Trimethyl Phosphite Research Articles

Synthesis of new aromatic polyamides containing α-amino phosphonate with high thermal stability and low heat release rate

The new aromatic polyamides containing α-amino phosphonate were synthesized from phosphorus-based dicarboxylic acid 4 and various aromatic diamines by direct polycondensation reaction. Dicarboxylic acid 4 was successfully synthesized from trimethyl phosphite, 4-aminobenzoic acid and terephthaldehyde via a three-component reaction. The polymerization reaction produced the polyamides 6a–f with high yield and desirable inherent viscosities. The thermal properties of the all samples were investigated by thermo-gravimetric analysis (TGA). The TGA results in N2 exhibited the 10% mass loss temperatures (T10) in the ranges of 324–345 °C, while the T10 resulted from thermo-oxidative degradation were higher than those. The main data obtained by microscale combustion calorimetry revealed acceptable combustion properties such as very low peak of heat release rate for the synthesized polyamides 6a–f. The all of the results indicated that these polyamides can be potentially utilized as additive for improvement of thermal resistance and combustion behavior of thermoplastic materials.

Highly efficient synthesis of pyrazolylphosphonate derivatives in biocompatible deep eutectic solvent

A straightforward and highly efficient one-pot preparation of biologically interesting pyrazolylphosphonate derivatives via a three-component reaction between pyrazolone or phenylpyrazolone, various aromatic, fused aromatic, heterocyclic, and aliphatic aldehydes, and triethyl or trimethyl phosphite in presence of an ammonium-based deep eutectic solvent (DES) at 25 °C has been developed. The ammonium-based DES was easily prepared from choline chloride and urea (1:2) at 80 °C for 2 h. It is biodegradable, fairly inexpensive, easily separated from the reaction mixture using water, and can be reused at least four times without loss of its catalytic activity. The most important features of this method are its eco-friendliness, high yields, high atom economy, and the fact that it does not require column chromatographic purification for isolation of the products. Thus, it represents an alternative method for the synthesis of a wide range of pyrazolylphosphonates with shorter reaction times.

Modulation of the solubility properties of arene ruthenium complexes bearing stannyl ligands as potential anti-cancer agents

Cleavage of the known ruthenium dimer [RuCl2(η6-C6H5OCH2CH2OH)]2 (1), bearing a hydrophilic substituent on the η6 coordinated aromatic ring, with the phosphine ligands: triphenyl phosphine, triphenyl phosphite, trimethyl phosphite, and 1,3,5-triaza-7-phosphaadamantane (PTA) afforded the known complexes [RuCl2(η6-C6H5OCH2CH2OH)(PPh3)] (2a), [RuCl2(η6-C6H5OCH2CH2OH){P(OPh)3}] (2b), [RuCl2(η6-C6H5OCH2CH2OH){P(OMe3)}] (2c), and [RuCl2 (η6-C6H5OCH2CH2OH)(PTA)] (4). The reaction of the known complex 2a with SnCl2 afforded, by facile insertion of the SnCl2 moiety into the RuCl bond, the novel complex [RuCl(η6-C6H5OCH2CH2OH)(PPh3)(SnCl3)] (3a). Similarly, the reaction of complex 2b with SnCl2 afforded the novel complex [RuCl(η6-C6H5OCH2CH2OH){P(OPh)3}(SnCl3)] (3b). Complexes 3a and 3b were fully characterized by spectroscopy (Infrared (IR) -spectroscopy, 1H, 31P and 119Sn Nuclear Magnetic Resonance (NMR) spectroscopy, UV–Vis spectroscopy and high resolution ESI-MS) and their thermal behaviour elucidated by Thermogravimetric Analysis (TGA). Density Functional Theory (DFT) calculations (Level of theory B3LYP, basis set for H, C, P, O, N and Cl is 6-31 + G (d,p) and for Ru and Sn is DGDZVP) for complex 3a, 3b and 4 were also carried out, in particular to elucidate the bonding situation between Ru and Sn in complexes. The hitherto unprecedented anti-cancer activity of the complexes 2a – 2c as well as the novel stannyl complexes 3a and 3b were evaluated against MCF-7 (oestrogen receptor positive) human breast adenocarcinoma cell lines. All complexes show activity active against MCF-7 cell lines, indicating potential application as an anti-tumor agent.

