Capillary gas chromatography of lower aliphatic C2?C5 aldehydes in the free form as a group of pungent odorants in air

The capillary gas chromatography of the C₂-C₅ lower aliphatic aldehydes (e.g.,acetaldehyde, propionaldehyde, n- and i-butyraldehydes, n- and i-valeraldehydes) which, in the free form in air, have unpleasant odors and low threshold odor values, has been studied using cold-trap preconcentration with liquid oxygen. The capillary column outlet was connected to enable simultaneous detection by FID, ECD, FPD AND FTD (SID).     

Analysis of light hydrocarbons C1–C5 with Porous Layer Open Tubular fused silica columns of aluminum oxide. Part 1: The column

A method is described for the preparation of a Porous Layer Open Tubular (PLOT) fused silica column coated with submicron particles of aluminum oxide for the analysis of light hydrocarbons. The column is thermally stable and provides reproducible analytical data over a long period of time. The column can be operated at temperatures easily controlled by commercially available gas chromatographic apparatus. 1,3-Butadiene is retarded much more than its principal impurities: thus the polarity of aluminum oxide is extremely useful for butadiene analysis because none of the contaminants is obscured by the butadiene peak. The analysis of the 16 most common C₁–C₄ hydrocarbons is achieved within 5 min at 60°C with helium as the carrier gas. Conditioning of the carrier gas with water vapor from CuSO₄.5H₂O to decrease the activity of the aluminum oxide is described. Some applications of a 30 m × 0.32 mm aluminum oxide PLOT column are given.     

Improvement of the Detection Limit in Capillary Gas Chromatographic Trace Analysis of C2–C4 Hydrocarbons by Post Column Cryogenic Trapping

A method for the improvement of signal-to-noise ratios and hence detection limits in capillary gas chromatographic trace analysis of C₂–C₄ hydrocarbons was developed. It is based on the post column cryogenic trapping of the separated hydrocarbons using liquid nitrogen as coolant and its fast reinjection into the detector by rapid heating of the capillary tubing used for trapping. The improved signal-to-noise ratios were applied to decrease the sample volume and/or to lower the detection limit 10 to 27 times. The concentrations of these hydrocarbons in an urban air sample determined without and with post column cryogenic trapping were in good agreement but the precision was better when applying the cryogenic trapping mode.     

Determination of the isomeric distribution and associated impurities in commercial diethylbenzenes by capillary gas chromatography

A capillary gas chromatographic method for the quantitative analysis of diethylbenzene fractions is described. Estimation of ortho-, meta- and para-isomers and other C₉ and C₁₀ aromatic impurities is covered. The conditions developed involve the use of a capillary column of Carbowax-1540 (300 feet × 0.01 inch) under isothermal operation. The retention index data for a number of aromatics are presented at four temperatures (90, 100, 110 and 120°C). The method offers a good choice for any level of concentration both for isomers and impurities commonly encountered within a reasonable analysis time.     

On the Constant Pressure Specific Heat CP of a Simple Fluid

Abstract

Calculation of C_P from a model soft-core equation of state reveals a line in the phase diagram on which C_P is equal to its zero pressure value C _{P 0} . This line commences on the temperature axis where the second virial coefficient has a point of inflexion. At higher temperatures (and pressures) C_P falls below C _{P 0} . The detailed behaviour of C_P is presented via contour maps, illustrating the effects of changing the exponent N(= 3/n, where n is the repulsive potential exponent) which parameterizes the model. For soft-core fluids at high temperatures C_P deviates only slightly from the ideal gas value over a wide range of temperature and density, in marked contrast to the behaviour of hard-core models.     

辐照气氛对异丙氧基杯[4]冠-6辐解的影响

异丙氧基杯[4]冠-6(1,3-交替-25,27-二(2-丙氧基)杯[4]芳烃-26,28-冠-6, 简称BPC6)对高放废液中的放射性Cs离子具有很好的选择萃取性能, 然而在萃取过程中BPC6 会受到强辐射场辐照, 所以有必要研究其辐射稳定性. 本文应用气相色谱(GC)、傅里叶变换显微红外(Micro-FTIR)和核磁共振(NMR)谱等手段分析了BPC6 固体分别在O₂和N₂气氛下的γ辐照效应. 结果表明, 当剂量为1 MGy时, O₂气氛下BPC6 的辐解率明显高于N₂(分别约为10.4%和2.5%), 而且气体辐解产物也有很大差异, 在O₂气氛下主要为H₂、CH₄、CO和CO₂,而在N₂辐照气氛下还有C₂H₄、C₂H₆、C₃H₆和C₃H₈等产物. 通过综合分析气体与固体辐解产物, 我们提出BPC6在不同气氛下具有不同的辐解途径, 这将为BPC6 萃取体系的辐射效应研究提供新的方法与思路, 加深对其辐解机理的认识.     

