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A mechanistic study on a direct arylation using a native picolylamine directing group is reported. Kinetic studies determined the concentration dependence of substrates and catalysts, as well as catalyst degradation, which led to the development of a new set of reaction conditions capable of affording a robust kinetic profile. During reaction optimization, a small impurity was observed, which was determined to be a dual C-H activation product. A second set of conditions were found to flip the selectivity of the C-H activation to form this tetracycle in high yield. A catalytic cycle is proposed for the intermolecular/intramolecular C-H activation pathway.

"Kinetic Approach to the Catalytic Hydrogenation of Nitroaliphatic Compounds, V. Dubois, G. Jannes, J. L. Dallons, and A. Van Gysel New Route to m-Aminophenol, Stephen E. Jacobson A New and Improved Synthesis of N-Butyl-1-Deoxynojirimycin, Mike G. Scaros, Michael L. Prunier, Rick J. Rutter, Peter K. Yonan, Roy Grabner, and Bryan Landis Homogeneous Asymmetric Catalysis as an Important Tool for the Production of Fine Chemicals and Pharmaceutical Products, A. S. C. Chan, S. A. Laneman, R. E. Miller, J. H. Wagenknecht, and J. P. Coleman The Use of a Fischer-Porter Apparatus for Chiral Homogeneous Catalytic Hydrogenation, Louis S. Seif, Daniel A. Dickman, Donald B. Konopacki, and Bryan S. Macri Application of Symmetric Catalysis to the Synthesis of Peptide Mimics, John T. Talley, Cathleen E. Hanau, Gary A. DeCrescenzo, and Michelle A. Schmidt Catalytic Amination of Alcohols and Its Potential for the Synthesis of Amines, Alfons Baiker High Selectivities in Hydrogenation of Halogenonitrobenzenes on Pd, Pt, or Raney Nickel as Catalysts, Georges Cordier, Jean Michel Grosselin, and Rose Marie Bailliard Solid-Acid-Catalyzed o-Tolidine Alkylation: Scope, Limitations, and Product Utility, Kevin R. Lassila, Michael E. Ford, Susan M. Clift, Jeremiah P. Casey, and Paula L. McDaniel Comparative Catalytic Hydrogenation Reactions of Aliphatic Dinitriles over Raney Nickel Catalysts, Marc Joucla, Philippe Marion, Pierre Grenouillet, and Jean Jenck Hydrogenation of Nitrosobenzene over Palladium Catalysts, Gerard V. Smith, Ruozhi Song, Marian Gasior, and Russell E. Malz, Jr. Past, Present, and Future of Catalytic Oxidation of Hydrocarbons, Jerzy Haber Oxidation of Glucose on Palladium Catalysts: Particle Size and Support Effects, M. Besson, P. Gallezot, F. Lahmer, G. FlEche, and P. Fuertes A Method for the Preparation of Pyromellitic Acid from Durene via Liquid Phase Oxidation, Walt Partenheimer Surface Chemistry and Engineering of HCN Synthesis, L. D. Schmidt and D. A. Hickman New Technology for Olefin Oxidation to Carbonyls Using a Palladium and Polyoxoanion Catalyst System, John H. Grate, David R. Hamm, and Suresh Mahajan Side Reactions in Reductive Alkylation of Aromatic Amines with Aldehydes and with Ketones, Harold Greenfield A Frontier Molecular Orbital Determination of the Active Sites on Dispersed Metal Catalysts, Robert L. Augustine and Konstantinos M. Lahanas Hydrogenations and Other Reactions on Titanium Mixed Metal Oxides, Gether Irick and Patricia N. Mercer Methacrylate Esters via the Homogeneous Carbonylation of 2-Bromopropene, Robert A. DeVries, Robert T. Klun, John