Presence Of HOAc Research Articles

Condition-Dependent Selective Synthesis of Indolo[1,2-c]quinazolines and Indolo[3,2-c]quinolines from 2-(1H-Indol-2-yl)anilines and Sulfoxonium Ylides.

In this paper, a selective synthesis of indolo[1,2-c]quinazolines and indolo[3,2-c]quinolines through the cascade reactions of 2-(1H-indol-2-yl)anilines with sulfoxonium ylides is presented. The formation of products involves the generation of a carbene species from sulfoxonium ylide and its N-H bond insertion reaction with 2-(1H-indol-2-yl)aniline followed by deoxygenative imine formation, intramolecular N- or C- nucleophilic addition and deoxygenative aromatization. This switchable synthesis was condition-dependent. In the presence of K2CO3 in CH3CN, the reaction mainly furnished indolo[1,2-c]quinazolines. In the presence of HOAc in dioxane, it selectively afforded indolo[3,2-c]quinolines. In addition, direct C-H/N-H functionalization of the products obtained provides a convenient and direct access to polycyclic heteroaromatic compounds. These novel protocols have advantages such as readily accessible substrates, easily tunable selectivity, good compatibility with diverse functional groups, and the use of air as a cost-free and sustainable oxidant.

Palladium-catalyzed hydroboration reaction of unactivated alkynes with bis (pinacolato) diboron in water.

A highly efficient and mild palladium-catalyzed hydroboration of unactivated internal alkynes in water is described. Both aryl- and alkyl-substituted alkynes proceeded smoothly within the reaction time to afford the desired vinylboronates in moderate to high yields. Bis (pinacolato) diboron was used to afford α- and β-hydroborated products in the presence of HOAc. These reactions showed high reactivities and tolerance, thus providing a promising method for the synthesis of alkenyl boron compounds.

Effect of Counteranions in Electrocatalytic Hydrogen Generation Promoted by Bis(phosphinopyridyl) Ni(II) Complexes.

We previously reported the preparation and characterization of a Ni(II) complex capable of electrocatalytic hydrogen generation. The complex [Ni(LNH2)2Cl]Cl (1) includes a 6-((diphenylphosphino)methyl)pyridin-2-amine ligand (LNH2), which has an amino group as a base that acts as a proton transfer site by virtue of its location near the metal center. In order to study the effect of counteranions in hydrogen generation, two additional NiII(LNH2) complexes with weakly coordinating/noncoordinating counteranions, [Ni(LNH2)2](OTs)2 (OTs- = p-toluenesulfonate) (2) and [Ni(LNH2)2](BF4)2 (3), were synthesized. Their X-ray crystal structures reveal that the Ni(II) ion is coordinated with two bidentate LNH2 ligands in both complexes. Complex 2 contains both trans and cis isomers in the unit cell. The former is in an axially elongated square-pyramidal geometry (τ5 = 0.17), and the latter is in a nearly square planar geometry (τ4 = 0.11) with two weakly interacting OTs- anions at the axial sites. Complex 3 has only the cis isomer in the solid state, which is in a nearly square planar geometry (τ4 = 0.10). These complexes are slightly different from 1, which has a distorted-square-pyramidal geometry (τ5 = 0.25) with a coordinated chloride anion. UV-vis spectra of 2 and 3 in MeCN show a spectral pattern characteristic of a square-planar Ni(II) complex. These spectra are slightly different from the unique spectrum of 1, which is typical of an axially coordinating Ni(II) species as a result of having a Cl- anion at the apical position. Electrocatalytic hydrogen generation promoted by these three Ni(II) complexes (1.0 mmol) demonstrates an increase in the catalytic current induced by stepwise addition of HOAc (pKa = 22.3 in MeCN) as a proton source. The complexes demonstrate turnover frequencies (TOF) of 3800 s-1 for 1, 5400 s-1 for 2, and 8800 s-1 for 3 in MeCN (3 mL) containing 0.1 M [n-Bu4N](ClO4) in the presence of HOAc (145 equiv) at overpotentials of ca. 530, 490, and 430 mV, respectively.

