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Pilot--and laboratory-scale granular activated carbon (GAC) studies were conducted to determine the extent of 2-methylisoborneol (MIB) removal from two conventionally treated waters. Two different GACs were evaluated, a wood-based carbon and a coal-based carbon. Greater MIB removal was observed with the wood-based GAC which contradicts previous studies using the powdered forms of the carbons. Equilibrium and kinetic parameters were derived from laboratory-scale adsorption isotherm and short bed adsorber (SBA) experiments, respectively, and used to describe the adsorption of MIB. However, the derived parameters were unable to accurately predict the removal of MIB in the pilot-scale columns using the homogenous surface diffusion model. This suggested that there were inherent limitations with the SBA experiments, in particular, the small volume of GAC and high filtration rates employed. Larger laboratory column experiments were shown to accurately simulate the pilot-scale columns. Adsorption still played a vital role in the removal of MIB, even though the GAC had been exhausted for the removal of organics in terms of dissolved organic carbon and ultraviolet absorbance measurements. Even after a 6-month operation, complete MIB removal was observed with up to 80% attributed to adsorption, and the remaining 20% attributed to biodegradation. DOI: 10.1061/(ASCE)EE.1943-7870.0000231 CE Database subject headings: Adsorption; Biological processes; Laboratory tests; Water treatment. Author keywords: Adsorption; Biodegradation; Granular activated carbon (GAC); Homogenous surface diffusion model (HSDM); 2-methylisoborneol (MIB).

Arbuscular mycorrhizal (AM) fungi are obligate biotrophs that acquire carbon (C) solely from host plants. AM fungi can proliferate hyphae in, and acquire nitrogen (N) from, organic matter. Although they can transfer some of that N to plants, we tested the hypothesis that organic matter is an important N source for the AM fungi themselves. We grew pairs of plants with and without the AM fungus Glomus hoi in microcosms that allowed only the fungus access to a [sup.15]N/[sup.13]C-labeled organic patch; in some cases, one plant was shaded to reduce C supply to the fungus. The fungal hyphae proliferated vigorously in the patch, irrespective of shading, and increased plant growth and N content; ~3% of plant N came from the patch. The extraradical mycelium of the fungus was N-rich (3-5% N) and up to 31% of fungal N came from the patch, confirming the hypothesis. The fungus acquired N as decomposition products, because hyphae were not [sup.13]C-enriched. In a second experiment, hyphae of both G. hoi and Glomus mosseae that exploited an organic material patch were also better able to colonize a new host plant, demonstrating a fungal growth response. These findings show that AM fungi can obtain substantial amounts of N from decomposing organic materials and can enhance their fitness as a result. The large biomass and high N demand of AM fungi means that they represent a global N pool equivalent in magnitude to fine roots and play a substantial and hitherto overlooked role in the nitrogen cycle. nutrient capture | organic patches | stable isotopes | fitness doi/ 10.1073/pnas.1005874107

We propose a novel strategy for determining the elemental composition of organic compounds using the peak ratio of isotopic fine structure observed by high-magnetic field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Using 3'-phosphoadenosine 5'phosphosulfate and CTU guanamine as standard organic compounds, isotopic peaks derived from [sup.15]N-, [sup.34]S-, and [sup.18]O-substituted forms were separated from [sup.13]C-substituted species. Furthermore, these isotopic peaks were quantitatively detected and closely matched the natural abundance of each element. These data successfully led us to determine the one elemental composition in a standard independent manner. The approach should be particularly amenable to the metabolomics research field. 10.1021/ac902931x

A method was developed to link size exclusion chromatography electrospray ionization mass spectrometry (SECESI-MS) analyses of fulvic and humic acids with SEC and organic carbon detection (SEC-OCD), the latter providing an absolute measure of the amount of organic matter eluting from the SEC column. This approach allows us to determine which molecular weight fraction of the complex polydisperse mixtures is detectable by ESI-MS. It could be shown that the cone voltage setting for the ESI interface has strong impact on ESI-MS detection. Using conventional settings for low molecular weight compounds, the high molecular weight (HMW) compounds are hardly amenable to ESI-MS. With increasing cone voltage, an increasing signal intensity is obtained for the HMW fraction that elutes at shorter retention times. However, mostly fragment ions are obtained under these conditions. Thus, the range of compounds amenable to ESI-MS analysis is restricted by the limited stability of the fulvic and humic acid molecules of higher molecular weight in the electrospray process rather than by the mass spectrometer used. Compounds above 1000 amu are hardly visible as intact ions. However, insight into structural characteristics of these compounds can be gained by investigating their fragment ions by SEC-ESI-MS. The use of SEC-OCD parallel to SEC-MS helps to assess and optimize the detection potential of ESI-MS for polydisperse mixtures.

Silicon based polymers obtained by ammonolysis of organochlorosilylboranes and their pyrolytic transformation into Si-B-C-N ceramics were studied by a detailed solid-state NMR investigation. Sol-gel polymerisation/pyrolysis routes were applied to form Si-B-C-N materials with exceptional high-temperature stability. The polymer to ceramic conversion was analyzed by [sup.11]B, [sup.13]C, [sup.15]N, and [sup.29]Si MAS NMR spectroscopy as well as by thermal analysis measurements coupled with mass spectroscopy (TGA-MS). The results showed that a significant change in the carbon-, silicon-, and boron-coordination environments occurs during pyrolysis. An evolution of cleavage of silcon-carbon-boron bridges and the formation of new B[N.sub.3] sites was observed. The NMR data obtained suggest the presence of a rather homogeneous dispersion of the boron atoms in the as synthesized silicon carbonitride phase, supporting the high thermal stability with respect to decomposition found in these compounds. Key words: organosilicon polymers, polymer pyrolysis, SiBCN ceramics, solid-state NMR.

The synthesis and characterization of stable bis(dihydroxymethylsilyl) derivatives are described. These compounds were obtained as microcrystalline powders by controlled hydrolysis in a biphasic medium (ethyl ether--water) of the corresponding bis(dimethoxymethylsilyl) organic precursors containing phenyl, biphenyl, stilbenyl, diphenylacetylene, and diphenylbut-l,3-diyne groups. All the solids obtained exhibited a layered structure. Condensation of the bis-silanediols could be effected by fluoride catalysis in solution at ambient temperature or simply by heating in solid state. The polysiloxanes obtained from the bis-silanediols have been compared with those obtained by hydrolysispolycondensation of the corresponding bis-dimethoxysilanes. The thermal route led to highly polycondensed solids arranged into thin plates as evidenced by TEM analysis; furthermore, in the case of the longer spacer, the organization was controlled by the arrangement of the Si-O-Si layers instead of the spacer. The X-ray study of these materials clearly evidenced the drastic influence of the length of the organic spacer, the polycondensation route and the nature of the leaving group (hydroxy or methoxy) on the short-range organization of the solids. Key words: silanols, hybrid materials, polycondensation, polysiloxanes.