W. Hull, Jr., and Kim A. Felty Production of Phenols from Haloaromatics in the Presence of Copper-Exchanged Zeolites: Synthesis of the Catalyst and Mechanistic Study, G. Perot, Y. Pouilloux, M. Guisnet, and M. Gubelmann Polymer-Bound Dialkylaminopyridine Catalysts: Synthesis and Applications, James G. Keay and Eric F. V. Scriven Metal Incorporation into Copper Aluminum Borates: Catalyst Structure and Catalytic Role in Dehydrogenation and Dehydrocyclization, Larry C. Satek and Patrick E. McMahon Amidation of Methyl Esters with Formamides in the Presence of KCN as the Catalyst, A. Benderly, L. Y. Dennis, and A. Bravo New Titanium Silicate Molecular Sieves: Properties and Catalysis, M. Deeba, C. F. Keweshan, G. S. Koermer, S. M. Kuznicki, and R. S. Madon Transvinylation Catalysts for the Production of Higher Vinylic Esters of Vinyl Acetate, F. J. Waller Protecting the Ozone Layer: Catalytic Synthesis of CFC Alternatives, Leo E. Manzer The Tertiary Organometallic Reagent Promoted Reductive Coupling of Aryl Halides, Thomas A. Puckette Catalysis of Organic Reactions by Inorganic Solids, Pierre Laszlo Preparation of Pharmaceutical Intermediates Using Zeolite Catalysis: Preparation of 4-Methylthiazole with ZSM-5, F. P. Gortsema, B. Beshty, J. J. Friedman, D. Matsumoto, J. J. Sharkey, G. Wildman, T. J. Blacklock, and S. H. Pan Hydrocarbon Fragmentation Patterns on Rhodium Surfaces, Shane L. Anderson, Dinesh Kalakkad, and Abhaya K. Datye Catalytic Cracking of Organic Amides: A Key Step in the Production of a New Specialty Polymer, G. E. Parris and J. N. Armor Production of Low-Cost Aliphatic Isocyanates, P. L. Brusky, J. H. Kyung, and R. A. Grimm Catalytic Oxidation of Secondary Alcohols, Robert L. Augustine and Lisa K. Doyle Synthesis of Bisaniline A and Derivatives with Perfluorinated Sulfonic Acid Resins, Michael E. Ford and Mark D. Conner Effect of Water on the Oxidation of 2-Butanone over V2O5, Ismat Jahan and H. H. Kung H2-Hydrogenation of Nitriles Catalyzed by Ruthenium Ditertiaryphosphine Complexes, Ajey M. Joshi, Kenneth S. MacFarlane, Brian R. James, and Piero Frediani Enhancement of CO Hydrogenation Activity of Pt Catalysts by CeO2 and TiO2 Supports, Dinesh Kalakkad and Abhaya K. Datye Hydrocarbon Conversion Reactions overt he Pt-Re Bimetallic Catalysts Modified by Sulfur, Changmin Kim and Gabor A. Somorjai Activation of Esters for Hydrogenolysis on Copper Titanias, Yeong-Jen Kuo, Patricia N. Mercer, and Gether Irick The Direct Conversion of Vinyl to Ethylidyne, Z. M. Liu, X. L. Zhou, D. A. Buchanan, J. Kiss, and J. M. White Hydrocarbon Probes for the Study of Acidity on Oxide Surfaces, C. R. Narayanan, S. Srinivasan, and Abhaya K. Datye Synthesis of (+)-Apopinene by Decarbonylation of (+)-Myrtenal: Application of the Mechanisms of Hydrogenation and Decarbonylation, Gerard V. Smith and Ruozhi Song New Hydrogenation Apparatus, Robert L. Augustine, Setrak K. Tanielyan, and Glenn Wolosh A Pd-Sn Catalyst for Toluene Acetoxylation, Setrak K. Tanielyan and Robert L. Augustine Characterization of Sulfided Platinum and Palladium Catalysts, D. S. Thakur, B. D. Roberts, T. J. Sullivan, G. T. White, N. Brungard, E. Waterman, and M. Lobur Selective Hydrogenation of Unsaturated Aldehydes over Silica- and Zeolite-Supported Metals, Akshay Waghray, Rachid Oukaci, and Donna G. Blackmond "