Phosphine-containing Diiron Propane-1,2-dithiolate Derivatives: Synthesis, Spectroscopy, X-ray Crystal Structures, and Electrochemistry

Biomimics for the active site of [FeFe]-hydrogenases, have been synthesized and characterized. Treatment of [Fe2(CO)6{μ-SCH2CH(CH3)S}] (1) and phosphine ligands tris(2-furyl)phosphine, tri(m-tolyl)phosphine, bis(diphenylphosphino)methane (dppm), or 1,2-bis(diphenylphosphino)benzene (dppbz) with Me3NO·2H2O as the decarbonylation agent afforded the corresponding phosphine-containing derivatives [Fe2(CO)5(L){μ-SCH2CH(CH3)S}] (L = P(2-C4H3O)3, 2; P(3-C6H4CH3)3, 3; Ph2PCH2PPh2, 4) and [Fe2(CO)4{κ2-(Ph2P)2(1,2-C6H4)}{μ-SCH2CH(CH3)S}] (5) in moderate to good yields. The new complexes 2‒5 have been structurally characterized by elemental analysis, IR, NMR spectroscopy, and further confirmed by X-ray diffraction analysis. The electrochemistry of complexes 2‒5 have been investigated by cyclic voltammetry, showing that they can catalyze the reduction of protons to H2 in the presence of HOAc.

Diiron ethane‐1,2‐dithiolate complexes with 1,2,3‐thiadiazole moiety: Synthesis, X‐ray crystal structures, electrochemistry and fungicidal activity

Four diiron ethane‐1,2‐dithiolate complexes containing 1,2,3‐thiadiazole moiety have been synthesized and characterized. Esterification of the starting complex [Fe2(CO)6{μ‐SCH2CH(CH2OH)S}] (1) with 4‐methyl‐1,2,3‐thiadiazole‐5‐carboxylic acid in the presence of 4‐dimethylaminopyridine and N,N′‐dicyclohexylcarbodiimide yielded the corresponding ester [Fe2(CO)6{μ‐SCH2CHCH2O2C(4‐C2N2SCH3)S}] (2) in good yield. Further treatment of complex 2 with a phosphine ligand triphenylphosphine, tris(2‐methoxyphenyl)phosphine, or tri(p‐tolyl)phosphine and the decarbonylation reagent Me3NO·2H2O resulted in the formation of phosphine‐substituted analogues [Fe2(CO)5L{μ‐SCH2CHCH2O2C(4‐C2N2SCH3)S}] [L = PPh3, 3; P(2‐C6H4OCH3)3, 4; P(4‐C6H4CH3)3, 5] in 60 − 80% yields. The new complexes 2–5 were characterized by elemental analysis, IR and NMR spectroscopy and further confirmed by X‐ray diffraction analysis. The electrochemical properties were studied by cyclic voltammetry, showing that these complexes can catalyse the reduction of protons to H2 in the presence of HOAc. In addition, the fungicidal activity studies revealed that the hydroxy group possibly play a significant role in the biological activity.

Amine‐containing tertiary phosphine‐substituted diiron ethanedithioate (edt) complexes Fe2(μ‐edt)(CO)6‐nLn (n= 1, 2): Synthesis, protonation, and electrochemical properties

