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Wax esters play critical roles in biological systems, serving functions from energy storage to chemical signaling. Their diversity is attributed to variations in alcohol and acyl chains, including their length, branching, and the stereochemistry of double bonds. Traditional analysis by mass spectrometry with collisional activations (CID, HCD) offers insights into acyl chain lengths and unsaturation level. Still, it falls short in pinpointing more nuanced structural features like the position of double bonds. As a solution, this study explores the application of 213-nm ultraviolet photodissociation (UVPD) for the detailed structural analysis of wax esters. It is shown that lithium adducts provide unique fragments as a result of Norrish and Norrish-Yang reactions at the ester moieties and photoinduced cleavages of double bonds. The product ions are useful for determining chain lengths and localizing double bonds. UVPD spectra of various wax esters are presented systematically, and the effect of activation time is discussed. The applicability of tandem mass spectrometry with UVPD is demonstrated for wax esters from natural sources. The UHPLC analysis of jojoba oil proves the compatibility of MS2 UVPD with the chromatography time scale, and a direct infusion is used to analyze wax esters from vernix caseosa. Data shows the potential of UVPD and its combination with CID or HCD in advancing our understanding of wax ester structures. [ABSTRACT FROM AUTHOR]

Fatty acids (FAs) contain a vast amount of structural diversity, and differences in fatty acid structure have been associated with various disease states. Accurate identification and characterization of fatty acids is critical to fully understand the biochemical roles these compounds play in disease progression. Conventional tandem mass spectrometry (MS/MS) workflows do not provide sufficient structural information, necessitating alternative dissociation methods. Gas‐phase charge inversion ion/ion reactions can be used to alter the ion type subjected to activation to provide improved or complementary structural information. Herein, we have used an ion/ion reaction between fatty acid (FA) anions and magnesium tris‐phenanthroline [Mg(Phen)3] dications to promote charge remote fragmentation of carbon‐carbon bonds along the fatty acid chain, allowing for localization of carbon‐carbon double bond (C=C) positions to successfully differentiate monounsaturated fatty acid isomers. Relative quantification was also performed to obtain the relative abundance of fatty acid isomers in different biological tissues. For example, the relative abundance of FA 18 : 1 (9) was determined to vary across regions of rat brain, rat kidney, and mouse pancreas, and FA 16 : 1 (9) was found to have a higher relative abundance in the dermis layer compared to the sebaceous glands in human skin tissue. [ABSTRACT FROM AUTHOR]

A series of nematic liquid crystal (LC) monomers, containing a reactive group in the lateral substituent, were designed and synthesised through an organic synthesis reaction. Considerable changes were made to the properties of the liquid monomers by varying the terminal alkyl chain lengths. The molecular structures of the intermediates and the LC monomers were characterised by flourier infrared absorption spectrometry and proton nuclear magnetic resonance (1H NMR) spectroscopy, leading to the identification of the target product. The phase transition temperatures of the LC monomers were observed and analysed using differential scanning calorimetry (DSC) and polarising optical microscopy (POM) with a hot stage. The two-way thermotropic liquid crystalline behaviour was observed during the heating process, providing insight into the effect of substituent changes on the phase transition temperature. [ABSTRACT FROM AUTHOR]

The tetrasilyl‐substituted distannene, (tBu2HSi)2Sn=Sn(SiHtBu2)26, was synthesized by mild thermolysis (70 °C in hexane) of tris(di‐tert‐butyl‐hydridosilyl)stannane 4. The X‐ray crystallography structure of 6 reveals the following unusual structural properties: a planar geometry around both Sn atoms (Σ∡Sn=359.87°), a non‐twisted Sn=Sn double bond, and the shortest Sn=Sn double bond of 2.599 Å among all acyclic distannenes. Thus, compound 6 is the first reported distannene having a structure closely analogous to a classic alkene. Reactions of 6 with CCl4 or with 2,3‐dimethylbuta‐1,3‐diene to produce 1,2‐dichlorodistannane 9 and the [2+4] cycloadduct 10, respectively, are characteristic for a Sn=Sn double bond. [ABSTRACT FROM AUTHOR]

This article presents a new method for synthesizing allenes, a class of organic compounds with a unique structure. The method involves using methylthioalkynes as precursors to alkylidene carbenoids, which are then combined with other compounds to form the desired allenes. The authors discuss the experimental conditions and improvements made to the process to enhance efficiency and control over the stereochemistry of the products. However, they also acknowledge that further research is necessary to fully comprehend the mechanism and enhance the results. [Extracted from the article]

A facile synthesis for unprecedented stibastannene (10) featuring a Sn=Sb‐double bond together with the homologous arsa‐ (9) and phosphastannenes (8) is presented. Chloride abstraction from respective stannyl pnictinidenes [E=P (5), As (6), Sb (7)], which were made accessible by reduction of ECl3 addition products at an intramolecular phosphine‐stabilized stannylene, gave the pnictastannenes in moderate yields. The pnictastannenes coordinate Pd(PPh3)2 fragments (12–14) and the phosphastannene forms also a nickel coordination compound with the Ni(PPh3)2‐fragment (11). 2,3‐Dimethylbutadiene shows a [2+4]‐cycloaddition (15–17) in reaction with the pnictastannenes (8–10). Products of a [2+2]‐addition (18, 19) were isolated as the phosphaalkyne reaction products for 8 and 9. Addition of an O−H bond at the Sn=P‐bond was found in reaction of water with phosphastannene 8. Reaction with ammonia afforded the NH3‐adducts (21–23) at the tin atom for pnictastannenes 8–10. Only in the case of the arsastannene an azide reaction product featuring a three membered Sn−As−N‐ring was obtained. [ABSTRACT FROM AUTHOR]

A facile synthesis for unprecedented stibastannene (10) featuring a Sn=Sb‐double bond together with the homologous arsa‐ (9) and phosphastannenes (8) is presented. Chloride abstraction from respective stannyl pnictinidenes [E=P (5), As (6), Sb (7)], which were made accessible by reduction of ECl3 addition products at an intramolecular phosphine‐stabilized stannylene, gave the pnictastannenes in moderate yields. The pnictastannenes coordinate Pd(PPh3)2 fragments (12–14) and the phosphastannene forms also a nickel coordination compound with the Ni(PPh3)2‐fragment (11). 2,3‐Dimethylbutadiene shows a [2+4]‐cycloaddition (15–17) in reaction with the pnictastannenes (8–10). Products of a [2+2]‐addition (18, 19) were isolated as the phosphaalkyne reaction products for 8 and 9. Addition of an O−H bond at the Sn=P‐bond was found in reaction of water with phosphastannene 8. Reaction with ammonia afforded the NH3‐adducts (21–23) at the tin atom for pnictastannenes 8–10. Only in the case of the arsastannene an azide reaction product featuring a three membered Sn−As−N‐ring was obtained. [ABSTRACT FROM AUTHOR]

In this review, the latest achievements in the field of multiply bonded organogermanium derivatives, mostly reported within the last two decades, are presented. The isolable Ge-containing analogues of alkenes, alkynes, 1,3-dienes, allenes, and vinylidenes are discussed, and for each class of unsaturated organogermanium compounds, the most representative examples are given. The synthetic approaches toward homonuclear multiply bonded combinations solely consisting of germanium atoms, and their heteronuclear variants containing germanium and other group 14 elements, both acyclic and cyclic, are discussed. The peculiar structural features and nonclassical bonding nature of the abovementioned compounds are discussed based on their spectroscopic and structural characteristics, in particular their crystallographic parameters (double bond length, trans-bending at the doubly bonded centers, and twisting about the double bond). The prospects for the practical use of the title compounds in synthetic and catalytic fields are also briefly discussed. [ABSTRACT FROM AUTHOR]

