EXTRACTION MECHANISM OF SC(III) AND SEPARATION FROM TH(IV),FE(III) AND LU(III) WITH BIS(2,4,4-TRIMETHYLPENTYL)PHOSPHINIC ACID IN N-HEXANE FROM SULFURIC-ACID-SOLUTIONS

The extraction equilibrium data of sulphuric acid and scandium(III) with bis(2,4,4-trimethylpentyl)phosphinic acid (H[BTMPP]) from sulphuric acid solutions have been obtained. There are two extraction mechanisms of scandium(III) with H[BTMPP] at different

ELECTROOXIDATION OF ASCORBIC-ACID AT THE BIS(4-PYRIDYL) DISULFIDE MODIFIED GOLD ELECTRODE

The electrooxidation of ascorbic acid (AA) at the bis(4-pyridyl)disulfide (PySSPy) modified gold electrode was studied. The results showed that the oxidation process was pH-dependent. It was mainly due to the static interaction between AA and the modified

ISOPOLYMOLYBDIC ACID-POLY(4-VINYL)PYRIDINE FILM MODIFIED ELECTRODE

Electrochemical polymerization of 4-vinylpyridine produced a uniform poly(4-vinyl)pyridine(PVP) film on the glassy carbon (GC) electrode surface. The isopolymolybdic acid-PVP film-modified electrode was prepared by soaking the PVP/GC electrode in the 0.05 M H2SO4 aqueous solution containing 0.005 M isopolymolybdic acid (H4Mo8O26). The latter (catalyst) is incorporated and held in the PVP film electrostatically. The electrochemical behavior and electrocatalytic properties of this H4Mo8O26-PVP/GC electrode was described. The results indicate that this modified electrode has good stability and electrocatalytic activity on the reduction of chlorate and bromate ions in aqueous solution. The catalytic process is regarded as an EC mechanism.

Comparative analysis of allantoin quercetin, and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid in Nitraria tangutorum Bobr. Seed by HPLC-APCI-MS and CE

This paper describes the simultaneous determination of allantoin, quercetin, and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (MTCCA) in Nitraria tangutorum Bobr seed by HPLC-APCI-MS and CE (capillary electrophoresis) methods. The final optimized chromatographic conditions were investigated in a reversed-phase Eclipse XDB-C8 column (150 x 4.6 mm, 5 mu m). A seventeen-minute gradient elution, (A: aqueous acetonitrile 20% (v/v); B: aqueous acetonitrile 60% (v/v); C: pure acetonitrile 100%) at a flow rate of 1.0 mL/min was selected for the separation of three natural products with diode array detection (DAD) at 220 nm. A CE experiment was carried out in a fused silica capillary with 32 mmol/L boric acid (pH 10), 32 mmol/L SDS and acetonitrile (10.0%, v/v). The applied potential and temperature was, respectively, set at 19 kV and 25 degrees C. After development, the validation was performed in parallel for HPLC and CE, with the same standards and sample to avoid differences due to the manipulation. The validation parameters of both techniques were adequate for the intended purpose.

Central nervous system drugs: Low temperature X-ray structures of (I) the base 5-(2,3-dichlorophenyl)-2,4-diamino-6-fluoromethyl-pyrimidine (4030W92) and (II) 5-(2,6-dichlorophenyl)-1-H-2,4-diamino-6-methyl-pyrimidine methanesulphonic acid salt (227C89)

The X-ray crystal structures of (I), the base 4030W92, 5-(2,3-dichlorophenyl)-2,4-diamino-6-fluoromethyl-pyrimidine, C11H9Cl2FN4, and (II) 227C89, the methanesulphonic acid salt of 5-(2,6-dichlorophenyl)-1-H-2,4-diamino-6-methyl-pyrimidine, C11H11Cl2N4 center dot CH3O3S, have been carried out at low temperature. A detailed comparison of the two structures is given. Structure (I) is non-centrosymmetric, crystallizing in space group P2(1) with unit cell a = 10.821(3), b = 8.290(3), c = 13.819(4) angstrom, beta = 105.980(6)degrees, V = 1191.8(6) angstrom(3), Z = 4 (two molecules per asymmetric unit) and density (calculated) = 1.600 mg/m(3). Structure (II) crystallizes in the triclinic space group P (1) over bar with unit cell a = 7.686(2), b = 8.233(2), c = 12.234(2) angstrom, alpha = 78.379(4), beta = 87.195(4), gamma = 86.811(4)degrees, V = 756.6(2) angstrom(3), Z = 2, density (calculated) = 1.603 mg/m(3). Final R indices [I > 2sigma(I)] are R1 = 0.0572, wR2 = 0.1003 for (I) and R1 = 0.0558, wR2 = 0.0982 for (II). R indices (all data) are R1 = 0.0983, wR2 = 0.1116 for (I) and R1 = 0.1009, wR2 = 0.1117 for (II). 5- Phenyl-2,4 diaminopyrimidine and 6-phenyl-1,2,4 triazine derivatives, which include lamotrigine (3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine), have been investigated for some time for their effects on the central nervous system. The three dimensional structures reported here form part of a newly developed data base for the detailed investigation of members of this structural series and their biological activities.