Degradation of dehydrochlorinated poly(epichlorohydrin) using photo-generated cationic catalysts

The photochemical reaction of polymer containing vinyloxy group (P-1), which was prepared from treating poly(epichlorohydrin) with base using a phase transfer catalyst, was investigated in the presence of a photo-generated cationic catalyst (PGCC). When the polymer with PGCC was irradiated, the vinyloxy group in the polymer disappeared rapidly. The rate of disappearance of the vinyloxy group in P-1 was strongly influenced by its content in the polymer and the kind of PGCC. P-1, containing about 65 mol% of vinyloxy group, had the highest photochemical reactivity, and PGCC with PF₆^? and SbF₆^? as counterions showed higher catalytic activity than those with BF₄^? The photochemical reaction of P-1 involved a number of reactions such as degradation, rearrangement, and crosslinking reaction competitively; however, P-1 with less vinyloxy group than 60 mol% degraded preferentially. These results suggested that P-1 is an excellent photodegradating polymer using PGCC. The thermal degradation of P-1 was also investigated.     

Computational investigation of solvent effect on the structure,spectroscopic properties (13C, 1H NMR and IR,UV), NLO properties and HOMO–LUMO analysis of Ru(NHC)2Cl2(=CH-p-C6H5) complex

This paper presents, a theoretical study of the structural, ¹³C and ¹H NMR chemical shifts, electronic transitions, vibrational analysis, and first hyperpolarizability for Ru(NHC)₂Cl₂(=CH-p-C₆H₅) complex in gas phase and different solvents. The solvent effect on structural parameters, frontier orbital energies, Ru=C_carbene and C_carbene-H stretching frequencies, and chemical shifts of C_carbene, C_NHC and H_carbene of complex was explored based on Polarizable Continuum Model (PCM). The wavenumbers of υ(Ru=C_carbene) and υ(C_carbene-H) of complex in different solvents were correlated with the Kirkwood–Bauer–Magat equation (KBM). As well as, the polarizability and the first order hyperpolarizability values of the investigated compound were computed in various solvents.     

Reductive Dimerization of Triruthenium Clusters Containing Cationic Aromatic N‐Heterocyclic Ligands

The cationic cluster complexes [Ru₃(μ‐H)(μ‐κ²N,C‐L¹ Me)(CO)₁₀]⁺ ( 1 ⁺; HL¹ Me=N‐methylpyrazinium), [Ru₃(μ‐H)(μ‐κ²N,C‐L² Me)(CO)₁₀]⁺ ( 2 ⁺; HL² Me=N‐methylquinoxalinium), and [Ru₃(μ‐H)(μ‐κ²‐N,C‐L³ Me)(CO)₁₀]⁺ ( 3 ⁺; HL³ Me=N‐methyl‐1,5‐naphthyridinium), which contain cationic N‐heterocyclic ligands, undergo one‐electron reduction processes to become short lived, ligand‐centered, trinuclear, radical species ( 1 – 3 ) that end in the formation of an intermolecular C? C bond between the ligands of two such radicals, thus leading to neutral hexanuclear derivatives. These dimerization processes are selective, in the sense that they only occur through the exo face of the bridging ligands of trinuclear enantiomers of the same configuration, as they only afford hexanuclear dimers with rac structures (C₂ symmetry). The following are the dimeric products that have been isolated by using cobaltocene as reducing agent: [Ru₆(μ‐H)₂{μ₆‐κ⁴N₂,C₂‐(L¹ Me)₂}(CO)₁₈] ( 5 ; from 1 ⁺), [Ru₆(μ‐H)₂{μ₆‐κ⁴N₂,C₂‐(L² Me)₂}(CO)₁₈] ( 6 ; from 2 ⁺), and [Ru₆(μ‐H)₂{μ₄‐κ⁸N₂,C₆‐(L³ Me)₂}(CO)₁₈] ( 7 ; from 3 ⁺). The structures of the final hexanuclear products depend on the N‐heterocyclic ligand attached to the starting materials. Thus, although both trinuclear subunits of 5 and 6 are face‐capped by their bridging ligands, the coordination mode of the ligand of 5 is different from that of the ligand of 6 . The trinuclear subunits of 7 are edge‐bridged by its bridging ligand. In the presence of moisture, the reduction of 3 ⁺ with cobaltocene also affords a trinuclear derivative, [Ru₃(μ‐H)(μ‐κ²N,C‐L^3′ Me)(CO)₁₀] ( 8 ), whose bridging ligand (L^3′ Me) results from the formal substitution of an oxygen atom for the hydrogen atom (as a proton) that in 3 ⁺ is attached to the C⁶ carbon atom of its heterocyclic ligand. The results have been rationalized with the help of electrochemical measurements and DFT calculations, which have also shed light on the nature of the odd‐electron species, 1 – 3 , and on the regioselectivity of their dimerization processes. It seems that the sort of coupling reactions described herein requires cationic complexes with ligand‐based LUMOs.     

