Chloride Adducts Research Articles

Reductive Thermal ALD of Pd and Pd2Ge From a Novel Recyclable Palladium Chloride Adduct

AbstractIn this work, a new ALD process for palladium metal thin films using dichlorobis(triethylphosphine)palladium(II) (PdCl2(PEt3)2) and 1,4‐bis(trimethylsilyl)‐1,4‐dihydropyrazine ((Me3Si)2DHP) as reactants, is developed. The metal precursor is chosen based on the known reactivity of metal halides with the DHP‐type reducing agents. Metallic Pd films are deposited at temperatures of 140–180 °C with a growth rate of 0.3–0.4 Å cycle−1. Furthermore using 1,4‐bis(trimethylgermyl)‐1,4‐dihydropyrazine ((Me3Ge)2DHP) as the co‐reactant yielded Pd2Ge thin films. Finally, full recyclability of the PdCl2(PEt3)2 is observed: unused molecules condensed in the exhaust tube can be collected by dissolving them into acetone, purified by recrystallization, and reused.

First Main‐Group Element Lewis Acid Thionyl Chloride Adduct and its Chemistry

AbstractAlthough the adduct of aluminum trichloride with thionyl chloride has been reported, no thionyl chloride adduct of a main group element Lewis acid or organometallic compound has been structurally characterized. In this communication we present the synthesis and reactivity of the structurally ascertained adduct of thionyl chloride with tris(pentafluoroethyl)gallane as a representative of a main group element Lewis acid. Gallium and indium compounds with electron withdrawing groups, e.g. the pentafluoroethyl ligand, display versatile properties. While gallates and indates, [MR4]−, behave as weakly coordinating anions, neutral gallanes and indanes, MR3, are strong Lewis acids. Salts with the tetrakis(pentafluoroethyl)gallate and ‐indate, [M(C2F5)4]− (M=Ga, In), have recently been studied in detail. In contrast to this, work on the syntheses of the free Lewis superacids M(C2F5)3 (M=Ga, In) is scarce and underdeveloped. The hydrates [M(C2F5)3(OH2)2] proved to be suitable starting materials, particularly due to their thermal stability. Herein we report on synthesis and characterization of reactive adducts, [M(C2F5)3D], with the weak donor molecules (D) SOCl2 and Me3SiF. The effective Lewis acidities of Ga(C2F5)3 and In(C2F5)3 were experimentally determined by the (modified) Gutmann‐Beckett method and their catalytic potential is showcased.

First Main-Group Element Lewis Acid Thionyl Chloride Adduct and its Chemistry.

Although the adduct of aluminum trichloride with thionyl chloride has been reported, no thionyl chloride adduct of a main group element Lewis acid or organometallic compound has been structurally characterized. In this communication we present the synthesis and reactivity of the structurally ascertained adduct of thionyl chloride with tris(pentafluoroethyl)gallane as a representative of a main group element Lewis acid. Gallium and indium compounds with electron withdrawing groups, e.g. the pentafluoroethyl ligand, display versatile properties. While gallates and indates, [MR4]-, behave as weakly coordinating anions, neutral gallanes and indanes, MR3, are strong Lewis acids. Salts with the tetrakis(pentafluoroethyl)gallate and -indate, [M(C2F5)4]- (M=Ga, In), have recently been studied in detail. In contrast to this, work on the syntheses of the free Lewis superacids M(C2F5)3 (M=Ga, In) is scarce and underdeveloped. The hydrates [M(C2F5)3(OH2)2] proved to be suitable starting materials, particularly due to their thermal stability. Herein we report on synthesis and characterization of reactive adducts, [M(C2F5)3D], with the weak donor molecules (D) SOCl2 and Me3SiF. The effective Lewis acidities of Ga(C2F5)3 and In(C2F5)3 were experimentally determined by the (modified) Gutmann-Beckett method and their catalytic potential is showcased.