According to the definition of molecular connectivity and the definition of a hyper-Wiener index, a novel set of hyper-Wiener indexes ([R.sub.n], [sup.m][R.sub.n]) are defined and are named the extended hyper-Wiener indexes. Where n = 1, 2, 3, 4, ... represents the type of subgraph units and is the number of endmost atoms of the subgraph unit, m is the number of atoms of the subgraph unit. Here n = 1 means the subgraph unit is an atom, n = 2 means the subgraph units are straight-line combinations of m atoms (m = 2, 3, 4, 5, 6, ...), and n = 3 means the subgraph units are Y types of combinations of m atoms (m = 4, 5, 6, 7, 8, ...), and so on. The potential usefulness of the extended hyper-Wiener index in QSAR and (or) QSPR is evaluated by its correlation with a number of [C.sub.3]-[C.sub.8] alkanes and by a favorable comparison with models based on the molecular connectivity index and the overall Wiener index. To verify the robustness and the predictive ability of the models, a cross-validation procedure, leave-one-out, and a random test were also performed. The results show that the extended hyper-Wiener indexes examined demonstrate a good potential for QSAR and QSPR studies. Considerably better statistics are obtained when extending the hyper-Wiener index to the extended hyper-Wiener index. The extended hyper-Wiener indexes provided statistical results as good as the molecular connectivity indexes and the overall Wiener index in all models, and the standard deviations provided by these three sets of indexes are rather close. Moreover, this method may provide a better way to apply the Wiener number and the hyper-Wiener index to the system of unsaturated hydrocarbons and organic compounds, including heteroatoms, according to the method of the molecular connectivity index. This can extend the usefulness of the Wiener number and hyper-Wiener index and can make them a kind of widely used topological index in practice. Key words: hyper-Wiener index (R), extended hyper-Wiener index, molecular connectivity index.

The dissolution of organic solvents from containment coatings into the sump water is expected to be a key rate-controlling process, influencing the pH, the steady-state water radiolysis product concentration, and the formation of organic iodides in containment following a postulated reactor accident. The dissolution process is therefore an important component in modelling iodine behaviour in post-accident containment. The rate of release of ethyl benzene and m- and o-xylene from Amerlock 400 epoxy paint in contact with water has been measured. The release rate was found to be comparable to the release rate of methyl isobutyl ketone from various polyurethane, vinyl, and epoxy paints. The pseudo-first-order rate constant for dissolution of the solvents from these containment coatings is dependent only upon paint thickness and temperature, whereas the total amount of solvent released depends upon paint thickness. The solvent-release process is governed by the rate of uptake of water by the coupons, a Fickian diffusion-controlled process. Key words: dissolution, kinetics, organic solvents, paint.

Useful derivatives of tetraphenylmethane and tetraphenylsilane have been synthesized by efficient methods that give crystalline products without chromatographic purification. New compounds include tetrakis(4-hydroxyphenyl)methane (21), tetrakis(4-formylphenyl)methane (22), tetrakis[(4-hydroxymethyl)phenyl]methane (23), tetrakis(4-bromophenyl)silane (24), tetrakis(4-iodophenyl)silane (25), tetrakis(4-hydroxyphenyl)silane (26), tetrakis[(4-hydroxymethyl)phenyl]silane (27), and tetrakis[(4-chloromethyl)phenyl]silane (28). These compounds are valuable precursors for the construction of complex molecules with tetrahedral geometries. Key words: organic synthesis, molecular and supramolecular design and construction, tetraphenylmethane, tetraphenylsilane, tetrahedral building blocks.

The volatility and decomposition of organic iodides in a reactor containment building are important parameters to consider when assessing the potential consequences of a nuclear reactor accident. However, there are few experimental data available for the volatilities (often reported as partition coefficients) or few rate constants regarding the decomposition (via hydrolysis) of organic iodides. The partition coefficients and hydrolysis rate constants of eight organic iodides, having a range of molecular structures, have been measured in the current studies. This data, and data accumulated in the literature, have been reviewed and discussed to provide guidelines for appropriate organization of organic iodides for the purpose of modelling iodine behaviour under postulated nuclear reactor accident conditions. After assessment of the partition coefficients and their temperature dependences of many classes of organic compounds, it was found that organic iodides could be divided into two categories based upon their volatility relative to molecular iodine. Similarly, hydrolysis rates and their temperature dependences are assigned to the two categories of organic iodides. Key words: organic iodide, hydrolysis, partition coefficient, iodine behaviour model, nuclear reactor safety.

The electrocatalytic hydrogenation (ECH) of phenol was carried out in aqueous media with catalytic powders. The catalytic powders were composed of palladium nanoaggregates deposited on various substrates such as [Al.sub.2][O.sub.3], BaS[O.sub.4], and BaC[O.sub.3]. Composite powders are trapped (upon stirring) into a reticulated vitreous carbon (RVC) matrix, allowing a rapid in situ build-up of the electrode and alleviating the use of a binder, since the latter may have a detrimental effect on the ECH. For a given amount of noble metal (5% palladium by weight), it is observed that the ECH of phenol to cyclohexanol increases in the following order: Pd/BaC[O.sub.3]

A capillary-dimension on-line sorption trap is used to preconcentrate organic vapors from large-volume air samples and inject the organic compounds into the separation column as a relatively narrow vapor plug. The multibed trap is made from a Co-Ni alloy for resistive heating during sample desorption and uses four different carbon-based adsorption materials that are graded from weakest to strongest in the direction of the sample gas flow during sample preconcentration. The flow direction then is reversed for sample injection. The multibed design and the flow direction reversal during thermal desorption prevents the higher-boiling-point compounds in the sample from reaching the strongest adsorbing material, from which they would be difficult to desorb as a sufficiently narrow vapor plug. A relatively high current pulse is used to rapidly achieve trap temperatures in the 200-400[degrees]C temperature range, and a lower current is used to maintain the maximum temperature for several seconds in order to ensure injection of the entire trapped sample. A temperature of 350[degrees]C is reached after ~1.5 s, and injection plug widths are typically in the range of 0.6-1.3 s. Plots of peak area versus sample collection time show excellent linearity and shot-to-shot relatively standard deviations of about [+ or -] 5%. Performance data are presented for a mixture of 42 volatile compounds spanning a volatility range from n-[C.sub.5] to n-[C.sub.12]. Data are presented for injection plug width and shape for both polar and nonpolar compounds. Decomposition of thermally labile compounds is observed for injection temperatures above 300[degrees]C.