X-ray crystallography and electrochemistry reveal electronic and steric effects of phosphine and phosphite ligands in complexes RuII(κ4-bda)(PR3)2 and RuII(κ3-bda)(PR3)3 (bda = 2,2′-bipyridine-6,6′-dicarboxylato)

We have examined coordination of PR3 = triphenylphosphine, triethylphosphine, triisopropyl phosphite, trimethyl phosphite, and 1,3,5-triaza-7-phosphaadamantane (PTA) to the fragment RuII(bda) to better understand how different phosphine and phosphite ligands influence the electronic and structural properties of the RuII complexes. PTA and P(OMe)3 afforded complexes with three phosphorus ligands bound to Ru, with the bda being tridentate (κ3-N,N,O) in complexes 4 and 5; for the other three phosphorus ligands, even in the presence of >2 equiv, only RuII(κ4-bda)(PR3)2 species 1–3 were seen. Both experimental and computational methods were used to study the complexes. Steric effects are the main factor determining whether bis- or tris(PR3) complexes are formed. Cyclic voltammetry studies of the complexes revealed an increase in RuIII/II potential upon having another phosphorus ligand in the equatorial position. Computational studies predict that the additional phosphine ligand in the equatorial plane of 4 engages in significant orbital mixing with the ruthenium center that results in lower energy bonding as compared to the axial phosphine ligands. This work provides the first evaluation of phosphorus ligand steric and electronic effects on the RuII(bda) fragment.

One-pot facile synthesis of novel 1,2,3-triazole-appended α-aminophosphonates

New α-aminophosphonates bearing 1,2,3-triazolyl moiety were easily synthesized by one-pot reaction of 1-aryl-1H-1,2,3-triazole-4-carbaldehydes, anilines and trimethyl phosphite in good to excellent yields. All the synthesized compounds were characterized by IR, 1H NMR and 13C NMR analysis. These novel 1,2,3-triazole-incorporated α-aminophosphonates may be potential biological compounds due to the presence of both important moieties, 1,2,3-triazole and aminophosphonates.

Carbon monoxide substitutions by trimethyl phosphite in diiron dithiolate complex: Fe-Fe bond cleavage, selectivity of the substitutions, crystal structures and electrochemical studies

The reaction of substitution of carbon monoxide by P(OMe)3 in the complex (μ-η2PhC(S) = C(S)Ph)Fe2(CO)61 under thermal activation afforded two colored compounds: a binuclear disubstituted complex (μ-PhC(S) = C(S)Ph)Fe2(CO)4 [P(OMe)3]22 and a mononuclear iron disubstituted complex (η2PhC(S) = C(S)Ph)Fe(CO)[P(OMe)3]23. Mass spectrometry, 1H NMR, IR and electrochemical studies established that two (CO) have been substituted by P(OMe)3 in complexes 2 and 3. The X-ray studies show that the two P(OMe)3 ligands are in apical positions in trans of the iron – iron bound of complex 2 and in equatorial positions in complex 3. However, the substitution reaction of (CO) by P(OMe)3 in complex 1 under electron transfer catalysis (ETC) led to the monosubstituted compound (μ-PhC(S) = C(S)Ph)Fe2(CO)5 [P(OMe)3] 4.

Diastereoselective α-Hydroxylation of N-tert-Butanesulfinyl Imidates and N′-tert-Butanesulfinyl Amidines with Molecular Oxygen

Diastereoselective α-hydroxylation using molecular oxygen has been achieved with chiral α-alkyl N-tert-butanesulfinyl imidates and α-aryl N'-tert-butanesulfinyl amidines. The aza-enolates generated from deprotonation of imidates/amidines can be intercepted by O2 with excellent diastereocontrol and subsequently transformed into α-hydroxylation products in the presence of the reductant trimethyl phosphite.

Renaissance of Sandmeyer-Type Reactions: Conversion of Aromatic C-N Bonds into C-X Bonds (X = B, Sn, P, or CF3).