Large Volume Injection in Fast Gas Chromatography with On‐Column Injector

In this work a fast gas chromatography set‐up with on‐column injection was optimized and evaluated with a model mixture of C₈–C₂₈ n‐alkanes. Usual injection volumes when using narrow‐bore (e. g., 0.1 mm i.d.) analytical columns are ca. 0.1 μL. The presented configuration allows introduction of 10–30‐fold larger sample volumes without any distortion of peak shapes. In the set‐up a normal‐bore retention gap (1 m×0.32 mm i. d.) was coupled to a narrow‐bore (4.8 m×0.1 mm i. d.×0.4 μm film thickness) analytical column using a low dead volume column connector. The effects of the experimental conditions such as inlet pressure, sample volume, initial injection temperature, and oven temperature on a peak focusing are discussed. H‐u curves for helium and hydrogen are used to compare their suitability for high speed gas chromatography and to show the dependence of separation efficiency on the carrier gas velocity at high inlet pressures. In the fast gas chromatography system a baseline separation of C₁₀–C₂₈ n‐alkanes was achieved in less than 3 minutes.     

High temperature gas chromatography for the analysis of fossil fuels: A review

For the past two or three decades geochemists have been concerned with the analyses and characterization of compounds, generally hydrocarbons, ranging from C₁? C₄₀. Significant amounts of information have resulted from these studies which have been extremely useful in many geochemical and environmental studies. However, in the past two or three years the commercial development and availability of high temperature gas chromatography columns has lead to the investigation of the occurrence and distribution of high molecular weight hydrocarbons (HMWHC), and other compounds, in the carbon number range C₄₀? C₁₀₀, present in oils, waxes, bitumens and rock extracts. The ability to study these compounds represents a major advance in organic geochemistry. In some samples these compounds may represent the bulk of the organic components but prior to development of the high temperature columns it was impossible to study their distributions. This paper will review advances that have occurred in terms of the application of high temperature gas chromatography (HTGC) to the analyses of fossil fuel samples and discuss the possible origin and significance of these compounds that have been identified. In addition, some of the potential problems involved in the analyses of these compounds will also be discussed.     

Direct Synthesis of Titanium Complexes with Chelating cis‐9,10‐Dihydrophenanthrenediamide Ligands through Sequential C?C Bond‐Forming Reactions from o‐Metalated Arylimines

