HCl In Acetone Research Articles

Condensed Tannin Changes along the Digestive Tract in Lambs Fed with Sainfoin Pellets or Hazelnut Skins

The variable anthelmintic efficacy of condensed tannins (CT) against gastrointestinal nematodes may depend on CT concentration, composition, or fate along the digestive tract. We analyzed CT concentration and composition by acetone-HCl-butanol and thiolysis coupled to HPLC-MS in digesta and feces of lambs. Lambs had been infected with Haemonchus contortus and Trichostrongylus colubriformis and received sainfoin pellets and hazelnut skins of contrasting prodelphinidin/procyanidin ratios. The digesta and feces had lower CT concentrations than the original feeds but similar concentration patterns across the digestive compartments. The changes in assayable CT concentrations between rumen, abomasum, and small intestine may be due to complex formation between CT and other dietary components. However, the large CT disappearance (61-85%) from feed to feces could also indicate that CT may have been structurally modified, degraded, or absorbed during digestion. Interestingly, there were no changes in the structural features of assayable CT in the digesta.

Sorption behavior of metal ions on thiourea-impregnated silica gel G and alumina stationary phases in aqueous HCl and acetone—HCl media: Quantitative separation of Pb2+ and Hg2+ from other metal ions

The sorption behavior of a number of metal ions was investigated on thiourea-impregnated silica gel G and alumina layers with aqueous HCl and acetone—HCl mobile phases. The mobility of the metal ions was examined under varying experimental conditions of mobile phase pH, effect of concentration of thiourea as the impregnant, and also the effect of solvent composition in acetone—HCl mixtures. The migration of metal ions depends on the solubility of metal salt, adsorption and precipitation of the ions in the network of the adsorbent. On impregnated silica gel G layers, for many ions, maximum adsorption occurs at pH 2 and above. 0.1 m and 0.2 m thiourea-impregnated alumina layers were found the most suitable for metal ion separations. For some metal ions, comparative study was made with thiourea and urea as the impregnant. Quantitative separations of Pb2+ and Hg2+ from some other metal ions and synthetic alloys were also carried out.

Highly sensitive electrochemical determination of sulfate in PM2.5 based on the formation of heteropoly blue at poly-l-lysine-functionalized graphene modified glassy carbon electrode in the presence of cetyltrimethylammonium bromide

A simple and sensitive electrochemical sensor based on the formation of heteropoly blue at poly-l-lysine (PLL)-functionalized graphene (GR) modified glassy carbon electrode (GR-PLL/GCE) was developed to detect sulfate in the presence of cetyltrimethylammonium bromide (CTAB). This method was based on the oxidation currents of the blue complex formed via 40s electrolysis of Mo (VI)–acetone–HCl solution containing sulfate at 0.1V vs. SCE and sulfate concentration. The structure and morphology of GR, PLL and GR-PLL were examined by Raman, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The fabricated sensor was further characterized using cyclic voltammetry (CV). Under optimum conditions, the sensor displayed a wide linear range of 0.8–1000μM for sulfate concentration with the coefficient of determination of 0.9996 and a detection limit of 0.26μM. The proposed sensor was further employed to detect sulfate in fine particles (PM2.5, particulates with aerodynamic diameters <2.5μm). The results obtained were in good agreement with those of using ion chromatography (IC), which indicates that this novel voltammetric sensor has promising applications for the detection of sulfate in environmental fields.