The Sandmeyer reaction represents an important organic transformation that converts an arylamine to an aryl halide using Cu(I) halide via a diazonium salt intermediate. The reaction was first reported by Sandmeyer in 1884, and a number of named reactions closely related to it have been developed and widely applied in organic synthesis throughout the 20th century. These include the Pschorr reaction for the synthesis of biaryl tricycles, the Gomberg-Bachmann reaction for biaryl formations, the Balz-Schiemann reaction for C-F bond formations, and the Meerwein reaction for arylation of α,β-unsaturated carbonyl compounds. However, all these reactions were discovered before 1940. In 1977, Doyle and co-workers reported an organic phase diazotization process, and Kikukawa and Matsuda used aryldiazonium salts in transition metal-catalyzed cross-coupling reactions. However, completely new processes involving diazonium salts have been seldom reported since then, although aryldiazonium salts are widely utilized in modern organic synthesis. In the past few years, diazonium salt chemistry has been revisited and become a fast-growing research topic. Several novel transformations based on diazonium salts have been developed and have been practiced in organic synthesis. In 2010, we reported a direct conversion of arylamines to pinacol boronates through the reaction of in situ generated aryl diazonium salts with B2pin2. This new strategy is under metal-free conditions and thus completely avoids contamination by transition metals in the boron products. From readily available arylamines various functionalized arylboronates, some of which are difficult to access by other methods, can be easily obtained with this reaction. Mechanistic investigations indicate the reaction likely follows a radical mechanism, which is similar to traditional Sandmeyer-type reactions. Subsequently, modified reaction conditions for this transformation appeared in the literature, which include light-induced reactions, aqueous-phase diazotization methods, and reactions with aryltriazenes as the arene diazonium salt surrogates. In addition to the borylation, we have also demonstrated the corresponding stannylation and phosphorylation of arylamines with similar Sandmeyer-type approaches. The stannylation of arylamines was achieved by the reaction of in situ generated diazonium salts with a distannane reagent, while phosphorylation is the reaction of arylamines with trimethyl phosphite in the presence of tert-butyl nitrite (t-BuONO). With the sequential borylation and stannylation approaches, the aromatic compounds bearing two amino groups are easily converted into trimethylstannyl arylboronates, which can be further used in consecutive Stille and Suzuki-Miyaura cross-couplings. Finally, direct conversion of the amino group of arylamines to the trifluoromethyl group has been developed through aryl diazonium salts almost simultaneously by several groups. These reactions represent a novel strategy to achieve trifluoromethylation of aromatic compounds. These developments show the revivification of this age-old chemistry, and this Account will summarize the Sandmeyer reaction-related transformations that have been developed since 2010.

Synthesis of 2-(3,4,5-trimethoxybenzoyl)-4(5)-phenyl-1H-imidazole

The condensation of (2E)-N-hydroxy-2-hydroxyimino-2-phenylethanamine with 3,4,5-trimethoxyphenylglyoxal afforded (1-hydroxy-5-phenyl-1H-imidazol-2-yl)phenylmethanone which reacted with trimethyl phosphite or chloroacetone to give 2-(3,4,5-trimethoxybenzoyl)-4(5)-phenyl-1H-imidazole.

First and Highly Stereoselective Synthesis of Both Enantiomers of Octahydroindole‐2‐phosphonic Acid (OicP)

We report the first stereoselective synthesis of (2R,3aR,7aR)‐ and (2S,3aS,7aS)‐octahydroindole‐2‐phosphonic acid 2 (OicP derivatives). The key points are the highly diastereoselective synthesis of cis‐fused bicyclic (3aR,7aR)‐ and (3aS,7aS)‐pyrrolidin‐2‐ones 4 through a dynamic kinetic resolution of racemic γ‐keto acid (±)‐5 with (R)‐ and (S)‐phenylglycinol via Meyers' bicyclic lactams, and the highly diastereoselective addition of trimethyl phosphite to the N‐acyliminium ions 3 obtained from 4.

Comparative Computational Study on the Reaction of Chloroacetone with Trimethylphosphite: Perkow versus Michaelis-Arbuzov Reaction Paths.

Two competitive mechanistic pathways for the reaction between trimethyl phosphite and chloroacetone are analyzed by high-level calculations. FMO analysis and HSAB-derived descriptors point to a preferential initial interaction of the nucleophile with the carbonyl group as electrophile. The Perkow reaction starts by chelotropic addition of the P atom to the carbonyl C-O bond, which is the rate-determining step in THF or CH2Cl2 solution, yielding an oxaphosphirane intermediate. The oxaphosphirane undergoes sequential P-C bond cleavage with elimination of chloride ion and O-demethylation. The alternative Michaelis-Arbuzov reaction involves nucleophilic displacement of chloride by the P atom and subsequent O-demethylation. The Perkow path is kinetically and thermodynamically favored with respect to the Michaelis-Arbuzov path in the gas phase, but it is only kinetically preferred in polar (THF or CH2Cl2) solvents.

Review on Bioorganometallic Chemistry and New Outcomes in the Synthesis and Substitution of Tetracarbonyl(pyrrolylimine) Complexes of Rhenium with Organophosphorus Ligands.

