Triethyl Phosphite Research Articles

Sol-Gel Synthesis of FHA Nanoparticles and CDHA Agglomerates from a Mixture with a Nonstochiometric Ca/P Ratio

The aim of this study was to investigate the sol gel synthesis of HA/FA nanoparticles and the possible formation of TCP phase or unstoichiometric calcium deficient hydroxyapatite (CDHA) from the precursors with a Ca/P ratio of 1.62. In order to prepare the sol, the solutions of Triethyl phosphite, ammonium fluoride and calcium nitrate in ethanol were used respectively as P, F and Ca precursors. The crystallinity, particle and crystallite size, powder morphology, chemical structure and phase analysis were investigated by SEM, XRD, FT-IR and Zeta sizer experiment. A multiphase compound containing hydroxyapatite (HA) and fluoroapatite (FA) nanoparticles and calcium deficient hudroxyapatite (CDHA) agglomerates was obtained. The size of the crystallites estimated from XRD patterns using Scherrer equation and the crystallinity of HA phase were about 5 nm and 66% respectively. The zeta sizer experiments for the dispersed particles in its own conditions showed an average size of 98 nm.

Synthesis of N-Substituted Pyrido[b]-Anellated Azaphospholes

Reported are the first examples of the syntheses and structures of 3-amino and 3-amido pyridine-2-phosphonates, and the conversion of the latter heterocycles into azaphospholo[4,5-b]pyridines. After considerable testing of various conditions, the phosphonates were synthesized in low yields via Pd-catalyzed cross-coupling of bromopyridines with triethyl phosphite. The low yields were suggested to be due to the deactivating effects of the pyridine nitrogen and the amino group. Reduction of the amido phosphonates with LiAlH4, followed by reaction with DMF dimethyl acetal led to the previously unknown P=C-N heterocycles in good yields. However, the compounds were found to be highly air-sensitive and their purification proved impossible in some cases.

Mild Oxidative Addition of C–H Bonds to a Hydrido‐Bridged Dinuclear Complex of Iridium(II) Induced by the Coordination of Heteroatomic Ligands

AbstractThe oxidative addition of C–H bonds to a dinuclear complex of divalent iridium, [Cp*Ir(μ‐H)]2 (1), has been investigated. Reactions of 1 with phosphorus compounds containing a phenyl ring (PR1R2Ph) at ambient temperature gave novel five‐membered diiridacyclic [(Cp*IrH)2(μ‐H)(μ‐R1R2PC6H4)] [R1 = R2 = Me (2a); R1 = Me, R2 = Ph (2b); R1 = R2 = Ph (2c); R1 = R2 = OEt (2d); and R1 = OEt, R2 = Ph (2e)] complexes through ortho‐C–H activation of the phenyl ring bound to the phosphorus atom. The reaction of 1 with tripropylphosphane gave a new four‐membered diiridacyclic [(Cp*IrH)2(μ‐H)(μ‐Pr2PCHCH2CH3)] (3) complex in a similar manner. On the other hand, the reaction of 1 with triethyl phosphite gave a Cp*‐metalated product, [Ir(H)(P(OEt)3)(μ,η5,η1‐C5Me4CH2)(μ‐H)Ir(H)(Cp*)] (4), through C–H activation of a methyl group on one of the Cp* ligands. Furthermore, similar mild C–H activation reactions of 1 with sulfoxides have also been revealed. Thus, reactions of 1 with dimethyl sulfoxide and a couple of sulfoxides containing phenyl groups brought about the activation of the C–H bonds of a methyl group and a phenyl group to give [(Cp*IrH)2(μ‐H)(μ‐MeS(=O)CH2)] (5) and [(Cp*IrH)2(μ‐H)(μ‐RS(=O)C6H4)] [R = Me (6a) and R = Ph (6b)], respectively. The structures of 2a, 4, 5, and 6a have been confirmed by X‐ray analysis. A plausible reaction pathway for these C–H activation reactions has been proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

ChemInform Abstract: Formation of Adducts (III) of Pyrilium Cations with Triethyl Phosphite.