The widely used alkyd resin suffers not only the flammability but also the autoignition of resin waste. Its autoignition should result from the air-drying exothermic effect due to autoxidation and conversion of double bond. However, the air-drying exothermic effect is seldom studied. In this study, five soybean oil-based alkyd resins were synthesized. The content of double bond measured by the titration method increased linearly with increasing the molar fraction of maleic anhydride. After air-drying, the infrared spectroscopy absorption peak for the double bond disappeared. Considering that the curing originated from the conversion of chemical bonds, the exothermic effect was theoretically analyzed to be 1163–1455 kJ mol−1 double bond based on the air-drying mechanisms and the differences among chemical bond energies. According to thermodynamics principles, the air-drying exothermic effect was also derived from the measured heat of combustion. When the content of double bond increased from 2.19 mol kg−1 resin to 2.56 mol kg−1 resin, the exothermic effect linearly increased from 1352 kJ mol−1 double bond or 2.96 kJ g−1 resin to 2508 kJ mol−1 double bond or 6.42 kJ g−1 resin. The steady and unsteady autoignition theoretical analyses implied that due to the air-drying exothermic effect the alkyd resin waste with a certain thickness would catch fire within one working day. [ABSTRACT FROM AUTHOR]

The design of porphyrin-based dendrimers featuring conjugated fluorenyl dendrons via alkene spacers allows evaluating the importance of the role of these spacers on the optical properties of interest. In the continuation of previous studies, a second-generation porphyrin-based dendrimer was synthesized and metalated by Zn(II) along with its known first-generation homologue. The targeted free-base porphyrin was obtained by repetitively cycling a Michaelis--Arbuzov reaction and a Horner--Wadsworth--Emmons reaction to construct the desired vinyl-containing dendrons. After metalation by Zn(II), meso-tetraphenylporphyrin-cored dendrimers with eight (ZnTPP-D1) and sixteen (ZnTPP-D2) fluorenyl arms at their periphery were eventually isolated. These species allow evaluating the influence of the central metal and of the 1,2-alkyne for 1,2-alkene exchange on fluorescence, oxygen photosensitization, and two-photon absorption. Such structure--property relationships are currently needed for the design of optimal dendrimeric photosensitizers allowing combined two-photon-based photodynamic therapy (2P-PDT) and imaging. [ABSTRACT FROM AUTHOR]

The topic of heavier main group compounds possessing multiple bonds is the subject of momentous interest in modern organometallic chemistry. Importantly, there is an excitement involving the discovery of unprecedented compounds with unique bonding modes. The research in this area is still expanding, particularly the reactivity aspects of these compounds. This article aims to describe the overall developments reported on the stable derivatives of silicon and germanium involved in multiple bond formation with other group 13, and heavier groups 14, 15, and 16 elements. The synthetic strategies, structural features, and their reactivity towards different nucleophiles, unsaturated organic substrates, and in small molecule activation are discussed. Further, their physical and chemical properties are described based on their spectroscopic and theoretical studies. [ABSTRACT FROM AUTHOR]

Linear polyester ether was prepared at room temperature by Michael polymerization of hydroxyl and double bond using phosphazene-bases as catalyst, 2-methyl-1,3-propanediol and diacrylate as monomers. The effects of catalyst type, catalyst concentration, feed ratio of monomer and monomer type of double bond on polymerization reaction were investigated. The polymer structure and polymer reaction mechanism were studied by fourier transform-infrared spectroscopy（FT-IR） and nuclear magnetic resonance（NMR）, and the molecular weight and molecular weight distribution of the prepared polymers were characterized by size-exclusion chromatography（SEC）. The results show that the relatively higher molecular weight of polymer was prepared by phosphazene-bases t-BuP2 with appropriate concentration. In addition, increasing the carbon chain length of double bond monomer or improving the molar ratio of diacrylate to alcohol hydroxyl monomer can reduce the interesterification side reaction, and obtain higher molecular weight linear polymers. [ABSTRACT FROM AUTHOR]

Local nature of the boron-nitrogen (BN) bonding with different formal multiplicities (B≡N, B=N, B-N) have been investigated for 25 experimentally established organoboron molecules in both real and the Hilbert space, using topological analysis of electron localization function (ELF), electron density (AIM), and natural bond orbital (NBO) method. Each BN bond has been represented (ELF) by the bonding disynaptic attractor V(B,N), with the basin electron population between 5.72e and 1.83e, confirming possible existence of all the three bond types. A covalent character of bonding can be associated with the dative mechanism due to the V(B,N) bonding basin formed mainly (91–96%) by the N electron density. Similarly, the NBO method shows 2-center natural orbitals, consisting largely of the hybrids from the N atom. The AIM analysis yields the features typical for shared (H(3,−1)(r) < 0) and closed-shell (∇2ρ(3,−1)(r) > 0) interactions. The delocalization indices, describing electron exchanges between B and N quantum atoms, are smaller than 1.5, even for formally very short triple B≡N bonds. [ABSTRACT FROM AUTHOR]

The average oil recovery by conventional water flooding from oil-wet and naturally fractured carbonate reservoirs is often less than 30%. Removal of adsorbed acidic components and/or asphaltene from the carbonate surface results in wettability alteration towards water-wet which is an effective approach to enhance oil recovery. Long chain fatty acids, long chain naphthenic acids and asphaltene are major components in crude oil which are responsible for wettability alteration in carbonate reservoirs while unsaturated acids have minor effect. In this study, a more accurate quantification of the effects of different types and structures of polar components that contribute to the initial oil-wetting extent of the reservoir rocks were used (aliphatic saturated acids, aliphatic unsaturated acids, naphthenic acids, aromatic acids and asphaltene). Different analytical tools (contact angle, zeta potential, Fourier transform infrared spectroscopy and thermal analysis) were utilized for all acids in order to study surface characteristics. The results indicated that polar organic compounds act in different ways according to their structure and properties. Presence of double bond could make the acid molecule more polar, reactive and less hydrophobic. In addition, it can affect the spatial arrangement of the molecule and hence its orientation on the surface. Presence of benzene ring increases the reactivity and polarity of carboxylic group. Moreover, it enhances hydrophilic properties of the acid due to electrons of π double bonds that can resonate over aromatic carbon atoms. The results revealed that, in the presence of water film, combination of acid dissociation in water, surface activity of acid and water solubility controls the acid adsorption and hence wettability alteration of the surface during aging process. Chemisorption of carboxylic acids/asphaltene changes the wettability of calcite surface. In addition to chemical adsorption, some acids adsorb physically on the surface. Physical adsorption of polar compounds may happen via hydrogen bonding between carboxylic groups and carbonate ions on the surface. Although physical adsorption is reversible and forms weak bonds between adsorbate and adsorbent, it may partially contribute to wettability alteration. • Polar organic compound act with calcite according to its structure and properties. • Double bond make the acid molecule more polar, reactive and less hydrophobic. • Presence of benzene ring increases the reactivity and polarity of carboxylic group. • Acid dissociation, surface activity and water solubility of acid control wettability. • Asphaltene adsorbed horizontally while carboxylic acids vertically on calcite. [ABSTRACT FROM AUTHOR]