As diiron subsite models of [FeFe]‐hydrogenases for catalytic proton reduction to hydrogen (H2), a new series of the phosphine‐substituted diiron ethanedithiolate complexes Fe2(μ‐edt)(CO)6‐nLn (n = 1, 2) were prepared from the variable substitutions of all‐CO precursor Fe2(μ‐edt)(CO)6 (A) and tertiary phosphines (L1‐L4) under different reaction conditions. While the Me3NO‐assisted substitutions of A and one equiv. ligands L1‐L4 [L = Ph2P(CH2NHBut), Ph2P(CH2CH2NH2), Ph2P(NHBut), and Ph2P(C6H4Me‐p)] produced the monosubstituted complexes Fe2(μ‐edt)(CO)5L (1–4) in good yields, the refluxing xylene solution of A and two equiv. ligand L1 prepared complex Fe2(μ‐edt)(CO)5{κ1‐Ph2P(CH2NHBut)} (1) in low yield. Meanwhile, the UV‐irradiated toluene solution of A and two equiv. ligand L3 resulted in the rare formation of the disubstituted complex Fe2(μ‐edt)(CO)4{κ1, κ1‐(Ph2PNHBut)2} (5) in low yield, whereas the Me3NO‐assisted substitution of A and two equiv. ligand L4 afforded the disubstituted complex Fe2(μ‐edt)(CO)4{κ1, κ1‐(Ph2PC6H4Me‐p)2} (6) in good yield. All the model complexes 1–6 have been characterized by elemental analysis, FT‐IR, NMR spectroscopy, and particularly for 1, 3, 5 by X‐ray crystallography. Further, the protonations of complexes 1–4 are studied and compared with excess acetic acid (HOAc) and trifluoroacetic acid (TFA) by using FT‐IR and NMR techniques. Additionally, the electrochemical and electrocatalytic properties of model complexes 1–6 are investigated and compared by cyclic voltammetry (CV), suggesting that they are electrocatalytically active for proton reduction to H2 in the presence of HOAc.

Synthesis, characterization, and electrochemistry of diiron ethane-1,2-dithiolate complexes with monosubstituted ethyldiphenylphosphine or dicyclohexylphenylphosphine

In this contribution, two diiron ethane-1,2-dithiolate complexes with one ethyldiphenylphosphine or dicyclohexylphenylphosphine ligand have been synthesized and characterized as mimics for the active site of [FeFe]-hydrogenases. Treatment of complex [Fe2(CO)6(μ-SCH2CH2S)] (1) with ethyldiphenylphosphine or dicyclohexylphenylphosphine and Me3NO · 2 H2O as decarbonylating agent gave complexes [Fe2(CO)5(Ph2PCH2CH3)(μ-SCH2CH2S)] (2) and [Fe2(CO)5{PhP(C6H11)2}(μ-SCH2CH2S)] (3) in 93% and 86% yields, respectively. Complexes 2 and 3 were characterized by elemental analysis, IR, and NMR spectroscopy. X-ray crystallographic studies confirmed the molecular structures of complexes 2 and 3, indicating that they contain a butterfly diiron ethane-1,2-dithiolate cluster with five terminal carbonyl ligands and an apically-coordinated phosphine ligand. Additionally, the electrochemical properties of these complexes were investigated by cyclic voltammetry, suggesting that they can be regarded as electrocatalysts for the reduction of protons to H2 in the presence of HOAc. A possible mechanism for the proton reduction was proposed.

Asymmetrically PNP-chelate diiron ethanedithiolate complexes Fe2(μ-edt)(CO)4{κ2-(Ph2P)2NR} as diiron subsite models of [FeFe]-hydrogenases: Structural and electrocatalytic investigation

As a further exploration of the desirable diiron subsite models of [FeFe]-hydrogenases for hydrogen (H2) evolution, the asymmetrically PNP-chelate diiron ethanedithiolate complexes Fe2(μ-edt)(CO)4{κ2-(Ph2P)2NR} (1–3) can be synthesized in good yields through the substitution reactions of diiron all-carbonyl complexes Fe2(μ-edt)(CO)6 (A, edt = SCH2CH2S) with different PNP ligands (PNP = (Ph2P)2NR, R = (CH2)2CHMe2, (CH2)3OMe, (CH2)3SMe) in the presence of Me3NO·2H2O as decarbonylating agent. These new complexes 1–3 have been fully characterized by elemental analysis, FT-IR, NMR spectroscopy, and particularly for 1 by X-ray crystallography. Further, the electrochemical and electrocatalytic properties of complexes 1–3 and their precursor A as a reference compound are studied and compared through cyclic voltammetry (CV) in the absence and presence of HOAc as a proton source, suggesting that they are all found to be electrochemically active but show the distinct electrocatalytic abilities for proton reduction to H2.