: After a short review dealing with bioorganometallic chemistry, the synthesis of tetracarbonyl (pyrrolylimine) complexes of rhenium bearing chirality on the pyrrolyl ligands was reported.The reactivity of these compounds towards the substitution of one carbonyl ligand with triphenyl phosphine, tricyclohexyl phosphine and trimethyl phosphite was studied. The rhenium becoming a stereogenic center in that transformation, the resulting tricarbonyl species were obtained as mixtures of diastereomers, with diastereomeric excesses varying from 8 to 84%, according to the reaction conditions and the relative steric hindrances of the pyrrolylimine and the organophosphorus ligands. These bioorganometallics are potential CO releasing molecules that could be used in the field of medicinal chemistry.

Synthesis, characterization and application of nitrogen–sulfur-doped carbon spheres as an efficient catalyst for the preparation of novel α-aminophosphonates

Nitrogen–sulfur-doped carbon spheres (NS-CSs) were prepared from sucrose and thiourea through a simple hydrothermal process. NS-CSs were characterized by TEM, FTIR, TGA, XRD, Raman spectroscopy and elemental analyses. The results revealed that the synthesized carbon spheres have an amorphous structure with diameters of 300–500 nm. The microspherical carbon catalyst that is recyclable has been used in the synthesis of α-aminophosphonates derived from 2-aminobenzothiazoles. Three-component reaction was performed between 2-aminobenzothiazoles, aromatic aldehydes and trimethyl phosphite in the presence of NS-CSs as microorganocatalyst at 50 °C under solvent-free conditions in high yield.

Photooxidation of Trimethyl Phosphite in Nitrogen, Oxygen, and para-Hydrogen Matrixes at Low Temperatures.

Trimethyl phosphite (TMPhite) was photooxidized to trimethyl phosphate (TMP) in N2, O2, and para-H2 matrixes at low temperatures to correlate the conformational landscape of these two molecules. The photooxidation produced the trans (TGG)-rich conformer with respect to the ground state gauche (GGG) conformer of TMP in N2 and O2 matrixes, which has diverged from the conformational composition of freshly deposited pure TMP in the low-temperature matrixes. The enrichment of the trans conformer in preference to the gauche conformer of TMP during photooxidation is due to the TMPhite precursor, which exists exclusively in the trans conformer. Interestingly, whereas the photooxidized TMP molecule suffers site effects possibly due to the local asymmetry in N2 and O2 matrixes, in the para-H2 matrix owing to the quantum crystal nature the site effects were observed to be self-repaired.

Insight into the Reaction Mechanism of α‐Amino Phosphonate Synthesis Using Succinic Acid as a Catalyst: Computational Kinetic Approach

The reaction mechanism in the synthesis of particular α‐amino phosphonates from 4‐methyl benzaldehyde, aniline, and trimethyl phosphite in the presence of succinic acid is theoretically investigated. The profile of the potential energy surface is constructed at both HF/6‐31 + G(d,p) and B3LYP/6‐31 + G(d,p) levels of theory for evaluating all the steps involved in the reaction mechanism. In order to investigate the effect of the structure on reactivity, some para‐substituted benzaldehydes are subjected to kinetic examination. The overall reaction in the presence of electron‐withdrawing groups is thermodynamically much more favorable than in the presence of the electron‐donating groups; similarly, the reaction is kinetically more favorable and much easier in the presence of electron‐withdrawing groups. Moreover, step 2 (imine formation) is recognized as the rate‐determining step at both levels of theory. Also, step 1 is diffusion‐controlled with both electron‐withdrawing and electron‐donating groups, while the other steps are chemically controlled in the reaction mechanism.

Photochemical functionalization of diazines: metal-free vinylation and phosphonylation

Under mild UVA irradiation, the CBr bond of bromodiazines can be activated to generate the corresponding radical intermediate. In the presence of alkynes, alkenylation reactions occurred to afford vinyl pyrimidine in moderate yields. Csp2-phosphorous bond can also be easily created in a photochemical version of the Arbuzov reaction. With UVA and a stoichiometric amount of trimethyl phosphite, the corresponding phosphonates were isolated in good to high yields. Very interesting selectivities were observed under these mild irradiation conditions. Functionalized substrates can be engaged and the resulting products could be further derivatized.