The first divinyldiarsenes [{(NHC)C(Ph)}As]2 (NHC=IPr 3 a, SIPr 3 b; IPr=C{(NAr)CH}2; SIPr=C{(NAr)CH2}2; Ar=2,6‐iPr2C6H3) are reported. Compounds 3 a and 3 b were prepared by the reduction of corresponding chlorides {(NHC)C(Ph)}AsCl2 (NHC=IPr 2 a, SIPr 2 b) with Mg. Calculations revealed a small HOMO–LUMO energy gap of 3.86 (3 a) and 4.24 eV (3 b). Treatment of 3 a with (Me2S)AuCl led to the cleavage of the As=As bond to restore 2 a, which is expected to proceed via the diarsane [{(IPr)C(Ph)}AsCl]2 (4). Remarkably, 4 as well as 2 a can be selectively accessed on treatment of 3 a with an appropriate amount of C2Cl6. Moreover, 3 a readily reacts with PhEEPh (E=Se or Te) at room temperature to give {(IPr)C(Ph)}As(EPh)2 (E=Se 5 a; Te 5 b), revealing the cleavage of As=As and E−E bonds and the formation of As−E bonds. Such highly selective stepwise oxidation (3 a→4→2 a) and bond metathesis (3 a→5 a,b) reactions are unprecedented in main‐group chemistry. [ABSTRACT FROM AUTHOR]

Abstract Oxygen rich organic coatings are synthesized in a dielectric barrier discharge at atmospheric pressure. The critical effect of the precursor structure on the final chemical and physical properties of the synthesized coatings and the plasma characteristics are reported. A correlation is proposed between the electrical, optical emission spectroscopy and atmospheric mass spectrometry (MS) measurements of the plasma phase with the chemical properties of the synthesized films. It is shown that the addition of a precursor in an argon plasma leads to a stabilization of the discharge, critically dependent on the precursor structure itself. Different polymerization pathways are evidenced for the saturated and unsaturated precursors by the monitoring of some specific fragments by MS. The polymerized coatings are also characterized with X-Ray Photoelectron Spectroscopy, Infrared Spectroscopy and Atomic Force Microscopy. The presented results not only evidence a stronger preservation of the precursor structure with double bonds in the plasma phase but also reveal the essential role of the distance separating the unsaturation and a function of interest. Highlights • Double bonds in organic precursors modify the electrical behaviour of an atmospheric DBD • Double bonds in organic precursor induce a specific polymerization pathway in the plasma phase • A specific fragment for polymerization is evidenced when double bonds are present • The position of the double bond is of crucial importance in the preservation of the precursor chemistry [ABSTRACT FROM AUTHOR]

In the present investigation, 48 new tertiary amine derivatives of cinnamic acid, phenylpropionic acid, sorbic acid and hexanoic acid (4d-6g, 10d-12g, 16d-18g and 22d-24g) were designed, synthesized and evaluated for the effect on AChE and BChE in vitro. The results revealed that the alteration of aminoalkyl types and substituted positions markedly influences the effects in inhibiting AChE. Almost of all cinnamic acid derivatives had the most potent inhibitory activity than that of other acid derivatives with the same aminoalkyl side chain. Unsaturated bond and benzene ring in cinnamic acid scaffold seems important for the inhibitory activity against AChE. Among them, compound 6g revealed the most potent AChE inhibitory activity (IC50 value: 3.64 µmol/L) and highest selectivity over BChE (ratio: 28.6). Enzyme kinetic study showed that it present a mixed-type inhibition against AChE. The molecular docking study suggested that it can bind with the catalytic site and peripheral site of AChE. [ABSTRACT FROM AUTHOR]

Supramolecular gels are soft materials formed mainly by low molecular weight units held together by intermolecular interactions. Stabilizing these kinds of materials is quite a challenge due to the influence of multiple factors interfering with the integrity of the supramolecular structure. In our previous studies, we have shown that the aminocarbohydrate meglumine (MEG) interacts with organic acids by ion-pairing leading to the formation of MEG-carboxylate adducts. These adducts undergo supramolecular polymerization by heat treatment, but the macromolecular assembly was stable for a short period due to hydrogen bond (H-bond) breakup. Herein, we attempt to study the influence of hydrophobic building blocks on the formation of these compounds aiming to stabilize H-bonds to produce polymerizable supra-amphiphiles in water. Oleic acid and stearic acid are two analogous fatty acids differing only in the presence of unsaturation that were used in our studies. Results demonstrated that the presence of unsaturation hinders gelation in water by interfering with the self-assembly behavior of supra-amphiphiles. Thus, unsaturated supra-amphiphiles behave like traditional surfactants and gelify water at high concentrations (above 30% w/w). On the other hand, supramolecular gels with a polymer-like behavior could be produced with a saturated supra-amphiphile in water (above 4% w/w). The material was characterized by a lamellar arrangement that facilitates the alignment of H-bonds necessary to stabilize the self-assembled structure. These results have pivotal importance on the design of polymerizable supra-amphiphiles and demonstrate that the double bond of hydrophobic building blocks is an important design factor to be considered by scientists studying similar materials. [ABSTRACT FROM AUTHOR]

This work studies the effects of length and unsaturation of alkyl chain on the hydrophobic binding of curcumin with Tween 20, 60 and 80 micelles. While Tween 20 and 60 possess 12 and 18 saturated carbons, respectively, in their alkyl chains, the alkyl chain of Tween 80, with one double bond, has the same length as Tween 60. Tween 60 micelles are superior to Tween 20 and 80 micelles for improving curcumin stability. The fluorescence measurement suggests that Tween 60 micelles provide curcumin with the most hydrophobic microenvironment, owing to the long and saturated alkyl chain of Tween 60. The p K a1 and binding constants of curcumin have the same order of Tween 60 > Tween 20 > Tween 80. These results show that the length increase, and unsaturation, of the alkyl chain of Tween surfactants have opposite effects on the hydrophobic binding of curcumin with Tween micelles. [ABSTRACT FROM AUTHOR]

Obtaining structural information for lipids such as phosphatidylcholines, in particular the location of double bonds in their fatty acid constituents, is an ongoing challenge for mass spectrometry (MS) analysis. Here, we present a novel method utilizing the doping of liquid matrix-assisted laser desorption/ionization (MALDI) samples with divalent metal chloride salts, producing ions with the formula [L+M]2+ (L = lipid, M = divalent metal cation). Multiply charged lipid ions were not detected with the investigated trivalent metal cations. Collision-induced dissociation (CID) product ions from doubly charged metal-cationized lipids include the singly charged intact fatty acids [snx+M–H]+, where ‘x’ represents the position of the fatty acid on the glycerol backbone. The preference of the divalent metal cation to locate on the sn2 fatty acid during CID was found, enabling stereochemical assignment. Pseudo-MS3 experiments such as in-source decay (ISD)-CID and ion mobility-enabled time-aligned parallel (TAP) MS of [snx+M–H]+ provided diagnostic product ion spectra for determining the location of double bonds on the acyl chain and were applied to identify and characterize lipids extracted from soya milk. This novel method is applicable to lipid profiling in the positive ion mode, where structural information of lipids is often difficult to obtain.MALDI of liquid lipid samples doped with divalent metal salt (e.g. BaCl2) produces doubly charged lipid-barium ions and enables structural elucidation via MS/MS and MS3 analysis [ABSTRACT FROM AUTHOR]