A series of new titanium(IV) complexes with o‐metalated arylimine and/or cis‐9,10‐dihydrophenanthrenediamide ligands, [o‐C₆H₄(CH?NR)TiCl₃] (R=2,6‐iPr₂C₆H₃ ( 3 a ), 2,6‐Me₂C₆H₃ ( 3 b ), tBu ( 3 c )), [cis‐9,10‐PhenH₂(NR)₂TiCl₂] (PhenH₂=9,10‐dihydrophenanthrene; R=2,6‐iPr₂C₆H₃ ( 4 a ), 2,6‐Me₂C₆H₃ ( 4 b ), tBu ( 4 c )), [{cis‐9,10‐PhenH₂(NR)₂}{o‐C₆H₄(HC?NR)}TiCl] (R=2,6‐iPr₂C₆H₃ ( 5 a ), 2,6‐Me₂C₆H₃ ( 5 b ), tBu ( 5 c )), have been synthesised from the reactions of TiCl₄ with o‐C₆H₄(CH?NR)Li (R=2,6‐iPr₂C₆H₃, 2,6‐Me₂C₆H₃, tBu). Complexes 4 and 5 were formed unexpectedly from the reactions of TiCl₄ with two or three equivalents of the corresponding o‐C₆H₄(CH?NR)Li followed by sequential intramolecular C? C bond‐forming reductive elimination and oxidative coupling reactions. Attempts to isolate the intermediates, [{o‐C₆H₄(CH?NR)}₂TiCl₂] ( 2 ), were unsuccessful. All complexes were characterised by ¹H and ¹³C NMR spectroscopy, and the molecular structures of 3 a , 4 a – c , 5 a , and 5 c were determined by X‐ray crystallography.     

On-line single column capillary gas chromatographic analysis of all reactants and products in the synthesis of fuel methanol from hydrogen and oxides of carbon

The main problems with complete analysis of the components of fuel methanol, or in Fischer-Tropsch studies, are the several classes of compound present in the sample (permanent gases, water, alcohols, hydrocarbons), its wide range of components, its boiling point range, and the wide range of component concentrations. A flexible on-line GC method has been developed for kinetic study of catalyzed chemical reactions of hydrogen and oxides of carbon. The single capillary column, temperature programmed method was designed for complete analysis of reactants and products (hydrogen, carbon monoxide, carbon dioxide, water, C₁-C₁₀ hydrocarbons, and C₁-C₆ alcohols): a sample selection valve is used to switch between either the heated line used for input of the synthesis gases or the heated line used to transport reaction products from the reactor. Sample is introduced to the capillary column by means of a 10-port heated gas sampling valve with two external injection loops (0.07 and 1.95 cm³); this results in the determination of components over a wide range of concentrations in the sample (ppm to percentage levels). Helium from a pressure-controlled supply is used as carrier gas and detection of the components is performed by serial connection of thermal conductivity and flame ionization detectors. Peak identification is performed by mass spectrometry and by comparison of component retention times. The automated analytical equipment is integrated with a process control computer and delivers repeatable analytical results for the individual components (RSDs varying between 0.3 and 10% depending strongly on the concentration of the component and the accuracy of the determination of its peak area).     

On-line gas chromatographic analysis of light Fischer-Tropsch synthesis products

Summary A simple gas chromatographic system has been developed for the rapid on-line analysis of light Fischer-Tropsch products. This involves a single chromatography fitted with two columns, a porous-layer open-tubular column coated with KCl deactivated alumina and a packed Porapak-Q column. The capillary column separates the 16 most common C₁−C₄ hydrocarbons and permits a reasonable analysis of the hydrocarbons in the C₅−C₇ range. The packed column is used for the separation of methane, carbon monoxide, carbon dioxide, water and methanol. Retention characteristics for the analysis on the capillary column are presented. The total analysis cycle is 30 minutes.     

Providing Support in Favor of the Existence of a PdII/PdIV Catalytic Cycle in a Heck‐Type Reaction

The complex [Pd(O,N,C‐L)(OAc)], in which L is a monoanionic pincer ligand derived from 2,6‐diacetylpyridine, reacts with 2‐iodobenzoic acid at room temperature to afford the very stable pair of Pd^IV complexes (OC‐6‐54)‐ and (OC‐6‐26)‐[Pd(O,N,C‐L)(O,C‐C₆H₄CO₂‐2)I] (1.5:1 molar ratio, at ?55 °C). These complexes and the Pd^II species [Pd(O,N,C‐L)(OX)] and [Pd(O,N,C‐L′)(NCMe)]ClO₄, (X=MeC(O) or ClO₃, L′=another monoanionic pincer ligand derived from 2,6‐diacetylpyridine), are precatalysts for the arylation of CH₂?CHR (R?CO₂Me, CO₂Et, Ph) using IC₆H₄CO₂H‐2 and AgClO₄. These catalytic reactions have been studied and a tentative mechanism is proposed. The presence of two Pd^IV complexes was detected by ESI(+)‐MS during the catalytic process. All the data obtained strongly support a Pd^II/Pd^IV catalytic cycle.     

