Synthesis,and crystal and molecular structures of anabasinium O,O-dialkyl phosphorothioates

The synthesis has been effected of anabasinium O,O-dialkyl phosphorothioates. The crystal and molecular structures of the complex compounds obtained have been determined by the method of x-ray structural analysis. It has been established that the cations and anions of the anabasinium O,O-dialkyl phosphorothioates are combined into cyclic associates each including two anions and two cations with different conformations.Institute of Organic Synthesis and Coal Chemistry, Academy of Sciences of the Kazakh SSR. A. N. Nesmayanov Institute of Organometallic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 500–505, July–August, 1990.     

Asymmetric total synthesis of the antimalarial drug (+)-mefloquine hydrochloride via chiral N-amino cyclic carbamate hydrazones

Mefloquine hydrochloride is an important antimalarial drug. It is currently manufactured and administered in racemic form; however there are indications regarding the biological activity of the two enantiomers that suggest the superiority of the (+)-form. The asymmetric total synthesis of the (+)-enantiomer of mefloquine hydrochloride is described. The key asymmetric transformation utilized is a novel asymmetric Darzens reaction of a chiral α-chloro-N-amino cyclic carbamate hydrazone derived from an N-amino cyclic carbamate (ACC) chiral auxiliary.     

Ionic Liquid‐Based Routes to Conversion or Reuse of Recycled Ammonium Perchlorate

New, potentially green, and efficient synthetic routes for the remediation and/or re‐use of perchlorate‐based energetic materials have been developed. Four simple organic imidazolium‐ and phosphonium‐based perchlorate salts/ionic liquids have been synthesized by simple, inexpensive, and nonhazardous methods, using ammonium perchlorate as the perchlorate source. By appropriate choice of the cation, perchlorate can be incorporated into an ionic liquid which serves as its own electrolyte for the electrochemical reduction of the perchlorate anion, allowing for the regeneration of the chloride‐based parent ionic liquid. The electrochemical degradation of the hazardous perchlorate ion and its conversion to harmless chloride during electrolysis was studied using IR and ³⁵Cl NMR spectroscopies.     

Quantitative analysis of perchlorate in extracts of whole fish homogenates by ion chromatography: comparison of suppressed conductivity detection and electrospray ionization mass spectrometry

The perchlorate anion (ClO ₄ ^– ) is an anthropogenic contaminant of increasing concern in water supplies, and has been shown to disrupt thyroid activity. Most perchlorate analyses are currently carried out by ion chromatography (IC) with suppressed conductivity detection (SCD). While this procedure has been demonstrated to provide acceptable performance for analysis of water samples, the determination of perchlorate in high-conductivity aqueous extracts of plant or animal material is not readily accomplished by IC-SCD unless lengthy cleanup protocols are applied. With the addition of electrospray ionization mass spectrometry (ESI-MS) to IC, it was hypothesized that the interference imposed by various ionic species could be significantly reduced without the need for purification; however, the analysis of perchlorate in relatively unpurified extracts of biologically derived homogenates by IC-ESI-MS has not previously been described in the literature. The research presented here represents a comparison of the capabilities of IC-SCD and IC-ESI-MS to detect perchlorate in reagent water and in crude extracts of perchlorate-exposed fish (threespine stickleback, Gasterosteus aculeatus). ESI-MS was found to compare favorably to SCD for the detection of perchlorate in deionized water, and to exceed SCD performance in perchlorate analysis of fish-derived extracts.     

Unexpected dependence of the protonation constant of 2,2'-bipyridyl on ionic strength

The protonation constants of 2,2'-bipyridyl and ammonia have been determined by pH titration at 25 degrees , at ionic strengths of 0.1, 0.2, 0.5, 1.0, 1.5 and 2.0M obtained by using LiNO(3), NaNO(3), KNO(3), LiClO(4) and NaClO(4) as background electrolytes. The protonation constants generally change by about 0.3-0.4 log units for both ligands in nitrate media. A similar change in the protonation constant of ammonia was observed in perchlorate media. There is, however, a change of about 0.8-0.9 log units in the protonation constant of bipyridyl in the perchlorate media. This phenomenon is interpreted by postulating ion-pair formation between perchlorate and the protonated form of bipyridyl, HBp(+) + ClO(4)(-) rlharr2; HBp(+).ClO(4)(-) with formation constants of 0.54 in 2M lithium nitrate and 0.45 in 2M sodium nitrate.     