Synthesis, characterization, and electrochemistry of monophosphine‐containing diiron propane‐1,2‐dithiolate complexes related to the active site of [FeFe]‐hydrogenases

Five monophosphine‐substituted diiron propane‐1,2‐dithiolate complexes as the active site models of [FeFe]‐hydrogenases have been synthesized and characterized. Reactions of complex [Fe2(CO)6{μ‐SCH2CH(CH3)S}] (1) with a monophosphine ligand tris(4‐methylphenyl)phosphine, diphenyl‐2‐pyridylphosphine, tris(4‐chlorophenyl)phosphine, triphenylphosphine, or tris(4‐fluorophenyl)phosphine in the presence of the oxidative agent Me3NO·2H2O gave the monophosphine‐substituted diiron complexes [Fe2(CO)5(L){μ‐SCH2CH(CH3)S}] [L = P(4‐C6H4CH3)3, 2; Ph2P(2‐C5H4N), 3; P(4‐C6H4Cl)3, 4; PPh3, 5; P(4‐C6H4F)3, 6] in 81%–94% yields. Complexes 2–6 have been characterized by elemental analysis, spectroscopy, and X‐ray crystallography. In addition, electrochemical studies revealed that these complexes can catalyze the reduction of protons to H2 in the presence of HOAc.

Synthesis, characterization, and electrochemistry of five diiron propane-1,3-dithiolate complexes with substituted phosphine ligands

In this paper, five diiron propane-1,3-dithiolate complexes containing substituted phosphine ligands were prepared and structurally characterized. Treatment of [Fe2(CO)6(μ-SCH2CH2CH2S)] (1) with a monophosphine ligand methyl diphenylphosphinite, ethyl diphenylphosphinite, 4-(dimethylamino)phenyldiphenylphosphine, tris(2-methoxyphenyl)phosphine, or tris(4-chlorophenyl)phosphine in the presence of Me3NO·2H2O as the decarbonylating agent gave the corresponding phosphine-substituted analogues [Fe2(CO)5(L)(μ-SCH2CH2CH2S)] [L = Ph2POCH3, 2; Ph2POCH2CH3, 3; Ph2P(4-C6H4 NMe2), 4; P(2-C6H4OCH3)3, 5; P(4-C6H4Cl)3, 6] in 73–93% yields. Complexes 2–6 have been characterized by elemental analysis, spectroscopy, and X-ray crystallography. Additionally, electrochemical studies have shown that 2–6 can catalyze the reduction of protons to H2 in the presence of HOAc.

Synthesis, characterization, and electrochemistry of phosphine-substituted diiron butane-1,2-dithiolate complexes

The reactions of the starting complex, [Fe2(CO)6{μ-SCH2CH (CH2CH3)S}] (1), with the phosphine ligands tris(4-methylphenyl)phosphine, diphenyl-2-pyridylphosphine, tris(4-fluorophenyl)phosphine, 2-(diphenylphosphino)benzaldehyde, or benzyldiphenylphosphine in the presence of the decarbonylating agent Me3NO·2H2O yielded the corresponding phosphine-substituted diiron butane-1,2-dithiolate complexes [Fe2(CO)5(L){μ-SCH2CH(CH2CH3)S}] (L = P(4-C6H4CH3)3, 2; Ph2P(2-C5H4N), 3; P(4-C6H4F)3, 4; Ph2P(2-C6H4CHO), 5; Ph2PCH2Ph, 6) in 75%–87% yields. The complexes have been characterized by elemental analysis, IR, 1H, and 31P{1H} NMR spectroscopy, as well as by single-crystal X-ray diffraction analysis. Moreover, the electrochemistry of 2–4 was studied by cyclic voltammetry, suggesting that they can catalyze the reduction of protons to H2 in the presence of HOAc.