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Converting dipyrrinones to lactim ethers to fluorescent N,N′-difluoroboryl derivatives

A high-yield straightforward conversion of lactams to lactim ethers is shown by the conversion of (10H)-dipyrrin-1-ones to (11H)-dipyrrin-1-ol methyl and ethyl ethers in 90% yield from heating in neat trimethyl or triethyl phosphite at 160°C. Unlike the parent dipyrrinones, which form intermolecularly hydrogen-bonded dimers in CHCl3, their lactim ethers are shown to be monomeric by vapor pressure osmometry. The latter react with boron trifluoride etherate to N,N′-bridged BF2 derivatives that exhibit strong fluorescence (φF 0.6–0.8) near 535 nm. X-Ray crystal structures were obtained of the lactim ethyl ether of kryptopyrromethenone and the BF2 derivative of the lactim ethyl ether 2,3-diethyl-7,8-dimethyl-(10H)-dipyrrin-1-one.

3-Amino- and 3-acylamido-2-phosphonopyridines: synthesis by Pd-catalyzed P–C coupling, structure and conversion to pyrido[ b]-anellated P [dbnd]C–N heterocycles

Palladium catalyzed cross-coupling of 3-amino- and 3-acylamido-2-bromopyridines 1a– f with triethyl phosphite allowed the synthesis of 3-amino- and 3-acylamido pyridine-2-phosphonic acid diethyl esters 2a– f, whereas nickel catalysts, although providing access to related anilido-2-phosphonates, proved inactive. Reduction of the aminophosphonate 2a with LiAlH 4 afforded 3-amino-2-phosphinopyridine ( 3a), which was cyclocondensed with dimethylformamide dimethyl acetal (DMFA) via phosphaalkene intermediates 4a to the novel pyrido[ b]-anellated 1,3-azaphosphole 5a. Reaction of amidophosphonates 2b– f with LiAlH 4 did not result in the expected reductive cyclization, as shown by closely related anilido-2-phosphonates, but led to product mixtures containing N-secondary 3-amino-2-phosphinopyridines 3b– f as the main or major component. The conversion of 3b, d, e with DMFA to 5b, d, e provides first examples of N-substituted pyrido[ b]-anellated azaphospholes. Structures were confirmed by multinuclear NMR and X-ray crystallography (for 2c, 3b).

First asymmetric Abramov-type phosphonylation of aldehydes with trialkyl phosphites catalyzed by chiral Lewis bases

Chiral phosphine oxides (Lewis bases) catalyze silicon tetrachloride-mediated, enantioselective phosphonylation of aldehydes with trialkyl phosphites (Abramov-type reaction), which leads to optically active α-hydroxyphosphonates with moderate enantioselectivities. 31P NMR analysis of the phosphonylation of benzaldehyde with triethyl phosphite supports the assumed reaction mechanism.

ChemInform Abstract: Nickel(0) Triethyl Phosphite Complex Catalyzed Allylic Substitution with Retention of Regio‐ and Stereochemistry.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Reactions of β‐Alkoxyvinyl Trihalogenomethyl Ketones with Triethyl Phosphite.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Structure of solvated mercury(ii) halides in liquid ammonia, triethyl phosphite and tri-n-butylphosphine solution