Ionic Liquid‐assisted Separation of Carbohydrates from Lignocellulosic Biomass

To utilize carbohydrates in lignocellulosic biomass, a fractionation of lignocellulose is crucial. In this study, poplar wood sawdust was treated with a mixture of ionic liquids, 1‐butyl‐3‐methylimidazolium acetate ([Bmim][OAc]) and 1,3‐dimethylimidazolium methyl phosphite ([Dmim][MeO(H)PO2]), to separate carbohydrate and lignin components from wood. Three types of product were isolated: water‐soluble wood (WSW), water‐insoluble wood (WIW), and wood in ionic liquids (WIL). At a dissolution temperature of 130°C for 18 h, WSW was found to have high carbohydrate and low lignin contents of 81.0 and 3.5%, respectively, corresponding to a delignification efficiency of 88.9%. WIW isolated under the same condition was found to have 55% of the lignin of native poplar. However, with an increase in the dissolution temperature and the time, the yield of WIL increased due to the increased phosphorylation in both carbohydrate and lignin, forming a mixture of carbohydrate and lignin having phosphorylated ionic functional groups.

Gas-phase ion-molecule reactions for the identification of the sulfone functionality in protonated analytes in a linear quadrupole ion trap mass spectrometer.

The oxidation of sulfur atoms is an important biotransformation pathway for many sulfur-containing drugs. In order to rapidly identify the sulfone functionality in drug metabolites, a tandem mass spectrometric method based on ion-molecule reactions was developed. A phosphorus-containing reagent, trimethyl phosphite (TMP), was allowed to react with protonated analytes with various functionalities in a linear quadrupole ion trap mass spectrometer. The reaction products and reaction efficiencies were measured. Only protonated sulfone model compounds were found to react with TMP to form a characteristic [TMP adduct-MeOH] product ion. All other protonated compounds investigated, with functionalities such as sulfoxide, N-oxide, hydroxylamino, keto, carboxylic acid, and aliphatic and aromatic amino, only react with TMP via proton transfer and/or addition. The specificity of the reaction was further demonstrated by using a sulfoxide-containing anti-inflammatory drug, sulindac, as well as its metabolite sulindac sulfone. A method based on functional group-selective ion-molecule reactions in a linear quadrupole ion trap mass spectrometer has been demonstrated for the identification of the sulfone functionality in protonated analytes. A characteristic [TMP adduct-MeOH] product ion was only formed for the protonated sulfone analytes. The applicability of the TMP reagent in identifying sulfone functionalities in drug metabolites was also demonstrated. Copyright © 2016 John Wiley & Sons, Ltd.

Lithium Diffusivity of Tin-based Film Model Electrodes for Lithium-ion Batteries

Lithium diffusivity of fluorine-free and -doped tin-nickel (Sn-Ni) film model electrodes with improved interfacial (solid electrolyte interphase (SEI)) stability has been determined, utilizing variable rate cyclic voltammetry (CV). The method for interfacial stabilization comprises fluorine-doping on the electrode together with the use of electrolyte including fluorinated ethylene carbonate (FEC) solvent and trimethyl phosphite additive. It is found that lithium diffusivity of Sn is largely dependent on the fluorine-doping on the Sn-Ni electrode and interfacial stability. Lithium diffusivity of fluorine-doped electrode is one order higher than that of fluorine-free electrode, which is ascribed to the enhanced electrical conductivity and interfacial stabilization effect. Keywords: Lithium-ion batteries, Lithium diffusivity, Tin-nickel anode, Film model electrode, Fluorine-doping, Interfacial stability

Lithium Diffusivity of Tin-based Film Model Electrodes for Lithium-ion Batteries

ABSTRACT Lithium diffusivity of fluorine-free and -doped tin-nickel (Sn-Ni) film model electrodes with improved interfacial (solidelectrolyte interphase (SEI)) stability has been determined, utilizing variable rate cyclic voltammetry (CV). The methodfor interfacial stabilization comprises fluorine-doping on the electrode together with the use of electrolyte including flu-orinated ethylene carbonate (FEC) solvent and trimethyl phosphite additive. It is found that lithium diffusivity of Sn islargely dependent on the fluorine-doping on the Sn-Ni electrode and interfacial stability. Lithium diffusivity of fluorine-doped electrode is one order higher than that of fluorine-free electrode, which is ascribed to the enhanced electrical con-ductivity and interfacial stabilization effect.Keywords: Lithium-ion batteries, Lithium diffusivity T, in-nickel anode, Film model electrode, Fluorine-doping In, terfacials tability Received July 13, 2015 : Accepted November 2, 2015 1. Introduction Tin (Sn)-based materials have been recognized asone of the attractive anode materials, which can replacethe commercialized graphite, primarily because of thelarger theoretical capacity (~994 mAhg