Synthesis, Spectral Characterization and Antioxidant Activity of Novel Zafirlukast Sulfonyl Derivatives

AbstractA new series of cyclopentyl 3‐(2‐methoxy‐4‐(piperazine‐1‐carbonyl)benzyl)‐1‐methyl‐1H‐indol‐5‐ylcarbamate sulfonyl derivatives were synthesized by the reaclion of 4‐((5‐(cyclopentyloxycarbonylamino)‐1‐methyl‐1H‐indol‐3‐yl)methyl)‐3‐methoxybenzoic acid (ZAK drug intermediate) with Boc piperazine in the presence of EDC⋅HCl, HOBt, TEA in DMF followed by deboxylation by using 2N HCl or 35 % HCl in acetone to get an intermediate compound. Further, this compound was treated with various substituted benzene sulfonyl chlorides in the presence of TEA in THF to afford title compounds. All the title compounds were characterized by 1HNMR, 13CNMR, IR and mass spectral data. The title compounds and starting material were evaluated for their antioxidant activity by using the DPPH, H2O2 and NO methods. The results revealed that some of the compounds have shown significant antioxidant activity.

Comparative study for the separation, preconcentration, and determination of copper and cadmium in real samples by using two different ligands

Two new solid phase extraction methods have been developed for simultaneous separation and preconcentration of Cu(II) and Cd(II) in some food and environmental samples before their determination by flame atomic absorption spectrometry (FAAS). One of these methods is based on the absorption of the Cu(II) and Cd(II) complexes with [3-(cyanomethyl)-5-(4-methylphenyl)-4$H$-1,2,4-triazol-4-yl]carbamate (L1) and the other is based on the absorption of the Cu(II) and Cd(II) complexes with 4-(4-methylphenyl)-5-{[pyridine-4-yl-4$H$-1,2,4-triazole-3-yl)thio]methyl}-4$H$-1,2,4-triazole-3-thiol (L2) on Amberlite XAD-1180 resin. The metal complexes are retained on resin at pH 6.0 and eluted with 1.0 mol L$^{-1}$ HCl in acetone in both methods. After the optimum conditions were determined, the methods were applied to seawater, stream water, rice, lentil, tea, tobacco, bulgur, chickpea, wheat, red pepper, black pepper, peppermint, and dried eggplant samples in order to determine the levels of copper and cadmium.

Synthesis of (2β,3α,6-2H3)cholesteryl linoleate and cholesteryl oleate as internal standards for mass spectrometry

The accurate analysis of trace component in complex biological matrices requires the use of reliable standards. For liquid chromatography/mass spectrometry analysis, the stable isotope-labeled derivatives of the analyte molecules are the most appropriate internal standards. We report here the synthesis of (2β,3α,6-2H3)cholesteryl linoleate and oleate containing three non-exchangeable deuterium in the steroid ring. The principal reactions used were: (1) trans diaxial opening of 2α,3α-epoxy-6-oxo-5α-cholestane with LiAlD4 and subsequent oxidation of the resulting (2β,6α-2H2)-3α,6β-diol with Jones’ reagent, followed by reduction of the resulting (2β-2H)-3,6-dione with NaBD4 leading to the (2β,3α,6α-2H3)-3β,6β-dihydroxy-5α-cholestane, (2) selective protection of the 3β-hydroxy group as the tert-butyldimethylsilyl ether, (3) dehydration of the 6β-hydroxy group with POCl3 and removal of tert-butyldimethylsilyloxy groups with 5M HCl in acetone, and (4) esterification of the resultant (2β,3α,6-2H3)cholesterol with linoleic and oleic acids using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. The isotopic purity was found to be satisfactory by mass spectrometry, and nuclear magnetic resonance properties of the new compounds were tabulated. The labeled compounds can be used as internal standards in liquid chromatography/mass spectrometry assays for clinical and biochemical studies.

Application of nanoclay for preconcentration of ultra trace amounts of palladium in environmental samples prior to its determination by ETAAS

In the present work, a batch preconcentration technique using nanoclay with 5-(4-dimethylaminobenzylidene)rhodanine coupled with electrothermal atomic absorption spectrometry was developed for the separation and determination of trace amounts of palladium. In this method, the sample solution was stirred with nanoclay as an adsorbent. Then, adsorbed palladium was subsequently eluted with HCl in acetone (1.5 mol L−1) and, finally, this eluate was injected to electrothermal atomic absorption spectrometry. Under the optimum conditions, the limit of detection and linear dynamic range were found to be 2.6 and 10.0–133 ng L−1 (in original solution), respectively. Furthermore, the enrichment factor and relative standard deviation of seven replicate determinations were 148 and ±5.1 %, respectively. This suggested method is simple, selective and sensitive and can be applied to the extraction and determination of palladium in water, tea leaves, synthetic sample and certified reference material with satisfactory results.

