Olefinic Double Bond Research Articles

Copolymerization of norbornene and n-butyl methacrylate catalyzed by bis-(β-ketoamino)nickel(II)/B(C6F5)3 catalytic system

Copolymerization of norbornene with n-butyl methacrylate (n-BMA) was carried out with catalytic systems of bis-(β-ketoamino)nickel(II) complexes Ni{RC(O)CHC[N(naphthyl)]CH3}2 (R = CH3, CF3) and B(C6F5)3 in toluene and exhibited high activity for both catalytic systems. Influence of the catalyst structure and comonomer feed content on the polymerization activity as well as on the incorporation rates were investigated. The catalysis was proposed to involve the insertion mechanism of norbornene and n-BMA catalyzed by bis-(β-ketoamino)nickel(II)/B(C6F5)3 catalytic systems, and the decreasing polymerization activity with an increasing content of n-BMA in the feedstock composition could be attributed to the competition of carbonyl group coordination onto the Ni(II) active center instead of the olefin double bond. The reactivity ratios were determined to be r n-BMA = 0.095 and r norbornene = 12.626 by the Kelen–TUdOs method. The copolymer films prepared show good transparency in the visible region. The vinyl-addition copolymerizations of norbornene and n-BMA, catalyzed by bis-(β-ketoamino)nickel(II) complex Ni{RC(O)CHC[N(naphthyl)]CH3}2 (R = CH3, CF3)/B(C6F5)3, led to a significant incorporation percentage of poly(n-butyl methacrylate) in the resulting copolymer with good solvent solubility and transparency. The complex Ni{RC(O)CHC[N(naphthyl)]CH3}2 with R = CF3 substitute exhibit higher catalytic activity than that with R = CH3 substitute in the presence of B(C6F5)3 as cocatalyst for the copolymerization.

Rapid Chemical Antagonism of Neuromuscular Blockade by l-Cysteine Adduction to and Inactivation of the Olefinic (Double-bonded) Isoquinolinium Diester Compounds Gantacurium (AV430A), CW 002, and CW 011

The ultra-short-acting neuromuscular blocker gantacurium is chemically degraded in vitro by rapid adduction of L-cysteine to its central olefinic double bond. Preliminary data have suggested that exogenous (intravenous) L-cysteine abolishes gantacurium blockade. Two new analogues of gantacurium (CW 002 and CW 011) have been synthesized to undergo slower L-cysteine adduction, yielding intermediate duration. L-cysteine adduction to and antagonism of these novel agents is further defined herein. Comparative reaction half-time for L-cysteine adduction in vitro of the three compounds was determined by high-performance liquid chromatography. ED95 for twitch inhibition in monkeys under isoflurane was calculated, and duration at approximately 4-5x ED95 was correlated with reaction half-time for adduction. Speed of L-cysteine antagonism was contrasted with anticholinesterase reversal. Potencies of CW 002 and its adduction product were compared to provide a basis for L-cysteine antagonism. Rate of L-cysteine adduction in vitro (reaction half-time) was 11.4 and 13.7 min for CW 002 and CW 011 versus 0.2 min for gantacurium, and was inversely related to duration of block (P < 0.0001). CW 002 and CW 011 were 3x longer acting than gantacurium (28.1 and 33.3 min vs. 10.4 min), but only half the duration of cisatracurium. The adduct of CW 002 was approximately 70x less potent than CW 002. L-cysteine (10-50 mg/kg intravenously) given 1 min after approximately 4-5x ED95 doses of all the three compounds abolished block within 2-3 min. L-cysteine adduction occurs at different rates by design in olefinic isoquinolinium diester neuromuscular blockers, yielding corresponding durations of action. Antagonism by exogenous L-cysteine is superior to anticholinesterases, inducing inactivation of the active molecules to restore function rapidly at any time.

ChemInform Abstract: Arylmethyl Esters as Protecting Groups for Carboxylic, Carbonic, and Carbamic Acids: Deprotection via Homogeneous Palladium-Catalyzed Hydrogenolysis.

Abstract 4-Quinolylmethyl (4-QUI) esters of carboxylic acids and 1-naphthylmethyl (1-NAP) esters of carbonic and carbamic acids are reduced by palladium-catalyzed hydrogenolysis by formate anion. The reaction conditions are compatible with the presence of a benzyl ester and of an alkene double bond.

Recent Progress in&amp;amp;nbsp;Oxidative Bromination of Organic Compounds

The research progress on oxidative bromination reactions of compounds with functional groups including α-carbonyl hydrogen,the ring of arene,alkene double bond,the side chain of arene and alkanes is reviewed.The main oxidation of bromide system is Br-/H2O2 and Br-/BrO-3.The different conditions of reaction are discussed in detail.The perspective on this research field is also suggested.