ASYMMETRIC-SYNTHESIS OF S-(+)-4-AMINO-5-HEXYNOIC ACID

4-Amino-5-hexynoic acid is efficiently synthesised in eight steps (overall yield 10%) from commercially available (S)-glutamic acid. The key step was conversion of an aldehyde to an acetylene using diethylmethydiazophosphonate.

Squaric acid/4-aminoquinoline conjugates: novel potent antiplasmodial agents

We report the synthesis and structure–activity relationship (SAR) analysis of a series of hybrid compounds containing a squaric moiety conjugated with heterocyclic moieties from well-known antimalarials. This novel series of compounds presents improved antiplasmodial activity compared with the squaric derivatives described in our previous work. Three compounds, 8b (IC50 = 99 nM), 8c (IC50 = 95 nM), and 8d (IC50 = 105 nM) had greater in vitro potency than chloroquine 1 (IC50 = 140 nM) against chloroquine resistant Plasmodium falciparum. In addition, they were noncytotoxic against NIH 3T3 and Hek 293T cells.

Temperature- and Pressure-induced Proton Transfer in the 1:1 Adduct Formed between Squaric Acid and 4,4 '-Bipyridine

We have applied a combination of spectroscopic and diffraction methods to study the adduct formed between squaric acid and bypridine, which has been postulated to exhibit proton transfer associated with a single-crystal to single-crystal phase transition at ca. 450 K. A combination of X-ray single-crystal and very-high flux powder neutron diffraction data confirmed that a proton does transfer from the acid to the base in the high-temperature form. Powder X-ray diffraction measurements demonstrated that the transition was reversible but that a significant kinetic energy barrier must be overcome to revert to the original structure. Computational modeling is consistent with these results. Modeling also revealed that, while the proton transfer event would be strongly discouraged in the gas phase, it occurs in the solid state due to the increase in charge state of the molecular ions and their arrangement inside the lattice. The color change is attributed to a narrowing of the squaric acid to bipyridine charge-transfer energy gap. Finally, evidence for the possible existence of two further phases at high pressure is also presented.

Short Communication: effects of 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester on milk production and composition of lactating Holstein dairy cows

Sixteen multiparous Holstein cows were used to determine the effects of 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester (HMBi: 0 vs. 1.26 g/kg of total ration dry matter (DM) and dietary crude protein (CP) concentration [14.7% (low) vs. 16.9% (standard), DM basis] on milk yield and composition using a replicated 4 x 4 Latin square design experiment with 4-wk periods. Cows were fed ad libitum a total mixed ration with a 1: 1 forage-to-concentrate ratio (DM basis), and diets provided an estimated 6.71 and 1.86% lysine and methionine, respectively, in metabolizable protein for the low-protein diet and 6.74 and 1.82% in the standard protein diet. Dry matter intake, milk yield, and composition were measured during wk 4 of each period. There were no effects on DM intake, which averaged 24.7 kg/d. There was an interaction between dietary CP and HMBi for milk yield and 3.5% fat-corrected milk (FCM). Feeding HMBi decreased milk and FCM yield when fed with the low-CP diet but did not affect milk or FCM yield when fed with the standard CP diet. Feeding HMBi increased milk protein concentration regardless of diet CP concentration and increased milk protein yield when added to the standard CP diet but not the low-CP diet. The positive effect of HMBi on milk protein yield was only observed at the standard level of dietary CP, suggesting other factors limited the response to HMBi when dietary protein supply was restricted.

Extraction behavior of the synergistic system 2,6-bis-(benzoxazolyl)-4-dodecyloxylpyridine and 2-bromodecanoic acid using Am and Eu as radioactive tracers

In this study, the extraction properties of a synergistic system consisting of 2,6-bis-(benzoxazolyl)-4-dodecyloxylpyridine (BODO) and 2-bromodecanoic acid (HA) in tert-butyl benzene (TBB) have been investigated as a function of ionic strength by varying the nitrate ion and perchlorate ion concentrations. The influence of the hydrogen ion concentration has also been investigated. Distribution ratios between 0.03-12 and 0.003-0.8 have been found for Am(III) and Eu(HI), respectively, but there were no attempts to maximize these values. It has been shown that the distribution ratios decrease with increasing amounts of ClO4-, NO3-, and H+. The mechanisms, however, by which the decrease occurs, are different. In the case of increasing perchlorate ion concentration, the decrease in extraction is linear in a log-log plot of the distribution ratio vs. the ionic strength, while in the nitrate case the complexation between nitrate and Am or Eu increases at high nitrate ion concentrations and thereby decreases the distribution ratio in a non-linearway. The decrease in extraction could be caused by changes in activity coefficients that can be explained with specific ion interaction theory (SIT); shielding of the metal ions, and by nitrate complexation with Am and Eu as competing mechanism at high ionic strengths. The separation factor between Am and Eu reaches a maximum at similar to1 M nitrate ion concentration. Thereafter the values decrease with increasing nitrate ion concentrations.