Porphyrin Clathrates. Crystal Structures of Two Unexpected Products Obtained by Solvothermal Reactions of Pt-tetra(4-carboxyphenyl)porphyrin with Copper Acetate

The X-ray crystal structure of IX, perchlorate salt of R-(–-2-ethyl-N-benzyl-4,7,19,13-tetraoxa-8,9-benzo-1-azacyclopentadec-8-ene has been determined. In the molecule, the protonated nitrogen atom participates in two N-HO hydrogen bonds. The unusually high proton affinity of aza crown ether leads to the formation of diastreomer instead of complex formation with chiral R-(+)-1-phenyl ethyl ammonium perchlorate and S-(–)-1-phenyl ethyl ammonium perchlorate. The complex ability of host ethers was evaluated in terms of structural modification.     

A Concise and Highly Enantioselective Total Synthesis of (+)‐anti‐ and (−)‐syn‐Mefloquine Hydrochloride: Definitive Absolute Stereochemical Assignment of the Mefloquines

A concise asymmetric (>99:1 e.r.) total synthesis of (+)‐anti‐ and (?)‐syn‐mefloquine hydrochloride from a common intermediate is described. The key asymmetric transformation is a Sharpless dihydroxylation of an olefin that is accessed in three steps from commercially available materials. The Sharpless‐derived diol is converted into either a trans or cis epoxide, and these are subsequently converted into (+)‐anti‐ and (?)‐syn‐mefloquine, respectively. The synthetic (+)‐anti‐ and (?)‐syn‐mefloquine samples were derivatized with (S)‐(+)‐mandelic acid tert‐butyldimethylsilyl ether, and a crystal structure of each derivative was obtained. These are the first X‐ray structures for mefloquine derivatives that were obtained by coupling to a known chiral, nonracemic compound, and provide definitive confirmation of the absolute stereochemistry of (+)‐anti‐ as well as (?)‐syn‐mefloquine.     

不对称合成(+)-(11R, 12S)-盐酸甲氟喹

疟疾药物、(+)-(11R, 12S)-盐酸甲氟喹的不对称合成,由购买得到的2－三氟甲基苯胺、三氟乙酰乙酸乙酯,环戊酮为起始原料经过7步反应以14％的收率得到。关键步骤为脯氨酸催化的不对称aldol反应和贝克曼重排,绝对构型由Mosher的方法确定。     

The ionic product of water in highly concentrated sodium perchlorate solutions

The ionic product of water, pK(w)=-log[H(+)][OH(-)], has been determined in aqueous solutions of sodium perchlorate over the concentration range of 1.0-8.0 M at 25 degrees C from high-precision potentiometric titrations carried out in cells with liquid junction using both glass and hydrogen electrodes. The glass electrode results are systematically lower probably as a result of interference by Na(+) ions.     

Ionic strength dependence of formation constants, complexation of nitrilotriacetic acid with tungsten(VI) ion

The dependence on ionic strength of protonation of nitrilotriacetic acid and its complexation with W(VI) is reported in sodium perchlorate, sodium nitrate and sodium chloride solutions as background salts. The measurements have been performed at 25°C and various ionic strengths in the range 0.1–1.0 mol dm⁻³, using a combination of potentiometric and spectrophotometric techniques. The overall analysis of the present and the previous data dealing with the determination of stability constants at different ionic strengths allowed us to obtain a general equation, by which a formation constant determined at a fixed ionic strength can be calculated, with a good approximation, at another ionic strength, if 0.1 ≤ ionic strength ≤ 1.0 mol dm⁻³ sodium perchlorate, sodium nitrate or sodium chloride.     