Reactivity of the Latent 12‐Electron Fragment [Rh(PiBu3)2]+ with Aryl Bromides: Aryl?Br and Phosphine Ligand C?H Activation

Oxidative addition of aryl bromides to 12‐electron [Rh(PiBu₃)₂][BAr^F₄] (Ar^F=3,5‐(CF₃)₂C₆H₃) forms a variety of products. With p‐tolyl bromides, Rh^III dimeric complexes result [Rh(PiBu₃)₂(o/p‐MeC₆H₄)(μ‐Br)]₂[BAr^F₄]₂. Similarly, reaction with p‐ClC₆H₄Br gives [Rh(PiBu₃)₂(p‐ClC₆H₄)(μ‐Br)]₂[BAr^F₄]₂. In contrast, the use of o‐BrC₆H₄Me leads to a product in which toluene has been eliminated and an isobutyl phosphine has undergone C? H activation: [Rh{PiBu₂(CH₂CHCH₃C H₂)}(PiBu₃)(μ‐Br)]₂[BAr^F₄]₂. Trapping experiments with ortho‐bromo anisole or ortho‐bromo thioanisole indicate that a possible intermediate for this process is a low‐coordinate Rh^III complex that then undergoes C? H activation. The anisole and thioanisole complexes have been isolated and their structures show OMe or SMe interactions with the metal centre alongside supporting agostic interactions, [Rh(PiBu₃)₂(C₆H₄O Me)Br][BAr^F₄] (the solid‐state structure of the 5‐methyl substituted analogue is reported) and [Rh(PiBu₃)₂(C₆H₄S Me)Br][BAr^F₄]. The anisole‐derived complex proceeds to give [Rh{PiBu₂(CH₂CHCH₃C H₂)}(PiBu₃)(μ‐Br)]₂[BAr^F₄]₂, whereas the thioanisole complex is unreactive. The isolation of [Rh(PiBu₃)₂(C₆H₄O Me)Br][BAr^F₄] and its onward reactivity to give the products of C? H activation and aryl elimination suggest that it is implicated on the pathway of a σ‐bond metathesis reaction, a hypothesis strengthened by DFT calculations. Calculations also suggest that C? H bond cleavage through phosphine‐assisted deprotonation of a non‐agostic bond is also competitive, although the subsequent protonation of the aryl ligand is too high in energy to account for product formation. C? H activation through oxidative addition is also ruled out on the basis of these calculations. These new complexes have been characterised by solution NMR/ESIMS techniques and in the solid‐state by X‐ray crystallography.     

Influence of the carrier gas on retention factors of gaseous hydrocarbons on polytrimethylsilylpropyne using capillary gas chromatography

The retention factor and height equivalent of a theoretical plate for gaseous hydrocarbons C₁—C₄ were studied on capillary columns with the layer of the new polymeric adsorbent polytrimethylsilylpropyne (PTMSP) as functions of the nature and pressure of the carrier gas. The retention factor k increases in the series helium < nitrogen < carbon dioxide. The k values depend linearly on the average pressure of the carrier gas in a capillary column with the adsorption PTMSP layer.     

Understanding the oxidation of the tricarbon radical C3H: A reaction pathway survey