Development of a New Solid Phase Extraction Procedure for Selective Separation and Enrichment of Au(III) Ions in Environmental Samples

A highly sensitive, selective and low cost solid phase extraction (SPE) procedure was developed for separation and enrichment of Au(III) ions in environmental samples prior to its flame atomic absorption spectrometric detection. Au(III)-2-pyridin-5-(4-tolyl)-1,3,4-oxadiazole (PYTOX) complex was adsorbed quantitatively on Amberlite XAD-4 resin in 0.5 mol L-1 HNO3 condition and the elution was carried out with 7.5 mL of 1.0 mol L-1 HCl in acetone. Some analytical parameters, affect the recoveries of Au(III) ions, such as HNO3 concentration of sample solution, amount of PYTOX, type, concentration and volume of eluent, sample volume and concomitants were examined. Adopting optimized experimental conditions, the limit of detection for Au(III) ions was 1.03 µg L-1 with preconcentration factor of 50 and a relative standard deviation (RSD) of 3.7%. The determination of Au(III) ions in anodic slime, gold ore, soil and sea and stream waters was performed after checking the accuracy of the method by addition-recovery tests.

Separation and preconcentration of copper in environmental samples on Amberlite XAD-8 resin after complexation with a carbothioamide derivative

A new solid phase extraction (SPE) method has been developed for the selective separation and preconcentration of Cu (II) ions in food and water samples prior to its flame atomic absorption spectrometry determination. The method is based on the adsorption of the Cu(II) - 2-{[4-Amino-3-(4-methylphenyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]acetyl}-N-phenyl hydrazinecarbothioamide complex on Amberlite XAD-8 resin. The metal complex retained on the resin was eluted with 7.5 mL of 2.0 mol L-1 HCl in acetone. The optimum conditions for the SPE of Cu(II) ions were investigated, and the method was subsequently applied to sea water, stream water, rice, tea, and tobacco samples for the determination of Cu(II) levels.

Selective Solid Phase Extraction for Separation and Preconcentration of Palladium from Gold Ore and Anode Slime after Complexation with a N4O2 Mixed Donor Ligand Derivative

AbstractA selective and sensitive method for the preconcentration, separation, and determination of palladium with flame atomic absorption spectrometry using 4,15‐bis[(4‐methylphenyl)sulfonyl]‐20,21‐dinitro‐2,3,4,5,6,7,9,10,12,13,14,15,16,17‐tetradecahydro‐8,11‐ethano‐1,18,4,8,11,15‐benzodioxa tetraaza cycloicosine (TNACIN) on XAD‐2010 was developed. TNACIN–Pd(II) complex formed acidic aqueous solution (0.075–0.100 M HNO3) was accumulated on XAD‐2010 and then eluted with 1 M HCl in acetone. The effects of some analytical parameters including pH, TNACIN amount, sample volume, eluent type, and concentration, sample flow rate and matrix ions were studied for optimization of the method. Detection limit and precision were calculated for Pd(II). This method was also verified with CRM and internal standard, and satisfactory results were obtained.

