Bridged polyaromatics: Synthesis and isomorphous properties of polymers and oligomers containing O,S, CH2 bridges

A study of the isomorphous relationships existing among five crystalline polyaromatic polymers containing O, S, CH₂ bridges, i.e., where Ph is phenyl, is reported. Appropriate series of oligomers corresponding to these polymers have also been prepared in order to investigate how the solid-state properties of the oligomers correlate with those of the polymers. A preliminary x-ray analysis is reported showing that the polymers are actually isostructural.     

Computer-simulated ESR spectra of irradiated poly(olefin oxides)—effect of glass transition temperature on the ESR spectra

Investigations on the effects of γ irradiation on poly(methylene oxide) (POM) and poly(ethylene oxide) (PEO) have been made employing electron spin resonance (ESR) spectroscopy. The ESR sextet and doublet spectra, recorded for POM and PEO, respectively, on irradition in air at room temperature are broadened as the temperature is lowered and show a reversible change in line shape with temperature. The spectra are analyzed by computer simulation, employing Lorentzian line-shape functions and the least-squares method of total curve fitting. The component spectra are evaluated and are assigned. Superposition of the component quartet, triplet, and doublet spectra, corresponding to the radicals ?H₃, ?H₂O , and O?HO , respectively, together with a singlet due to the radicals ?CH₂ is considered to be the best fit to the observed spectrum for POM. The doublet spectrum recorded for PEO has been assigned to the radicals ?HO . The reversible broadening of the spectra has been associated with the mechanism of molecular motions around the glass transition temperatures of these polymers.     

Synthesis and psychotropic properties of furyl- and thienyl-germatranes

Trihalogermyl-furans and -thiophenes were prepared by inserting germanium dibromide (GeBr₂) generated from the dibromogermane(II) dioxanate complex into the carbon-halogen bond of halo-furans and -thiophenes. Their ethanolysis and transesterification by triethanolamine yielded the germatranes which were subjected to psychotropic activity assays. The psychotropic properties of germatranes were found to depend on the type of the heterocycle and on the position of the germatrane moiety.     

Polymerization photoinitiated by carbonyl compounds. VIII. Solvent and photoinitiator concentration effects

The interaction of benzil and thioxanthone triplets with triethylamine leads to the production of free radicals that are able to initiate the polymerization of methylmethacrylate and vinyl acetate. The process is mediated by a charge transfer complex. The initiation efficiency is higher in benzene than in acetonitrile, a result explained in terms of competition between back electron transfer, production of free ions and ketyl radical formation. The initiation efficiency decreases when the carbonyl concentration increases, because of the occurrence of a radical molecule reaction such as The α-hydroxy radicals produced in this reaction are unable to initiate the polymerization chain.     

ESR evidence for main-chain scission produced by mechanical fracture of polymers at low temperature

ESR spectra have been observed from several polymers (polyethylene, polypropylene, polymethylmethacrylate, polytetrafluoroethylene, and polybutadiene) which were mechanically fractured in vacuum at 77°K. The spectra permit identification of the free radicals produced in chain scission. It has been demonstrated for the polymers of the type such as polypropylene and poly(methyl methacrylate), that the mechanical fracture produces two different scission radicals in pairs, namely, The results indicate convincingly that microscopic scission of polymer chains is caused by macroscopic destruction of polymeric material. The critical molecular size for mechanical rupture of polyethylene chains was experimentally determined to be a degree of polymerization between 70 and 100. This size agrees fairly well with the value predicted from a theoretical model.     

Enzyme‐Catalyzed Preparation of Aliphatic Polythioester by Direct Polycondensation of Diacid Diester and Dithiol

Summary: Aliphatic dithiol‐diacid type polythioesters were first enzymatically prepared by the direct polycondensation of hexane‐1,6‐dithiol and diacid diesters using the immobilized lipase from Candida antarctica (lipase CA). As a typical example, diethyl sebacate and hexane‐1,6‐dithiol were polymerized using lipase CA in bulk in the presence of molecular sieves 4A to produce the corresponding polythioester with an of 10 200 in 90% yield. Both the melting and crystallization temperatures of the produced polythioesters were higher when compared to those of the corresponding polyoxyesters. A higher molecular weight polythioester was produced using lipase in a two‐step procedure, i.e., cyclization with subsequent ring‐opening polymerization.

Preparation of polythioester and melting temperature of various polythioesters and polyoxyesters.     

Massenspektrometrische Untersuchung organischer Stickstoffverbindungen. XXVII—Intramolekulare Redoxreaktionn bei ionisierten ortho-substituierten Nitroaromaten

Collisional activation demonstrates that the stable ions from o-nitrobenzaldehydedimethylacetale possess the structure of ionized o-nitroso benzoic acid methyl ester. Contrary to previous conclusions it is demonstrated that the structure of the stable ions (m/e 135) from different precursors [i.e. o-nitrobenzyl alcohol o-nitrobenzyl cyanide and o-nitrobenzaldoxime is best represented by 2,1-benzisoxazoline-3-one. Ionized o-nitrosobenzaldehtde rearranged to 2,1-benzisoxazoline-3-one prior to collision induced decomposition, whereas 2-benzoxazolinone and 3-hydroxy-1,2-benzisoxazole do not rearrange within 10^?5 s.     

Polyorthocarbonates

Hitherto unreported aromatic polyorthocarbonates have been synthesized by the reaction of dichlorodiphenoxymethane and various aromatic dihydroxy compounds. The polymers possess the structure of a methanetetra-ol ether (carbonic acid orthoester) in the main chain. The direct structural evidence was obtained by ¹³C NMR. High molecular weight, linear polyorthocarbonates were derived from sterically unhindered bisphenols. The polymers were noncrystalline, and clear, flexible films were obtained by casting from solution. Aromatic polyorthocarbonates decomposed above 360°C under nitrogen. The polymers were extremely stable under basic conditions but were unstable in strongly acidic media, particularly at elevated temperatures.     

