate of acetate release into solution. The reaction of ZCA with formate anions exhibited a unique zeroth-order kinetics release of acetate, providing the possibility of developing tunable nanostructured anion release sources by use of variations in the size of the exchange species.

Kinetics of in situ epoxidation of soybean oil in bulk catalyzed by ion exchange resin

AbstractThe kinetics of the epoxidation of soybean oil in bulk by peracetic acid formed in situ, in the presence of an ion exchange resin as the catalyst, was studied. The proposed kinetic model takes into consideration two side reactions of the epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups as well as the reactions of the formation of the peracid and epoxy groups. The catalytic reaction of the peracetic acid formation was characterized by adsorption of only acetic acid and peracetic acid on the active catalyst sites, and irreversible surface reaction was the overall rate‐determining step. Kinetic parameters were estimated by fitting experimental data using the Marquardt method. Good agreement between the calculated and experimental data indicated that the proposed kinetic model was correct. The effect of different reaction variables on epoxidation was also discussed. The conditions for obtaining optimal epoxide yield (91% conversion, 5.99% epoxide content in product) were found to be: 0.5 mole of glacial acetic acid and 1.1 mole of hydrogen peroxide (30% aqueous solution) per mole of ethylenic unsaturation, in the presence of 5 wt% of the ion exchange resin at 75°C, over the reaction period of 8 h.

Aldol Reactions with Erythrulose Derivatives: Stereoselective Synthesis of Differentially Protected syn-α,β-Dihydroxy Esters

Boron enolates of 1-O-silylated erythrulose 3,4-acetonides prepared with Brown's chloro-dicyclohexylborane/tertiary amine system have been shown to react with achiral aldehydes in a highly stereoselective way to yield a 1,2-syn/1,3-syn stereoisomer. Through oxidative cleavage of the aldol adducts with periodic acid hydrate, enantiopure syn-α,β-dihydroxy esters with either hydroxyl group differently protected have been prepared. These erythrulose derivatives therefore behave as a chiral hydroxy acetate (glycolate) enolate equivalent.

Competitive Extraction of Some Bases by Carbollylcobaltate Anion from Water Into Chloroform

The bis[undecahydro-7,8-dicarbaundecaborato(2-)]cobaltate(1-) (X-) has been used for complementary study of its ionic associates with some cations of organic bases and quaternary salts. For the optimization of present analytical methods, quinuclidin-3-yl hydroxy(diphenyl)acetate, 1-(1-phenylcyclohexyl)piperidine, dibenzo[b,f][1,4]oxazepine and cocaine, were studied by competitive extraction method. X- labelled with 60Co was used as carrier anion, triphenylmethane and azo dyes as competitive anions. The aqueous phase was 0.1 and 0.01 M HCl, the organic phase was chloroform. A comparison was made with earlier results obtained by extraction spectrophotometry.

A novel and efficient stereoselective synthesis of the southern part of pamamycin-607

The C 1′C 11′ portion of the antibiotic pamamycin-607 was synthesized from the enantiomerically pure hydroxy acetate 3, readily available by enzymatic transesterification of the corresponding diol with vinylacetate. This synthesis entailed a series of stereoselective transformations: the absolute configurations of C 6′ and C 8′ were fixed by an aldol condensation followed by an anti-reduction of the resulting β-hydroxyketone. The configurations of the last two asymmetric centers C 2′ and C 3′ were controlled by a novel highly diastereoselective intramolecular cyclization catalyzed by fluoride ions.

Microbial metabolism of fluazifop-butyl

A microbial mixed culture able to grow on fluazifop-butyl and fluazifop was isolated. Fluazifop degradation by this microbial population was studied either when the herbicide was applied as the sole carbon source or in the presence of a second carbon source (sodium acetate or sodium propionate). The degradation rate was enhanced by sodium propionate. The degradation was found to be stereoselective. The S-enantiomer of fluazifop was degraded at a much higher rate than the R-enantiomer. Fluazifop disappearance was accompanied by formation of three metabolites which were identified by UV, IR, MS and NMR analyses. The metabolites were shown to be: 4-(5-trifluoromethyl-2-pyridyl)oxyphenol, 5-trifluoromethyl-2- hydroxypyridine and 2-(5-trifluoro-methyl pyridyl)hydroxy acetate.