(2E)-1-(1,3-Benzodioxol-5-yl)-3-(2-bromo-phen-yl)prop-2-en-1-one.

The mol­ecule of the title compound, C16H11BrO3, is essentially planar with a maximum deviation of 0.178 (4) Å and the configuration of the keto group with respect to the olefinic double bond is typically s-cis. In the crystal structure, inter­molecular Br⋯O inter­actions [3.187 (3)Å] give rise to chains parallel to the b axis. Adjacent chains are further linked along the a axis by C—H⋯π inter­actions. The crystal studied was a racemic twin with a 0.595 (13):0.405 (13) ratio.

Modular synthesis of a block copolymer with a cleavable linkage via “click” chemistry

A diblock copolymer poly(ethylene glycol)-block-polystyrene or PEG-b-PS with an olefinic double bond at the PEG and PS junction has been prepared by modular synthesis via “click” chemistry. This involved the synthesis of PS by atom transfer radical polymerization and the nucleophilic substitution of the terminal bromide group with azide to yield azide-terminated PS. PEG with an alkynyl terminal group was prepared from reacting carboxyl-end-functionalized PEG with 4-hydroxybut-2-enyl prop-2′-ynyl succinate, which contained an alkynyl group as well as an olefin group. The PS and PEG polymers were linked via the 1,3-dipolar cycloaddition of the end azide and alkyne groups. The obtained copolymer was characterized by 1H NMR spectroscopy and size exclusion chromatography (SEC). SEC analysis indicated that the diblock copolymer produced could be readily cleaved by ozonolysis to regenerate the constituent homopolymers.

(3E,5E)-3,5-Bis(4-allyloxybenzylidene)-1-benzylpiperidin-4-one

In the title compound C32H31NO3, the all­yloxy groups on either side of the piperidin-4-one ring are conformationally disordered. The contribution of major and minor components of the allyloxy group at the 3rd position of the ring are 0.576 (4) and 0.424 (4), respectively, and those at the 5th position are 0.885 (3) and 0.115 (3), respectively. The six-membered piperidin-4-one ring adopts a sofa conformation with the benzyl group occupying an equatorial position and the olefinic double bonds possessing an E configuration. Flanking phenyl substituents are stretched out on either side of the six-membered ring. π–π inter­actions with a centroid–centroid distance of 3.885 (1) Å give rise to mol­ecular dimers and short C—H⋯π contacts lead to chains along the c axis.

(E)-1-Nitro-4-(2-nitroethenyl)benzene

The asymmetric unit of the title compound, C8H6N2O4, consists of two independent mol­ecules with similar geometries, each adopting a trans configuration about the olefinic double bond. The two mol­ecules are both almost planar (r.m.s. deviations = 0.034 and 0.035 Å) and form a dihedral angle of 83.62 (2)°. Short N⋯O contacts [2.834 (3)–2.861 (3) Å] are observed between the nitro groups of neighbouring mol­ecules, with the O atom located directly atop the p orbital of the N atom. In the crystal, the mol­ecules are linked into a three-dimensional network by the N⋯O inter­actions and by C—H⋯O hydrogen bonds.

1,5-Bis(pentafluorophenyl)-3-phenylpent-2-ene-1,5-dione

In the title compound, C23H8F10O2, the three arene rings are twisted one with respect to the other: the two perfluorinated arene rings are tilted to each other by an angle of 60.39 (7)°. They are inclined to the non-fluorinated phenyl unit by 38.85 (7) and 78.74 (7)°. The olefinic double bond adopts an E configuration. The carbonyl groups are not in a coplanar alignment with reference to the neighbouring arene rings. The crystal packing features a number of weak C—H⋯F inter­actions, which leads to the formation of a three-dimensional network.

(E)-1-(2-Nitroethenyl)naphthalene

The title mol­ecule, C12H9NO2, adopts a trans configuration about the olefinic double bond. The dihedral angle between the naphthalene ring system (r.m.s. deviation = 0.012 Å) and the nitro­ethenyl group (r.m.s. deviation = 0.032 Å) is 12.66 (5)°. The mol­ecules are linked into a two-dimensional network parallel to the bc plane by C—H⋯O hydrogen bonds. The substituted benzene rings in adjacent networks are stacked with a centroid–centroid distance of 3.6337 (11) Å, indicating π–π inter­actions.

Dichlorido(η4-cycloocta-1,5-diene)bis(triphenylphosphine)osmium(II)

The OsII atom in the title compound, [OsCl2(C8H12)(C18H15P)2], is located on a crystallographic twofold axis and adopts a distorted octa­hedral coordination geometry. The two triphenyl­phosphine ligands are trans to each other, while the two chlorine ligands are cis-disposed. The coordination is completed by the cyclo­octa­diene (COD) ligand with bonding to the two olefin double bonds. The C=C bond has a length of 1.403 (6) Å, which is significntly longer than a free olefinic double bond (≃1.34 Å).