The saturated LPC18:0 and unsaturated LPC18:1 lysophosphatidylcholines have important roles in inflammation and immunity and are interesting targets for immunotherapy. The synthetic cationic lipid DODAB has been successfully employed in delivery systems, and would be a suitable carrier for those lysophosphatidylcholines. Here, assemblies of DODAB and LPC18:0 or LPC18:1 were characterized by Differential Scanning Calorimetry (DSC) and Electron Paramagnetic Resonance (EPR) spectroscopy. LPC18:0 increased the DODAB gel-fluid transition enthalpy and rigidified both phases. In contrast, LPC18:1 caused a decrease in the DODAB gel-fluid transition temperature and cooperativity, associated with two populations with distinct rigidities in the gel phase. In the fluid phase, LPC18:1 increased the surface order but, differently from LPC18:0, did not affect viscosity at the membrane core. The impact of the different acyl chains of LPC18:0 and 18:1 on structure and thermotropic behavior should be considered when developing applications using mixed DODAB membranes. [Display omitted] • DODAB vesicle structure can be modulated by lysophosphatidylcholine acyl chain. • Saturated lysophosphatidylcholine rigidified the gel phase of cationic membranes. • Unsaturated lysophosphatidylcholine destabilized the gel phase. • Saturated lysophosphatidylcholine rigidified the fluid phase of cationic membranes. • Unsaturated lysophosphatidylcholine rigidified the surface of the fluid phase. [ABSTRACT FROM AUTHOR]

Due to the existence of water, it is still a challenge to conduct chemical modification on cellulose nanofiber (CNF) hydrogels with active double bonds. A simple one-pot and one-step method for constructing "living" CNF hydrogel with double bond was created at room temperature. The chemical vapor deposition (CVD) of methacryloyl chloride (MACl) was used to introduce physical-trapped, chemical-anchored and functional double bonds into TEMPO-oxidized cellulose nanofiber (TOCN) hydrogels. TOCN hydrogel could be fabricated within just 0.5 h, the minimum dosage of MACl could be reduced to 3.22 mg/g (MACl/TOCN hydrogel). Furthermore, the CVD methods showed high efficiency for mass production and recyclability. Moreover, the chemical "living" reactivity of the introduced double bonds were verified by the freezing and UV crosslinking, radical polymerization and thiol-ene click reaction. Compared with pure TOCN hydrogel, the obtained functionalized TOCN hydrogel exhibited remarkable improvements in mechanical properties, with enhancements of 12.34 times and 2.04 times, as well as an increase in hydrophobicity by 2.14 times and a fluorescence performance improvement of 2.93 times. • TOCN hydrogels with active double bonds were prepared via a facile one-pot and one-step MACl CVD method; • Both physical trapped and chemical anchored double bonds were introduced into TOCN hydrogels; • MACl CVD method was mild, efficient and capable of mass production and recycle; • Double bond functionalized TOCN hydrogels displayed good chemical "living" reactivity; • Double bond functionalized TOCN hydrogels, laid the foundation for the subsequent hydrophobic and fluorescent modification. [ABSTRACT FROM AUTHOR]

• Global sensitivity analysis is utilized to build a skeletal oxidation mechanism for 1-hexene. • A set of skeletal oxidation mechanisms for C7–C14 1-alkenes is derived using reaction rate rules. • The effect of the C = C double bond is evaluated by BDE calculation and ROP analysis. • Satisfactory agreements between simulations and experiments are obtained for all test fuels. Olefins, accounting for one-fifth proportion of gasoline fuel, are also essential intermediates in the combustion of large hydrocarbons and vital precursors of large polycyclic aromatic hydrocarbons and soot. The unsaturated C = C bond of alkenes renders a more complex low-temperature reaction scheme compared with their corresponding n -alkanes. Thus, it is of great necessity to obtain a thorough knowledge of the chemical kinetics of alkenes. However, the studies on the chemical kinetics of long-chain olefins are far from sufficient. In this work, a collection of skeletal oxidation mechanisms for 1-alkenes from 1-hexene (C 6 H 12 -1) to 1-tetradecene (C 14 H 28 -1) were constructed in light of recent advances in skeletal mechanism construction for fuels sharing similar structures based on reaction rate rules. For each 1-alkene, the skeletal mechanism includes ∼54 species and ∼216 reactions. Meanwhile, the effect of the C = C double bond was evaluated by conducting a bond dissociation energy calculation to assist the skeletal mechanism construction and derivation. It is discovered that the allylic position is preferred for H-atom abstraction reactions owing to its lowest bond dissociation energy among different locations for all heavy 1-alkenes. Furthermore, the reactions of OH addition to the C = C bond become important at low temperatures, which competes with the H-atom abstraction reactions. This results in the lower reactivity of 1-alkenes compared with corresponding n -alkanes at low temperatures. The acquired skeletal mechanisms were validated against extensive experimental data including laminar flame speeds, ignition delay times in shock tubes, and key species concentrations in jet-stirred reactors, flow reactors, and premixed laminar flames. The good agreements between experiments and simulations demonstrate the prediction capability of all the skeletal mechanisms of 1-alkenes although minor discrepancies exist in the concentration predictions for C 2 –C 3 species, which might stem from a highly reduced C 2 –C 3 sub-mechanism being utilized in the present mechanism. [ABSTRACT FROM AUTHOR]

Long chain alkenones (LCAs) are among the most successful biomarkers for paleotemperature reconstructions. However, fundamental questions regarding the biosynthesis and cellular functions of alkenones in haptophyte algae remain poorly understood. Recent discoveries of LCAs with double bond positions and chain lengths that differ from common structures further highlight the importance of continued research into structural variations of this important class of lipid biomarkers to improve LCA applications as temperature proxies. Double bond positions on alkyl chains can be effectively determined by preparing mono-double bond adducts with dimethyl disulfide (DMDS-1), and subsequent gas chromatography–mass spectrometry (GC–MS) analysis. However, previously published procedures for adduct preparation were originally designed for mono-unsaturated fatty acids, and generally produce low product yields when applied to alkenones. Here we demonstrate that the problem originates mainly from DMDS and alkenone overreaction at high temperatures for long time periods, and, secondarily, insufficient amount of iodine catalyst. The overreaction results in DMDS reacting with multiple double bonds, and the possible formation of intermolecular linkages, creating non-volatile products. These products are of little use for elucidating alkenone structures. We demonstrate that by reducing the reaction temperature and time, and by using an optimal amount of iodine, we can maximize the yield of transient DMDS-1 adducts for alkenone structure determination. [ABSTRACT FROM AUTHOR]

