Dimethyl Phosphite Research Articles

Searching for the Achilles' Heel of Urethane Linkage-An Energetic Perspective.

A sudden increase in polyurethane (PU) production necessitates viable recycling methods for the waste generated. PU is one of the most important plastic materials with a wide range of applications; however, the stability of the urethane linkage is a major issue in chemical recycling. In this work, termination reactions of a model urethane molecule, namely methyl N-phenyl carbamate (MPCate), are investigated using G3MP2B3 composite quantum chemical method. Our main goal was to gain insights into the energetic profile of urethane bond termination and find an applicable chemical recycling method. Hydrogenation, hydrolysis, methanolysis, peroxidation, glycolysis, ammonolysis, reduction with methylamine and termination by dimethyl phosphite were explored in both gas and condensed phases. Out of these chemicals, degradation by H2, H2O2 and CH3NH2 revealed promising results with lower activation barriers and exergonic pathways, especially in water solvation. Implementing these effective PU recycling methods can also have significant economic benefits since the obtained products from the reactions are industrially relevant substances. For example, aniline and dimethyl carbonate could be reusable in polymer technologies serving as potential methods for circular economy. As further potential transformations, several ionizations of MPCate were also examined including electron capture and detachment, protonation/deprotonation and reaction with OH-. Alkaline digestion against the model urethane MPCate was found to be promising due to the relatively low activation energy. In an ideal case, the transformation of the urethane bond could be an enzymatic process; therefore, potential enzymes, such as lipoxygenase, were also considered for the catalysis of peroxidation, and lipases for methanolysis.

Anticorrosive and antimicrobial efficiency of photopolymerizable phosphorus (meth)acrylate oligomers-based coating materials

Novel photopolymerizable phosphorus (meth)acrylate oligomers were verified as anticorrosive and antimicrobial coating materials. Oligomers containing P-atoms were prepared by a solution-free UV-initiated telomerization process of aliphatic (meth)acrylates and styrene in the presence of different organic phosphorus compounds (P-telogens). The influence of the P-telogen structure on the photoaging process of coatings, as well as their anticorrosion and antibacterial properties was investigated. Relatively the highest anticorrosive efficiency was revealed for a varnish based on a telomers syrup containing dibutyl phosphite (DBPh) and dibutyl phosphate (DBP) due to the relatively long alkyl chain. In turn, UV-photocurable coatings exhibited moderate antibacterial and good anti-yeast activity but the best properties were found for the coating with dimethyl phosphite (DMPh). The higher resistance to photodegradation was observed in the case of the diphenyl phosphite (DPPh) due to the large phenyl substituent. Regardless of the structure of the organophosphorus compound, all coatings showed excellent adhesion to the glass substrate.

SILYLATION OF PHOSPHORYLATED CELLULOSE

In our work, using correlation analysis, we attempted to determine the effect of prior phosphorylation of the substrate with various organophosphorus compounds (OPC) of different nature on the degree of modification of the substrate with organosilicon compounds (OSC). We also tried to determine the dependence of silicon content in % by mass on the temperature and time of modification using the single-factor analysis of variance. It has been established that the pre-phosphorylation of the substrate increases the degree of its modification by the studied OSC. It is most likely due to the fact that polar OPC molecules, which have better penetrating and fixing abilities in the substrate, act as “conductors” of OSC into the substrate structure. The most effective “conductor” of OSC into the substrate, depending on modification time, can be considered tricresylphosphate (TCP) at a modification temperature of 20 degrees, because under these conditions, the correlation coefficients of OSC are higher than for other conditions of OPC processing. Dimethylphosphite (DMP) can be considered the most effective “conductor” of OSC into the substrate depending on the modification temperature because the correlation coefficients for all OSC are higher under these conditions than under other OPC processing conditions. It was found that there was a strong, direct correlation between the time of modification and the percentage of silicon content in the cellulose. The variation in the values of the calculated correlation coefficients ranged from 0.8927 to 0.9827. However, the direct correlation between the modification temperature and silicon content in cellulose in % was stronger and the scatter of correlation coefficients ranged from 0.9719 to 1.

Phosphorus-Containing Telomers as UV-Curable Binders of Solvent-Free Varnish Coatings.