Investigation of the electron spin resonance spectra of vanadyl ions in single crystals of tris(octamethyl-pyrophosphoramide)magnesium perchlorate

ESR studies have been made on the single crystals of tri(octamethylpyrophosphoramide)-magnesium perchlorate doped with the paramagnetic vanadyl ion at 295 and 77 K. The spectra are characterized by a parallel and perpendicular set of hyperfine lines usually seen for the vanadyl ion. The lowering of the g value and increasing of the A value has been attributed to the extremely ionic metal—ligand bonding.     

Aquation of (N,Ndimethylformamide) pentaamminecobalt (III) perchlorate in aqueous perchlorate media

The first-order rate constants for aquation of Co(NH₃)₅(DMF)³⁺ were determined in aqueous perchlorate media. The rate constants were independent of hydrogen ion concentration and ionic strength, but decreased with increasing perchlorate ion concentration. Proton magnetic resonance studies showed that dimethylformamide was not hydrolyzed to formic acid and dimethylamine in the aquation step. Mass-spectrometer studies showed that cobalt–oxygen bond breaking occurred in 98 percent, or more, of the aquation acts. Enthalpies and entropies of activation were determined. It was concluded that aquation occurred by an I_d mechanism.     

Remote asymmetric induction in an intramolecular ionic Diels-Alder reaction: application to the total synthesis of (+)-dihydrocompactin

The total synthesis of (+)-dihydrocompactin via an intramolecular ionic Diels-Alder reaction that proceeds with remote stereocontrol is described. This reaction proceeds by an intermediate vinyl-oxocarbenium ion (6), the conformational constraints of which lead to the observed asymmetric induction. The sense of asymmetric induction appears contrasteric and is explained by the proposed reactive conformation shown in Figure 1.     

Dialkyl sulfoxides complexes with nickel(II) nitrate and perchlorate

Nickel(II) perchlorate and nitrate complexes containing dimethyl, di-n-propyl, di-n-butyl, di-i-butyl and di-t-butyl sulfoxides have been synthesized and characterized by IR and electronic spectroscopies, magnetic-susceptibility and electrolytic-conductance measurements. In the complexes containing perchlorate, the metal: sulfoxide molar ratio is 1:6 and the perchlorate groups are ionic. In the nitrate compounds, the molar ratio decreases from 1:6 to 1:2 according to the increase in the steric bulk of the alkyl group from methyl to t-butyl. The nitrate group may either be non-coordinating or behave as a monodentate or bidentate ligand. All the complexes contain O-bonded sulfoxide molecules and are characterized as high-spin, with an octahedral or distorted octahedral geometry. The dialkyl sulfoxides studied in this work fall in the same position as dimethyl sulfoxide in the spectrochemical and nephelauxetic series. Electrolytic conductivities suggest that the compounds containing ionic nitrate exhibit sulfoxide—nitrate exchange in nitromethane solutions.     

Hydrolysis of Protactinium(V). II. Equilibrium Constants at 40 and 60°C: A Solvent Extraction Study with TTA in the Aqueous System Pa(V)/H2O/H+/Na+/ClO− 4

The hydrolysis of protactinium (V) was studied at tracer scale (ca. 10^–12 M) with the solvent extraction method involving the aqueous system: Pa(V)/H₂O/H⁺/Na⁺/ClO^– ₄ at 40 and 60°C for three values of ionic strength. Extraction experiments were conducted using the chelating agent thenoyltrifluoroacetone (TTA) in toluene. Hydrolysis constants are reported for each ionic strength investigated. An SIT modeling is presented and extrapolated constants to zero ionic strength are derived, as well as interaction coefficients involving Pa(V) and perchlorate ions.     

Crystal chemistry of protonated 1,2-bis(di-R-aminomethyl)benzenes. Part VI: 1,2-bis(diethylaminomethyl)-4,5-dichlorobenzene perchlorate

The crystals of a 1:1 complex of 1,2-bis(diethylaminomethyl)-4,5-dichlorobenzene perchlorate with HClO₄ were studied using X-ray diffraction and FT-IR spectroscopy. There are two symmetry-independent ionic pairs in the crystal, monoclinic, space group P2₁/n. In both symmetry-independent cations, the diethylaminomethyl substituents are in a similar Z conformation relative to the phenyl moieties, however significant conformational differences in the diethylaminomethyls have been noted. The diethylaminomethyls are linked by intracationic ⁺N–H⋯N hydrogen bonds of 2.758(9) and 2.721(7) Å in two symmetry-independent cations. The protons in these H-bonds are disordered in two off-center sites, which is most likely to be connected with the considerable disorder of the perchlorate anions. The IR spectrum of the crystals shows a broad intense band and a relatively intense continuous absorption indicating relatively large proton polarizability in the intramolecular hydrogen bond of a medium length.     