Synthesis, characterization and electrochemical properties of two isomers of diiron diselenolato complexes and a new pathway to the μ4-Se twin cluster

Two isomers of diiron diselenolato complexes (ea)-(μ-SeC6H4-4-tBu)2Fe2(CO)6 (1), (ee)-(μ-SeC6H4-4-tBu)2Fe2(CO)6 (2) have been synthesized by treatment of (p-tBuC6H4Se)2 with Fe3(CO)12 at ambient temperature in 2 h. Moreover, a tetranuclear cluster complex [(μ-SeC6H4-4-tBu)Fe2(CO)6]2(μ4-Se) (3) was isolated by this simple and convenient way in 14% yield. All the three complexes were characterized by elemental analysis, FT-IR, NMR (1H, 13C) spectroscopy, as well as by X-ray diffraction analyses. Crystal structures reveal that complex 1 crystallizes in a chiral space group P4 (3), and the diselenolate substituents are axial-equatorial. For complex 2, both of the PhBu-t groups attached to their Se atoms by equatorial bonds. The structure of complex 3 consists of two [(μ-C6H4-4-tBu)Fe2(CO)6] units bridged by a pseudotetrahedral Se atom. Furthermore, the electrochemical properties for 1–3 were investigated by cyclic voltammetry. The results indicated that all the complexes could be used as electrocatalysts for reduction proton to hydrogen in the presence of HOAc in MeCN solution.

Triacetin Enhances Levels of Acrolein, Formaldehyde Hemiacetals, and Acetaldehyde in Electronic Cigarette Aerosols.

The health effects of inhaled electronic cigarette (e-cigarette) flavoring compounds are largely unknown. Earlier reports of their chemical reactivity have been conflicting, with some claiming, for example, that the degradation of flavoring chemicals in e-cigarettes to aldehydes is statistically insignificant. It is thus important to understand how these molecules react to afford enhanced aerosol products. The purpose of the current study was to investigate the origin of formaldehyde, acrolein, and acetaldehyde in e-cigarettes that contain the popular additive, triacetin (TA). By using 13C labeling and a combination of 1H NMR and 13C NMR, we were able to identify that ester hydrolysis of TA occurs to form acetic acid (HOAc) during aerosolization. The released HOAc acts as a catalyst in the degradation of propylene glycol (PG) and glycerol (GLY), increasing the formation of formaldehyde hemiacetals, acrolein, and acetaldehyde. A solution of 10% TA in 1:1 PG/GLY e-liquid was aerosolized using two different e-cigarettes at two wattages. Each device exhibited a significant increase in aldehyde levels, of up to 185% compared to the aerosol from a 1:1 PG/GLY e-liquid. In addition, the GLY formaldehyde hemiacetal was more predominant within the presence of HOAc, indicating that GLY may be relatively more prone to degradation from protonation.

Metal-free benzannulation of yne-allenone esters for atom economical synthesis of functionalized 1-naphthols

A metal-free benzannulation reaction of yne-allenone esters with H2O or aromatic amines in the presence of HOAc is reported, providing an atom economical protocol toward functionalized 1-naphthols with good to excellent yields.

Synthesis and electrochemical properties of [FeFe]-hydrogenase model complexes with acid-functionalized or base-functionalized ligands