Polyol-induced extraction (PIE) is applied to the extraction of essential oils, using glycerol as a mass separating agent. In 1:1 acetonitrile (ACN)/water solvent mixtures, two immiscible phases can be generated. PIE as an alternative extraction technique was assessed by the extraction of the main flavor and fragrance compounds that comprise six essential oils. In the extraction of eugenol (4-allyl-2-methoxyphenol) from clove buds, the partition coefficients were determined and the % recovery and thermodynamic data in the temperature range of −20 to 20°C were calculated. The main components present in each essential oil extract were identified through gas chromatography/mass spectrometry (GC/MS) and the compositional profile was compared to traditional extraction techniques. The optimized extraction conditions (−10°C, 1:1 ACN/water (v/v), 20% glycerol) for eugenol at −10°C give a partition coefficient (KPC) of 87 and an extraction efficiency of 97% in the acetonitrile-rich phase. The eugenol migration to the organic phase is a spontaneous process (ΔG° = −9.3 kJ/mol) and an endothermic process (ΔH° = 9.2 kJ/mol) with entropy being the driving force behind the reaction (ΔS° = 70 J/K, TΔS° = 18.4 kJ). The technique was applied to five other essential oils (cinnamon bark, caraway seed, spearmint leaf, peppermint leaf, and anise seed oils) with similar results.

Raw menhaden fish oil was developed for biomonitoring polycyclic aromatic hydrocarbons (PAHs) using fluorescence spectroscopy. Menhaden (Genus Brevoortia) were collected in 2010 and/or 2011 from Delaware Bay, New Jersey, USA; James River, Virginia, USA; Vermillion Bay, Louisiana, USA (VBLA); and Barataria Bay, Louisiana, USA (BBLA). Barataria Bay, Louisiana received heavy oiling from the Deepwater Horizon oil spill. Method development included determining optimal wavelengths for PAH detection, fish oil matrix interferences, and influence of solvent concentration on extraction. Results showed that some fish oils contained high molecular weight PAH-like compounds in addition to other fluorescent compounds such as albumin and vitamin A and vitamin E. None of these naturally occurring compounds interfered with detection of high molecular weight PAHs. However, data suggested that the lipid component of fish oil was altering fluorescence spectra by supporting the formation of PAH excimers. For example, the most intense excitation wavelength for hydroxypyrene shifted from Ex285/Em430 to Ex340/Em430. Comparison of Deepwater Horizon crude oil and fish oil spectra indicated that some fish oils contained crude oil-like PAHs. Using wavelengths of Ex360/Em430, fish oil concentrations were calculated as 3.92 μg/g, 0.61 μg/g, and 0.14 μg/g for a Delaware Bay sample, BBLA 2011, and VBLA 2011, respectively. Overall, these results supported using menhaden fish oil to track PAH exposures spatially and temporally.

Headspace solid-phase microextraction (HS-SPME) was used in combination with gas chromatography-mass spectrometry (GC-MS) for the analysis of polycyclic aromatic hydrocarbons (PAH) at part per billion levels in fish oil samples collected from menhaden fish. The method was initially developed using fish oil from capsules spiked with a standard PAH mixture. The final HS-SPME-GC-MS method presented a linear range from 3 to 1,500 ng/g, with precision for most analytes

Racemic secondary allylic alcohols were transformed into optically active secondary alcohols by a combined Ru-catalyzed isomerization/asymmetric transfer-hydrogenation reaction. The catalyst was generated in situ in isopropyl alcohol from di-μ-chlorobis[(p-cymene)chlororuthenium(II)], the chiral ligand (1S,2S)-N-(p-tolylsulfonyl)-1,2-diphenylethylenediamine, and K2CO3, and the products were afforded in yields up to 97 % with up to 93 % enantiomeric excess without the use of hydrogen gas. A Hammett study revealed that the reaction rate was enhanced with electron-withdrawing aryl substituents. The reaction supports the recent work published by Adolfsson et al. as new methodology for the synthesis of chiral compounds from allylic alcohols.