Active species in chloroaluminate ionic liquids catalyzing low-temperature polyolefin deconstruction

Chloroaluminate ionic liquids selectively transform (waste) polyolefins into gasoline-range alkanes through tandem cracking-alkylation at temperatures below 100 °C. Further improvement of this process necessitates a deep understanding of the nature of the catalytically active species and the correlated performance in the catalyzing critical reactions for the tandem polyolefin deconstruction with isoalkanes at low temperatures. Here, we address this requirement by determining the nuclearity of the chloroaluminate ions and their interactions with reaction intermediates, combining in situ 27Al magic-angle spinning nuclear magnetic resonance spectroscopy, in situ Raman spectroscopy, Al K-edge X-ray absorption near edge structure spectroscopy, and catalytic activity measurement. Cracking and alkylation are facilitated by carbenium ions initiated by AlCl3-tert-butyl chloride (TBC) adducts, which are formed by the dissociation of Al2Cl7− in the presence of TBC. The carbenium ions activate the alkane polymer strands and advance the alkylation cycle through multiple hydride transfer reactions. In situ 1H NMR and operando infrared spectroscopy demonstrate that the cracking and alkylation processes occur synchronously; alkenes formed during cracking are rapidly incorporated into the carbenium ion-mediated alkylation cycle. The conclusions are further supported by ab initio molecular dynamics simulations coupled with an enhanced sampling method, and model experiments using n-hexadecane as a feed.

“Exploring the Inhibitory Potential of Acetoxime-Zinc Chloride Adduct in Saline Environments for Mild Steel Corrosion Protection”

ABSTRACT In this work, acetoxime, zinc chloride and acetoxime adduct of zinc chloride, [ZnCl2.2{HON=C(CH3)2}] (ZA) were investigated as corrosion inhibitor's in 3.5%NaCl solution on mild steel. The electrochemical analysis was carried out using polarization measurements and electrochemical impedance technique and surface analysis was done by Scanning electron microscope coupled with Energy-dispersive X-ray spectroscopy. Using surface analysis and electrochemical data it was concluded that an inhibition synergy was developed when ZA was taken instead of acetoxime or zinc chloride alone in solution phase. Scanning electron microscope methods were used to examine the samples surface in the presence of inhibited solutions. The efficiency of inhibition increases with the increasing concentration and attained the values of 97.18% for the 3mM concentration of ZA.

ESI(-)FT-ICR MS for the determination of best conditions for producing extract abundant in phenolic compounds from leaves of E. uniflora and FTIR-PCA as a sample screening method.

E. uniflora leaves are a rich source of phenolic compounds with biological activities, including myricitrin. In this study, the chemical profile of nine extracts prepared with leaves collected in three regions (mountain, beach, and mangrove) and at three different times of the day (8 am, 1 pm, and 6 pm) was evaluated from spectra originating from ultra-high resolution mass spectrometry (Fourier transform ion cyclotron resonance, FT-ICR) coupled to electrospray ionisation (ESI). The best time of the day and location for collecting the leaves of E. uniflora used as raw materials for producing extracts and the best ethanol concentration for obtaining an extract more abundant in compounds of interest were verified. Several flavonoids and phenolic acids were detected in their deprotonated form in the regions from m/z 200 to 1200. Myricitrin ([C21H20O12-H]-, m/ztheo 463.08820), its chloride adduct ([C21H20O12+Cl]-, m/ztheo 499.06488), other myricitrin derivatives, and some tannins were the main compounds detected. Considering obtaining an extract rich in phenolic compounds, including myricitrin, the best place and time of the day to collect E. uniflora leaves is in the beach region at 1 pm. In contrast, the best ethanol concentration for extract production is 70 wt%. Therefore, extraction at 96 wt% ethanol is better for obtaining an extract more abundant in phenolic acids, although 70 wt% ethanol also extracted these compounds. FTIR-PCA models were used to check for possible similarities in the data according to collection time of the day and location. These models demonstrated an excellent solution for sample screening.

Alkali Chloride Adducts of Acyclic Acylaluminum: Synthesis, Structure, and Reactivity Studies

AbstractTwo acyclic acylaluminums and one cyclic acylaluminum dimer were synthesized by reaction of the recently reported Al‐anion with acyl chloride. The reaction of the acylaluminums with TMSOTf and DMAP gave a ring‐expanded iminium‐substituted aluminate and a 2‐C−H cleaved product. In the reaction of acylaluminums toward C=O and C=N bonds, acyclic acylaluminums reacted as an acyl nucleophile, while the cycilc dimer showed no reactivity. Amide‐bond forming ligation using acyclic acylaluminums and hydroxylamines was further demonstrated. Throughout the study, acyclic acylaluminums exhibited higher reactivity than that of the cyclic dimer.