The very recent observation of molecular oxygen in interstellar space appeals for the great need of mechanistic understanding of the oxidation processes of various interstellar species. In this article, we report for the first time, the oxidation mechanism of the chainlike l‐C₃H by molecular oxygen, which is known as one of the interesting carbon‐chain hydrocarbon series C_nH detected in space. This reaction is also relevant to the combustion processes where various carbon hydrides are involved. The detailed reaction pathways were identified at the CCSD(T)/aug‐cc‐pVTZ//B3LYP/6‐311++G(d,p)+ZPVE level including various fragmentation channels. Three types of fragmentation channels are identified as the C‐transfer product P₂ (CO₂+C₂H) (?129.2kcal/mol), the C,O‐exchange product P₁ (CO+HC₂O) (?154.7kcal/mol), and the O‐transfer product P₆ (³O+HC₃O) (?44.8kcal/mol). The initially entered unstable dioxygen isomer 1a HCCCOO (?26.6 kcal/mol) would either undergo the direct O‐extrusion to give P₆ (the intrinsic barrier 7.5 kcal/mol) or take a 1,2‐O‐shift (0.8 kcal/mol barrier) to give a stable isomer 5 HCCC(O)O (?139.2kcal/mol) that can either dissociate to P₁ or to P₂. The intrinsic barrier from 5 to P₁ and P₂ is 29.1 and 23.6 kcal/mol, respectively. Clearly, the entrance thermicity 26.6 kcal/mol of 1a can sufficiently initiate the subsequent formation of all the three products. To quantitatively evaluate the kinetic competition of the three products, we performed the master equation rate constant calculations. It was shown that at 298 K, the most favorable product is P₂ (64.8%) followed by P₆ (23.6%), and P₁ (11.6%). Interestingly, at elevated temperatures, the ratio of P₆ increases with the decrease of P₂, whereas that of P₁ is little changed. Notably, the thermodynamically most stable product P₁ is kinetically the least favorable, indicative of the importance of considering the kinetics. The dominant formation of P₂ (CO₂+C₂H) shows that the important carbyne radical l‐C₃H can be effectively degraded by O₂ via the chain‐shortening step. The reactivity of the cyclic c‐C₃H radical toward O₂ is also discussed. The results are expected to enrich our understanding of the chemistry of the simplest C₃‐radical in both combustion and interstellar processes. © 2013 Wiley Periodicals, Inc.     

Structure-permeability relationships in silicone polymers

Permeability coefficients P for He, O₂, N₂, CO₂ CH₄, C₂H₄, C₂H₆, and C₃H₈ in 12 different silicone polymer membranes were determined at 35.0°C and pressures up to 9 atm. Values of P for CO₂, CH₄, and C₃H₈ were also determined at 10.0 and 55.0°C. In addition, mean diffusion coefficients D and solubility coefficients S were obtained for CO₂, CH₄, and C₃H₈ in 6 silicone polymers at 10.0, 35.0, and 55.0°C. Substitution of increasingly bulkier functional groups in the side and backbone chains of silicone polymers results in a significant decrease in P for a given penetrant gas. This is due mainly to a decrease in D , whereas S decreases to a much lesser extent. Backbone substitutions appear to have a somewhat lesser effect in depressing P than equivalent side-chain substitutions. The selectivity of a silicone membrane for a gas A relative to a gas B, i.e., the permeability ratio P (A)/P (B), may increase or decrease as a result of such substitutions, but only if the substituted groups are sufficiently bulky. The selectivity of the more highly permeable silicone membranes is controlled by the ratio S (A)/S (B), whereas the selectivity of the less permeable membranes depends on both the ratios D (A)/D (B) and S(A)/S(B). The permeability as well as the selectivity of one silicone membrane toward CO₂ were significantly enhanced by the substitution of a fluorine-containing side group that increased the solubility of CO₂ in that polymer.     

Palladium(II) complexes of Y,C,Y‐chelated phosphines: synthesis,structure, and catalytic activity in Suzuki–Miyaura reaction

The phosphines L¹PPh₂ (1) and L²PPh₂ (2) containing different Y,C,Y‐chelating ligands, L¹ = 2,6‐(^tBuOCH₂)₂C₆H₃^? and L² = 2,6‐(Me₂NCH₂)₂C₆H₃^?, were treated with PdCl₂ and di‐µ‐chloro‐bis[2‐[(N,N‐dimethylamino)methyl]phenyl‐C,N]‐dipalladium(II) and yielded complexes trans‐{[2,6‐(^tBuOCH₂)₂C₆H₃]PPh₂}₂PdCl₂ (3), {[2,6‐(Me₂NCH₂)₂C₆H₃]PPh₂} PdCl₂ (4), {[2,6‐(^tBuOCH₂)₂C₆H₃]PPh₂}Pd(Cl)[2‐(Me₂NCH₂)C₆H₄] (5) and {[2,6‐(Me₂NCH₂)₂C₆H₃]PPh₂}Pd(Cl)[2‐(Me₂NCH₂)C₆H₄] (6) as the result of different ability of starting phosphines 1 and 2 to complex PdCl₂. Compounds 3–6 were characterized by ¹H, ¹³C, ³¹P NMR spectroscopy and ESI‐MS. The molecular structures of 3,4 and 6 were also determined by X‐ray diffraction analysis. The catalytic activity of complexes 3–6 was evaluated in the Suzuki‐Miyaura cross‐coupling reaction. Copyright © 2010 John Wiley & Sons, Ltd.