Racemic secondary allylic alcohols were transformed into optically active secondary alcohols by a combined Ru-catalyzed isomerization/asymmetric transfer-hydrogenation reaction. The catalyst was generated in situ in isopropyl alcohol from di-μ-chlorobis[(p-cymene)chlororuthenium(II)], the chiral ligand (1S,2S)-N-(p-tolylsulfonyl)-1,2-diphenylethylenediamine, and K2CO3, and the products were afforded in yields up to 97 % with up to 93 % enantiomeric excess without the use of hydrogen gas. A Hammett study revealed that the reaction rate was enhanced with electron-withdrawing aryl substituents. The reaction supports the recent work published by Adolfsson et al. as new methodology for the synthesis of chiral compounds from allylic alcohols.

A quantitative investigation was undertaken to determine experimentally the relative reaction rates of the heterochiral and homochiral species of B-chlorodiisopinocampheylborane (Dip-Cl), a reagent that exhibits asymmetric amplification. Using the method of flooding to reduce the apparent second-order reaction to pseudo-first-order conditions, rate constants of 3.8 (±1.0) × 10−4 and 1.7 (±0.8) × 10−5 m−1 s−1 (at −15°C) were found for the homochiral and heterochiral species, respectively. The resulting relative reaction rate, the value of g in Kagan and co-workers' model, was 0.04 ± 0.03. Additional experiments were conducted to confirm this value. The deterioration of the chiral purity of the final product was simulated throughout reaction conversion and compared with actual values. Through minimization, a relative reaction rate (g) of 0.08 ± 0.04 was determined. Finally, using 8-hydroxyquinoline complexation, the change in isomeric ratio of the Dip-Cl remaining in the reaction solution was measured. The relative reaction rate (g) required to consume the isomers at the observed rate was determined as 0.08 ± 0.01. Thus, three independent methods have been used to determine the relative reaction rate (g) of the heterochiral to homochiral species with good agreement to give an average value of 0.07 ± 0.03. Copyright © 2004 John Wiley & Sons, Ltd.

The Suzuki–Miyaura cross-coupling reaction using heterogeneous Pd/C has a homogeneous component. The soluble palladium concentration increases during the reaction reaching a maximum at ca. 90% conversion before falling to

Raw menhaden fish oil was developed for biomonitoring polycyclic aromatic hydrocarbons (PAHs) using fluorescence spectroscopy. Menhaden (Genus Brevoortia) were collected in 2010 and/or 2011 from Delaware Bay, New Jersey, USA; James River, Virginia, USA; Vermillion Bay, Louisiana, USA (VBLA); and Barataria Bay, Louisiana, USA (BBLA). Barataria Bay, Louisiana received heavy oiling from the Deepwater Horizon oil spill. Method development included determining optimal wavelengths for PAH detection, fish oil matrix interferences, and influence of solvent concentration on extraction. Results showed that some fish oils contained high molecular weight PAH-like compounds in addition to other fluorescent compounds such as albumin and vitamin A and vitamin E. None of these naturally occurring compounds interfered with detection of high molecular weight PAHs. However, data suggested that the lipid component of fish oil was altering fluorescence spectra by supporting the formation of PAH excimers. For example, the most intense excitation wavelength for hydroxypyrene shifted from Ex285/Em430 to Ex340/Em430. Comparison of Deepwater Horizon crude oil and fish oil spectra indicated that some fish oils contained crude oil-like PAHs. Using wavelengths of Ex360/Em430, fish oil concentrations were calculated as 3.92 μg/g, 0.61 μg/g, and 0.14 μg/g for a Delaware Bay sample, BBLA 2011, and VBLA 2011, respectively. Overall, these results supported using menhaden fish oil to track PAH exposures spatially and temporally.

A new class of chiral indenes (verbenindenes), in which a verbenone moiety is annulated to an indene core, is prepared by a sequence of Shapiro lithiation and Nazarov cyclization reactions. Since the initial indenes are resistant to deprotonation, they are isomerized via [1,5]-sigmatropic shifts to obtain indenes that are readily deprotonated with n-butyllithium. Reaction of the indenide anions with chloro(1,5-cycloctadiene)rhodium dimer produces verbenindenyl transition-metal complexes. Coordination of the indenyl ligand may occur with the gem-dimethyl bridge of the verbenone moiety syn or anti to the metal. Selectivity favors the less hindered anti complexes, and a crystal structure of a member of this series is presented.