Hydrolytic and reductive action of fermenting yeast on a keto acetate: synthesis of (+)-endo-brevicomin

The keto acetate 1 in fermenting yeast gives the diol 2 with high enantiomeric excess. The product arises from hydrolysis–reduction and is transformed into (+)-endo-brevicomin. The hydroxy acetate from direct reduction of 1 is racemic.

Total synthesis of analogues of the β-lactam antibiotics. Part 4. 4-t-Butoxycarbonyl-8-oxo-1,3,4-triazabicyclo[4.2.0]oct-2-ene-2-carboxylates

t-Butyl hydroxy(4-iodomethyl-2-oxoazetidin-1-yl)acetate (6a) was transformed into t-butyl 4-t-butoxycarbonyl-8-oxo-1,3,4-triazabicyclo[4.2.0]oct-2-ene-2-carboxylate (9a) by sequential reactions involving thionyl chloride [to give the chloroacetate (7a)], t-butyl carbazate [to give the 2-t-butoxycarbonylhydrazinoacetate (5a)], and silver(I) oxide. In the last reaction, the 2-t-butoxycarbonylhydrazinoacetate (18a) is a likely intermediate. The structure of compound (9a) was supported by its conversion into methyl 1-t-butoxycarbonyl-3-methoxycarbonyl-1,4,5,6-tetrahydro-1,2,4-triazin-5-ylacetate (11b) by the action of sodium hydroxide followed by iodomethane, and confirmed by a single crystal X-ray analysis. The p-nitrobenzyl and benzyl esters of the triazabicyclo-octene, i.e. compounds (9c,d), were prepared from the carbinols (6b,c) by a similar reaction sequence. Hydrogenolysis of the benzyl ester (9d) gave the acid (9b), the sodium salt of which lacked antibacterial activity.

A synthesis of the (+)-Prelog–Djerassi lactone

cis-5,7-Dimethylcyclohepta-1,3-diene, which is readily available using organoiron chemistry, was converted to all cis-3,7-diacetoxy-4,6-dimethylcycloheptene (5), which was subjected to asymmetric enzymatic hydrolysis to give hydroxy acetate (6), and this compound was converted in four steps to the (+)-Prelog–Djerassi lactone having high optical purity.

Synthetic studies on dl-aspterric acid, a carotane-type sesquiterpene. II Synthesis of dl-aspterric acid.

Total synthesis of dl-aspterric acid (1) has been accomplished. Robinson annulation of the keto ester (2) with methyl vinyl ketone, followed by reduction with LiAlH4 and oxidation with MnO2, afforded the enone alcohol (4), which was converted to the hydroxy-ether (6) via three steps (I2-Ag2O, AgOAc, and alkaline hydrolysis). Successive treatment of 6 with tert-butyldimethylsilyl chloride, tert-BuOK-MeI, NaBH4, Ac2O-pyridine and 5% HCl afforded the hydroxy acetate (18). The hydroxy acetate (18) was converted to the hydroxy ketone (20) via catalytic hydrogenation under medium pressure, Jones oxidation, and alkaline hydrolysis. Treatment of 20 with PCl5 gave the norketone (21), which is the degradation product of 1. The dimethylacetal (25) of 20 was treated with Me3SiCN-SnCl2 to give the methoxy cyanides A (26) and B (27). The major methoxy cyanide B (27) was successively treated with KOH, Me3SiCl-NaI, Ac2O, and 5% HCl to give the monoacetate (31), which was finally converted to 1 via ring contraction with PCl5 and alkaline hydrolysis.

Enzymatic hydrolysis of 3,7-diacetoxycloheptene derivatives

Hydrolysis of 3,7-diacetoxycycloheptene using electric eel acetylcholinesterase gives optically pure (3R,7S)-3-hydroxy-7-acetoxycycloheptene, and hydrolysis using lipase enzyme from Candida cyclindracea gives the same hydroxy acetate, but in only 44% enantiomeric excess, in contrast to the normal behaviour of lipase which gives (S) alcohols for related hydrolyses; 3,7-diacetoxy-4,6-dimethylcycloheptene (10) is not hydrolysed by acetylcholinesterase, but is readily hydrolysed by lipase to give (3S,4R,6S,7R)-3-hydroxy-7-acetoxy-4,6-dimethylcycloheptene.