A diepoxide (( E )-1,2-di(7- oxabicyclo [4.1.0]heptan-3-yl)ethane, named DCE), possessing two cyclohexane rings bridged by a double bond was obtained via self-metathesis approach. This unique epoxy structure shows great potential in substantially overcoming the poor performances of plant oil materials in thermal and mechanical aspects. The molecular structure of DCE is more compact and regular than the commercial 3,4-epoxycyclohexylmethyl-3,4- epoxycyclohexanecarboxylate (ECHM) and was evidenced by the small-/wide-angle X-ray scattering. After conetwork was built between epoxidized soybean oil (ESO) and DCE, stiff crosslinks were created through the double bonds of DCE, which restricts the backbone rotation of ESO (P-ESO) networks. DCE-rich domains with dimensions ranging from 0.5 to 2 μm were observed with the increase of DCE, revealed by atomic force microscopy (AFM) phase image and voltage-distance curve. These DCE-rich domains act as micro-scale reinforcements homogenously dispersed in the ESO matrix, effectively sustaining the applied stress and preventing the chain break from high force loading. Compared to P-ESO, the co-polymerized ESO-DCE at 30 wt % DCE loading showed tensile strength of 62 MPa and glass transition temperature of 163 °C that are much higher than 4 MPa and 10 °C for P-ESO, respectively. ECHM also showed significant reinforcement effects on the thermal and mechanical properties of ESO, but DCE's reinforcement effects is doubled compared to ECHM. [ABSTRACT FROM AUTHOR]

The carbon-carbon double bond functionalized 24-nuclear copper cluster was successfully synthesized. The cluster can capture an impressive quantity of dyes, such as RhB (rhodamineB), MB (methylene blue) and CV (crystal violet). By the interaction between double bond and ions, the complex can selective separate cationic dyes from aqueous solution effectively. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) incorporating vinyl-bearing 3-hydroxyalkanoates were prepared in 8.5-12.9 g L yield. The molar ratios (0-16 mol%) of the vinyl-bearing 3-hydroxyalkanoate derivatives were controlled by the continuous feeding of undecylenate at various concentrations. Subsequently, the PHAs were functionalized by UV-initiated thiol-ene click reaction and chemical modification. H NMR spectra suggested that 3-mercaptopropionic acid and 2-aminoethanethiol were successfully introduced into the vinyl-bearing PHA. Subsequently, chemical modification using fluorescein or a fibronectin active fragment (GRGDS) was attempted. The former yielded a PHA derivative capable of emitting fluorescence under UV irradiation, which was useful for determining the miscibility of PHA in a composite film comprising poly-ʟ-lactic acid (PLLA) and PHA. In the latter case, PHA bearing GRGDS peptides exhibited cell adhesiveness, suggesting that its biocompatibility was improved upon peptide introduction. Taken together, the UV-initiated thiol-ene click reaction was demonstrated to be useful in PHA modification. [ABSTRACT FROM AUTHOR]

A novel near-infrared TCF-aza-BODIPY-based fluorescent probe was rationally synthesized and exhibited "turn-on" fluorescence phenomenon at 670 nm upon exposure to HOCl/ClO- both in solutions and living cells, attributing to the quick oxidation of the conjugated double bond accompanied with the inhibition of the intramolecular charge transfer (ICT) process. [Display omitted] • A novel TCF-aza-BODIPY-based NIR fluorescent probe for HOCl was successfully developed. • It selectively and sensitively responded to HOCl with fluorescence "turn-on" property. • A strong and new emission at 670 nm appeared due to addition/oxidation of C C bond. • It can sensitively detect both exogenous and endogenous HOCl in living cells. Hypochlorous acid/hypochlorite (HOCl/ClO-) plays important roles in killing bacterial and causing damage to living tissues, and its abnormal levels could lead to many diseases. Although great efforts have been devoted, fluorescent probes for HOCl/ClO- with near-infrared fluorescence, good selectivity/sensitivity, and low background are still important and urgent. In this work, a novel double-bond-linked TCF-aza-BODIPY-based near-infrared fluorescent probe (3) was rationally designed, successfully prepared, and applied for sensing HOCl/ClO- in both solutions and living RAW264.7 cells, showing good selectivity and fluorescence "turn-on" phenomenon at 670 nm with low background. The limit of detection towards ClO- was determined to be 0.36 μM through the linear fluorescence changes at 670 nm in a broad ClO--concentration range of 0–150 μM. Furthermore, the sensing mechanism was investigated by mass spectrometry and compared with 1 , suggesting that the remarkable spectroscopic changes could be ascribed to the oxidization of the double bond to the aldehyde group, accompanied with the leaving of the TCF group. Confocal imaging experiments also confirmed the remarkable intracellular fluorescence enhancements through incubation of ClO- and phorbol ester 12-myristate 13-acetate (PMA) in RAW264.7 cells. Therefore, for the first time, we reported a near-infrared TCF-aza-BODIPY-based fluorescent probe for highly sensitive and fluorescence "turn-on" detection of both exogenous and endogenous HOCl in living RAW264.7 cells through the quick oxidation of a conjugated double bond. [ABSTRACT FROM AUTHOR]

Dietary unsaturated fatty acids ( FA) are intensively hydrogenated in the rumen, resulting in reduced amount of poly-unsaturated fatty acids ( PUFA) and accumulation of several biohydrogenation ( BH) products. In this study, BH of PUFA originating from different oilseeds (linseed, soya beans, sunflower seed and rapeseed) present in crushed oilseeds or their free oils were assessed in vitro. The assay substrates were incubated in buffered rumen fluid for 0, 6, 12 and 24 h. After incubation, the FA pattern of the incubated samples was analysed using gas chromatography. Biohydrogenation is defined as disappearance of double bonds ( DB) calculated from the contents of unsaturated FA. After 24-h incubation, the DB contents of all oilseeds were reduced (p < 0.001) by 40-60%. The reduction was higher (p < 0.001) for the crushed form compared with the oil form. In addition, linseed and sunflower seed known as oilseeds with high contents of linolenic acid C18:3 c9,12,15 ( LNA) and linoleic acid C18:2 c9,12 ( LA), respectively, showed a higher (p < 0.001) accumulation of the BH intermediates conjugated linoleic acid ( CLA, isomer C18:2 c9t11) and vaccenic acid (C18:1 t11) for the crushed form, when compared with the oil. These results suggest an inherent effect of the physical form of the assay oilseeds on in vitro BH. Changes in FA pattern during BH in vitro can be attributed to both source and physical form of the assay oilseeds. However, further investigations are warranted to ensure whether the observed in vitro effects on ruminal BH can be confirmed in vivo. [ABSTRACT FROM AUTHOR]

After seminal reports of covalent uranium carbene U˭C complexes in the 1980s by Gilje, the area fell dormant for around 30 years. However, in the past five years, there has been a resurgence of interest in the area. Despite recent advances, the classification of these U˭C complexes as either methanediides, carbenes, or alkylidenes has remained a contentious issue. Herein, we review U˭C complexes reported to date, along with reactivity and computational studies, and conclude that although U˭C complexes sit midway on the continuum between rare-earth methanediides and Schrock-type alkylidenes, they can be justifiably described as carbenes. [ABSTRACT FROM AUTHOR]

