Synthesis of α, ω perfluoropolyether iodides

Perfluoropolyether (PFPE) diacyl halides of formula XCOCF₂O[(CF₂O)_n(CF₂CF₂O)_m]_pCF₂COX, with X = Cl, F and molecular weight (MW) 400-4000 g mol⁻¹ are smoothly converted in high yields to the corresponding α, ω diiodides in the absence of solvent, employing KI or LiI at 210 °C with extrusion of CO. During the reactions, β-elimination of COF₂ from the terminal difluoromethylene oxide units (CF₂O, C₁ unit) occurs to some extent until a tetrafluoroethylene oxide unit (OCF₂CF₂, C₂ unit) is encountered yielding a OCF₂CF₂I terminus. This considerably alters the MW distribution of the final diiodide especially for low MW PFPEs. Operating in supercritical conditions of CO (scCO) or both scCO and CO₂ (scCO₂) on low (<600 g mol⁻¹) MW diacyl halides, lowers β-elimination from 95 to 52 mol% if KI is used or from 43 to 30 mol% if LiI is used. With higher MW (>600 g mol⁻¹) β-elimination is lowered from 15 to <1 mol% in scCO conditions employing KI.     

Synthesis and Acid-Base Properties of α-Aminophosphoryl Compounds

-Aminophosphoryl compounds of the phosphonate, phosphine oxide, and ,-bis(phosphine oxide) series and some of their thiophosphoryl analogs were synthesized. Potentiometric measurements of the pK_a of the conjugate acids revealed an insignificant effect of variation of substituents on the phosphorus, nitrogen, and -carbon atoms on the basicity of the phosphorylated amines. The latter are weak bases. Organophosphorus groups decrease the basicity of the amines by almost 5 pK _a units. The role of the hydrophobic effect and intramolecular H-bonding in the obtained substances was discussed.     

Synthesis and Properties of Phosphorylated and Silylated α-Mercaptocarbonyl Compounds

Abstract

Phosphorylation and silylation of α -mercaptooarbonyl compounds have been investigated. A novel type of 1.4 S-O migration trimethylsilyl and P(III) groups has been discovered. The thiophosphite-thiophosphonate rearrangement when exposed to oxygen as well as heterocyclization with the formation of 1,3,2-oxathiaphospholenes and 1,3,2-oxathiasilalenes were also found. Some regularities of these processes and the properties of heterocycles synthesized have also been brought out.     

Synthesis and Properties of Aromatic Side Chained N‐Acyltaurate Surfactants

A series of anionic N‐acyltaurate surfactants, side chain containing aromatic nucleus (abbreviated as SAATT), were synthesized via Williamson reaction, hydrolyzation, and acylation. Krafft temperatures and surface properties of these surfactants at 30°C, that is, critical micelle concentration, cmc, surface excess concentration, Γ_max, surface area demand per molecule, A _min, efficiency in surface tension reduction, pC₂₀, effectiveness in surface tension reduction, π_cmc, and cmc/C₂₀ parameter were determined. It was shown that these surfactants exhibit good solubility which was confirmed by measuring Krafft temperature. The cmc of SAATT was much smaller than that of conventional surfactants with similar effective carbon numbers, and shifted to lower concentration with increasing hydrocarbon chain length. In addition, the γ_cmc decreased with decrease in Γ_max. The pC₂₀ and the cmc/C₂₀ got larger with the increase in hydrocarbon chain length. From the fluorescence intensity ratios of I ₁ (373 nm) and I ₃ (384 nm) using pyrene as a probe, it was indicated that the molecules of SAATT formed loose micelles with a broad size distribution.     

Kinetic Study on Models of the Noncatalyzed Reaction Between α, ω -Dicarboxypolyamide-11 and α, ω -Dihydroxypolyoxyalkylenes

The kinetics of the noncatalyzed reaction between α, ω -dicarboxypoly-amide-11 and α, ω -dihydroxypolyoxyalkylenes is investigated by using the reactions of 11-dodecylamidoundecanoic acid with 1-dodecanol, 2-tridecanol, α-dodecyl-ω-hydroxypolyoxyethylene or α-dodecyl-ω;-hydroxypolyoxypropylene as models. Kinetic data fit a 3rd overall order (2 in acid and 1 in alcohol). Rate constants and activation parameters are determined and compared.     

Kinetic Study on Models of the Tetrabutqxyzirconium-Catalyzed Reaction Between α, ω -Dicarboxypolyamide-11 and α, ω -Dihydroxypolyoxyethylene

The kinetics of the tetrabutoxyzirconium-catalyzed esterifications between 11-dodecylamideundecanoic acid and 1-dodecanol, 2-tridecanol, a-dodecyl-ω-hydroxypolyoxyethylene are studied and compared to that of α, ω-dicarboxypolyamide-l 1 and α, ω-dihydroxypolyoxyethylene. The reaction with 2-tridecanol is characterized by an autoacceleration phenomenon. In the other cases the reaction rate is not greatly affected by catalyst concentration. An explanation involving the formation of catalyst condensates at the very beginning of the reaction is put forward.     