Alkali Chloride Adducts of Acyclic Acylaluminum: Synthesis, Structure, and Reactivity Studies.

Two acyclic acylaluminums and one cyclic acylaluminum dimer were synthesized by reaction of the recently reported Al-anion with acyl chloride. The reaction of the acylaluminums with TMSOTf and DMAP gave a ring-expanded iminium-substituted aluminate and a 2-C-H cleaved product. In the reaction of acylaluminums toward C=O and C=N bonds, acyclic acylaluminums reacted as an acyl nucleophile, while the cycilc dimer showed no reactivity. Amide-bond forming ligation using acyclic acylaluminums and hydroxylamines was further demonstrated. Throughout the study, acyclic acylaluminums exhibited higher reactivity than that of the cyclic dimer.

Electrospray ionisation mass spectrometry (ESI-MS) adduct formation by mobile phase additives: A case study using nitrile functional groups containing selective androgen receptor modulators (SARMs).

The formation of mass adducts is common during electrospray ionization mass spectrometry (ESI-MS). However, the mechanism that leads to adduct formation is poorly understood and difficult to control. Multiplication of mass adducts at once will adversely impact the sensitivity of mass analysis and cause misinterpretation of the level of detection. Prior studies on selective androgen receptor modulators (SARMs) revealed an immense mass adduct formation in both positive and negative ESI modes. In this study, additives in the mobile phases are investigated as a potential means of controlling mass adduct formation in various SARMs. The first evidence of chloride adduct formation when SARMs are detected via ESI-MS has been reported in this research. A series of mobile phase combinations were tested in order to achieve the optimal condition for HPLC-MS. A comparison was also made between adduct formation on various grades of water used for preparing the mobile phase. A validation study using equine urine and plasma was also conducted to assess the suitability of the developed method. The results of this study will allow for a more accurate identification of SARMs, which will make it easier to investigate their illicit use in horse racing.

Silver Dependent Enantiodivergent Gold(I) Catalysed Asymmetric Intramolecular Hydroamination of Alkenes: A Theoretical Study

We report a theoretical study of the first silver-dependent enantiodivergent gold-catalysed reaction. The combination of a single chiral binuclear gold(I) chloride complex and silver perchlorate catalyses the asymmetric intramolecular hydroamination of alkenes and affords both enantiomers of the products by applying a simple solvent change from toluene to methanol. A gold-silver chloride adduct that occurs only in methanol appears to control the enantioinversion. If one gold atom coordinates and activates the alkene moiety, the other gold is included in an adduct with silver chloride, which coordinates a methanol solvent molecule and further interacts with the amine function. If the use of toluene implies free anions and affords (S)-enantiomer, methanol allows a proximal interaction with the amine, leads to an opposite stereodifferentiation of the two diastereomeric intermediates during the final protodeauration step and results in the (R)-enantiomer.

Glycoprofiling of Oligosaccharides of Regular and Lactose-Free Milk by Mass Spectrometry

Oligosaccharides from regular milk and lactose-free milk were analyzed by Electrospray Ionization interface coupled with Ion Trap Mass Spectrometry (IT-MS). The negative mode mass spectrometry of sugar compositions was obtained either by direct infusion and mass spectrometry with Liquid Chromatography (LC). Hexose (Hex) and the other oligomeric sugar components were observed in both regular and lactose-free milk. While lactose derivatives (deprotonated lactose dimer, chloride adducts, chloride dimer) in regular milk have seen to be dominated, monosaccharide derivatives (Hex-H2O, Hex, Hex-Cl) in the lactose-free milk were observed as abundant which was lytic product of lactose. Phosphate/sulfate ester substitution on lactose and sialyllactose in both regular and lactose-free milk samples were observed with similar intensity thus it has been understood that these important milk components are not digested during lactose removing process.