A method for localizing double bonds in triacylglycerols using high-performance liquid chromatography-tandem mass spectrometry with atmospheric pressure chemical ionization (APCI) was developed. The technique was based on collision-induced dissociation or pulsed Q collision-induced dissociation of the CHN adducts ([M + 55]) formed in the presence of acetonitrile in the APCI source. The spectra were investigated using a large series of standards obtained from commercial sources and prepared by randomization. The fragmentation spectra made it possible to determine (i) the total number of carbons and double bonds in the molecule, (ii) the number of carbons and double bonds in acyls, (iii) the acyl in the sn-2 position on the glycerol backbone, and (iv) the double-bond positions in acyls. The double-bond positions were determined based on two types of fragments (alpha and omega ions) formed by cleavages of C-C bonds vinylic to the original double bond. The composition of the acyls and their positions on glycerol were established from the masses and intensities of the ions formed by the elimination of fatty acids from the [M + 55] precursor. The method was applied for the analysis of triacylglycerols in olive oil and vernix caseosa. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: The primary goal of this work was to study the thermal conversion of polyunsaturated fatty acids to hydrocarbon for use as renewable chemicals and fuels. Linoleic acid (cis,cis-9,12-octadecedienoic acid) was selected as a model polyunsaturated fatty acid. Batch pyrolysis reactions were conducted at temperatures from 350 to 450°C for 0.5 to 8h reaction times. Gas chromatography and mass spectrometry were used to analyze and identify products in the gas and liquid product fractions. Analysis of the gas phase showed concurrent production of CO and CO2, indicating that deoxygenation reaction proceeded through both decarbonylation and decarboxylation mechanisms. The gas product encompassed alkanes and alkenes with carbon numbers ranging C1–C5 with ethane and propane as the major products. Analysis of the liquid fraction revealed series of n-alkanes, alkenes, cyclic alkanes and alkenes, and fatty acids. The presence of the unsaturation resulted in cracking at the allylic C C and predominance of C6 to C10 hydrocarbons and C9 and C10 fatty acids. This work uncovers the dominant reaction pathways in the pyrolysis of free polyunsaturated fatty acids and demonstrates the viability of this pyrolysis to produce renewable hydrocarbons immediately compatible with the existing petrochemical infrastructure. [Copyright &y& Elsevier]

Abstract: A novel cross-linked fluorinated poly (aryl ether oxadiazole) s having diallyl methylimidazole groups (FPAEO-DA-x) membranes were prepared via copolymerization, bromination, solution casting and hydroxide exchanging using a thermal cross-linking method. The membrane materials synthesized via copolymerization of 2,5-bis(2,3,4,5,6-pentafluorophenyl)-1,3,4-oxadiazole (FPOx) and diallyl bisphenol A (DABPA), bromination of the allyl and imidazolidation with N-methylimidazole (NMI). The anion exchange membranes (FPAEO-DA-x) were obtained by solution casting method, followed by hydroxide exchanging in sodium hydroxide solution and cross-linked by using the thermal cross-linking method. The chemical structures and properties of the cross-linked FPAEO-DA-x membranes (CFPAEO-DA-x) were studied. The highest ionic conductivity of the CFPAEO-DA-x membrane was achieved at 1.94 × 10−2 S cm−1 at 20 °C. Its swelling ratio and TGA properties revealed their good mechanical and thermal stability. [Copyright &y& Elsevier]

Abstract: Future fuels will be developed from a variety of biomass and fossil sources, and this presents an opportunity to design new fuels that carry a much reduced environmental burden. To this end, understanding how the molecular structure of a fuel impacts on the processes of combustion and emissions production is critical in selecting suitable feed-stocks and conversion methods. This paper presents experimental studies carried out on a diesel engine supplied with a range of single-molecule fuels to investigate the effect of fuel molecular structure on combustion and emissions. Four isomers of octene, 1, trans-2, cis-3 and trans-3, were investigated so as to ascertain the way in which the position and arrangement of a double bond within an alkene molecule affects diesel combustion and emissions. The engine tests were carried out at constant injection timing and they were repeated at constant ignition timing and at constant ignition delay, the latter being achieved through the addition of small quantities of ignition improver (2-ethylhexyl nitrate) to the various fuels. The order of ignition delay (shortest first) was found to be 1-octene, cis-3-octene, trans-3-octene and trans-2-octene. The higher reactivity of the cis isomer was attributed to the need of trans isomers to adopt the cis conformation prior to undergoing certain low temperature radical branching reactions. The longer ignition delay of trans-2-octene relative to trans-3-octene suggests a greater net reactivity of the saturated alkyl portions of the latter molecule. At constant injection and constant ignition timings, the combustion phasing and the exhaust level of NOx emitted by each fuel were dictated by the duration of ignition delay. With ignition delay equalised, an effect of increasing particulate emissions with the movement of the double bond towards the centre of the molecule was observed. [Copyright &y& Elsevier]

This review covers the discovery and development of radical thiol-ene addition reactions as functionalization and polymerization method. First, some general and important developments within the field of polymer chemistry are introduced. However, the utilization of this efficient coupling procedure for the syntheses of materials derived from plant oils are the focus of this manuscript. Applications of this unique reaction will also be discussed in terms of green chemistry requirements as well as reaction conditions and efficiency. [ABSTRACT FROM AUTHOR]

Abstract: The biosynthesis of medium chain length poly(3-hydroxyalkanoates) mcl PHAs by Pseudomonas guezennei using glucose, sodium octanoate, and 10-undecenoic acid as sole or mixed carbon sources was investigated. Chemical composition of polyesters was analyzed by GCMS and NMR. The copolyester produced by P. guezennei from glucose mainly consisted of 3-hydroxyoctanoate and 3-hydroxydecanoate, and the presence of 3-hydroxydodec-5-enoate was demonstrated. Using sodium octanoate as the sole nutrient, the microorganism produced a poly(3-hydroxyoctanoate) (PHO) polymer containing up to 94mol% 3-hydroxyoctanoate. Biosynthesis of poly[(3-hydroxyoctanoate)-co-(3-hydroxyundecenoate)] (PHOU) copolymers bearing terminal reactive double bonds on its side chains with unsaturation degree ranging from 8.8% to 78.2% was obtained by tuning the ratio of sodium octanoate/10-undecenoic acid in the medium. Thermal analysis indicated semi-crystalline polymers with melting temperatures (T m) ranging from 46 to 55°C, fusion enthalpy (ΔH) comprised between 3 and 35J/g and glass transition temperature (T g) from −36 to −44°C, except for the highly amorphous 78.2% unsaturated PHOU with a low T g (−50°C). Molecular weights determined by GPC ranged from 119000 and 530000g/mol. The biosynthesis of natural polyesters with controlled ratio of vinyl-terminated side chains is of great interest for further chemical modifications. [Copyright &y& Elsevier]

Fatty acid profile of the vegetable oil and animal fats plays a major role in determining the properties of biodiesel derived from them. Eventhough the type of fatty acids in vegetable oils are similar, their distribution is different. The percentage distribution of fatty acids differs by a significant magnitude with respect to the type of vegetable oil. In the present investigation the effect of single double bond fatty acids in the vegetable oil on its physical and chemical properties are investigated. Different vegetable oils based on the type and geography were selected and the properties of biodiesel derived from it were analysed with respect to its fatty acid of single double bond. From the results of the investigation it is inferred that the fatty acids with single bond plays an important role in determining the properties of biodiesel as a CI engine fuel. [ABSTRACT FROM AUTHOR]