A series of 1,3,5-triphenyl-2-pyrazoline (TPP) nanocrystals were prepared by the reprecipitation method. The electronic transitions of TPP nanocrystals have been studied using both absorption and fluorescence spectra. An absorption feature at about 400 nm gradually appeared with increasing nanocrystal size. This feature resulted from the formation of the charge-transfer (CT) exciton in nanocrystals. It was also supported by the longer decay time of the nanocrystal emission from CT compared with that of the solution emission from [S.sub.1] at 298 K. On the other hand, the different behavior of the molecular [pi]-[pi] * and n-[pi] * transitions originates from the different overlapping modes of the pyrazoline [pi] orbital and n-electron orbital, according to the molecular model calculations. The nanocrystal emission from both the [S.sub.1] and CT states was found at 77 K; moreover, the emission intensity redistributed from [S.sub.1] to CT with increasing nanocrystal size. In contrast, at 298 K, only the emission from the CT states was observed, since the thermal fluctuation easily relaxes the excited electrons into CT states through vibration. Key words: reprecipitation method, organic nanocrystals, charge-transfer exciton, size-dependent property.

This paper describes a systematic study for the evaluation of different substituted [beta]-cyclodextrins ([beta]-CDs), as agents for the enhancement of the aqueous solubility of two major organic pollutants, trichloroethylene (TCE) and perchloroethylene (PCE). The aqueous solubility enhancement occurs through the formation of host--guest inclusion complexes between the CD molecule (host) and the polychloroethylene (guest) and is driven primarily by hydrophobic forces. The CDs evaluated are: methyl-[beta]-CD (M[beta]-CD), hydroxypropyl-[beta]-CD (HP[beta]-CD), carboxymethyl-[beta]-CD (CM[beta]CD1, CM[beta]-CD2), and sulfated-[beta]-CD (S[beta]-CD1, S[beta]-CD2); the degree of substitution was also varied. Using a 5% (w/v) aqueous CD solution, solubility enhancement factors ([S.sub.t]/[S.sub.o]) up to 5.5 and 14 were determined for TCE and PCE, respectively. Binding constants ([K.sub.11]) for TCE with the substituted CDs were evaluated using an (1) H NMR technique; these were found to range from 3 to 120 [M.sup.-1]. It was shown that solubility enhancement, as well as the binding constant, is dependent on the type and degree of substitution of the [beta]-CD molecule; the determining factors are discussed. The CDs are also capable of effective removal of PCE and TCE retained by soil organic matter. Thus, a suitably substituted [beta]-CD may be a valuable additive in pump-and-treat protocols for site remediation of polychlorinated organics. Key words: cyclodextrin, trichloroethylene, perchloroethylene, solubility enhancement, binding constant, soil and water remediation.

Research has been conducted on the garnesoate esters. The permanganate oxidation of these esters has produced perhydro-2,2'-bifuranyl compounds with relative stereoshemistry control at stereocenters.

Research has been conducted on theunsymmetrically arene-substituted oxabenzonorbornadienes. The application of the rhodium-catalyzed nucleophilic ring opening methodology to these compounds is reported, and the study of ring-opening regioselectivity carried out via the use of nucleophiles producing dihydronaphthalene is presented.

The compound [4-C[H.sub.3][C.sub.6][H.sub.4]-SS-C[H.sub.2]C[H.sub.2]-N(C[H.sub.3]) [C.sub.6][H.sub.4]C[([C.sub.6][H.sub.4]N[(C[H.sub.3]).sub.2]-4).sub.2]]Cl (1a) consists of the triarylmethyl chromophore of crystal violet appended to an organic disulfide, to entail direct attachment of this dye to gold surfaces. Addition of 1a to colloidal dispersions of the metal produced a stable dispersion in methanol-water mixtures. Transmission electron microscopy of Freeze-Fracture sections shadowed with carbon and platinum confirmed that the dispersion remains unaggregated. Local-field effects and coupling to the surface plasmon of gold magnified the interaction of the chromophore with optical fields. A large oscillator strength in the visible spectrum (f ca. 35) and a first hyperpolarizability ([beta] ca. [10.sup.-26] esu, hyper-Rayleigh scattering) were observed as the colloid adsorbed dye molecules. A Hill-type analysis indicated that the adsorption process is cooperative. This combination of organic chromophore and nanoparticle was adapted for incorporation into PMMA-based composite films whose electrooptic coefficient ([r.sub.113] = 2.20 pm [V.sup.-1]) is larger than the sum of the individual contributions of dye and metallic particles. Key words: chromophores, colloids, gold, local-field effects, nonlinear optical materials.

1,1,3-Trichloro-2,4,5,6-tetrahydro-1H-1[[lambda].sup.4] -benzo[b]tellurophene (a = 8.807(1), b = 14.495(2), c = 9.263(1) [Angstrom], [beta] = 110.18(1)[degrees]; [P2.sub.1]/a, Z = 4, R[F.sup.2] > 2[sigma]([F.sup.2])] = 0.0383), prepared by reacting 1-ethynyl-1-cyclohexanol with tellurium tetrachloride, displays a hexagonal grid structure made of four-membered [Te.sub.2][Cl.sub.2] and 12-membered [Te.sub.6][Cl.sub.6] rings formed by self-assembly of Cl-Te-Cl rods through Te ... Cl secondary bonds into a supramolecular 2D network. The comparison with structurally related compounds reveals that 2D layers can also be formed by similar self-assembly of eight-membered [Te.sub.4][I.sub.4] rings alone or in a combination of four-membered [Te.sub.2][I.sub.2] with eight-membered [Te.sub.4][I.sub.4] rings. Key words: diorganotellurium(IV), supramolecular 2D assembly, self-assembly, secondary bonding.