Synthesis of a new class of spiro heterocycles

A new class of spiro heterocycles viz., spiropyrazolidinediones, isoxazolidinediones, pyrimidinetriones or thioxopyrimidinediones are developed from methyl 3‐aryl‐2‐(Z‐arylethenenylsulfonyl)acrylate by double Michael addition reaction with dimethyl malonate followed by cyclocondensation with appropriate nucleophiles.     

Kinetics of the First Order Autocatalytic Decomposition Reaction of Nitrocellulose （13.86% N）

The kinetics of the first order autocatalytic decomposition reaction of nitrocellulose (NC, 13.86% N) was studied by using DSC. The results show that the DSC curve for the initial 50% of conversion degree of NC can be de scribed by the first order autocatalytic equation dy/dt =-10^16.3 exp (-181860/RT)y-10^16.7ex(-173050/RT)y(1-y) and that for the latter 50% conversion degree of NC described by the reaction equations dy/dt=-10^16.4exp(-154820/RT)y (n=1) and dy/dt=-10^16.9 exp(-155270/RT) y^2.80(n≠1).     

Darstellung und Eigenschaften von Ti-substituierten N-Heterocyclen

Preparation and Properties of Ti-substituted N-Heterocycles The compounds (x = 2 to 6) have been prepared by transamination of Ti(NMe₂)₄ with the heterocyclic amines and have been characterised by elemental analyses and ¹H NMR and IR spectroscopy. The dependence on both x and n of the thermal decomposition has been studied for the series and . The results can be interpreted in terms of the steric strain of the R₂N and substituents. Apart from the piperidido groups none of the ligands exhibit protective group properties comparable to the R₂N groups.     

Amino-phosphane. X. Einige Additionsreaktionen von N-Diphenylphosphinotetraphenyldiphosphin-imid

Diphenylphosphorous chloride and methyl iodide add readily to the N-bonded P(III)-atom of (C₆H₅)₂P? P(C₆H₅)₃?N? P(C₆H₅)₂ forming the salts [(C₆H₅)₂P? P(C₆H₅)₂ N P(C₆H₅)₂? P(C₆H₅)₂]Cl and [(C₆H₅)₂P? P(C₆H₅)₂ N P(C₆H₅)₂. CH₃]I, respectively. A similar behaviour is observed with sulfur: Under mild conditions (C₆H₅)₂P? P(C₆H₅)₂?N? P(C₆H₅)₂ = S is formed but forcing conditions are required to produce S = P(C₆H₅)₂? P(C₆H₅)₂?N? P(C₆H₅)₂?S. The monosulfide is also obtained by treating (C₆H₅)₂P(S)N[Si(CH₃)₃]₂ with diphenylphosphorous chloride, indicating the favoured formation of the phosphazene system as compared with the phosphazane system Confirmation of the structures comes from ³¹P nmr and IR data, and for the sulfides also from their degradation with bromine.     

Structural changes in polymers of diethyl succinylsuccinate(1,4-diethoxycarbonyl-2,5-dihydroxy-1,4-cyclohexadiene) with diamines at high temperatures

The structural changes of the polymers having the following structures: at high temperatures were studied by the spectroscopic and thermal analysis. When the polymers were heated in air, they were oxidized predominantly to polymers having the structure: The rate of oxidation was fast and the reaction was almost completed within 2 hr at 180°C. In the case of polymer 3, an intramolecular cyclization to form acridone was detected as a minor reaction.     

Layer‐by‐Layer Assembled Nanotubes as Biomimetic Nanoreactors for Calcium Carbonate Deposition

Enzyme‐loaded magnetic polyelectrolyte multilayer nanotubes prepared by layer‐by‐layer assembly combined with the porous template could be used as biomimetic nanoreactors. It is demonstrated that calcium carbonate can be biomimetically synthesized inside the cavities of the polyelectrolyte nanotubes by the catalysis of urease, and the size of the calcium carbonate precipitates was controlled by the cavity dimensions. The metastable structure of the calcium carbonate precipitates inside the nanotubes was protected by the outer shell of the polyelectrolyte multilayers. These features may allow polyelectrolyte nanotubes to be applied in the fields of nanomaterials synthesis, controlled release, and drug delivery.

     

Metastable decompositions of cyclopentanol ions and [C5H10O]+˙ ions with the oxygen on the first carbon

Ionized cyclopentanol and [C₅H₁₀O]+˙ ions with the oxygen on the first carbon lose methyl, ethylene, ethyl, ethane and water in their metastable decompositions. We show by collisionally activated decompositions of the products that the losses of ethyl form CH₃CH₂C?O⁺, the losses of ethylene form , and the losses of methyl probably yield . Deuterium labeling indicates that ethyl loss from ionized cyclopentanol occurs following α-cleavage of the ring, isomerization to the enol isomer of ionized n-pentanal and subsequent isomerization to the 3-pentanone ion.     

Phenacyl esters of acetic acid derivatives and their application for the synthesis of 2‐oxo‐4‐phenyl‐5‐(phenylhydrazono)‐2,5‐dihydro‐furan‐3‐derivatives

Coupling of various substituted phenacyl acetates 1 and diazonium salts 3 was studied. If the phenacyl acetates were substituted by an electronaceptor group such as CN or COOEt 3‐substituted phenyl‐5‐(phenyl‐hydrazono)‐5H‐furan‐2‐ones 4 were formed. Also synthesis of aza and diaza analogs is described. The compounds were characterized using MS and NMR spectroscopy.