In the presence of Me3NO in THF solution, the treatment of a diiron model complex (μ-dmedt)Fe2(CO)6 (dmedt = 2,3-butanedithiol) with carboxylic acid-functionalized (3-carboxypyridine) and amino-functionalized (4-aminopyridine) ligands afforded two new diiron model complexes, (μ-dmedt)Fe2(CO)5(3-COOHPy) (2) and (μ-dmedt)Fe2(CO)5(4-NH2Py) (3). Research on the influence of the 3-COOHPy and 4-NH2Py ligands upon the electrocatalytic characteristics of the diiron dithiolate core have been discussed in terms of spectroscopic and electrochemical findings. In the presence of HOAc in CH3CN solution, electrochemical studies show that complexes 2 and 3 can catalyse hydrogen evolution, with TOFs (the turnover frequencies) of 174.09 and 74.88 mol H2 (mol·cat)−1 h−1 cm−2 for complexes 2 and 3 at −1.96 V versus Fc+/Fc, respectively. The hydrogen evolution overpotentials of complexes 2 and 3 in the presence of HOAc in CH3CN solution were 0.73 and 0.82 V, respectively. Comparatively, complex 2 produces hydrogen at an overpotential 90 mV lower than complex 3 does. Complex 2 also has a better ability for electrocatalytic H2 production than complex 3. These studies provide a basic perception of the stereo-electronic characteristics related to the design for effective hydrogenase model complexes. Two new diiron model complexes, (μ-dmedt)Fe2(CO)5(3-COOHPy) (2), (μ-dmedt)Fe2(CO)5(4-NH2Py) (3), have been prepared, which served as efficient molecular electrocatalysts in the CH3CN solution, and the electrochemical studies show that complexes 2 and 3 can catalyse hydrogen evolution with TOFs of 174.09 and 74.88 mol H2 (mol·cat)−1 h−1 cm−2 for complexes 2 and 3 at −1.96 V versus Fc/Fc+, respectively.

Synthesis of Allenyl Sulfones via a TBHP/TBAI-Mediated Reaction of Propargyl Alcohols with Sulfonyl Hydrazides.

A new TBHP/TBAI-mediated reaction of propargyl alcohols with sulfonyl hydrazides in the presence of HOAc has been established, in which a wide variety of allenyl sulfones were obtained in moderate to excellent yields. Mechanistic studies indicate that this transformation involves HOAc-promoted sulfonohydrazide intermediate formation, sequential C-O, C-N, and N-S bond cleavage, and C-S bond formation. Significantly, this sulfonohylation proceeds in a radical process and shows highly functional group compatibility and excellent regioselectivity, with a short reaction time and inexpensive reagents.

CO Substitution Reactions of Diiron Complexes [{(μ‐SCH2)2X}Fe2(CO)6] and [{(μ‐SeCH2)2X}Fe2(CO)6] (X = O, CH2) with Ph2PCl/Me3NO to Give Ph2PCl‐, Ph2PNMe2‐, and Ph2PP(=O)Ph2‐Substituted Complexes Related to [FeFe] Hydrogenases

AbstractDiiron carbonyl complex [{(μ‐SCH2)2O}Fe2(CO)6] (A) reacted with Ph2PCl and Me3NO in MeCN at room temperature to give the expected and unexpected Ph2PCl‐, Ph2PNMe2‐, and Ph2PP(=O)Ph2‐substituted complexes [{(μ‐SCH2)2O}Fe2(CO)5L] [1, L = Ph2PCl; 2, L = Ph2PNMe2; 3, L = Ph2PP(=O)Ph2], whereas complex [{(μ‐SCH2)2CH2}Fe2(CO)6] (B) reacted with Ph2PCl and Me3NO under similar conditions to afford only the unexpected complexes [{(μ‐SCH2)2CH2}Fe2(CO)5L] [4, L = Ph2PNMe2; 5, L = Ph2PP(=O)Ph2]. Similarly, complex [{(μ‐SeCH2)2O}Fe2(CO)6] (C) reacted with Ph2PCl and Me3NO in MeCN at room temperature to give the unexpected complexes [{(μ‐SeCH2)2O}Fe2(CO)5L] [6, L = Ph2PNMe2; 7, L = Ph2PP(=O)Ph2], and the corresponding unexpected complexes [{(μ‐SeCH2)2CH2}Fe2(CO)5L] [8, L = Ph2PNMe2; 9, L = Ph2PP(=O)Ph2] were produced by the reaction of complex [{(μ‐SeCH2)2CH2}Fe2(CO)6] (D) with Ph2PCl and Me3NO under similar conditions. The structures of 1–9 were characterized by elemental analysis and spectroscopy, and for 1–5 and 7–9 by X‐ray crystallography. Possible pathways for the formation of the functionalized phosphine‐substituted complexes 1–9 have been suggested. Complexes 1–9 can be regarded as models for [FeFe] hydrogenases as their structures are similar to the active site of [FeFe] hydrogenases, and some have been found to be catalysts for proton reduction to hydrogen in the presence of HOAc.