Oral fluid as a new investigative matrix for the determination of organic gunshot residue exposure

In recent years, increased use of ammunition without lead and heavy metals was observed, leading to a growing interest in the detection of organic gunshot residues (OGSR) as evidence of firearms related crimes. The wide range of compounds belonging to the OGSR class hinders their mass spectrometric detection as different ionization techniques may be needed to obtain good results for all compounds.The purpose of this work was the development of a reliable analytical method by means of UHPLC-HRMS for the determination in oral fluid (OF) of the most common explosives and the most used stabilizers, arising from fire discharge and post-deflagration residues.For this purpose, SPE was used for OF clean-up before UHPLC-HRMS analysis. All target analytes were chromatographically separated by means of a Polar-C18 column. A chlorinated compound was added to the mobile phases in order to promote the formation of chloride adduct ions in the electrospray ion source operating in polarity switching to allow the best conditions for each analyte. The detection was conducted by means of a high-resolution mass spectrometer equipped with Orbitrap technology working in data dependent acquisition mode, in order to detect both the precursor ions and/or the most intense fragments for stabilizers.To verify its potential, the method was tested on real samples: a shooting session was performed in an open shooting range; the shooters fired from 2 to 20 rounds with a 9x21 caliber, thereafter OF was sampled. Samples were analyzed confirming that explosives may be detected in OF; the use of this matrix may be of great interest for investigative purposes as it is less affected by secondary transfer when compared to other commonly sampled matrices. The developed method could be a useful tool for law enforcement authorities for the detection of explosives in forensic potential scenarios, including biological matrices.

Sphingolipidomics of Bovine Pink Eye: A Pilot Study.

Simple SummaryThe liquid tear film, which protects the eye from the environment, is a dynamic fluid containing a large number of complex lipids. Disruptions of these lipids by infections can result in damage to the eye and ultimately blindness. In this study we characterized various lipid subfamilies present in the tear film of the eye and the effect of pink eye infections in cattle. Our findings demonstrate that the pink eye infections dramatically decrease the levels of lipids in the tear film covering the eye and suggest that this is a major factor in the development of blindness in infected cattle.Sphingolipids are essential structural components of tear film that protect the surface of the eye from dehydration. A detailed analysis of the effects of pink eye infections on the sphingolipidome in cattle has not previously been undertaken. We recently published a new assay utilizing high-resolution mass spectrometric monitoring of the chloride adducts of sphingolipids that provides enhanced sensitivity and specificity. Utilizing this assay, we monitored decreases in the levels of tear film ceramides with short-chain fatty acids, hydroxy-ceramides, phytoceramides, and hydroxy-phytoceramides. Dihydroceramide levels were unaltered and increased levels of ceramides with long-chain fatty acids (24:0 and 24:1) were monitored in cattle with pink eye. The data from this pilot study (n = 8 controls and 8 pink eye) demonstrate a major disruption of the lipid tear film layer in pink eye disease, that can result in severe eye irritation and damage.

Diphenyl‐ and Dimesityl‐Phosphanyl‐Substituted 3,3,4,4,5,5‐Hexafluorocyclopentenyl‐Gold(I) Dimers – Syntheses and Solid‐State Structures

Abstract1,2‐Dichloro‐3,3,4,4,5,5‐hexafluorocyclopentene (F6cypCl2) was functionalized with diphenyl‐ and dimesitylphosphanyl groups by a salt‐elimination reaction of the respective chlorophosphane (PPh2Cl, PMes2Cl) with in situ generated lithiated F6cyp(Li)Cl. F6cyp(PR2)Cl (R=Ph, Mes) was functionalised again to obtain the corresponding trimethylstannyl substituted compounds F6cyp(PR2)(SnMe3) (R=Ph, Mes). These tin‐precursors were used in tin‐gold exchange reactions to synthesize the dinuclear gold(I) dimers [F6cyp(PR2)Au]2 (R=Ph, Mes). For the mesityl substituted compound, the phosphanegold chloride adduct F6cyp(PMes2AuCl)(SnMe3), the intermediate of the tin‐gold exchange reaction, could also be isolated. All compounds were characterized by multinuclear NMR spectroscopy and X‐ray diffraction experiments.