Abstract: A series of biodegradable functional amino acid-based poly(ester amide)s (PEA-AG) were designed and synthesized by the solution co-polycondensation of amino acid (l-phenylalanine and dl-2-allylglycine) based monomers and dicarboxylic acid based monomers. Pendant carbon–carbon double bonds located in the dl-2-allylglycine were incorporated into these PEA-AGs, and the double bond contents could be adjusted by tuning the feed ratio of l-phenylalanine to dl-2-allylglycine monomers. Chemical structures of this new functional PEA-AG family were confirmed by FTIR and NMR spectra. The thermal properties of these polymers were investigated; increasing the methylene chain in both the amino acid and dicarboxlic acid segments resulted in a reduction in the polymer glass-transition temperature. The short-term in vitro biodegradation properties of PEA-AGs were investigated as a function of PEA-AG chemical structures and enzymes. Based on the weight loss data, PEA-AGs biodegraded much faster in an enzyme solution than in a PBS buffer solution. The utility of the pendant functional carbon–carbon double bonds in PEA-AG was demonstrated by synthesizing additional functional PEA derivatives. The incorporation of the functional pendant carbon–carbon double bonds along the PEA-AG chains could significantly expand the biomedical applications of these functional PEA-AGs via either their capability to conjugate bioactive agents or prepare additional useful functional derivatives. [Copyright &y& Elsevier]

Abstract: A chemical derivatization technique in TOF-SIMS along with ultra-low angle sample cutting technique were used to perform a quantitative study of the surface and in-depth double bond profile of the photo-initiated polymerized thin film. We found out that the characteristic peaks at m/z 185 and 199 were obtained from the thin film composed of acrylate monomer and methacrylate monomer, respectively, after reaction with bromine gas. The detection sensitivity of certain chemical indicators is affected by changing the primary ion species. The Bi3 + primary ion results in the best chemical sensitivity. The surface double-bond density obtained by TOF-SIMS and the Br 3d signal intensity of XPS showed a good linear relationship in the limited region due to the effect of matrix hardness. The thin film was cut with microtome about 1° angle and was left to react with bromine and was measured using TOF-SIMS. It was clearly observed from this technique that double bond of acrylate and methacrylate monomer remained much more at the surface of the photo-initiated polymerized thin film, due to the inhibition of polymerization by oxygen. From the surface to 1μm depth, both monomers show the same behavior, but the rate of polymerization of methacrylate monomer was lower than that of acrylate in deeper layers. [Copyright &y& Elsevier]

Abstract: Biodiesel is a notable alternative to petroleum derived diesel fuel because it comes from natural domestic sources and thus reduces dependence on diminishing petroleum fuel from foreign sources, it likely lowers lifecycle greenhouse gas emissions, and it lowers an engine''s emission of most pollutants as compared to petroleum derived diesel. However, the use of biodiesel often slightly increases a diesel engine''s emission of smog forming nitrogen oxides (NO x ) relative to petroleum diesel. In this paper, previously proposed theories for this slight NO x increase are reviewed, including theories based on biodiesel''s cetane number, which leads to differing amounts of charge preheating, and theories based on the fuel''s bulk modulus, which affects injection timing. This paper proposes an additional theory for the slight NO x increase of biodiesel. Biodiesel typically contains more double bonded molecules than petroleum derived diesel. These double bonded molecules have a slightly higher adiabatic flame temperature, which leads to the increase in NO x production for biodiesel. Our theory was verified using numerical simulations to show a NO x increase, due to the double bonded molecules, that is consistent with observation. Further, the details of these numerical simulations show that NO x is predominantly due to the Zeldovich mechanism. [Copyright &y& Elsevier]

Abstract: In the biosynthetic pathway of Spodoptera littoralis sex pheromone, (E,E)-10,12-tetradecadienoic acid is produced from (Z)-11-tetradecenoic acid by desaturation and concomitant migration of the precursor double bond. With the aim of identifying the enzyme involved in this biotransformation, yeast Δelo1/Δole mutants, which are both elongase 1 and Δ9 desaturase-deficient, were transformed with the S. littoralis Δ11 desaturase gene using a Cu+2 inducible expression vector. The transformants produced a recombinant polyhistidine-tagged Δ11 desaturase that could be detected by immunoblotting from cell lysates. Lipid analysis revealed that besides producing large quantities of C11-monounsaturated fatty acids, mainly (Z)-11-hexadecenoic acid, (E,E)-10,12-tetradecadienoic acid and minor amounts of (E,Z)-10,12-hexadecadienoic acid were also produced, as well as very low quantities of another tetradecadienoate, which was tentatively identified as the (E,Z)-10,12-tetradecadienoic isomer. None of these dienes was detected with the Δ11 desaturase gene of Trichoplusia ni, which does not produce conjugated dienes as pheromone components. We conclude that the Δ11 desaturase of S. littoralis is a bifunctional enzyme with both Δ11 and Δ10,12 desaturation activities. The relationship between the substrate structure and the stereochemical outcome of the reaction is discussed. [Copyright &y& Elsevier]

The ability of human subjects to distinguish between aliphatic C6 alcohols differing in presence, position, or configuration (i.e., cis–trans geometry) of a double bond was tested. In a forced-choice triangular test procedure, 20 subjects were repeatedly presented with all 21 binary combinations of the seven stimuli and asked to identify the bottle containing the odd stimulus. I found (a) that as a group, the subjects performed significantly above chance level in all tasks but two and thus were clearly able to discriminate between most of the odor pairs presented; (b) marked interindividual differences in discrimination performance, ranging from subjects who were able to significantly distinguish between all 21 odor pairs to subjects who failed to do so with 10 of the tasks; (c) that odor pairs involving two hexenols were significantly more difficult to discriminate than odor pairs that involved hexanol and one of the hexenols; (d) that odor pairs involving hexenols sharing the same geometry but differing in the position of the double bond by only one carbon atom were significantly more difficult to distinguish than odor pairs that involved hexenols differing by two carbon atoms; (e) that odor pairs involving 4-hexenols were significantly easier to discriminate than 3-hexenols, which, in turn, were significantly easier to distinguish than 2-hexenols; and (f) that odor pairs involving two cis-hexenols were significantly more difficult to discriminate than odor pairs that involved two trans-hexenols. These findings demonstrate that the presence as well as the position and configuration of a double bond affected discriminability in a systematic manner and suggest that these molecular structural features may be important determinants of the interaction between stimulus molecule and olfactory receptor and thus may affect odor quality of aliphatic alcohols. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between the surface activities and their antibacterial activities of synthesized octadecanoyl acetal sodium sulfite series containing different numbers of double bonds (HOU-C18:n ) was studied. The results showed that with an increasing number of double bonds in HOU-C18:n , the hydrophobic activity and adsorbed amount on the surface would be decreased, while the antibacterial activity of HOU-C18:n and the membrane permeability of bacteria caused by HOU-C18:n would be increased. It was discussed that HOU-C18:0 exerted the bacteriostasis by hydrophobic adsorption and free diffusion through the membrane of bacteria, and unsaturated HOU-C18:n exerted the bacteriostasis mainly by double bonds and destructing the membrane. [Copyright &y& Elsevier]