Liquid ammonia, trialkyl phosphites, and especially trialkylphosphines, are very powerful electron-pair donor solvents with soft bonding character. The solvent molecules act as strongly coordinating ligands towards mercury(ii), interacting strongly enough to displace halide ligands. In liquid ammonia mercury(ii) chloride solutions separate into two liquid phases; the upper contains tetraamminemercury(ii) complexes, [Hg(NH(3))(4)](2+), and chloride ions in low concentration, while the lower is a dense highly concentrated solution of [Hg(NH(3))(4)](2+) entities, ca. 1.4 mol dm(-3), probably ion-paired by hydrogen bonds to the chloride ions. Mercury(ii) bromide also dissociates to ionic complexes in liquid ammonia and forms a homogeneous solution for which (199)Hg NMR indicates weak bromide association with mercury(ii). When dissolving mercury(ii) iodide in liquid ammonia and triethyl phosphite solvated molecular complexes form in the solutions. The Raman nu(I-Hg-I) symmetric stretching frequency is 132 cm(-1) for the pseudo-tetrahedral [HgI(2)(NH(3))(2)] complex formed in liquid ammonia, corresponding to D(S) = 56 on the donor strength scale. For the Hg(ClO(4))(2)/NH(4)I system in liquid ammonia a (199)Hg NMR study showed [HgI(4)](2-) to be the dominating mercury(ii) complex for mole ratios n(I(-)) : n(Hg(2+)) > or = 6. A large angle X-ray scattering (LAXS) study of mercury(ii) iodide in triethyl phosphite solution showed a [HgI(2)(P(OC(4)H(9))(3))(2)] complex with the Hg-I and Hg-P bond distances 2.750(3) and 2.457(4) A, respectively, in near tetrahedral configuration. Trialkylphosphines generally form very strong bonds to mercury(ii), dissociating all mercury(ii) halides. Mercury(ii) chloride and bromide form solid solvated mercury(ii) halide salts when treated with tri-n-butylphosphine, because of the low permittivity of the solvent. A LAXS study of a melt of mercury(ii) iodide in tri-n-butylphosphine at 330 K resulted in the Hg-I and Hg-P distances 2.851(3) and 2.468(4) A, respectively. The absence of a distinct I-I distance indicates flexible coordination geometry with weak and non-directional mercury(ii) iodide association within the tri-n-butylphosphine solvated complex.

Development of a Thermal Evaporation Cell for Gas-Phase Infrared Absorption Spectroscopy of Compounds with Low Volatility

To facilitate in-depth hazard prediction models, we must understand the spectral properties of expulsion plumes from conventional weapon attacks. Precise data on the spectral absorption of three chemical weapon agent simulants, in the infrared regime, are required to properly determine the mass of simulant in expulsion plumes from field demonstrations and small scale tests. Data for triethyl phosphate (a Soman simulant), triethyl phosphite (a Sarin simulant), and tributyl phosphate (a VX simulant) are presented. A thermal evaporation cell was designed and built that incorporated features that are not commercially available.

The Michaelis–Arbuzov rearrangement of anomeric thiocyanates: synthesis and application of S-glycosyl thiophosphates, thiophosphonates and thiophosphinates as glycosyl donors

Reaction of anomeric thiocyanates with triethyl phosphite, dimethyl phenylphosphonite and methyl diphenylphosphinite afforded the corresponding S-glycosyl thiophosphates, thiophosphonates and thiophosphinates in good yields. These derivatives were applied as glycosyl donors in the synthesis of benzyl glycosides and disaccharides with excellent stereoselectivity.

Formation of adducts of pyrilium cations with triethyl phosphite

Formation of adducts of pyrilium cations with triethyl phosphite

Nickel(0) Triethyl Phosphite Complex-Catalyzed Allylic Substitution with Retention of Regio- and Stereochemistry

Nickel(0) triethyl phosphite complex-promoted reaction of allylic acetates with thiols produced allylic sulfides with retention of configuration without allylic rearrangement. A similar reaction of allylic acetates with alcohols and phenols also proceeded with retention of regio- and stereochemistry.

Improvement of bonding strength to titanium surface by sol–gel derived hybrid coating of hydroxyapatite and titania by sol–gel process