High throughput and very specific screening of anabolic-androgenic steroid adulterants in healthy foods based on stable isotope labelling and flow injection analysis-tandem mass spectrometry with simultaneous monitoring proton adduct ions and chloride adduct ions

In this work, a stable isotope labelling-flow injection analysis-tandem mass spectrometry (SIL-FIA-MS/MS) with simultaneous monitoring [M+H]+ and [M+Cl]− method was developed for very specific and high throughput screening of anabolic-androgenic steroids (AAS) illegally added to healthy foods. Initially, a simple centrifugation step was carried out for liquid samples, and for solid samples, a solid-liquid extraction step was conducted. Afterwards, batch chemical derivatization was carried out. After adding a certain amount of 13C6-3-NPH labelled AAS standards as the internal standards, it can be directly transferred for FIA-MS/MS analysis based on the no MS response characteristics of 3-NPH. The 3-NPH labelled AAS showed dual-polarity property, observing chloride adduct ion ([M+Cl]−) in negative ion mode and proton adduct ion ([M+H]+) in positive ion mode. The average time cost for pretreatment of each sample was less than 1 min by carrying out batch processing. The subsequent FIA-MS/MS detection enabled rapid and high throughput detection. The addition of 13C6-3-NPH-labelled AAS as internal standards can correct the matrix effect to achieve accurate quantitative analysis. The detection sensitivity was also improved by 2–5 folds after 3-NPH labelling. The limits of detection (LODs) in positive MRM mode were in ranges of 0.1–0.3 ng/mL. The validated method with simultaneous monitoring [M+H]+ and [M+Cl]− was validated in the range of 6.0–1000 ng/mL with the linear coefficient (R2) greater than 0.997. Satisfactory recoveries were found to be in ranges of 93.0–108.7%. The intra-day and inter-day RSDs were in the range of 3.5–9.9% and 5.1–14.1%, respectively. No changes in detection sensitivity of the mass spectrometry and no carry-over effects were found after numerous consecutive injections of AAS derivates. Compared with previously reported methods, the proposed method proved accurate, very specific, high throughput with good sensitivity.

Reactions of Imidazolio‐Phosphides with Organotin Chlorides: Surprisingly Diverse

AbstractReactions of primary imidazolio‐phosphides (“imidazolylidene‐phosphinidenes”) with R2SnCl2 yield as main products spectroscopically detectable Lewis pairs which undergo base‐induced dehydrochlorination in the presence of excess dichlorostannane to afford zwitterionic chloride adducts of distannylated imidazolio‐phosphines. In contrast, reactions with R3SnCl proceed under dismutation to furnish mixtures containing imidazolium salts and stannylated (oligo)phosphines P(SnR3)3 and P7(SnR3)3, respectively. DFT studies were used to rationalize the divergent behavior based on the presumption that the reactions proceed under thermodynamic control and the products observed represent the most stable species under the specific reaction conditions. Computational simulation of selected reaction steps provides a model mechanism for Lewis‐acid promoted creation of PP‐bonds, which is a prerequisite for oligophosphine formation. The computational studies further highlight parallels between reactions of imidazolio‐phosphides with Lewis and Brønsted acids, and allow also to extrapolate the behavior of the P‐nucleophiles towards other electrophiles than organotin chlorides.

Effects of Metal Ions on Aqueous-Phase Decomposition of α-Hydroxyalkyl-Hydroperoxides Derived from Terpene Alcohols.

We report the results of a mass spectrometric study of the effects of atmospherically relevant metal ions on the decomposition of α-hydroxyalkyl-hydroperoxides (α-HHs) derived from ozonolysis of α-terpineol in aqueous solutions. By direct mass spectrometric detection of chloride adducts of α-HHs, we assessed the temporal profiles of α-HHs and other products in the presence of metal ions. In addition, reactions between α-HHs and FeCl2 in the presence of excess DMSO showed that the amount of hydroxyl radicals formed in a mixture of α-terpineol, O3, and FeCl2 was 5.7 ± 0.8% of the amount formed in a mixture of H2O2 and FeCl2. The first-order rate constants for the decay of α-HHs produced by ozonolysis of α-terpineol in the presence of 5 mM acetate buffer at a pH of 5.1 ± 0.1 were determined to be (4.5 ± 0.1) × 10-4 s-1 (no metal ions), (4.7 ± 0.2) × 10-4 s-1 (with 0.05 mM Fe2+), (4.7 ± 0.1) × 10-4 s-1 (with 0.05 mM Zn2+), and (4.8 ± 0.2) × 10-4 s-1 (with 0.05 mM Cu2+). We propose that in acidic aqueous media, the reaction of α-HHs with Fe2+ is outcompeted by H+-catalyzed decomposition of α-HHs, which produces the corresponding aldehydes and H2O2, which can in turn react with Fe2+ to form hydroxyl radicals.