Separation of Mg, Ca and Fe from geological reference materials for stable isotope ratio analyses by MC-ICP-MS and double-spike TIMS

Near quantitative separation of analyte elements from the sample matrix is commonly required to obtain precise and accurate stable isotope data, especially if MC-ICP-MS is used in conjunction with the standard-sample bracketing (SSB) technique for mass bias drift correction. Here, we report a robust procedure that allows for the combined chemical separation of Mg, Ca and Fe, using ion-exchange columns that contain 1 ml AG50W-X8 (200–400 mesh) cation exchange resin. Magnesium was separated for isotope ratio analyses from many geological sample types by a single pass through this column. For Mg purification, Be, Ti, Mn, Fe and Al are selectively eluted using dilute HF and an acetone–HCl mixture. The separation of Mg from Ca-dominated carbonate samples and/or a combination of Mg, Ca and Fe separation from the same sample aliquot, is achieved by the adsorption of Ca and Fe onto the ion-exchange resin from 10 M HCl. Following purification, geological reference materials, including water, bone, carbonate and sediment samples, igneous and sedimentary rocks and a chondritic meteorite were analysed by MC-ICP-MS (Mg and Fe isotopes) and double-spike TIMS (Ca isotopes). Average external repeatabilities were ±0.16‰ for 26Mg/24Mg, ±0.26‰ for 44Ca/40Ca and ±0.05‰ for 56Fe/54Fe (2sd; n ≥ 5). Comparison with published data documents the accuracy of the results. For Mg isotope analyses using SSB-MC-ICP-MS, matrix-induced mass bias effects were studied using element additions. The artificial matrices left a memory in subsequent standard analyses, likely due to depositions on the cones. This observation allowed for the detection of matrix effects in unknown samples. Finally, the current status of Mg and Ca zero-delta reference materials is briefly discussed.

Chemical aromatization of 19-hydroxyandrosta-1,4-diene-3,17-dione with acid or alkaline: Elimination of the 19-hydroxymethyl group as formaldehyde

In order to determine whether or not a 19-hydroxymethyl group of 19-hydroxyandrosta-1,4-diene-3,17-dione ( 2, 19-hydroxy ADD), an intermediate of aromatase-catalyzed estrone formation from ADD, a suicide substrate of aromatase, is eliminated as formaldehyde, we examine chemical nature of removal of the 19-hydroxymethyl group. 19-Acetate 3 and 19-tert-butyldimethylsiloxy compound 4 are known to convert rapidly to estrone with treatment of NaOH or n-Bu 4NF. Since compound 2 was unstable and unobtainable under these conditions, compounds 3 and 4 as equivalents to compound 2 were used in this study. The acetate 3 with 5 mol/l HCl in acetone and 10% KOH in MeOH along with the silyl ether 4 with 5 mol/l HCl in acetone and 1 mol/l n-Bu 4NF in THF gave formaldehyde and estrone in which a ratio of the aldehyde to estrone was near 1. This result indicates that the 19-hydroxymethyl groups of compound 3 and 4 are eliminated as formaldehyde along with estrone derived from the steroid skeleton under the acid or base treatment. The findings suggest that a single hydroxylation at the 19 carbon of ADD ( 1) would be, chemically, all that was required for estrone formation.

A new solid-phase extraction method for the determination of Cu(II) and Fe(III) in various samples by flame atomic absorption spectrometry using N-benzoyl-N-phenylhydroxylamine

A novel column solid phase extraction method was developed for the determination of Cu(II) and Fe(III) in various samples by flame atomic absorption spectrometry (FAAS) after preconcentration as their N-benzoyl-N-phenylhydroxylamine complexes on Amberlite XAD-1180 resin. Elution was performed with 1 mol L−1 HCl in acetone. The effects of some analytical parameters such as pH, amount of reagent, eluent type, concentration and volume, flow rate of sample and elution solutions, volume of the sample solution and matrix interference were investigated. The recoveries of Cu(II) and Fe(III) under optimum conditions were ≥95%. A good relative standard deviation (≤2.0%), a good preconcentration factor (50) and low detection limits (0.82 μg L−1 for Cu and 1.05 μg L−1 for Fe) were obtained. The accuracy of the procedure developed was confirmed by determining the analytes in three certified reference materials (TMDA-54.4 fortified lake water, SRM 1643e trace elements in water, SRM 1568a rice flour) and the analysis of spiked water samples. The results showed a good agreement with the certified values. The method was applied to the determination of the analytes in water (sea water, dam water, lake water and waste water), vegetable, rice and spices samples.