(E)-3-(4-Fluorophenyl)-1-phenyl-2-propen-1-one

In the title compound, C15H11FO, the configuration of the keto group with respect to the olefinic double bond is s–cis. The dihedral angle between the planes of the two benzene rings is 10.61 (10)°. The crystal packing is stabilized by C—H⋯π inter­actions involving both benzene rings.

(E)-1-(4-Nitrophenyl)-3-phenylprop-2-en-1-one

In the title compound, C15H11NO3, the configuration of the keto group with respect to the olefinic double bond is s–cis. The two benzene rings form a dihedral angle of 5.00 (5)°. The mol­ecules are linked into a two-dimensional network parallel to (04) by C—H⋯O hydrogen bonds.

Synthesis, crystal structure and silver complexation of a novel saddle-shaped stilbenophane: NMR and theoretical study on the complex

A new Z,Z-stilbenophane was synthesised and characterised. According to an X-ray structure analysis, the structure has a saddle shape, with the π-electrons of the double bonds and the oxygen atoms pointing towards the centre of a cavity. The ligand forms a 1:1 complex with Ag+. Both NMR spectra and theoretical analysis (Gauge-independent atomic orbitals (GIAO) and Quantum theory of atoms in molecules (QTAIM)) suggest that the silver cation is bound within the molecular cavity. The metal is coordinated by the two olefinic double bonds and the four oxygen atoms in an approximately octahedral environment. The coordination motif is unusual because the soft silver cation prefers the interaction with the four hard oxygen atoms over the bonding to the arene units, which is frequently observed in Ag+ arene complexes.

Synthesis and Structural Characterization of [Ag(H-dpa) (η2-styrene)]BF4: Comparing Silver and Copper for Olefin Binding

The molecular structure of the complex bis-(2-pyridyl)amine(η2-styrene)silver(I) tetrafluoroborate has been determined. The geometry about the Ag+ ion is pseudo-trigonal planar, with coordination sites occupied by the two pyridyl nitrogen atoms and the midpoint of the alkene double bond. Crystal packing of the molecule is influenced by hydrogen bonding of the amine with the tetrafluoroborate anion, in addition to intermolecular Ag+···aromatic contacts. 1H NMR confirms crystallographic data that suggest weak metal to olefin π-backbonding. Crystal data: space group P21/n, a = 12.764(3), b = 10.590(2), c = 13.624(3) A, β = 91.17(3)°, V = 1841.3(7) A3, Z = 4, R = 0.0453, wR 2 = 0.1098. The geometry about the Ag+ ion in [Ag(H-dpa)(η2-styrene)]BF4 is pseudo-trigonal planar, with coordination sites occupied by the two pyridyl nitrogen atoms and the midpoint of the alkene double bond. Crystal packing of the molecule is influenced by hydrogen bonding of the amine with the tetrafluoroborate anion, in addition to intermolecular Ag+···aromatic contacts.

Carbon xerogel supported noble metal catalysts for fine chemical applications

Carbon xerogels are mesoporous materials obtained upon pyrolysis of the dried gels resulting from polycondensation of resorcinol and formaldehyde. Treatment with nitric acid under severe conditions introduces high amounts of oxygen containing functional groups onto the surface of the material, leading however to the collapse of its porous structure. The resulting material is then used to support 1 wt.% Pt, Ir and Ru monometallic catalysts by wet impregnation using organometallic precursors. The catalysts are characterized by N 2 adsorption–desorption isotherms at 77 K, temperature programmed desorption coupled with mass spectrometry, scanning and transmission electron microscopy, and H 2 chemisorption. The liquid-phase selective hydrogenation of cinnamaldehyde to cinnamyl alcohol is used in order to assess the catalytic performance of the prepared materials. Pt and Ru catalysts are initially very selective towards the hydrogenation of the olefinic double bond, while Ir is mostly selective towards the carbonyl group. After a thermal post-reduction treatment at 973 K, selectivity towards cinnamyl alcohol is significantly improved regardless of the metal nature. The Pt catalyst exhibits the best behavior, a complete shift in C=C to C=O hydrogenation being detected. The improvement in selectivity is rationalized in terms of both an increase in metal particle size and a modification in the surface chemistry of the catalyst after the post-reduction treatment.

