New poly(amide-imide)s syntheses. II. Soluble poly(amide-imide)s derived from 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene and various N-(ω-carboxyalkyl)-trimellitimides,N-(carboxyphenyl)trimellitimides,or N,N″-bis(ω-carboxyalkyl)pyromellitimides

Various dicarboxylic acids with preformed imide rings were readily obtained by the condensation of ω-amino acids and aminobenzoic acids with trimellitic anhydride, and omega;-amino acids with pyromellitic dianhydride. New tetraphenylthiophene-containing poly(amide-imide)s having inherent viscosities of 0.58-1.54 dL/g were prepared by the direct polycondensation reaction of 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene with the imide-containing dicarboxylic acids using triphenyl phosphite and pyridine as condensing agents. These polymers were amorphous and readily soluble in a variety of solvents such as dimethylacetamide (DMAc), dimethylformamide (DMF), and N-methyl–2-pyrrolidone (NMP), and could be easily solution cast into transparent, flexible, and tough films. Most of the poly(amide-imide)s showed clear glass transition on the heating traces of differential scanning calorimetry (DSC) in the range of 146–244°C. Almost all the poly(amide-imide)s exhibited no appreciable decomposition below 400°C, with 10% weight loss being recorded above 420°C in nitrogen. © 1992 John Wiley & Sons, Inc.     

A Mild and Efficient Procedure for the Preparation of Chromone-2-carboxylates

Chromone-2-carboxylates are widely used for the pharmacological activity of several of its derivatives1. The general synthesis of such chromone derivates includes two steps (Scheme 1): a Claison condensation of dialkyl oxalate with 2-hydroxyacetophenones to achieve alkyl 3-(2-hydroxyphenyl)-3-oxopropanoates in the presence of NaH, NaOEt, or NaOMe; cyclodehydration of the alkyl 3-(2-hydroxyaryl)-3-oxopropanoates to obtain chromones under acid condition. The total yield of the two steps is q…     

Synthesis and properties of aromatic polyamides derived from 1,2-bis(4-aminophenoxy)benzene and aromatic dicarboxylic acids

1,2-Bis(4-aminophenoxy)benzene was synthesized in two steps by the preparation of 1,2-bis(4-itrophenoxy)benzene from 1,2-dihydroxybenzene (catechol) and p-chloronitrobenzene and subsequent reduction with a 10% Pd-C catalyst and hydrazine hydrate. Aromatic polyamides with an inherent viscosity in the range of 1.08–2.00 dL/g were prepared by the direct polycondensation of this diamine with various aromatic dicarboxylic acids in N-methyl-2-pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Most of the polymers formed were soluble in aprotic solvents such as NMP and N,N-methylacetamide (DMAc), and afforded transparent, flexible, and tough films upon casting from DMAc solutions. Most of the cast films showed obvious yield points in their stress-strain curves and had tensile strength among 64–89 MPa, elongation at break among 5–23%, and initial modulus in 1.7–2.5 GPa. The glass transition temperatures (T_g) of these polymers were in the range of 207–278°C, and the 10% weight loss temperatures were recorded above 475°C in nitrogen and above 452°C in air. © 1995 John Wiley & Sons, Inc.     

Catalysis by Hydrogen Carbonate and Silicate Anions of the Oxidation of Diethyl Sulfide with Hydrogen Peroxide in Aqueous and Aqueous–Alcoholic Media

The kinetics of the oxidation of diethyl sulfide (Et₂S) with hydrogen peroxide, catalyzed by hydrogen carbonate and silicate anions, agree with the assumption that peroxymonocarbonate (HCO^– ₄) and peroxymonosilicate (HSiO^– ₄) anions are formed as intermediates. The rate of reaction of Et₂S with HCO^– ₄ is about 100 times as fast as with H₂O₂. Transfer to aqueous–alcoholic solutions leads to an increase in the solubility of Et₂S while retaining the catalytic effects.     