Binding and Glutathione Conjugation of Porphyrinogens by Plant Glutathione Transferases

Overexpression in Escherichia coli of a tau (U) class glutathione transferase (GST) from maize (Zea mays L.), termed ZmGSTU1, caused a reduction in heme levels and an accumulation of porphyrin precursors. This disruption was highly specific, with the expression of the closely related ZmGSTU2 or other maize GSTs having little effect. Expression in E. coli of a series of chimeric ZmGSTU1/ZmGSTU2 proteins identified domains responsible for disrupting porphyrin metabolism. In addition to known heme precursors, expression of ZmGSTU1 led to the accumulation of a novel glutathione conjugate of harderoporphyrin(ogen) (2,7,12,18-tetramethyl-3-vinylporphyrin-8,13,17-tripropionic acid). Using the related protoporphyrinogen as a substrate, conjugation could be shown to occur on one vinyl group and was actively catalyzed by the ZmGSTU. In plant transgenesis studies, the ZmGSTUs did not perturb porphyrin metabolism when expressed in the cytosol of Arabidopsis or tobacco. However, expression of a ZmGSTU1-ZmGSTU2 chimera in the chloroplasts of tobacco resulted in the accumulation of the harderoporphyrin(ogen)-glutathione conjugate observed in the expression studies in bacteria. Our results show that the well known ability of GSTs to act as ligand binding (ligandin) proteins of porphyrins in vitro results in highly specific interactions with porphyrinogen intermediates, which can be demonstrated in both plants and bacteria in vivo.

Effect of Glucose Concentration on Formation of AGEs in Erythrocytes in Vitro

Posttranslational modifications, such as advanced glycoxidation and lipoxidation end products (AGE/ALEs), are implicated in the pathogenesis of diabetic complications and atherosclerosis. Recent studies have demonstrated that AGE/ALEs are generated not only in extracellular matrix proteins, but also in intracellular proteins from metabolic intermediates. In this study we investigate the effect of glucose concentration on the formation of the AGE/ALEs, Nepsilon-(carboxymethyl)lysine (CML), Nepsilon-(carboxyethyl)lysine (CEL), S-(carboxymethyl)cysteine (CMC), and S-(2-succinyl)cysteine (2SC) in erythrocytes as a function of glucose concentration. Human erythrocytes (10% hematocrit) were incubated in Dulbecco's modified Eagle's medium (DMEM) containing 5 mM or 30 mM glucose for 5 days at 37 degrees C. Globin was recovered by precipitation with 0.25 M HCl in acetone. Following acid hydrolysis, amino acids were converted to their trifluoroacetyl methyl ester derivatives and analyzed by GC/MS/MS. The CML and CEL content of globin increased in a time- and glucose-dependent manner and also increased 1.3- and 1.8-fold, respectively, in incubations containing 30 mM glucose; whereas CMC and 2SC content did not change during the five-day incubations. Furthermore, CEL content of globin in erythrocytes incubated with 30 mM was the highest in the other AGEs, indicating that methylglyoxal may play a major role in AGE formation in erythrocytes. The erythrocyte system should be useful for cellular screening of the efficacy of inhibitors of AGE/ALE formation.

Changes of humic substances characteristics from forested to cultivated soils in Ethiopia