Abstract: Two random reduction procedures (NH2NH2/H2O2 and NH2NH2/O2) were compared and conditions optimized for the reduction of two synthetic pheromone compounds (9Z,11E)-9,11-tetradecadienyl acetate and (9Z,12E)-9,12-tetradecadienyl acetate on a 300μg scale at 60°C. The relative amounts of the four products (completely reduced acetate, unreacted diene acetate and two monoene acetates), characterized by gas chromatography (GC) from the reaction mixture, depended on the reaction conditions. The reduction was straightforward without any detectable undesired side products. The reaction yields were reproducible with both the reducing reagents. The optimized reduction conditions thus established were utilized to reduce seven synthetic compounds (four diene and three triene acetates) on a micro scale (5μg). In all cases, expected compounds were identified by GC–MS. After reduction, two methods were used to locate the position of double bonds in the partially reduced compounds. In the first method, the products from the above seven compounds were isolated by extraction with hexane and reacted with dimethyl disulfide to give the DMDS adducts. In the second method (“one-pot”), the reduced compounds were not isolated but instead, the solvents were evaporated and the DMDS derivatives formed. In both cases, determination of the position of the double bonds was possible by GC–MS analyses. The complete procedure (reduction and DMDS derivative formation) could be carried out on a 100ng scale. Although neither of the partial reduction methods offered significant advantages over the other, partial reduction with NH2NH2/H2O2 was more convenient and hence should be the method of choice, together with DMDS derivative formation to locate double bonds in pheromones. In addition, a new procedure is described using ND2ND2/H2O2 and DMDS derivative formation capable of distinguishing between the double bond positions in (Z)-9-tetradecenyl acetate and (9Z,12E)-9,12-tetradecadienyl acetate (1:1 mixture). [Copyright &y& Elsevier]

The aim of this paper is to investigate the bonding in simple ylides in a physically meaningful fashion. Simple ylides have unique electronic structures because the behavior of electrons in the compounds does not conform to that expected solely on the basis of carbon–carbon and carbon–hydrogen bonds. The C&z.sbnd;S bonds in the molecules SH2CH2 and (CH3)2SCH2 are investigated by using the sharing amplitudes and the sharing indices [R.L. Fulton, J. Chem. Phys. 97 (1993) 7516]. The sharing indices between the carbon and the sulfur indicate an intermediate single–double bond character in the ylides. On the basis of the group basin charges and the inter-group sharing indices between the CH2 groups and the SH2 or S(CH3)2 groups, the bonds are ionic with full double bond characters. Detailed comparisons of the results for the ylides PHCH2, PH3CH2, SH2CH2 and NH3CH2 are presented. [Copyright &y& Elsevier]

The terminal phosphide complex of tungsten Cp(CO) 3 W{PN(Me)CH 2 CH 2 PNMe} ( 3 ) prepared from Cp(Sn n Bu 3 )(CO) 2 W{PN(Me)CH 2 CH 2 NMe(OMe)}, BF 3 ·OEt 2 , and NaBPh 4 in situ reacts with PhCH 2 Cl to give cis -Cp(CO 2 )ClW{PN(Me)CH 2 CH 2 NMe(CH 2 Ph)} ( cis-4 ). During the reaction, C--Cl bond addition takes place toward a tungsten-phosphorus double bond. In contrast, isolated 3 does not react with PhCH 2 Cl. Isolated 3 , however, reacts with PhCH 2 Cl in the presence of BPh 3 and BF 3 to give trans-4 and cis-4 , respectively. [ABSTRACT FROM AUTHOR]

• The capture and conversion of H 2 S into value-added mercaptan acids was developed. • TSILs were designed and presented as both absorbents and catalysts. • The highest H 2 S solubility was achieved in triethylbutylammonium maleate. • Water extraction was employed to separate the product from the reaction system. The capture and conversion of H 2 S is of importance towards long-standing economic and environmental challenge. Hence, a series of task-specific ionic liquids were developed and presented as both absorbents and catalysts for simultaneous capture and conversion of H 2 S into high valuable mercaptan acids using unsaturated acids as starting materials. Good to quantitative conversion was realized with catalytic loading of ILs. Water extraction was employed to separate the product from the reaction system. The kinetic isotherm demonstrated that the addition reaction can achieve 98% conversion at 90 °C and 50 mol% of catalyst loading within 1 h. A plausible reaction-separation-integration strategy was further proposed. This work discloses a green, simple, and mild but effective method for the capture and catalytic conversion of H 2 S into high valuable mercaptan acids. [ABSTRACT FROM AUTHOR]

Abstract: A novel ionic reducing reagent, 3-butyl-1-methylimidazolium borohydride ([bmim][BH4]), was synthesized and successfully used for the selective reduction of carbon–carbon double bonds in conjugated alkenes as well as the α,β-carbon–carbon double bonds in highly activated α,β,γ,δ-unsaturated alkenes. The reagent can be regenerated and reused several times without losing its activity. [Copyright &y& Elsevier]

Local nature of the boron-boron (BB) bond has been investigated in 23 molecules using the topological analysis of Electron Localisation Function (ELF) and the electron density (AIM) frameworks. The wave function has been approximated using the CCSD//CCSD(T), CASSCF and DFT(M062x) methods and triple-zeta basis sets. The calculations yielded a formally triple bond, B B, with population of 5.87–4.67e, a double bond B B with population of 4.39–3.58e, a single bond, B–B with population of 2.49–2.04e and one electron bond, B.B with 0.38e. Topological analysis of ρ(r) field has shown the non-nuclear attractor, NNA, for the BB bond in ten molecules (CCSD, DFT) with r opt (B,B) smaller than 1.6 Å. Population of the pseudo-atom basin ranges from 0.28e to 1.42e (CCSD) and from 0.32e to 1.27e (DFT). An overview of the results from topological analysis of ELF together with a detailed discussion of electronic structure for 14 small molecules has been presented. Image 1 • The B B, B B, B–B, and one-electron, B.B, bonds are supported by topological analysis of ELF in 23 molecules. • The population of one-electron B.B bond, studied at the DFT(mPW1PW91) level, is 0.38e. • The non-nuclear attractor (NNA) of the ρ(r) field is found for the BB bond in 10 molecules with r opt (B,B) < 1.6 Å. • Population of the pseudo-atom basin ranges from 0.28e to 1.42e (CCSD) and from 0.32e to 1.27e (DFT). • Classification of BB bonds using Lewis formulas due to basin population is complex, and depends on studied molecule. [ABSTRACT FROM AUTHOR]

• Current chromatography method cannot fully distinguish cis/trans isomers of CLA/CLnA. • Combination of GC and Ag+-HPLC is the most effect method so far. • Ion mobility spectrometry offers potential for fast conjugated lipid characterization. • Chemo-metric methods coupling mass spectrometry are another possible approach. Conjugated linoleic and linolenic acids (CLA and CLnA) can be found in dairy, ruminant meat and oilseeds, these types of unsaturated fatty acids consist of various positional and geometrical isomers, and have demonstrated health-promoting potential for human beings. Extensive reviews have reported the physiological effects of CLA, CLnA, while little is known regarding their isomer-specific effects. However, the isomers are difficult to identify, owing to (i) the similar retention time in common chromatographic methods; and (ii) the isomers are highly sensitive to high temperature, pH changes, and oxidation. The uncertainties in molecular structure have hindered investigations on the physiological effects of CLA and CLnA. Therefore, this review presents a summary of the currently available technologies for the structural determination of CLA and CLnA, including the presence confirmation, double bond position determination, and the potential stereo-isomer determination. Special focus has been projected to the novel techniques for structure determination of CLA and CLnA. Some possible future directions are also proposed. [ABSTRACT FROM AUTHOR]