Thermal behaviour of covalently bonded phosphate and phosphonate flame retardant polystyrene systems

Pyrolyses of the reactively flame retarded polystyrene copolymers styrene/diethyl(acryloyloxyethyl)phosphate(S/DEAEP), styrene/diethyl(methacryloyloxyethyl)phosphate(S/DEMEP), styrene/diethyl(methacryloyloxymethyl)phosphonate(S/DEMMP) and styrene/diethyl(acryloyloxymethyl)phosphonate(S/DEAMP) have been investigated with a view to obtaining information pertinent to the mechanism of their flame retardant behaviour. Studies were also carried out on the additive polystyrene systems containing triethylphosphate (TEP) and diethylethylphosphonate (DEEP) for comparison. All the systems contained 3.5 wt% of phosphorus. A range of techniques were used, namely TG with EGA, DSC, SEM, laser and microfurnace pyrolysis mass spectrometry and isothermal pyrolysis/GC-MS, to study the decompositions under a range of conditions. In the case of the additive systems, the additive was shown to be evolved before polymer decomposition occurred. Very little, if any, char residues were observed. Thus the main mechanism of fire retardant action of the phosphorus incorporated into the polystyrene as an additive would occur in the vapour phase. This mechanism prevailed regardless of whether the additive was a phosphate (TEP) or a phosphonate (DEEP). The effectiveness of the fire retardant action would be limited as the fire retardant and fuel did not volatilise together. There was evidence that some interaction occurred in the condensed phase. In all the copolymers the phosphorus content of the char was substantial. This is characteristic of the condensed phase fire retardant action of phosphorus. SEM studies showed the interior of the char to be a network of channels which would give the char a sponge-like interior which would enhance thermal insulation. The surfaces were relatively dense thus providing a barrier to escape for any gaseous products formed in the interior. Char formation and cross-linking are assumed to be the result of the presence of the strong phosphoric and phosphonic acids resulting from initial pyrolysis. Since phosphonic is the weaker acid, the polymer degradation and release of volatile products may be less inhibited in the case of the phosphonate-containing copolymers compared to the phosphate-containing copolymers. This is consistent with their shorter times to ignition. There was also evidence for some potential phosphorus vapour phase fire retardant action as phosphorus-containing species were identified among the pyrolysis products for all samples. The rate of volatile evolution from the copolymers was reduced compared to that of the corresponding additive system.     

二乙胺液相催化羰化制备二乙基甲酰胺

考察了反应压力、催化剂、助催化剂和反应温度对二乙胺（ＤＥＡ）液相羰基化合成二乙基甲酰胺（ＤＥＦ）反应的影响，确定了量佳反应条件．结果表明，ＣＯ分压（Ｐ∞）对反应有明显影响，生成ＤＥＦ的速率随Ｐ∞增大而增大；催化剂浓度对反应的速率影响较小，添加剂环氧丙烷（ＰＯ）对催化剂有较强的助催化作用，而且助催化作用随ＰＯ浓度的增加而增大，生成ＤＥＦ的选择性随ＰＯ浓度的增加而降低，温度对反应也有明显的影响，确定最佳反应条件为：ＣＯ分压小于６．０ＭＰａ，反应温度为８０℃至９０℃，催化剂浓度不大于０．０５ｍｏｌ／Ｌ，助催化剂ＰＯ浓度不大于４．０ｍｏｌ／Ｌ．此时选择性不小于９６％．     

Oxidation of Diethyl Sulfide in Aqueous Solutions by Peroxynitrite and the H<Subscript>2</Subscript>O<Subscript>2</Subscript>-NO<Stack><Subscript>2</Subscript><Superscript>−</Superscript></Stack> System

It was found that nitrite anions are effective activators of hydrogen peroxide in the reaction with diethyl sulfide. The observed kinetics are consistent with the proposed intermediate formation of peroxynitrous acid (ONOOH). The rate constants for the reaction of diethyl sulfide Et₂S with the acid ONOOH (k₀ = 1.8⋅10³ L/mol⋅s) and with the anion ONOO⁻ (k₋ = 6⋅10⁻² L/mol⋅s) are respectively 10⁵ and three times higher than with hydrogen peroxide. __________ Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 41, No. 5, pp. 290–295, September–October, 2005.     