We show that complexation of B-chlorodiisopinocampheylborane (Dip-Cl) with 8-hydroxyquinoline results in an air- and moisture-stable complex. Using enantiomerically pure (+)-α-pinene, the (+,+)-Dip-quinoline complex, [(+)-C10H17]2B(η2-N,O-C10H6NO), was isolated and characterized by spectroscopic and crystallographic methods. When Dip-Cl is prepared from enantiomerically impure (+)-α-pinene a mixture of heterochiral, (+,−)-Dip-Cl, and homochiral, (+,+)-Dip-Cl and (−,−)-Dip-Cl, stereoisomers are formed. We have developed the 8-hydroxyquinoline complexation method for quantification of these stereoisomers by chiral HPLC. Since this is the first quantitative analysis of a reagent that exhibits asymmetric amplification, it enables us to verify part of Kagan's model for this phenomenon and evaluate the terms β and K which are measures of the relative amounts of stereoisomers. Our analysis shows that there is a preference for the formation of the heterochiral (+,−)-Dip-Cl isomer; therefore, the stereoisomers are...

The influence of reaction conditions on enantioselectivity in the Ru II -(binap)-catalyzed asymmetric hydrogenation of allylic alcohols is discussed. This work highlights the importance of considering kinetic influences in addition to the stereochemical aspects of the chiral catalytic environment in interpreting catalytic behavior in asymmetric hydrogenation reactions.

(Trifluoromethyl)tetramethylcyclopentadiene, ΗC5Me4CF3 (Cp⧧H), reacts with Ru3(CO)12 in refluxing n-decane to produce [(η5-C5Me4CF3)Ru(μ-CO)(CO)]2 (1). In chlorinated hydrocarbon solutions, 1 reacts with the solvents in the presence of visible light to produce [(η5-C5Me4CF3)Ru(CO)2(Cl)] (3a). Compound 1 reacts with iodine in refluxing CH2Cl2 to produce [(η5-C5Me4CF3)Ru(CO)2(I)] (3b). The X-ray crystal structure of compound 3b is presented. Compound 3b reacts with triphenylphosphine in refluxing ethanol to produce [(η5-C5Me4CF3)Ru(CO)(PPh3)(I)] (4). The HC5Me4CF3 ligand reacts with Fe(CO)5 in refluxing heptane to produce [(η4-HC5Me4CF3)Fe(CO)3] (5). Compound 5 represents a new mode of coordination (η4) for HC5Me4CF3. The spectroscopic properties of compound 1 and its previously reported iron analog, [(η5-C5Me4CF3)Fe(μ-CO)(CO)]2 (2), are compared with those of their η5-C5H5 and η5-C5Me5 “parent” analogs of the type [(η5-C5R5)M(μ-CO)(CO)]2 (M = Fe, Ru). Compounds 1 and 2 were characterized by single-crystal ...

Examples from both homogeneous and heterogeneous catalytic systems are presented which demonstrate the role that reaction dynamics may play in dictating the ultimate enantioselectivity observed in asymmetric hydrogenation reactions. The hydrogenation of allylic alcohols using Ru(S)-binap and the hydrogenation of α-keto esters using cinchona-modified supported Pt are discussed. This work highlights the importance of considering reaction kinetics in addition to the stereochemical aspects of the chiral catalytic environment in interpreting catalytic behavior in asymmetric hydrogenation reactions.

The synthesis, characterization, and vis−NIR−IR vapochromic/spectroscopic studies are reported for isocyanide compounds of the form [Pt(arylisocyanide)4][Pt(CN)4] (where arylisocyanide = p-CNC6H4CnH2n+1; n = 1, 6, 10, 12, 14). The dark blue, solid materials change color in the NIR (near-infrared) spectral region upon exposure to the ambient room-temperature vapor pressure of volatile organic compounds (VOCs). At room temperature the PtPt compounds exhibit strong solid-state absorption and emission bands in the NIR region of the spectrum that are red-shifted from similar bands in the PtPd analogues; (n = 1, λmax abs = 744, λmax emit = 958; n = 6, λmax abs = 841, λmax emit = 910; n = 10, λmax abs = 746, λmax emit = 944; n = 12, λmax abs = 764, λmax emit = 912; n = 14, λmax abs = 690, λmax emit = 876 nm). The positions of these broad bands depend on the number of carbons in the alkyl substituent. The absorption and emission bands for the solid material (n = 10 compound) also exhibit a substantial red-shift u...