The synthesis of novel phosphorus-containing telomers (P-telomers) was conducted via a solution-free UV-initiated telomerization process of butyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate, and styrene, different phosphorus telogens (dimethyl phosphite (DMPh), dibutyl phosphite (DBPh), diphenyl phosphite (DPPh) or dibutyl phosphate (DBP)), and a radical photoinitiator-acylphosphine oxide (APO). The course of the UV-phototelomerization process was monitored by photo-DSC and the chemical structures of telomers were assessed by FTIR. Final UV-photocurable varnish compositions consisted of prepared P-telomer syrups, crosslinking monomer (pentaerythritol triacrylate; PETIA), and a radical UV-photoinitiator (α-hydroxyalkylphenone, HAP). The influence of P- telomers on the optical and mechanical features of coatings was investigated. Relatively the highest hardness and satisfactory scratch values, as well as water and solvent resistance, were observed for varnish based on DMPh-telomers. While the strongest adhesive bond to a glass substrate was reported for DPPh-telomers. It is worth pointing out that the P-telomers did not affect the gloss values of varnishes in comparison to the telomer-free reference sample.

Modifier Based on Dicyandiamide and Dimethyl Phosphite for Fire and Heat Resistant Elastomer Materials

Modifier Based on Dicyandiamide and Dimethyl Phosphite for Fire and Heat Resistant Elastomer Materials

Design and preparation of flame-retardant cellulose fabric with low strength loss using polycarboxylic acid as crosslinker

To decrease strength loss of flame-retardant cotton fabric using polycarboxylic acid as the crosslinker, a series of multi-amino phosphoramide (BPEI/DPn) was synthesized using branched polyethyleneimine (BPEI) and dimethyl phosphite (DP). The flame retardant coating was fabricated on cotton fabric with the assist of 1,2,3,4-butanetetracarboxylic acid (BTCA). The optimum multi-amino phosphoramide was obtained by investigate the effect of different BPEI/DPn on washing durability and flame retardancy of modified cotton fabrics. The results found that BPEI/DP4 (mole ratio of BPEI and DP was 1:4) coated cotton fabric presented superior flame retardancy with self-extinguishing action and 27.9% of LOI value. Also, this flame-retardant cotton fabric can withstand a certain number of standard washing cycles. The heat and smoke release of cotton fabric during the combustion were significantly inhibited after modification with BPEI/DP4, and HRR value decreased by 35.0% compared with the unmodified cotton. Additionally, BPEI/DP4 can greatly improve the mechanical capability of cotton fabric modified with BTCA, and almost 80% of breaking force can be remained owning to partially neutralizing the acidic circumstance of BTCA solution, which might provide an efficient method to prepare functional cotton fabric with high performance.

Synthesis, characterization and in vitro bioactivity studies of isoindolin‐1‐3‐phosophonate compounds

AbstractIn this work, efficient synthesis of isoindolin‐1‐one‐3‐phosphonates under catalyst‐ and solvent‐free conditions was reported to afford the desired compounds in excellent yields with potent pharmacological properties. The synthesis method involves the preparation of isoindolin‐1‐one‐3‐phosphonates by a “one‐pot” three‐component reaction of 2‐formylbenzoic acid with primary amines and dimethyl phosphite under solvent‐ and catalyst‐free conditions. All new compounds were characterized by 1H NMR, 13C NMR, FT‐IR and elemental analysis techniques. The compounds were investigated for their bioactivities against a group of microorganisms, Leishmania major, Toxoplasma gondii parasites, and the DA‐MB‐231 and MCF‐7 cancer cell lines in vitro. Compound 4a was found to be the most active against L. M. luteus, L. monocytogenes and C. albicans microorganisms, with inhibition zones of 35, 22 and 38 mm, respectively. The compounds were also investigated for their antiparasitic activities, and compounds 4a and 4b were the most active against L. major amastigotes and promastigotes with EC50 < 1 μM. All tested compounds had potent anticancer activity against the MDA‐MB‐231 and MCF‐7 human cell lines with EC50 < 1.5 μM. Compounds 4a and 4b are good drug candidates for antimicrobial, antileishmanial and anticancer drug discovery, and further in vivo studies are highly recommended prior to any clinical trials.