The dynamics of the stable fractions of soil organic matter (SOM), the humic substances, has been rarely studied in tropical soils. We evaluated extraction yields, elemental composition, isotopic δ 13C abundance and solid-state 13C NMR spectra of humic fractions isolated from five forested and cultivated soils in Ethiopia in order to assess the influence of deforestation and subsequent cultivation on the composition of humic fractions. In all locations, humic (HA) and fulvic (FA) acids, humin (HU) and a humic hydrophobic fraction extracted with an acetone–HCl solution (HE) were decreased as a result of deforestation and cultivation, but the magnitude of decrease was site-specific. While the elemental composition of HA, FA and HU did not vary significantly with land use, that of the hydrophobic HE generally decreased with deforestation. Cultivation varied the δ 13C values of humic fractions with location and their high values suggested a history of C4 plants incorporation in soil. The 13C NMR spectra of HA, FA and HU showed that hydrophobic components (HB) were generally lower than hydrophilic ones (HI), resulting in a degree of hydrophobicity (HB/HI) being < 1.00. On average, cultivation decreased the HB/HI values of these humic fractions in all soils except for the Andisol. The HE material was much richer in hydrophobic groups showing a HB/HI ranging from 1.48 to 3.44 in the forested sites, but cultivation substantially reduced HB/HI ratios also for HE. Our data suggest that deforestation and progressive cultivation in tropical conditions decreased the content of soil humic substances and that the resulting humic pool was poorer in alkyl components and less hydrophobic than in forested conditions.

Functional phosphines XV. Ruthenium complexes containing C 5H 8(PR 2) 2 and [formula omitted] ligands (R = Me, Ph, OPh; R′ = H, Me): synthesis and application to homogeneous [lbond2]C [dbnd]O hydrogenation and transfer hydrogenation

Treatment of [Ru(η 4-C 8H 12){η 3-(CH 2) 2CMe} 2] with C 2 chiral cyclopentane-1,2-diyl-bis(phosphines) trans-1,2-C 5H 8(PR 2) 2 in hexane afforded the chelate complexes [Ru{η 3-(CH 2) 2CMe} 2{1,2-C 5H 8(PR 2) 2}], where R = Me ( 2), Ph ( 3), NC 5H 10 ( 4), and OPh ( 5). The mixed-ligand compounds [ RuCl 2 { 1 , 2 - C 5 H 8 ( PR 2 ) 2 } ( Ph 2 PCH 2 CR 2 ′ NH 2 ) ] [R′ = H: R = Me ( 6), Ph ( 7), OPh ( 8); R′ = Me: R = Ph ( 9)] were obtained by reactions of the bis(2-methylallyl) precursors 2, 3, and 5 with methanolic HCl in acetone, followed by the addition of the required aminophosphine in DMF. The ( P∩ P) 2- and ( P∩ N) 2-chelated complexes [RuCl 2{1,2-C 5H 8(PMe 2) 2} 2] ( 1) and [RuCl 2(Ph 2PCH 2CMe 2NH 2) 2] ( 10) resulted from RuCl 3 · 3H 2O and 1,2-C 5H 8(PMe 2) 2 or Ph 2PCH 2CMe 2NH 2 under reducing conditions. The crystal structures of 1, 3, 4, 6, 7, 9, and 10 were determined by single-crystal X-ray diffraction. Complexes 7, 9, and 10, activated by KOBu- t, i-PrOH, were used as catalysts for the transfer hydrogenation of acetophenone with i-PrOH as the hydrogen source. Base modified complex 10 also turned out to be an active catalyst for the direct hydrogenation of the ketone by H 2 under pressure.

Determination of palladium in various samples by atomic absorption spectrometry after preconcentration with dimethylglyoxime on silica gel