The new molecules P3RhMe3-n(OTf)n are reported (n = 0−2; P3 = MeC(CH2PMe2)3; OTf = OS(O)2CF3). The known fac-(Me3P)3RhMe3 was converted to mer-(Me3P)3RhMe3-nCln (n = 1, 2) by cleavage with HCl in ether. X-ray photoelectron spectra (XPS) of these were recorded, and all except the P3RhMe3-nCln series afforded clean spectra. XPS were also obtained for the known CnRhMe3-nXn (n = 0−2; X = Cl, Br, OTf; Cn = 1,4,7-trimethyl-1,4,7-triazacyclononane), CnRhX3 (X = Cl, Br), CnRhMe(OH)(OTf), and [CnRhMe2(CO)]OTf. An X-ray crystal structure of P3RhMe3 is reported, and the geometry at the metal is compared among P3RhMe3, (Me3P)3RhMe3, and CnRhMe3. Core binding energies (BEs) for the series L3RhMe3-nXn (L3 = Cn, P3) change linearly with n for a given L3 and X. For CnRhMe3-nXn, replacement of methyl by chloride or bromide gives similar ΔBE values (∼0.7 eV), while triflate-for-methyl substitution gives a much larger ΔBE (1.2 eV). Triflate-for-methyl substitution in P3RhMe3-n(OTf)n, however, causes a ΔBE of only 0.8 eV. Th...

p-Decylphenyl isocyanide, p-C(10)H(21)-C(6)H(4)-NC or C(17)H(25)N, and p-decylbenzonitrile, p-C(10)H(21)-C(6)H(4)-CN or C(17)H(25)N, are isomorphous. The molecules lie in mirror planes, with the C(6) rings perpendicular to the mirror. The packing of both molecules includes an aliphatic region, with close to ideal packing of the C(10)H(21) chains, and an aromatic region, with phenyl ring-CN interactions. In addition, the CN ends of the molecules are also involved in a CN.NC dipolar interaction.

Titration calorimetry has been used to determine the heath of protonation (ΔH HM ) of the fac-W(CO) 3 (PR 3 ) 3 (PR 3 =PMePh 2 , PEtPh 2 , PMe 2 Ph, PEt 2 Ph, PMe 3 , PEt 3 ) and fac-W(CO) 3 (L 3 ) (L 3 =PhP(CH 2 -CH 2 PPh 2 ) 2 , MeC(CH 2 PPh 2 ) 3 ) complexes with CF 3 SO 3 H in 1,2-dichloroethane solvent at 25.0 o C.

We demonstrate that Pd/C without added ligands catalyzes the Suzuki cross-coupling reaction with aryl chlorides. The ability of heterogeneous Pd to activate the C−Cl bond is explained in terms of a synergistic anchimeric and electronic effect that occurs between the Pd surface and the aryl chloride. Furthermore, the importance of selectivity control following C−Cl bond activation is illustrated by the striking role that solvents play in determining homo- vs cross-coupling pathways of the aryl chlorides.

Dissolution studies are critical tests for measuring the performance of a drug product. We have developed a novel technique using in situ ATR-IR spectroscopy to monitor dissolutions of pharmaceutical drug products. The accuracy of this technique is +/-3% relative to HPLC using salicylic acid calibrator tablets and acetaminophen OTC tablets. This novel approach also gives the research laboratory the capability of analyzing individual ingredients in multiple tablets; for example, individual components of salicylic acid and acetaminophen tablets are easily distinguished. In addition, the individual ingredients of a multi-component tablet containing acetylsalicylic acid and acetaminophen are readily distinguished. The ATR-IR system was found to have good sensitivity and can analyze samples as low as 0.03 mg/ml. With improved sensitivity, this is a promising method for monitoring dissolution of pharmaceutical tablets with an excellent in situ capability for distinguishing individual components.