ChemInform Abstract: The Action of Mercaptoacetic Acid on a Trialkyl Epoxide.

Abstract2,3‐Epoxy‐2‐methylpentane (I) reacts with mercaptoacetic acid (II) to yield the oxathianone (III) and the hydroxy acetate (IV).

Radical-cations as intermediates in the oxidation of alkenes by metal ions

The formation of hydroxy acetates in the reaction of some alkenes with lead(IV), cobalt(III), and manganese(III) in acetic acid is demonstrated to involve the intermediacy of alkene radical-cations. A study employing a range of aryl-substituted alkenes has shown that there is an inverse relationship between the yield of hydroxy acetate and the ionisation potential of the organic substrate. The electron deficiency in the radica-cations derived from these alkenes appears to be localised on the double bond: no evidence could be obtained for reaction at the aromatic ring. The introduction of a chlorine atom into this ring had the effect of repressing electron-transfer in cobalt(III) and manganese(III) oxidations but not in those involving lead(IV).

Competition of two participating groups in hypobromous acid addition to some 4-cholestene derivatives

Hypobromous acid addition to the 4,5-unsaturated hydroxy acetate VIII results in formation of the cyclic bromo ether XXIXa as a product of 5(O)n participation. Participation by hydroxy group is thus preferred over 5(O)π,n process by acetoxyl. Under the same conditions the 4,5-unsaturated diacetate IX afforded the diaxial bromohydrin XXXI arising from 4α,5α-bromonium ion with 5(O)π,n participation by the 3β-acetoxyl whereas an alternative 6(O)π,n participation by the 19-acetoxyl is not operative. The 3-epimeric diacetate XV reacts with hypobromous acid in a more complex way: the molecule is attacked by the electrophile from both α- and β-sites to give two diastereoisomeric bromonium ions XXXII and XXXIII. The former is simply cleaved with water as an external nucleophile to afford the diaxial bromohydrin XXXIV. The latter undergoes fission both with 5(O)π,n and 6(O)π,n participation: The first route leads to the trans-bromohydrin XXXVI. In the second pathway the acyloxonium ion XXXVII postulated as an intermediate is further cleaved with 6(O)π,n participation by 19-acetoxyl to give the acyloxonium ion XXXVIII, which is trapped by water to yield an unusual cis-bromohydrin XXXIX. The differences in the reaction course are discussed.

Chemistry of the Podocarpaceae. XXIX. The preparation of 6-oxygenated derivatives of Abieta-8,11,13-trien-18-oic acid

��� Peracid oxidation of the enol acetate (23) derived from the C 7 ketone (6) provides a method for introducing an oxygenated substituent into the C 6 position of abieta-8,11,13-trien-18-oic acid (1). Reduction of the keto acetate (10) with sodium borohydride and hydrogenolysis of the C 7 hydroxy group of the hydroxy acetate (28) affords the 6-acetate (33) in 55% overall yield from methyl abieta- 8,11,13-trien-18-oate (2). Hydrolysis of the acetoxy ester (33) followed by re-methylation of the C 4 carboxy group and oxidation of the hydroxy ester (34) gives the C 6 ketone (35).

Terpenoids—LXI : Conversion of eudesmol to di- and tetrahydrocostol

Dihydro-β-eudesmol (IV), obtained by catalytic hydrogenation of β-eudesmol (II), on pyrolysis via the benzoate gives dihydro-β-selinene (V). Its epoxyderivative (VI) is converted on treatment with acetic acid to the hydroxy acetate (VII), the benzoate of which on pyrolysis, followed by saponification, affords dihydrocostol (XI), converted by hydrogenation to tetrahydrocostol (XII). The alcohol (XI) is not identical with agarol to which the same stereoformula has been assigned previously. These results would necessitate a re-examination of the structure and stereochemistry of agarol which has already been undertaken.