Tetraalkyl Hydroxymethylene-bisphosphonate and Dialkyl 1-Diphenylphosphinoyl-1-hydroxy-ethylphosphonate Derivatives by the Pudovik Reaction and Their Rearranged Products.

The reaction of diethyl α-oxoethylphosphonate and diethyl oxobenzylphosphonate with diethyl phosphite, dimethyl phosphite, and diphenylphosphine oxide affords, depending on the substrates and conditions (nature and quantity of the amine catalyst, temperature, and solvent), the Pudovik adduct and/or the corresponding >P(O)–CH–O–P(O)< product formed by rearrangement. The nature of the substituent on the central carbon atom (a methyl or phenyl group) influences the inclination for the rearrangement. The asymmetric products (either adducts or rearranged species) with different P(O)Y functions (Y = RO or Ph) exhibit interesting NMR features.

High Chemoselectivity in the Construction of Aryl Methyl Sulfones via an Unexpected C–S Bond Formation between Sulfonylhydrazides and Dimethyl Phosphite

AbstractA highly chemoselective route to aryl methyl sulfones via an unexpected C–S bond formation between sulfonylhydrazides and dimethyl phosphite catalyzed by NaI under mild conditions has been established. This transformation provides an alternative and metal-free pathway to acquire various aryl methyl sulfones in good to excellent yields. Notably, dimethyl phosphite was employed as a stable and readily available alkyl source.

Ultraviolet and infrared light decontamination and the secondary pollution products of G-series nerve agent simulant model molecules contaminating TiO2/Ti surfaces

• Photo-decontaminations of G-series nerve agent simulant model molecules were tested under scanning 266-nm laser, UVA/UVB/UVC, and IR. • Photodecomposition products and the reaction pathways were discussed on the basis of GC, Mass, XPS, EDXS, and FT-IR. • Cleavages of P−CH 3 , P H, P O, C–H, PO−CH 2 CH 3 , and POCH 2 −CH 3 bonds of DMMP, DMP, DEMP, and DEP were fully discussed. • Dissociative adsorption and photocatalytic dissociation were discussed with active species of O 2 ― , h + and •OH. • MeOH and EtOH were major products dependent on light exposure, wavelength, photon flux, and the chemical groups. Ultraviolet (UV) photodecontamination of chemical warfare agents (CWAs) has been an attractive way for decontamination of target areas unapproachable by a wet chemical method. Herein, decontamination was demonstrated using UV and infrared lamps and a home-built scanning 266-nm pulse laser under air and N 2 conditions for the G-series nerve agent simulant model molecules of dimethyl methylphosphonate, dimethyl phosphite, diethyl methylphosphonate, and diethyl phosphite contaminating TiO 2 /Ti sheets. Volatile secondary photodecomposition products were examined by gas chromatography and mass spectrometry, and nonvolatile surface residues by X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction crystallography, and Fourier-transform infrared spectroscopy. The wavelength- and power-dependent mechanisms of the formation of diverse secondary products, the role of active O 2 − , h + and •OH species, and the mechanisms of dissociative adsorption and photodecontamination were fully discussed and found valuable for the development of a remote laser photodecontamination method applicable to diverse CWA-contaminated target areas.

UV light decontamination and secondary pollution products of G-series chemical warfare model molecules contaminated on Mo and MoOx surfaces

Understanding decomposition mechanism and analysis of secondary products for a chemical warfare agent (CWA) simulant on a contaminated target area are very important for better treatments of contaminated primary and secondary pollutants, and the development of a decontamination method. Herein, UV light (lamp and 266-nm laser high power pulses) photodecomposition method was introduced for the decontamination of G-series dimethyl methylphosphonate, dimethyl phosphite, diethyl methylphosphonate, and diethyl phosphite CWA model molecules contaminated on Mo and MoOx surfaces under various conditions. The secondary gas products were fully examined by gas chromatography and mass spectrometry, and the surface residues were also examined by scanning electron microscopy, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy before and after UV decontamination. Density function theory was employed to calculate the bond dissociation energies of the major chemical bonds for the CWA simulants. The full database for the photodecontamination products, the decomposition mechanism, the bond energies, and the roles of active species of O2−, h+ or OH reported in the present study provide valuable information on the development of future remote UV laser CWA decontamination system.