Titration calorimetry has been used to determine the heats of protonation ([Delta]H[sub HM]) of cis-M(CO)[sub 2](L-L)[sub 2] complexes (M = Cr, Mo, W; L-L = dppm, dppe, dppp, arphos, dmpe) with CF[sub 3]SO[sub 3]H in 1,2 dichloroethane solvent at 25C. Spectroscopic studies show that protonation occurs at the metal center to form [M(H)(CO)[sub 2](L-L)[sub 2]]CF[sub 3]SO[sub 3] complexes with trans CO groups. For the M(CO)[sub 2][Ph[sub 2]P(CH[sub 2])[sub n]PPh[sub 2]][sub 2] complexes, [Delta]H[sub HM] becomes less exothermic as the chelate size increases from n = 1 ([minus]29.7 kcal mol[sup [minus]1]) to n = 3 ([minus]19.0 kcal mol[sup [minus]1]) for Mo and from n = 1 ([minus]31.5 kcal mol[sup [minus]1]) to n = 2 ([minus]25.1 kcal mol[sup [minus]1]) for W. The higher basicities of complexes with small chelates are ascribed to distortions imposed on the M(CO)[sub 2](L-L)[sub 2] complexes by the chelate ligand and to reduced steric hindrance in the protonated product. Substituting the dppe chelates in Mo(CO)[sub 2](dppe)[sub 2] with dmpe increases metal basicity, and with the arphos ligand metal basicity is decreased ([Delta]H[sub HM] = [minus]23.8 kcal mol[sup [minus]1]). In descending group 6, the basicities ([Delta]H[sub HM]) of the M(CO)[sub 2](dppm)[sub 2] complexes increase in the order Cr W. The group 8 complex, ([eta][sup 5]-C[sub 5]Me[sub 5])[sub 2]Os is substantially more basic than ([eta][sup 5]-C[sub 5]Me[sub 5])[sub 2]Ru. The heats of protonation ([Delta]H[sub HN]) of a series of organonitrogen bases have also been determined.« less

Rhodium and iridium catalysts containing trifluoromethyl-substituted indenyl ligands (Ind'MCod, Ind' = C9H7, (1-CF3)C9H6, (2-CF3)C9H6, (1,3-CF3)2C9H5) have been developed for the directed hydroboration of 4-(benzyloxy)cyclohexene to cis-3-(benzyloxy)cyclohexanol. Compared to unsubstituted complexes, trifluoromethyl substitution yields a 3-10% increase in selectivity which is attributed to the strong electron-withdrawing effect of the trifluoromethyl group. Rhodium complexes give selectivities of 74-84%, and iridium complexes give high levels of selectivity (93-98%).

Recently, a new method for the palladium-catalyzed synthesis of 9,10-dihydrophenanthrenes was published. A proposed mechanism indicated that the reaction proceeds via a disrotatory 6pi electrocyclic ring closing reaction. Although the synthetic methodology is excellent for the preparation of 9,10-phenanthrenes, we propose an alternative mechanism that occurs through an intramolecular Heck reaction. Using theoretical calculations, we have investigated both mechanisms and find that the intramolecular Heck mechanism is lower in energy by 21.3 kcal/mol than the electrocyclic pathway.

A simple, precise, accurate and validated, acetonitrile-free, reverse phase high performance liquid chromatography (HPLC) method is developed for the determination of melamine in dry and liquid infant formula. The separation is performed on a Kromasil C18 column (150 mm x 3.2 mm I.D., 5 microm particle size) at room temperature. The mobile phase (0.1% TFA/methanol 90:10) is pumped at a flow rate of 0.3 mL min(-1) with detection at 240 nm. Melamine elutes at 3.7 min. A linear response (r0.999) is observed for samples ranging from 1.0 to 80 microg mL(-1). The method provides recoveries of 97.2-101.2% in the concentration range of 5-40 microg mL(-1), intra- and inter-day variation in1.0% R.S.D. The limit of detection (LOD) and limit of quantification (LOQ) values are 0.1 microg mL(-1) and 0.2 microg mL(-1), respectively.