A bis(imido)phosphine dianion, [[R'P[(NR).sub.2]].sup.2-] (R' = n-Bu, R = N-N = C[Ph.sub.2]) is produced from the reaction of P[Cl.sub.3] with benzophenone hydrazone (1:3 equiv) in THF-N[Et.sub.3] followed by metallation of the reaction mixture with 3 equiv n-BuLi. A more straightforward synthesis of a comparable dianion (with R' = Ph, R = N-N = C[Ph.sub.2]) is the reaction of PhP[Cl.sub.2] with benzophenone hydrazone (1:2 equiv) in THF-N[Et.sub.3] followed by metallation of the reaction mixture with 2 equiv n-BuLi. Key words: phosphorus, lithium, imido, complexes, X-ray.

Reaction of 1,8-bis(trimethylstannyl)naphthalene (1) with an excess of BC[l.sub.3] at -78[degrees], followed by warming to 0[degrees]C, results in the exclusive formation of the novel bifunctional Lewis acid 1-(chlorodimethylstannyl)-8-(dichloroboryl)naphthalene (2), a compound in which a boryl and a stannyl moiety coexist at the peri-positions of a naphthalene core. At elevated temperature compound 2 undergoes a chloride-methyl exchange, which affords 1-(dichloromethylstannyl)-8-(chloromethylboryl)naphthalene (3). Compounds 2 and 3 have been characterized by multi-nuclear NMR spectroscopy. The single crystal X-ray analysis for compound 3 reveals a sterically crowded structure with an essentially trigonal planar boron center, and a tin center pentacoordinated in a [4+1]-fashion. Upon exposure to traces of water, compound 3 is converted into the borinic acid derivative 1-(dichloromethylstannyl)-8-(hydroxymethylboryl)naphthalene (4), which has been characterized by multi-nuclear NMR spectroscopy and single crystal X-ray analysis. Key words: multidentate Lewis acids, organoboranes, organostannanes.

The ligand [C.sub.5][H.sub.4](C[H.sup.2]C[H.sub.2]C[Ar.sup.F][sub.2]OH) (3) ([Ar.sup.F] = 3,5-[C.sub.6][H.sub.3][(C[F.sub.3]).sub.2]) was prepared in two steps, from the iodo ester IC[H.sub.2]C[H.sub.2]C[O.sub.2]Me by way of the cyclopentadienyl ester [C.sub.5][H.sub.5]C[H.sub.2]C[H.sub.2]C[O.sub.2]Me (2), in 55% overall yield. Thermal reaction of 3 with [{Y[N[(Si[Me.sub.3]).sub.2]].sub.2][(THF).sub.2]([micro]-Cl)}.sub.2] afforded the neutral chloride complex {[[eta].sup.5]:[[eta].sup.1] -[C.sub.5][H.sub.4][C[H.sub.2]C[H.sub.2]C(O) [(3,5-[C.sub.6][H.sub.3][(C[F.sub.3]).sub.2]).sub.2]]}YCl[{THF}.sub.n] (5a: n = 2, 5b: n = 1). Metathesis reactions of 5 with 1 equiv of NaN[(Si[Me.sub.3]).sub.2], LiO-2,6-t-[Bu.sub.2][C.sub.6][H.sub.3], and LiCH[(Si[Me.sub.3]).sub.2] afforded {[[eta].sup.5]: [[eta].sup.1]-[C.sub.5][H.sub.4][[C[H.sub.2]C[H.sub.2]C(O) [(3,5-[C.sub.6][H.sub.3][(C[F.sub.3]).sub.2]).sub.2]]}Y {N[(Si[Me.sub.3]).sub.2]} [{THF}.sub.n] (6), {[[eta].sup.5]:[[eta].sup.]-[C.sub.5][H.sub.4] [C[H.sub.2]C[H.sub.2]C(O)(3,5-[C.sub.6][H.sub.3] ([[C[F.sub.3]).sub.2]).sub.2]}Y {O-2,6-t-[Bu.sub.2][C.sub.6][H.sub.3]}[{THF}.sub.n] (7), and {[[eta].sup.5:[[eta].sup.1]-[C.sub.5[H.sub.4]C[H.sub.2]C[H.sub.2]C(O) (3,5-[C.sub.6][H.sub.3][[(C[F.sub.3]).sub.2]).sub.2]]}Y{ CH[(Si[Me.sub.3]).sub.2]}[{THF}.sub.n] (8), respectively, (a: n = 2, b: n = 1). Exposure of the bis(THF) solvates to reduced pressure resulted in desolvation to the mono(THF) adducts for 5-8. The solid state structure of 6b was established by X-ray crystallography. In addition, formation of a spirocyclic ether ([C.sub.4][H.sub.6]C[H.sub.2]C[H.sub.2]C(O)(3, 5-[C.sub.6][H.sub.3][[(C[F.sub.3]).sub.2]).sub.2] 4), obtained by the intramolecular cyclization of ligand 3, was confirmed by X-ray crystallography. Key words: yttrium, organometallic, cyclopentadienyl, X-ray, alkoxide, chelate, alkyl, hybrid ligand, NMR, cyclization.

Raman and FT-IR absorption spectra of aqueous tert-butyl alcohol (t-BuOH) and tert-butylamine (t-BuN[H.sub.2]) in the region of the O-H and N[H.sub.2] stretching and bending modes have been measured as a function of organic co-solvent concentration in the whole co-solvent mole fraction region. The major observed changes of the aqueous binary solution spectra compared with the solvent spectra are a loss or gain of band intensity. In particular, the observed changes in intensities and linewidths of some bands were significantly more pronounced at low concentrations of organic co-solvents in water, where t-BuOH and t-BuN[H.sub.2] tend to integrate into the water structure. Clear evidence of structural enhancement of the network is obtained in dilute solutions as well as destruction of the network by hydrophobic interactions as the concentration is increased. Generally, the interpretation of the spectra is in agreement with the capacity of the hydrophobic co-solvent to break the structure of water in the more concentrated aqueous solutions and to enhance the structure in dilute solutions. Vibrational intensities and frequency shifts of some bands show definite trends with varying the concentration of the solutions. In the concentration-dependence study, unusual linewidth changes of certain bands were observed. Key words: infrared, Raman spectra, aqueous, tert-butanol, tert-butylamine.