In this study, we investigated the hydroxyapatite(HA)/titania(TiO 2) hybrid coating on Ti substrate in order to combine advantages of both materials, namely the adhesion strength of TiO 2 on the substrate as well as the bioactivity of the HA. Composite sols of HA and TiO 2 were synthesized using calcium nitrate tetrahydrate and triethyl phosphite with various ratio. They were dropped onto cp Ti substrate and followed by spin-coating at 2000rpm for 10s. Then dried for 24h at room temperature and were heat-treated at 500°C for 2h. The crystalline phases, roughness and thickness of the coating films were measured by XRD, surface profiler, and SEM, respectively. The scratch test was performed as a criterion of adhesion strength between the coating film and the substrate. The critical load at which the coating film was peeled off completely from the substrate is determined using spherical diamond stylus. The bioactivity was observed after suspended in a simulated body fluid at 37°C. Effect of composition on the cell attachment onto the substrate was determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) method according to the amount of TiO 2 addition. Preosteoblast-like MG 63 cells were selected in this determination. According to increase the amount of TiO 2, the debonding strength of the hybrid coating film from Ti substrate was increased as well as the attachment density of MG 63 cells as expected. The debonding strength and the cell attachment density showed significant higher value than that of pure HA when the amount of TiO 2 was exceeded 30% and 50%, respectively ( p < 0.05). These hybrid coating films were proved to be bioactive from the needle-shaped bone-like apatite formation after 2weeks of exposure to simulated body fluid.

Triethyl Phosphite Mediated Domino Reaction: Direct Conversion of ω‐Nitroalkenes into N‐Heterocycles.

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One-pot Synthesis of Stable Phosphite Ylides by three component reaction between Acetylenic Esters, Aldehyde Semicarbazones and Tributyl or Triethyl Phosphite

Three-component reaction between acetylenic esters, aldehyde semicarbazones and tributyl- or triethyl phosphite leads to stable crystalline phosphite ylides at one step in nearly quantitative yields.

Limitations of the Wittig–Horner-type annulation of fluorobutenolide moiety to 3-hydroxyquinoline-2,4(2 H,3 H)-diones. Novel modifications of the Perkow reaction including fluorinated acyloxy leaving groups

3-(Fluoroacyloxy)quinoline-2,4(1 H,3 H)-diones react with triethyl phosphite to afford either the product of the Perkow reaction or the corresponding 4-ethoxyquinolin-2(1 H)-one. In both reactions, the fluorocarboxylate anion acts as the leaving group. For the corresponding 3-(fluoroiodoacetoxy) derivative this observation precludes the application of the intramolecular Wittig–Horner synthesis to modify quinoline-2,4(1 H,3 H)-diones by the annulation of a fluorinated but-2-enolide moiety.

Amphiphilic Conjugated Block Copolymers: Synthesis and Solvent‐Selective Photoluminescence Quenching

A novel, amphiphilic, conjugated block copolymer is described, which was prepared by a Suzuki-type cross-coupling of 2-bromo-[9,9-bis(2-ethylhexyl)fluorene]-7-pinacolato boronate as an AB-type monomer and monobromo-substituted poly[3-(6-bromohexyl)thiophene] (Br-P3BrHT) as a polymeric end capper in the key step. PF-P3PHT (P2; PF = poly(9,9-dialkylfluorene); P3PHT = poly[3-(6-diethylphosphonato-hexyl)thiophene]) as the amphiphilic target polymer was then generated in a polymer-analogous conversion of the alkyl bromide side chains of the PF-P3BrHT (P1) precursor into polar alkyl phosphonate groups by reaction with triethyl phosphite. P2 shows a strong influence of the solvent polarity on the optical spectra (absorption, emission). Treatment of solutions of P2 in tetrahydrofuran (THF), a nonselective solvent, with increasing amounts of solvents that are selective for the polar polythiophene blocks (water) or the nonpolar polyfluorene blocks (hexane), respectively, results in the formation of two different types of core-shell aggregates, which show rather different optical properties (photoluminescence quenching, excitation energy transfer).

Reactions of β-alkoxyvinyl trihalogenomethyl ketones with triethyl phosphite

The Perkow reaction of triethyl phosphite and β-alkoxyvinyl trihalogenomethyl ketones, which have common acyclic or cyclic structural fragment: –O–C C–C(O)CX 2Cl, yielded dienyl phosphates: –O–C C–C[OP(O)(OEt) 2] CX 2 where X = F or Cl, whereas γ-bromo-β-methoxy-α,β-unsaturated trifluoromethyl ketone CF 3C(O)CH C(OMe)CH 2Br gave diene CF 3C[OP(O)(OEt) 2] CH–C(OMe) CH 2.