A new cumulene diiron complex related to the active site of Fe-only hydrogenases and its phosphine substituted derivatives: Synthesis, electrochemistry and structural characterization

A new cumulene diiron complex related to the Fe-only hydrogenase active site [(μ-SCH 2C(S) C CH 2)Fe 2(CO) 6] ( 1) was obtained by treatment of (μ-LiS) 2Fe 2(CO) 6 with excess 1,4-dichloro-2-butyne. By controllable CO displacement of 1 with PPh 3 and bis(diphenylphosphino)methane (dppm), mono- and di-substituted complexes, namely [(μ-SCH 2C(S) C CH 2)Fe 2(CO) 5L] ( 2: L = PPh 3; 3: L = dppm) and [(μ-SCH 2C(S) C CH 2)Fe 2(CO) 4L 2] ( 4: L = PPh 3; 5: L = dppm) could be prepared in moderate yields. Treatment of 1 with bis(diphenylphosphino)ethane (dppe) afforded a double butterfly complex [(μ-SCH 2C(S) C CH 2)Fe 2(CO) 5] 2(μ-dppe) ( 7). With dppm in refluxing toluene, a dppm-bridged complex [(μ-SCH 2C(S) C CH 2)Fe 2(CO) 4(μ-dppm)] ( 6) was obtained. These model complexes were characterized by IR, 1H, 31P NMR spectra and the molecular structures of 1, 2 and 5– 7 were determined by single crystal X-ray analyses. The electrochemistry of 1– 3 was studied and the electrocatalytic property of 1 was investigated for proton reduction in the presence of HOAc.

Kinetic Study on Oxirane Cleavage of Epoxidized Palm Oil

AbstractA ring‐opened product (EPO‐HOAc) was prepared using epoxidized palm oil (EPO) and acetic acid (HOAc). The kinetics of the oxirane cleavage of EPO were investigated at 50, 60, 70, 80, and 90 °C, respectively, in the presence of HOAc. The rate equation of oxirane cleavage was as follows: r = k[Ep][CH3COOH]1.6 ([Ep] is the molar concentration of oxiranes, [CH3COOH] is the molar concentration of HOAc), and the activation energy of oxirane cleavage was 40.28 kJ mol−1. The structure of EPO‐HOAc was confirmed by FT‐IR and 1H NMR. The oxidative stability of EPO‐HOAc was better than that of palm oil (PO), and the pour point of EPO‐HOAc was lower than that of PO and EPO, which made EPO‐HOAc more suitable for biodegradable lubricant materials than PO and EPO.

Synthesis and Characterization of New Coordination Polymers with Tunable Luminescent Properties Generated from Bent 1,2,4-Triazole-Bridged N,N′-Dioxides and Ln(III) Salts

A new bent 1,2,4-triazole-bridged N,N'-dioxide ligand, namely, 3,5-bis(3-pyridyl-N-oxide)-4-amino-1,2,4-triazole (L2), was designed and synthesized by the oxidation of 3,5-bis(3-pyridyl)-4-amino-1,2,4-triazole with H(2)O(2) in the presence of HOAc at ambient temperatures. Eleven Ln(III)-based coordination polymers have been successfully prepared by the solution reactions of L2 with various Ln(III)-perchlorates. The structures of these new Ln(III) polymers clearly reflect the effect of the lanthanide contraction. Compounds 1-6 feature a two-dimensional net, in which the Ln(III) atoms adopt a nine-coordinate {LnO(9)} sphere due to their larger ionic radii, whereas the Ln(III) centers in the one-dimensional double-stranded chains of 7-11 with smaller ionic radii lie in a {LnO(8)} coordination environment. In addition, the tunable emission intensity was realized on 7 by controlling the type of the involved counterion on the basis of a reversible solid-state anion exchange. Such reversible solid-state anion exchange might provide an alternative approach to tuning the luminescence.