Synthesis,Thermal Properties,and Radiolysis of Poly(Cyclohexyl α-Chloroacrylate)

Cyclohexyl α-chloroacrylate (CCA) was polymerized by radical anionic and γ-radiation initiation. The anionic polymerization of cyclohexyl α-chloroacrylate gave moderately isotactic polymer in toluene and syndiotactic-rich polymer in THF. Poly(cyclohexyl α-chloroacrylate) (PCCA) was found to undergo two-stage weight loss in thermogravimetric analysis, and the first-stage weight loss was attributed to the lactonization reaction. PCCA degraded under γ-radiation, and the radiation yields of crosslinking and scission, G _x and G _s, were 0.6 and 3.8, respectively.     

Cerium Alkoxides—Synthesis, Properties and Their Use in Michael Addition Reaction

Cerium(III) alkoxides served as an effective and attractive promoter for the Michael addition reaction with excellent chemical yields under mild conditions in short reaction time.     

A Short,Convenient Synthesis of 2-Arylglycidates via Aryl-Grignard Addition to an α-Bromopyruvate

A simple procedure has been developed for the preparation of a series of 2-arylglycidates required for herbicidal evaluation. Treatment of the α-bromopyruvate 5 with various aryl Grignard reagents at low temperature gave directly the glycidates 4. Saponification of these then afforded the desired sodium salts 7.     

A Facile Synthesis of Secondary α-Alkoxy or α-Acetoxy Aromatic Ketones

Abstract: The treatment of HNIB with aromatic ketones and subsequent solvolysis using alcohol or acetic acid in one-pot system makes it possible to give corresponding secondary α-alkoxy or α-acetoxy ketones in high yields.     

Chiral α-Aminophosphonates: Synthesis and Transport Properties

Abstract

Synthesis of chiral α-aminophosphonates and their transport properties (rates, enantioselectivity) as membrane carriers for oxy and amino acids are discussed.     

Synthesis and characterization of α,ω-dichloro-polymethylphenylsilane

The synthesis of a functional polysilane, α,ω-dichloro-polymethylphenylsilane (α,ω-dichloro-PMPS), based on the Wurtz-type reductive coupling, has been considered. A study of some reaction parameters shows that both yield and molecular weight distribution of α,ω-dichloro-PMPS can be greatly influenced by the work-up conditions, reaction time, monomer concentration and temperature during the initiation of the polymerization. By varying the synthesis conditions, different ratios of high and low molecular weight fractions were obtained. Samples of different molecular weight were isolated by fractional precipitation of the crude polymers. The chlorine-end functionalization was confirmed by ²⁹Si NMR spectroscopy and the concentration of end-groups was quantitatively determined by elemental analysis of chlorine.     

Synthesis and Properties of Phosphabetaine Structures: III. Phosphabetaines Derived from Tertiary Phosphines and α,β-Unsaturated Carboxylic Acids. Synthesis, Structure, and Chemical Properties

Methods of synthesis of acylate phosphabetaines by reactions of triphenylphosphine with methacrylic, cinnamic, and p-methoxycinnamic acids are developed. The phosphabetaine form is proposed to exist in equilibrium with the ⁵-oxaphospholane form. The features of methylation of the phosphabetaines are discussed.     

Synthesis,Structure and Properties of Inverse-Keggin Potassium Tetraniobooctatungstosilicate

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Synthesis,Characterization and Antimicrobial Properties of Superparamagnetic α-Fe2O3 Nanoparticles Stabilized by Biocompatible Starch

Journal of Cluster Science - In the present study we have synthesized α-Fe2O3 nanoparticles in a more conventionally established NaBH4 reduction, but using a bio-macromolecule, starch. The...     

Synthesis and Properties of Aryloxy-terminated Polydimethylsiloxanes

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Solvothermal Synthesis of α-Fe_2O_3 Porous Nanobelts and Their Enhanced Acetone-sensing Properties

Porous α-Fe_2O_3 nanobelts have been prepared via a solvothermal route and subsequent calcination. The as-prepared nanostructure was characterized by XRD, FESEM, TEM, N_2 adsorption-desorption isotherms, etc. The α-Fe_2O_3 nanobelts presented obvious porous structures with the length of ca. 1～2μm, width of ca. 200～350 nm and thickness of ca. 30～60 nm. It was found that the assistance of inorganic additives played an important role in the shape control of α-Fe_2O_3 nanostructure. The gas-sensing performance of the fabricated sensor based on α-Fe_2O_3 nanobelts sample was also investigated, and the response towards 1000 ppm acetone can reach 24.4. In addition, the gas-sensing conductive mechanism of the sensor was also proposed.     

Metal-Free Synthesis of Benzo[α]phenanthridines from Aromatic Aldehydes,Cyclohexanones,and Aromatic Amines

A three-component synthesis of benzo[α]phenanthridines from aromatic aldehydes,cyclohexanones,and aromatic amines has been developed,which is mediated by KI/DMS...