Hemoglobin carries oxygen in circulation within red cells but does not function outside the cells because it fails not only to release oxygen but also dissociates into dimers that make up the tetrameric protein. Bifunctional anionic acylating agents that contain a structurally rigid bridge introduce cross-links that stabilize hemoglobin and alter its oxygen affinity so that it could be used to carry oxygen outside cells. Nitric oxide binds to hemoglobin and in circulation this causes undesirable increases in blood pressure. It had been reported that higher weight collections of hemoglobin do not cause vasoconstriction. Reagents with two pairs of reaction sites joined by a rigid link connect and cross-link two hemoglobins. The resulting bis-tetramers lack the cooperativity of the native protein and bind oxygen too tightly to be useful; occupation by oxygen blocks the sites from nitric oxide. Nitric oxide may be delivered from thionitrosyl groups, which occur in hemoglobin in the red cell. Cross-linked hemoglobin can be specifically nitrosylated. These species can then serve as circulating sources of nitric oxide resulting from an internal electron transfer. Key words: proteins, hemoglobin, cross-link, red cells, cooperativity, connecting.

The purpose of this study is a comparative presentation of the different types of the amperometric biosensors based on cholinesterases for the determination of organophosphorous pesticides using the bibliographical information of the last 20 years. The study contains the presentation of the structure and properties of the cholinesterases, the main reactions implied in the functioning of the amperometric biosensors, their applications and factors influencing the detection or (and) the inhibition process. The detection limit of the mono- or bi-enzymatic amperometric biosensors are relatively higher than those corresponding with the immunobiosensors or with gas and liquid chromatography, which are still considered as the reference methods. As shown, for many other amperometric biosensors, the Michaelis-Menten's kinetic treatment used for reactions catalyzed by free enzymes can be extended to describe the response of amperometric biosensors based on immobilized cholinesterases. The positive compromise between advantages and drawbacks, as well as the "soft" experimental conditions, point to the amperometric monoenzymatic bioelectrode, as an attractive analytical tool for the detection of organophosphorous pesticides. Key words: amperometric biosensor, acetylcholinesterase, organophosphorous pesticides, kinetic, inhibition.

High level ab initio molecular orbital theory calculations have been used to study the geometries and thermochemistry of molecules and free radicals substituted by B[H.sub.2], BHC[H.sub.3], and B[(C[H.sub.3]).sub.2]. The heats of formation and RR'B--X bond strengths (RR' = H, H; H, C[H.sub.3]; C[H.sub.3], C[H.sub.3] and X = C[H.sub.3], N[H.sub.2], OH, F, Si[H.sub.3], P[H.sub.2], SH, and Cl) together with those for the open-shell systems RR'B--Y. (RR' = H, H; H, C[H.sub.3]; C[H.sub.3], C[H.sub.3] and Y = C[H.sub.2], NH, O, Si[H.sub.2], PH, and S) have been calculated at the G3 level of theory. The trends observed for the homolytic bond strengths in the closed-shell systems are those expected from electronegativity arguments, i.e., as the difference in electronegativity between the two atoms in the B--X bond increases, the bond strength increases. Methyl substitution on B in the closed- and open-shell species increases the ionic contribution to the bond thereby decreasing the bond strength. The lowest possible homolytic dissociation energy for the free radicals RR'BY. is lower than those of their closed-shell counterparts, yet the B--Y. bonds are shorter. This is due to the demands of spin conservation in the dissociation of the radicals favouring the formation of higher energy products. Key words: ab initio calculations, bond dissociation energy, organoboron compounds, thermochemistry.

The rates of proton transfer reactions between C-acids of the series of nitroalkanes with increasing bulk of R = H, Me, Et, i-Pr substituent as: 4-nitropbenylnitromethane (0), 1-(4-nitrophenyl)-l-nitroethane (1), 1-(4-nitrophenyl)-1-nitropropane (2), 2-methyl-l-(4-nitrophenyl)-l-nitropropane (3) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 7-methyl-l,5,7-triazabicyclo [4.4.0]dec-5-ene (MTBD) have been measured in acetonitrile at pseudo-first-order conditions. The product of the proton transfer reaction with MTBD in acetonitrile is dissociated into free ions while that of the TBD reaction is composed of a comparable amount of ions and ion pairs. The second-order rate constants [(k.sub.2H)] for these bases of almost equal strength in acetonitrile [(pk.sub.a.] = 24.70, 24.97 for MTBD and TBD) and C-acids 1, 2, and 3 are: 317, 86, 7.6 [dm.sup.3] [mol.sup.-1]; and [s.sup.-l]; and 15 200, 5300, 1100 [dm.sup.3] [mol.sup.-1] [s.sup.-1], respectively. The appropriate primary deuterium kinetic isotope effects [(k.sub.H./k.sub.D) are 12.5, 10.8, 6.9; and 9.9, 11.2, 12.6. The influence of steric hindrance brought by reacting C-acids and bases is discussed. The different structure of the transition states and the products as mono-and double-hydrogen bonded complexes for these series of C-acids and MTBD and TBD bases is manifested by a distinct reaction mechanism which we attempt to explain. Key words: proton transfer, kinetic study, C-acids, organic bases, acetonitrile, kinetic isotope effects.

This review describes the development of a new, synthetically useful method of asymmetric synthesis in organic photochemistry. Similar in many ways to the Pasteur procedure for resolving racemic carboxylic acids and organic amines, the method relies on the use of crystalline organic salts in which the enantioselectivity of a photochemical reaction of an achiral organic ion (for example, a carboxylate anion) is governed in the solid state by the presence of an optically pure counterion (for example, an optically active ammonium ion). Such optically pure counterions are termed ionic chiral auxiliaries. Salts containing ionic chiral auxiliaries are required to crystallize in chiral space groups, which provide the asymmetric environment necessary for chiral induction. Using this methodology, we have obtained near-quantitative optical yields in a wide variety of photochemical reactions. Key words: photochemistry, solid state, chiral auxiliaries, asymmetric synthesis, crystal structure-reactivity relationships.

The diborylated ferrocene compound 1,1'-Fc[[B[([C.sub.6][F.sub.5]).sub.2]].sub.2] (2) was prepared via a transmetallation reaction involving 1,1'-Fc[(HgCl).sub.2] and two equivalents of ClB[([C.sub.6][F.sub.5]).sub.2]. Although this reaction is very clean spectroscopically, isolated yields of 2 were never greater than 40% owing to the high solubility of the compound in non-donor solvents. Compound 2 is similar in its properties to the related monoborylated complex FcB[([C.sub.6][F.sub.5]).sub.2] (1) reported previously, particularly the UV-vis spectrum, which exhibits an intense charge transfer absorption ([[lambda].sub.max] = 233 nm, [epsilon] = 1.64 x [10.sup.4]) assignable to an [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] transition. However, 2, is significantly more Lewis acidic than 1, reacting with weak donors such as acetonitrile at room temperature, and effecting methide abstraction from [Cp.sub.2]Zr[Me.sub.2] under mild conditions. Complex 2 also forms a bis(trimethylphosphine) adduct (3), which was structurally characterized via X-ray crystallography. Key words: organoboranes, ferrocene derivatives, multidentate Lewis acids.