Determination of perchlorate in drinking water by ion chromatography using macrocycle-based concentration and separation methods

Macrocycle-based ion chromatography provides a convenient, reliable method for the determination of perchlorate ion, which is currently of great interest to the environmental community. This study shows that effective perchlorate determinations can be made using standard conductimetric detection by combining an 18-crown-6-based mobile phase with an underivatized reversed-phase mobile phase ion chromatography (MPIC) column. One unique feature of this method is the flexibility in column capacity that is achieved through simple variations in eluent concentrations of 18-crown-6 and KOH, facilitating the separation of target analyte anions such as perchlorate. Using a standard anion exchange column as concentrator makes possible the determination of perchlorate as low as 0.2 ug/L in low ionic strength matrices. Determination of perchlorate at the sub-ug/L level in pure water and in spiked local city hard water samples with high background ion concentrations can be achieved this way. However, like other IC techniques, this method is challenged to achieve analyses at the ug/L level in the demanding high ionic strength matrix described by the United States Environmental Protection Agency (EPA) (1,000 mg/L chloride, sulfate and carbonate). We approached this challenge by use of the Cryptand C1 concentrator column, provided by Dionex Corporation, to effectively preconcentrate perchlorate while reducing background ion concentrations in the high ionic strength matrix. The retention characteristics of the concentrator column were studied in order to maximize its effectiveness for perchlorate determinations. The method makes possible the determination of perchlorate at the 5 ug/L level in the highest ionic strength matrix described by the EPA.     

General solution for Poisson-Boltzmann equation in semiinfinite planar symmetry

Self-assembled multilayer thin films have been prepared on Au substrate by alternate surface derivatization with L-cysteine hydrochloride and cupric perchlorate. The layer-by-layer structure at each step of multilayer formation was investigated by X-ray photoelectron spectroscopy. The measurements indicate that there are two structure modes in the multilayers. One is that Cu(2+) sandwiches between two amino acid groups. The other one is that Cu(+) is bonded through disulfide and thiolate. This process is also confirmed by cyclic voltammetry of Cu ion at different self-assembled multilayers. Steps further on will lead to repeated multilayer films.     

Biphasic asymmetric hydroformylation and hydrogenation by water-soluble rhodium and ruthenium complexes of sulfonated (R)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl in ionic liquids

A biphasic catalytic system with water-soluble rhodium complexes of sulfonated (R)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (labeled as (R)-BINAPS) in ionic liquid BMI·BF₄ has been developed for the asymmetric hydroformylation of vinyl acetate under mild conditions. The corresponding ruthenium complexes have been investigated for the biphasic asymmetric hydrogenation of dimethyl itaconate. The biphasic asymmetric hydroformylation of vinyl acetate provided 28.2% conversion and 55.2% enantiomeric excess when BMI·BF₄–toluene was used as the reaction medium at 333 K and 1.0 MPa for 24 h. The biphasic asymmetric hydrogenation of dimethyl itaconate in BMI·BF₄–ⁱPrOH at 333 K and 2.0 MPa afforded 65% enantiomeric excess with an activity similar to the homogenous analogs. Both biphasic catalytic systems with (R)-BINAPS ligand could be reused several times without significantly decrease in the activity, enantio- and regio-selectivities. The effects of properties of ionic liquid, molar ratio of ligand to rhodium, temperature, pressure and reaction time have been discussed.     

Coprecipitation of carrier-free96TcO4 − with tetraphenylarsonium perchlorate

An effective coprecipitation method of carrier-free⁹⁶TcO₄ ^– with tetraphenylarsonium perchlorate has been developed. The precipitation yield is independent of pH. However, it depends on the concentrations of tetraphanylarsonium and perchlorate ions. A possible coprecipitation mechanism is discussed.