A Green Protocol for the Synthesis of α-Amino Phosphonates Catalyzed by Orange Peel Powder

A simple and green protocol has been developed for the synthesis of α-aminophosphonates from different substituted aromatic aldehydes, aniline and dimethyl phosphite in the presence of orange peel powder (OPP) as a natural catalyst under reflux conditions. The main advantages of this method are the high yield of product, simple workup procedure, short reaction time and easily available catalyst.

Visible-light induced Cross-Dehydrogenative-Coupling (CDC) reactions of N-aryl tetrahydroisoquinolines under aerobic conditions

A visible-light induced cross-dehydrogenative-coupling (CDC) reaction of N-aryl tetrahydroisoquinolines was developed under mild aerobic conditions. This protocol proceeded smoothly with a large range of nucleophiles (nitroalkane, dimethyl phosphite, dimethyl malonate, N-methyl indole, TMSCN) under metal-free conditions and an oxygen atmosphere, forming a new CC bond. Visible-light played a significant acceleration effect in this reaction.

Studies on the Genesis and Proton Conductivity of Imidazole-Based Linear and Open-Framework Zinc Phosphites.

Three new zinc phosphites, [HIm]2[Zn3(HPO3)4] (1), [Zn2(HPO3)2Im2] (2), and [Zn(HPO3)Im] (3) (Im = imidazole), have been synthesized from the hydro/solvothermal reaction of zinc acetate, dimethyl phosphite, and imidazole by varying the temperature and solvent of the reaction medium. The structure of 1 is built from vertex-sharing of four HPO3-capped Zn3P3 units and adopts an open framework with 12-ring channels stabilized by HIm cations via N-H···O hydrogen bonds. For 2, the inorganic skeleton is comprised of alternating ZnO4 and HPO3 tetrahedra, while the coordinatively associated ZnN2O2 fragments occupy the 12-ring hexagonal channels. Compound 3 adopts a ladder-type one-dimensional structure and exhibits N-H···O hydrogen-bonding interactions to afford a supramolecular assembly. A plausible rationale on the genesis of 1-3 has been put forth by reacting the preformed inorganic zinc phosphites Zn{OP(O)(OMe)H}2 or [Zn2(HPO3)2(H2O)4]·H2O with imidazole as the structure-directing ligand. Alternating-current impedance measurements reveal that 1 and 3 exhibit proton conductivities on the order of 10-3-10-4 S cm-1 between 25 and 100 °C under 35 and 77% relative humidity in repeated impedance cycles (Ea = 0.22-0.35 eV). On the contrary, the conduction property is completely impaired in 2 under similar conditions.

Challenging synthesis of bisphosphonate derivatives with reduced steric hindrance

An alternative approach is reported for the synthesis of methyl ester protected bisphosphonate building blocks, such as methylene bisphosphonate, vinylidenebisphosphonate and aryl substituted prochiral vinylidenebisphosphonates, that cannot be obtained directly from dimethyl phosphite and dichloromethane.

Recoverable Phospha-Michael Additions Catalyzed by a 4-N,N-Dimethylaminopyridinium Saccharinate Salt or a Fluorous Long-Chained Pyridine: Two Types of Reusable Base Catalysts.

Phospha-Michael addition, which is the addition reaction of a phosphorus-based nucleophile to an acceptor-substituted unsaturated bond, certainly represents one of the most versatile and powerful tools for the formation of P-C bonds, since many different electrophiles and P nucleophiles can be combined with each other. This offers the possibility to access many diversely functionalized products. In this work, two kinds of basic pyridine-based organo-catalysts were used to efficiently catalyze phospha-Michael addition reactions, the 4-N,N-dimethylaminopyridinium saccharinate (DMAP·Hsac) salt and a fluorous long-chained pyridine (4-Rf-CH2OCH2-py, where Rf = C11F23). These catalysts have been synthesized and characterized by Lu’s group. The phospha-Michael addition of diisopropyl, dimethyl or triethyl phosphites to α, β-unsaturated malonates in the presence of those catalysts showed very good reactivity with high yield at 80–100 °C in 1–4.5 h with high catalytic recovery and reusability. With regard to significant catalytic recovery, sometimes more than eight cycles were observed for DMAP·Hsac adduct by using non-polar solvents (e.g., ether) to precipitate out the catalyst. In the case of the fluorous long-chained pyridine, the thermomorphic method was used to efficiently recover the catalyst for eight cycles in all the reactions. Thus, the easy separation of the catalysts from the products revealed the outstanding efficacy of our systems. To our knowledge, these are good examples of the application of recoverable organo-catalysts to the DMAP·Hsac adduct by using non-polar solvent and a fluorous long-chained pyridine under the thermomorphic mode in phospha-Michael addition reactions.