The rates of displacement of 3-methyl-4-nitrophenoxide ion from the pesticide, fenitrothion, by alkali metal ethoxides in anhydrous ethanol were followed spectrophotometrically. Through product analysis experiments, which included [sup.31]P NMR and GC-MS, as well as spectrophotometric analysis, three reaction pathways were identified: nucleophilic attack at the phosphorus centre, attack at the aliphatic carbon, and a minor [S.sub.N]Ar route ([is less than or equal to]7%). Furthermore, a consecutive process was found to occur on the product of attack at the phosphorus centre. For purposes of kinetic treatment, the processes at the aliphatic and aromatic carbon were combined (i.e., the minor [S.sub.N]Ar pathway was neglected), and the observed reaction rate constants were dissected into rate coefficients for nucleophilic attack at phosphorus and at aliphatic carbon. Attack at phosphorus was found to be catalyzed by the alkali metal ethoxides in the order KOEt > NaOEt > LiOEt. Catalysis arises from alkali metal ethoxide aggregates in the base solutions used (0-1.8 M); treatment of the system as a mixture of free ethoxide, ion-paired metal ethoxide, and metal ethoxide dimers resulted in a good fit with the kinetic data. An unexpected dichotomy in the kinetic behaviour of complexing agents (e.g., DC-18-crown-6, [2.2.2]cryptand) indicated that the dimers are more reactive than free ethoxide anions, which are in turn more reactive than ion-paired metal ethoxide. The observed relative order of reactivity is explained in the context of the Eisenman theory in which the free energy of association of the metal ion with the rate-determining transition state is largely determined by the solvent reorganization parameter. In contrast with displacement at the phosphorus centre, attack at the aliphatic carbon was not found to be catalyzed by alkali metals. In this case, the free ethoxide anion was more reactive than either the ion-paired metal ethoxide or the dimeric aggregate. The differing effects of alkali metals on the two pathways is ascribed largely to the leaving group [pK.sub.a]. For carbon attack, the [pK.sub.a] value estimated for demethyl fenitrothion, 2.15, is sufficiently low that metal ions are not required to stabilize the rate-determining transition state. In contrast, for phosphorus attack, 3-methyl-4-nitrophenoxide, with a [pK.sub.a] of 7.15, requires stabilization by metal ion interactions. Hence, alkali metal ions catalyze attack at phosphorus, but not attack at the carbon centres. Key words: organophosphorothioate, pesticide, fenitrothion, ethanolysis, alkali metal ethoxide, ion-pair reactivity, dimers, catalysis, competitive pathways.

The addition reactions of organolithium and Grignard reagents to chiral, enantiomerically pure ortho-formyl (arene)tricarbonylchromium acetal complex (2) have been studied. The diastereoselectivity of the addition process is fair in the absence of an additional Lewis acid, and good in the presence of Ti([O.sup.i]Pr)4. The nature of the newly formed chiral centre, and studies on the possible nature of the nucleophilic species suggest that the Lewis acid acts through monodentate coordination to the aldehyde carbonyl, and thereby alters the carbonyl rotamer population more heavily in favour of the s-trans conformation. Nucleophilic attack then occurs on the face anti- to that bearing the Cr[(CO).sub.3] unit. Key words: (arene)tricarbonylchromium complexes, asymmetric synthesis, carbonyl additions, Lewis acids.

The hydrosilylation reaction of phenylacetylene, generated on the surface of solid catalysts (such as Pt and Ru) supported on inorganic matrices such as MgO obtained by the sol-gel process, yields vinylsilanes as the main products. The products' distribution, specific activity, and turnover reactions were determined for the case of the hydrosilylation reaction of PhC[equivalent]CH with [R.sub.3]SiH (R = [Ph.sub.3], [Ph.sub.2]Me, and Ph[Me.sub.2]). For [Ph.sub.3]SiH and [Ph.sub.2]MeSiH, the presence of [beta]-trans and [alpha] isomers is observed. Addition of Ph[Me.sub.2] SiH to phenylacetylene leads to the formation of [beta] (cis and trans) and [alpha] isomers. These catalytic systems provide a new synthetic route to Si--C. Key words: vinylsilanes, cataleseur sol-gel, hydrosilylation et phenylacetylene.

Treatment of the thermally stable aminosilylene Si[[{N(C[H.sub.2]tBu)}.sub.2][C.sub.6][H.sub.4]-1,2] [[equivalent to] Si(NN)] with a tris(cyclopentadienyl)- group 3 or -lanthanide metal compound Ln[Cp.sub.3] (Cp = [[eta].sub.5]-[C.sub.5][H.sub.5] and Ln = Y or Yb) in toluene at ambient temperature afforded the first earliest transition or f-block metal- silylene complexes [Ln[Cp.sub.3]{Si(NN)}]*[C.sub.7][H.sub.8] (Ln = Y (1) or Yb (2)), characterized by NMR spectroscopy and X-ray crystallography: complex 1 (monoclinic, space group P[2.sub.1]/c (no. 14), a = 15.641(5), b = 15.895(7), c = 14.876(5) [Angstrom], [beta] = 112.93(3), Z = 4, RI = 0.067 for 6194 observed data), and 2 (monoclinic, space group P[2.sub.1]/c (no. 14), a = 15.635(3), b = 15.795(2), c = 14.842(2) [Angstrom], [beta] = 112.87(2), Z = 4, RI = 0.044 for 9829 observed data). The Ln atom in each of the isoleptic complexes 1 and 2 has distorted trigonal monopyramidal geometry, with the approximately trigonal silicon atom in the apical position. The Ln--Si bond length is 3.038(2) (1) or 2.984(2) [Angstrom] (2). Variable temperature [sup.29]Si{[sup.1]H} NMR spectra in toluene-[d.sub.8] show that each complex readily dissociates (Y > Yb) into its factors; at 188 K, the [sup.29]Si{[sup.1]H} signal for (1) was a doublet centred at [delta] 119.5, [sup.1]J([sup.29]Si-[sup.89]Y)=59 Hz. Key words: crystallography, NMR, silylene, yttrium, ytterbium, organometallic complexes.