A preconcentration method based on the adsorption of palladium-dimethylglyoxime (DMG) complex on silica gel for the determination of palladium at trace levels by atomic absorption spectrometry (AAS) has been developed. The retained palladium as Pd(DMG) 2 complex was eluted with 1 mol l −1 HCl in acetone. The effect of some analytical parameters such as pH, amount of reagent and the sample volume on the recovery of palladium was examined in synthetic solutions containing street dust matrix. The influence of some matrix ions on the recovery of palladium was investigated by using the developed method when the elements were present both individually and together. The results showed that 2500 μg ml −1 Na +, K +, Mg 2+, Al 3+ and Fe 3+; 5000 μg ml −1 Ca 2+ ; 500 μg ml −1 Pb 2+; 125 μg ml −1 Zn 2+; 50 μg ml −1 Cu 2+ and 25 μg ml −1 Ni 2+ did not interfere with the palladium signal. At the optimum conditions determined experimentally, the recovery for palladium was found to be 95.3±1.2% at the 95% confidence level. The relative standard deviation and limit of detection (3 s/ b) of the method were found to be 1.7% and 1.2 μg l −1, respectively. In order to determine the adsorption behaviour of silica gel, the adsorption isotherm of palladium was studied and the binding equilibrium constant and adsorption capacity were calculated to be 0.38 l mg −1 and 4.06 mg g −1, respectively. The determination of palladium in various samples was performed by using both flame AAS and graphite furnace AAS. The proposed method was successfully applied for the determination of palladium in the street dust, anode slime, rock and catalytic converter samples.

Bis(6-hydroxy-6,8,8′-trimethyl-5-aza-1-azonia-bicyclo[3.3.0]octa-1,3-diene) osmium hexachloride: synthesis and solid-state structure

The title compound is accessible by the reaction of OsO 4 ( 1) with pyrazole (pz) in the presence of HCl in acetone as solvent. As intermediate the osmium(VI) transition metal complex trans-[OsO 2Cl 2(pz) 2] ( 3) is formed. A possible mechanism for the formation of [C 6H 5N 2Me 3(OH)] 2OsCl 6 ( 4) is presented. Compound 4 crystallises in the triclinic space group P 1 ̄ with cell parameters a=7.8993(1), b=9.3019(1), c=10.1790(1) Å, α=114.397(1), β=100.527(1), γ=96.014(1)°, Z=1 and V=4848.67(10) Å 3. The 5-aza-1-azonia-bicyclo[3.3.0]octa-1,3-diene cation consists of a planar and a saturated envelope-structured C 3N 2 five-membered cycle of which the two nitrogen atoms are the connecting points for the bicyclic unit. As counter-ion [OsCl 6] 2− is acting. The osmium chloride distances are 2.3301(8), 2.3538(8) and 2.3365(8) Å. Typical separations for the bicyclic [C 6H 3N 2Me 3(OH)] + building blocks are: NN 1.344(4), NC [aliphatic ring 1.488(4), 1.499(4) Å; aromatic ring: 1.337(4), 1.339(4) Å] and CC [aliphatic ring: 1.527(5), 1.534(5) Å; aromatic ring: 1.384(5), 1.390(5) Å].

A New Class of Herbicides that are Derivatives of 8-Oxabicyclo[3.2.1]oct-6-en-3-one

Treatment of 8-oxabicyclo[3.2.1]oct-6-en-3-one with a catalytic amount of osmium tetraoxide and excess hydrogen peroxide resulted in the formation of the acetonide exo-6,exo-7-isopropylidenedioxy-8-oxabicyclo[3.2.1]oct-3-one (2), in 96% yield. This acetonide was converted into several aromatic alcohols (4a–k) through a Grignard reaction. The alcohols were treated with aqueous HCl in acetone, and the corresponding alkenes (5a–c,e–g, j,k) were obtained in 26–46% overall yield, from the ketone (2). The herbicidal activity of the alkenes was evaluated at a concentration of 6.6 µg g−1. All compounds showed an inhibitory effect (21–66%) on the Sorghum bicolor radicle growth. The inhibition of the accumulation of fresh and dried weight of the aerial parts of Cucumis sativus, after 14 days, varied from 7.1 to 60.7% and from 0.0 to 41.6%, respectively. Compounds (5a,e–g) caused 100% mortality of C. sativus, after 20 days. Compound (5g) (exo-6,exo-7-isopropylidenedioxy-3-(3-methylphenyl)-8- oxabicyclo[3.2.1]oct-2-ene) was evaluated against several weeds, and it caused 100% mortality of Desmodium tortuosum and Pennisetum setosum.