A New Synthetic Route to Diastereomerically Pure Cyclopropane-Phosphorus Derivatives Utilizing the Chiron 5-L-Men-thyloxy-3-bromo-2(5H)-furanone and Racemic Dialkyl α-Hydroxyalkanephosphonate

ＩｎｔｒｏｄｕｃｔｉｏｎＣｙｃｌｏｐｒｏｐａｎｅ ｃｏｎｔａｉｎｉｎｇｎａｔｕｒａｌａｎｄｎｏｎｎａｔｕｒａｌｐｒｏｄｕｃｔｓｈａｖｅｒｅｃｅｉｖｅｄｃｏｎｓｉｄｅｒａｂｌｅａｔｔｅｎｔｉｏｎａｓｓｙｎｔｈｅｔｉｃｔａｒｇｅｔｓａｓｔｈｅｉｎｃｏｒｐｏｒａｔｉｏｎｏｆｔｈｅｒｉｇｉｄｉｆｉｅｄｃｙｃｌｏｐｒｏｐｙｌｍｏｔｉｆｉｎｔｏｂｉｏａｃｔｉｖｅａｎａｌｏｇｕｅｓｌｅａｄｔｏｃｏｎｆｏｒｍａｂｌｙｃｏｎ ｓｔｒａｉｎｅｄｍｏｌｅｃｕｌｅｓ .1,2 Ｓｕｃｈｍｏｄｉｆｉｃａｔｉｏｎｓａｒｅｅｘｐｅｃ…     

Molecular motions in poly(diethyl siloxane) studied by solid-state29Si NMR

Molecular motions in poly(diethyl siloxane) were studied by solid-state²⁹Si-NMR in the temperature range 180–350 K. In this temperature range two solid phases ₁ and ₂, a mesophase _m, and an amorphous isotropic phase exist. The nature of the chain mobility in the different phases was deduced from the resulting changes in the NMR line-shape governed by anisotropic chemical shift. In the intermediate solid phase ₂ its anisotropy is reduced by 25% compared with the low temperature phase ₁ due to the onset of oscillations around the chain axis and conformational transitions. In the mesophase _m the polymer chain rotates about its long axis yielding an axially symmetric chemical shift tensor opposite in sign to that in the ₁, ₂ phases. The broad transition of the mesophase into the isotropic phase is accompanied by an increase in a narrow Lorentzian line arising from the amorphous phase. The results are compared with previous¹H NMR, Raman-spectroscopy and x-ray measurements.After completion of this work we learnt that PDES has recently also been studied through¹³C-MAS and²⁹Si-NMR by Möller et al. [13].     

Synthesis and characterization of two new open-framework zinc phosphites [M(C6N4H18)][Zn3(HPO3)4] (M=Ni, Co) with multi-directional intersecting 12-membered ring channels

Two new open-framework zinc phosphites, [M(C₆N₄H₁₈)][Zn₃(HPO₃)₄] (M=Ni, Co), have been prepared under hydrothermal conditions. Single-crystal X-ray diffraction analysis shows that [Ni(C₆N₄H₁₈)][Zn₃(HPO₃)₄] (1) and [Co(C₆N₄H₁₈)][Zn₃(HPO₃)₄] (2) are isostructural and both crystallize in the monoclinic space group C2/c with , , , β=109.83(3)°, Z=4, R₁=0.0408 (I>2σ(I)), and wR₂=0.1104 (all data) for 1, and , , , β=109.328(2)°, Z=4, R₁=0.0380 (I>2σ(I)), and wR₂=0.1093 (all data) for 2. The structures of 1 and 2 are built up from strictly alternating ZnO₄ tetrahedra and HPO₃ pseudo-pyramids linked through oxygen vertices to form the three-dimensional (3-D) open-frameworks with multi-directional intersecting 12-membered ring (12-MR) channels. The M(TETA) (M=Ni, Co) complexes self-assembled under hydrothermal system connect with the inorganic host via M-O-P linkages and interact with inorganic framework through weak H-bonds. The two compounds show intense photoluminescence upon photoexcitation at 235 nm.