The photobromination of 1,1,3,3,5,5-hexamethyl-1,3,5-trisilacyclohexane (1) almost exclusively attacks C[H.sub.2] groups and results in 2,2-dibromo-trisilacyclohexane (2) as well as 2,2,4,4-tetrabromo-trisilacyclohexane (3) in high yields. Starting from a mixture of C-brominated trisilacyclohexanes the isomeric 2,2,9-tribromo-1,3,3,5,5,8,8,l0,10,13, 13-undecamethyl-1,3,5,8,10,13-hexasilabicyclo[7.2.2]tridec-6-yne (6) had been obtained in very low yield in an attempt to establish a preparative route to adamantanes with ] a [C.sub.4][Si.sub.6] skeleton, i.e., with C bridgeheads and Si[R.sub.2] bridges. By ICl-cleavage of a Si--methyl bond in 2 and subsequent substitution with [Br.sub.3]CLi, the trisilacyclohexane 4 with functional groups in opposite positions of the ring can be obtained. Linking the step-by-step synthesized Cl-[Me.sub.2]Si-C[equivalent]C-Si[Me.sub.2]-C[H.sub.2]-Si[Me.sub.2]-Ph to the C[Br.sub.3] group of 4 results after HBr-cleavage of the Si--Ph bond in ([omega]-bromo-octynyl)-trisilacyclohexane (12). A ring closure of 12 would result in an isomeric hexasila-bicyclo[7.2.2]tridec-6-yne. The compounds were characterized by [sup.1]H, [sup.13]C, and [sup.29]Si NMR spectra. Additionally, the molecular structures of 4 and 6 were confirmed by X-ray single crystal investigations. Key words: 1,1,3,3,5,5-hexamethyl-1,3,5-trisilacyclohexane, bromination, 2,2,9-tribromo-1,3,3,5,5,8,8,10,10,13,13-undecamethyl-1,3,5,8,10, 13-hexasilabicyclo[7.2.2]tridec-6-yne, carbosilane synthesis, NMR data, crystal structure investigation.

Synthesis has been carried out of diarylboron chelates of 2- and 3-hydroxynitrones, of 2- and 3-hydroxyoximes, and of 2-carboxynitrones and a 2-carboxyoxime. The structures have been determined from spectroscopic data and from X-ray analyses of Sd, 9a, 11b, and 19. Crystals (at 180 K) of 5d are monoclinic, a = 10.543(2), b = 19.085(4), c = 10.2667(3) = [Angstrom], [beta] = 90.4978(7)[degrees], Z = 4, space group P[2.sub.1]/c; those of 9a are orthorhombic, a = 10.9913(5), b = 14.9329(7), c = 10.2460(13) [Angstrom], Z = 4, space group P[2.sub.1] [2.sub.1]2; those of 11b are monoclinic, a = 11.227(2), b = 9.967(2), c = 17.0537(4) [Angstrom], [beta] = 105.4179(5)[degrees], Z = 4, space group P[2.sub.1]/n; those of 19 are monoclinic, a = 11.1847(15), b = 13.715(3), c = 11.5559(5) [Angstrom], [beta] = 104.8730(10)[degrees], Z = 4, space group P[2.sub.1]/n. The structures were solved by direct methods and refined by full-matrix least-squares procedures to R(F, I [greater than or equal to] 3 [sigma](I)) = 0.049, 0.047, 0.042, and 0.047, respectively, for CCD data for 5d, 9a, lib, and 19. The four molecules contain five-, seven-, six-, and five-membered rings, respectively, with O-B-N groups in the Sd, llb, and 19, and O-B-O in 9a; the rings exhibit various deviations from planarity, particularly the seven-membered ring. Key words: diarylboron chelates, hydroxyoximes, hydroxynitrones, carboxyoximes, carboxynitrones, organoboron compounds, crystal structure.

5-Chloro-1,5-dihydro-2H-pyrrol-2-ones are easily alkylated at the 5-position by organomagnesium or organozinc compounds and diethyl sodiomalonate leading to corresponding 5-alkyl-1,5-dihydro-2H-pyrrol-2- ones in high yields. Key words: organometallic compounds, alkylation, 1,5-dihydro-2H-pyrrol-2-one.

Metal-catalyzed coupling reactions are very efficient and reliable methods for the introduction of new carbon-carbon bonds onto molecules attached to a solid support. This review summarizes recent advances in utilizing the three most used methods, the Suzuki reaction, the Heck reaction, and the Stille reaction, in the field of solid phase organic synthesis resulting in small organic molecule libraries. Key words: metal-catalyzed coupling reactions, carbon--carbon bonds, solid phase synthesis, combinatorial chemistry, drug discovery.

For more than a century, organic chemists have been playing in Nature's laboratory. Their first goal was to understand the organization of atoms in the living matter and then to reproduce it by synthesis. This quest gave rise to several efficient techniques to synthesise molecules; many of them still in use nowadays, as such or with little modifications. Even at the beginning of this journey, the chemists discovered that their methods were far from being as efficient as the ones used by Nature to produce substances. The natural molecules were chiral and there was even an enantiomer that was produced over the other;a lesson of perfection. This was another challenge for the chemists and they succeeded by first developing techniques to separate enantiomers and more recently reagents and reactions to produce only the desired stereoisomer. Asymmetric synthesis uses chiral auxiliaries, reagents or catalysts to create chirality into the desired compound. The common perception, as a minimum condition, was that the chiral substance used to perform such a transformation has to be of the highest enantiomeric purity to obtain a very high selectivity. The relation between the enantiomeric excesses of the chiral substance and the product was suggested to be linear. But there were a lot of surprises left in the laboratory. Who would have thought that an impure substance could give an enantiomeric excess in the product higher than its own purity? The molecules are acting in different ways in solution. Self-organization and aggregation can arise depending on the structure of the substance or its environment. Such phenomenon can generate deviations to the awaited behaviour of the molecules that can be observed in many cases. This article tries to present some examples of the historical reports of such peculiar behaviours, their influence on physico-chemical properties and the final discovery of the now well-known nonlinear effects in asymmetric synthesis. Key words: asymmetric synthesis, diastereomeric interactions, nonlinear effects.