Titration calorimetry has been used to determine the enthalpies of protonation (ΔH HM ) of the iridium in the Cp'Ir(1,5−COD) (Cp'=C 5 Me x H 5−x , x=0, 1, 3−5) complexes according to the following reactions: Cp'Ir(1,5−COD)+CF 3 So 3 H (0.1 M)→[Cp'Ir(H)(1,5−COD) + CF 3 So 3 − , at 25.0°C in 1,2-dichloroethane

The design and synthesis of environmental sensors have become an increasingly important area of research. Particularly acute is the need to detect environmentally hazardous substances such as VOCs (volatile organic compounds) down to the part per million level and lower. Many detection systems that consist of a chemically sensitive layer and a transducer device have been proposed: conducting polymers; Langmuir-Blodgett multilayers deposited on waveguide surfaces, a quartz crystal microbalance (QCM), or a surface acoustic wave (SAW) device; and lifetime sensing of fluorescence with phase modulated detection. In general, the underlying data acquisition and analysis instrumentation of the transducer is in hand, but the design of rugged, well-characterized chemically sensitive layers has only more recently been addressed. We have set out to design, synthesize, and study crystalline host compounds that show a pronounced shift in visible absorption or emission spectra upon inclusion of organic vapor guest molecules ({open_quotes}vapochromism{close_quotes}). Host compounds of this type with the proper sensitivity and selectivity could easily find use as the chemically sensitive layer in optical detection schemes. Described here are the first mechanistic studies of the [Pt(aryl isonitrile){sub 4}][Pd(CN){sub 4}] compounds reported by Nagel{sup 5} to change color reversibly when exposed to VOC vapors. 17 refs.,more » 3 figs., 1 tab.« less

For a direct quantitative investigation of the Csp(2)-Csp(2) reductive elimination rate within a catalytic cycle, a novel oxidative coupling system in the presence of a Ni catalyst and desyl chloride as the oxidant is devised. The reaction progress profiles of arylzinc reagents exhibit zero-order kinetic behavior, and a reductive elimination step is confirmed as the rate-determining step. This allows direct measurement of the Csp(2)-Csp(2) reductive elimination rate constant within a catalytic cycle. The rate constants of p-MePhZnCl are obtained in the range 0.23 to 3.5 s(-1) from 0 to -35 degrees C, which are unusually fast reaction rates. According to the Arrhenius equation, the values of DeltaH(double dagger) and DeltaS(double dagger) (DeltaH(double dagger) = 9.7 kcal mol(-1), DeltaS(double dagger) = 35 J mol(-1) K(-1)) are obtained. The small value of DeltaH(double dagger) reveals that the reductive elimination step of Csp(2)-Ni-Csp(2) is an extremely facile process.

Union College is a small liberal arts college in the northeast with a good reputation in science. It is also one of the oldest schools in the nation, having been founded in 1795. Langmuir and Steinmetz taught here as did Chandler, the founder of the American Chemical Society and Ellery, one of the longest tenured Secretaries of Sigma Xi. Arthur and Carter became U.S. Presidents. We claim a Nobel Prize winner, the inventor of transistors, the person who developed the methods for producing quartz crystals and fiber optics. The presidents of du Pont and Kodak attended Union College. We are referred to as the "Mother of Fraternities," and we had the first radio station on a college campus (although not through the airways). Still, until recently, our reputation has been less than admirable among radiation safety experts. This article highlights some of the experiences of a new RSO at this well-acknowledged institution.

Tetramethyltrifluoromethylcyclopentadienide 1 a is unstable in solution but it can be readily generated in the gas phase. The proton affinities and fluoride binding energies of la and several other trifluoromethyl substituted cyclopentadienides are measured. The data is found to fit an additivity scheme, which suggests that pentakis(trifluoromethyl)cyclopentadiene is an exceptionally strong gas-phase acid, and indicates that substituted trifluoromethylcyclopentadienides may be accessible in solution under the appropriate reaction conditions.