Photo-decontamination of chemical warfare dimethyl methylphosphonate, dimethyl phosphite, diethyl methylphosphonate, diethyl phosphite model molecules on Al and oxidized Al foils

Decontamination of organophosphorus chemical warfare nerve agents (CWNAs) is gaining importance for human security. Herein, we have employed a dry-photodecontamination method for CWNA model molecules of dimethyl methylphosphonate, dimethyl phosphite, diethyl methylphosphonate, and diethyl phosphite contaminated on aluminum (Al) and oxidized Al foils. For understanding their photo-degradation pathways, the photo-decomposition secondary chemical products generated as a result of UVC-decontamination were fully examined for the contaminated Al and oxidized Al target areas in a closed reactor system by gas chromatography and mass spectrometry. Solid residues were also fully examined by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Density functional theory at the B3LYP/6–31 G level was used for geometric optimization, and the electronic energy state calculation was conducted on the level of TD-SCF/B3LYP/6–31 G. The new results further deepen the photo-decomposition mechanism of CWNAs, the development of dry UV light photo-decontamination methods, and the treatment of secondary by-products.

Stereochemistry of the Kabachnik‐Fields Condensation of Terpenic Amino Oximes with Aldehydes and Dimethyl Phosphite

AbstractThree‐component condensation of aldehydes and dimethyl phosphite with α‐amino oximes derived from (−)‐α‐pinene and (+)‐3‐carene (Kabachnik‐Fields reaction) resulted in amino phosphonates as pairs of diastereomers. Diastereomeric ratio depends on the catalyst used (SnCl2×2H2O, SiO2, Al2O3‐H+) and the heating type (conventional or microwave). The best results were achieved by MW irradiation with simultaneous cooling. Stereochemical assignment of the key derivatives was made by X‐ray diffractometry. According to quantum chemical calculations (DFT PBE0/def2‐TZVPP) and spectroscopic data, the terpenic α‐amino phosphonates should be conformationally inhomogeneous, exhibiting a tendency to form H‐bonded dimers (DFT M06/def2‐SVP, IR). One‐bond spin‐spin coupling 1JP–C was found to be diagnostic for the configuration assignment since the value 1JP–C depends on the dihedral angle between bond C−P and axis of the electron lone pair at the neighboring nitrogen (NMR, DFT PBE0/aug‐cc‐pVTZ−J).

α-Hydroxyphosphonates as intermediates in the Kabachnik–Fields reaction: New proof of their reversible formation

The rearrangement of dimethyl α-hydroxybenzylphosphonate to the corresponding benzylphosphate in the presence of an alkali carbonate in acetone under phase transfer catalytic conditions was accompanied by the formation of dimethyl α–hydroxyisopropylphosphonate, proving the reversibility of the formation of the hydroxyphosphonate from benzaldehyde and dimethyl phosphite in the Pudovik reaction. The dimethyl phosphite formed in situ from the adduct under the conditions of the rearrangement reaction was trapped by acetone.

Zinc-Catalyzed Phosphonylation of Alcohols with Alkyl Phosphites.

In the presence of a catalytic amount of either Zn(acac)2 or bis(2,2,6,6-tetramethyl-3,5-heptanedionato)zinc(II) (Zn(TMHD)2), primary, secondary, and tertiary alcohol substituents on a wide range of substrates, including acyclic and cyclic structures, carbohydrates, steroids, and amino acids, reacted with dimethyl phosphite to afford the corresponding H-phosphonate diesters in high to excellent yields.