Thermal decomposition of the chloride and nitrate adducts of pentaerythritol tetranitrate in air at ambient pressure using a cross flow design tandem ion mobility spectrometry

The thermal decomposition of the chloride adduct of pentaerythritol tetranitrate (PETN) has been studied with a new cross-flow sample introduction, dual shutter, ion mobility spectrometer. Chloride anions, produced in an ion source, react with PETN introduced by a nebulizer into a flow of heated gas orthogonal to the drift gas flow. This cross-flow procedure allows PETN introduction from solution at drift gas temperatures where the PETN∙Cl¯ intensity is sufficiently intense and stable to allow characterization of its thermal decomposition kinetics. Dual shutter operation allows the selection of PETN∙Cl¯ for observation of its thermal decomposition in the electrostatic drift field. In this adduct, Cl¯ displaces NO3¯ in an SN2 reaction with an activation energy of 80 ± 7 kJ mol-1 over the temperature range 145 °C–165 °C. At temperatures above 165 °C, decomposition occurs before ion selection, resulting in the release of NO3¯ and PETN∙NO3¯ becomes the sole adduct ion. PETN∙NO3¯ decomposes over the temperature range 175 °C–200 °C with an activation energy of 92 ± 8 kJ mol-1. Density functional calculations are used to interpret the results.

Human Brain Lipidomics: Utilities of Chloride Adducts in Flow Injection Analysis.

Ceramides have been implicated in a number of disease processes. However, current means of evaluation with flow infusion analysis (FIA) have been limited primarily due to poor sensitivity within our high-resolution mass spectrometry lipidomics analytical platform. To circumvent this deficiency, we investigated the potential of chloride adducts as an alternative method to improve sensitivity with electrospray ionization. Chloride adducts of ceramides and ceramide subfamilies provided 2- to 50-fold increases in sensitivity both with analytical standards and biological samples. Chloride adducts of a number of other lipids with reactive hydroxy groups were also enhanced. For example, monogalactosyl diacylglycerols (MGDGs), extracted from frontal lobe cortical gray and subcortical white matter of cognitively intact subjects, were not detected as ammonium adducts but were readily detected as chloride adducts. Hydroxy lipids demonstrate a high level of specificity in that phosphoglycerols and phosphoinositols do not form chloride adducts. In the case of choline glycerophospholipids, the fatty acid substituents of these lipids could be monitored by MS2 of the chloride adducts. Monitoring the chloride adducts of a number of key lipids offers enhanced sensitivity and specificity with FIA. In the case of glycerophosphocholines, the chloride adducts also allow determination of fatty acid substituents. The chloride adducts of lipids possessing electrophilic hydrogens of hydroxyl groups provide significant increases in sensitivity. In the case of glycerophosphocholines, chloride attachment to the quaternary ammonium group generates a dominant anion, which provides the identities of the fatty acid substituents under MS2 conditions.

Cold‐spray ionization mass spectrometry of the choline chloride‐urea deep eutectic solvent (reline)

Cold-Spray Ionization mass spectrometry (CSI-MS) that can be compared to an electrospray ionization (ESI) source acting with a nebulizing gas cooled by liquid nitrogen is used for analyzing reline as Deep Eutectic Solvent (DES). The association of cholinium chloride salts with urea molecules is evidenced in negative CSI-MS through the chloride adduct formation. The structure of the supramolecular assemblies forming the reline ions that are observed on CSI mass spectra is rationalized by chemical quantum calculations. The theoretical studies indicate that the ionic network organization is only supported by a maximization of hydrogen bonds of the chlorides with the hydroxyl and methyl moieties of the cholinium cations and the amino groups of urea. The studies of gas-phase fragmentation of the supra-molecular ionic assemblies detected in CSI-MS are performed using the in-source collision-induced dissociation experiments. The experimental measurements in CSI-MS, interpreted at the light of the molecular modelization results, suggest that the insertion of urea in adducts of chlorides with cholinium cations does not lead to the most stable ions.