A systematic study of the diastereoselective alkylation of anions derived from racemic N-substituted P-alkyl 1,3,2-diazaphosphorinane 2-oxides was carried out with variation of the N-substituent. High diastereoselectivity for the methylation of a P-benzyl anion has been achieved with N-neopentyl derivative 5d. Similarly, a P-ethyl anion derived from N-neopentyl derivative 6d showed high diastereoselectivity upon benzylation. The observed difference in alkylation diastereoselectivity between P-ethyl and P-benzyl anions for various N-alkyl substituents is discussed. Key words: phosphonamide-stabilized carbanions, alkylation, asymmetric, stereoselective, organolitihium.

Organosulfur compounds in garlic, like allyl methyl disulfide, have been found to be involved in antimutagenic, anticarcinogenic, antithrombotic, and lipid-lowering activities, and it has also been found to act as an antioxidant. Ab initio molecular computations were performed on dihydrogen disulfide (1) with respect to torsional angle [[tau].sub.1] = [tau](H.S-S.H), hydrogen methyl disulfide (2) with respect to torsional angle [[tau].sub.1] = [tau](H.S-S.C[H.sub.3]), and allyl methyl disulfide (3) with respect to torsional angles [[tau].sub.1] = [tau]([H.sub.3][C.sub.2].C[H.sub.2].S-S.C[H.sub.3]), [[tau].sub.2] = [tau]([H.sub.3][C.sub.2].C[H.sub.2]-S.S.C[H.sub.3], and [[tau].sub.3] = [tau]([H.sub.3][C.sub.2-C[H.sub.2].S.S-C[H.sub.3]). Potential energy curves (PEC) were obtained from 1 and 2, i.e., E = E([[tau].sub.1]), from which optimized structures were obtained at the HF/6-31G* level of theory. These optimized structures were used to investigate the potential energy hypersurface surface (PEHS) of 3, i.e., E = E([[tau.sub.1],[[tau].sub.2],[[tau].sub.3]). One-dimensional scans along [[tau].sub.2] and [[tau].sub.3] (where [[tau].sub.1]= [+ or -]90[degrees]; [[tau].sub.1] = 180[degrees]) were performed at the HF/3-21G* level of theory. From these scans, six lower energy pairs of enantiomeric minima (i.e., [[g.sup.+][g.sup.+][g.sup.+] | [g.sup.-] [g.sup.-][g.sup.-]], [[g.sup.+]a[g.sup.-] | [[g.sup.-]a[g.sup.+]], [[g.sup.+][g.sup.-][g.sup.+] |[g.sup.-][g.sup.+][g.sup.-]], [[g.sup.+][g.sup.+][g.sup.-] | [g.sup.-] [g.sup.-][g.sup.+]], [[g.sup.+]a[g.sup.-] | [g.sup.-]a[g.sup.+]], and [[g.sup.+][g.sup.-][g.sup.-] | [g.sup.-][g.sup.+][g.sup+]]) as well as 3 higher energy minima (i.e., [[g.sup.+][g.sup.+]s | [[g.sup.-][g.sup.-]s], [[g.sup.+] as | [g.sup.-]as], and [g+[g.sup.-]s | [g.sup.-][g.sup.+]s]) were optimized at [[tau].sup.1] = [+ or -]90[degrees] at the HF/6-31G* and B3LYP/6-31G* levels of theory. The global minimum was determined to be the [[g.sup.+][g.sup.-][g.sup.+] | [g.sup.-][g.sup.+][g.sup.-]] enantiomeric pair of conformers, and the fully symmetrical anti-anti-anti [a a a] structure was determined to be a second-order saddle point on the PEHS of 3. Although there are no stereocentres in 3, there is chirality in the conformational twist with respect to the [a a a] conformation through [[tau].sub.1] = [[tau].sub.2] = [[tau].sub.3] = 180[degrees]. Based on the energies and MO diagrams of the HUMO and LUMO +l of 3, the anticarcinogenic and cholesterol lowering activity mechanism of 3 is presented. Key words: ab initio MO computations, allyl methyl disulfide, multidimensional conformational analysis (MDCA), anticarcinogenic, cholesterol lowering.

Experimental data are compared with results from a model developed for nonionic surfactant solubilization of hydrophobic organic compounds (HOCs) in soil/aqueous systems. The model parameters that describe each of the major physicochemical processes affecting sorption and micellar uptake of both nonionic surfactant and hydrophobic organic compounds can be characterized with values obtained independently from separate experiments involving aqueous, soil, or soil/aqueous systems. The experimental data presented in this paper demonstrate that the modeling approach is reasonably valid for several nonionic surfactants. It is also shown that treating a soil with successive surfactant washings results in greater removal of HOC than a single washing with the same total mass of surfactant. An inverse method is evaluated with experimental data. This method permits the determination of a ratio of the values of two of the model parameters from gross experimental data such that if one parameter is measured the other can be calculated.

Research has been conducted on alkyl and cyclic acetals and ketals. The chemoselective method developed for the cleavage of these compounds via the use of catalytic cerium(III) trifluoromethane sulfonate in wet nitromethane at room temperature is described.

A comparative analysis of zinc compounds in natural organic matter of surface water from various sources is presented.

The authors review the publications on Lewis acids. The topics include the analysis of all reactions carried out in the presence of Lewis acids, and the use of these acids in organic synthesis.

Research has been conducted on alkyl-, ketoalkyl- and haloalkyl-2-ethoxycarbonyl-1,3-dithianes. The authors report that these compounds can be prepared from primary or secondary alkyl bromides, ethyl chloroformate and 1,3-dithiane.

Research has been conducted on 5-center 4-electron bonding. The authors have discovered the existence of this bonding in (C...H...C...H...C) molecule I fragment.

Research has been conducted on fullerenes. The authors have discovered that after heating fullerenes in the presence of noble gas, a small fraction of fullerene molecules contains the atom or molecule, and that the addition of potassium cyanide to the reaction mixture can enhance the incorporation fraction.

Research has ben conducted on fine-tunable phosphite-pyrine ligands. The authors describe the use of these ligands in Cu(I)-catalyzed diethylzinc conjugate addition to acyclic enones.

Research has been conducted on arene and heteroarene sulfonamides. The authors describe the preparation of these compounds from aryl and heteroaryl bromides carried out via conversion into the Grignard reagents using magnesium or isopropylmagnesium chloride.