Synthesis of All-Trans High Molecular Weight Poly(N-alkylcarbazole-2,7-vinylene)s and Poly(9,9-dialkylfluorene-2,7-vinylene)s by Acyclic Diene Metathesis (ADMET) Polymerization Using Ruthenium−Carbene Complex Catalysts

Syntheses of poly(9,9-dialkylfluorene-2,7-vinylene)s (PFVs, alkyl = n-hexyl, n-octyl, 2′-ethylhexyl) and poly(N-alkylcarbazole-2,7-vinylene)s (PCVs, alkyl = n-octyl, 9′-heptadecanyl) by acyclic diene metathesis (ADMET) polymerization using Ru−carbene complexes have been explored. The polymerizations in the presence of Ru(CHPh)(Cl)2(IMesH2)(PCy3) and Ru(CH-2-OiPr-C6H4)(Cl)2(IMesH2) [Cy = cyclohexyl, IMesH2 = 1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene] afforded relatively high molecular weight PFVs, PCV (alkyl = 9′-heptadecanyl) with unimodal molecular weight distributions, and the olefinic double bonds in the resultant polymers possessed highly trans regularity in all cases. The resultant defect-free PFVs possessed higher absolute quantum yields (Φ = 92−99%) than those reported previously, whereas no significant differences in the UV−vis and the fluorescent spectra (absorption bands, peak maxima) in the resultant PFVs were observed as an effect of alkyl side chain in the 9-position. The UV−vis an...

Efficient Synthesis of Functionalized Polyolefin by Incorporation of 4-Vinylcyclohexene in Ethylene Copolymerization Using Half-Titanocene Catalysts

Copolymerizations of ethylene with vinylcyclohexene (VCHen) by using Cp′TiCl2(X) [X = O-2,6-iPr2C6H3, Cp′ = Cp* (1); X = N═CtBu2, Cp′ = Cp* (2) and Cp (3)] catalyst systems with MAO have been explored. The copolymerizations proceeded via vinyl addition/insertion affording high molecular weight copolymers containing cyclohexenyl side chains (with uniform compositions as well as with unimodal molecular weight distributions) accompanied with certain degree of side reaction (intramolecular cyclization after VCHen insertion). Degree of the side reaction (cyclization) was dependent upon the catalyst employed, polymerization temperature, but was not affected by the time course, the Al/Ti molar ratios. The Cp−ketimide analogue (3) showed the best catalyst performance in terms of both the catalytic activity and the selectivity (lowest degree of the subsequent intramolecular cyclization) in the copolymerization. Quantitative epoxidation of the olefinic double bonds in the resultant copolymer has been achieved by us...

Metathesis of carbonyl containing olefins by 2nd generation Ru alkylidene catalysts: A computational study

The metathesis reaction of cis-1,4-diacetoxy-2-butene ( 2) mediated by a second generation ruthenium alkylidene catalyst (IMesH 2)Cl 2Ru CHPh ( 1) where IMesH 2 is 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene group has been modeled at PBE0/LACV3P*//PBE0/LACVP* level of theory. The calculations demonstrate that the driving force of the metathesis reaction is the formation of a Ru–O coordination bond in the corresponding Ru acetoxyethylidene complex 8a-II. The free activation energy of metathesis by 8a-II complex is higher than that of the metathesis reaction mediated by the conventional ruthenium alkylidene catalyst ( 8b), due to the additional stabilization of the Ru center by a carbonyl oxygen revealing lower reactivity of carbonyl containing ruthenium carbene species. It has been shown that conjugation between carbonyl and olefin double bonds decreases the reactivity of olefins due stabilization of nonproductive complex between Ru center and carbonyl group of the olefin.

Photochemical [2+2] cycloaddition of the olefinic double bonds in the supramolecular rectangle [Ru4(η6-p-cymene)4(μ-oxalato)2(μ-4,4′-bipyridylethylene)2]4+

Abstract Self-assembly of 4,4′-bipyridylethylene (bpe) bidentate connector with the dinuclear arene ruthenium clip [Ru2(η6-p-cymene)2(μ-oxalato)Cl2] in the presence of silver triflate affords the cationic organometallic rectangle [Ru4(η6-p-cymene)4(μ-oxalato)2(μ-bpe)2]4+ ([1][CF3SO3]4). Upon UV irradiation of a methanol solution of [1]4+, dimerisation of the olefinic double bonds of the two parallel bpe ligands occurs, thus giving rise to the [2+2] cycloaddition derivative [Ru4(η6-p-cymene)4(μ-oxalato)2(μ-tpcb)]4+ ([2][CF3SO3]4) (tpcb = tetrakis(4-pyridyl)cyclobutane). The [2+2] photodimerisation reaction was followed by 1H NMR spectroscopy. Moreover, the molecular structure of these two systems was deduced by one-dimensional and two-dimensional NMR experiments (1H, 13C, ROESY, COSY, HSQC). These data suggest the formation of only the rctt-tetrakis(4-pyridyl)cyclobutane isomer.