Molecular confirmation and crystal structure of the β form of poly(ethylene oxybenzoate)

The crystal structure of the β form of poly(ethylene oxybenzoate) was analyzed by x-ray diffraction. Four nearly extended molecular chains pass through a unit cell with parameters a = 8.19 Å, b = 11.07 Å, c (fiber axis) = 19.05 Å, β = 114.8°, and the space group P2₁/n-C. The structural difference between the α and β forms is mainly due to the internal rotation angles for the virtual bond and the ? CH₂? CH₂? bond. They are essentially in trans confirmation in the β form, while the α form contains cis and gauche (? CH₂? CH₂? ) conformations.     

Synthesis and radical ring-opening polymerization of spiro o-carbonates

Syntheses and radical ring-opening polymerization of spiro o-carbonates(I-IV) were investigated. These polymers were yellow powders and soluble in common organic solvents. The infrared and NMR spectra indicated that the polymers were alternate copolymers of either and carbonate containing double bonds. The polymerization mechanism is discussed.     

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.     

Holes and Ledges Created by Multilayer Assembly on Polyelectrolyte Brushes: A Novel Route for the Three‐Dimensional Nanoscale Design of Surfaces

The layer‐by‐layer (LBL) assembly of poly(diallyldimethylammonium chloride) and poly(sodium styrene sulfonate) on poly(sulfo propyl methacrylate) brushes resulted in films with nanometer‐ and micrometer‐sized holes and ledges, observed by atomic force microscopy and scanning electron microscopy. Polyelectrolyte assembly was followed by the quartz microbalance technique. The formation of ledges and holes is explained by the interaction of the brush polymers with the incoming polyelectrolytes during the LBL assembly, inducing a spatially localized and self‐organized accumulation of the assembled polymers.

     

Ab-initioMRD–CI calculations on a C?NO2 decomposition pathway of nitrobenzene

To study molecular decomposition pathways it is necessary to use ab initio multireference determinant–configuration interaction or MCSCF (multiconfiguration SCF ) calculations. The MRD –CI (multireference double excitation–configuration interaction technique of Buenker and Peyerimhoff) calculations on the decomposition pathway of nitrobenzene were carried out using all of the occupied molecular orbitals in the region of the bond being dissociated, plus all of the virtual orbitals. An effective CI Hamiltonian was used into which were folded the effects of all of the occupied molecular orbitals from which excitations were not allowed. So far we have investigated the lowest ¹A₁, ³A₁, ¹A₂, ³A₂, ¹B₁, ³B₁, ¹B₂, ³B₂ states and are investigating the higher states. Our results show a wealth of structure in the potential energy surfaces for the various electronic states of nitrobenzene as a function of distance. A number of the states are predissociative and change dominant configuration one or more times along these potential energy surfaces.     

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.     

Self‐Complementary Nucleoside‐Thiophene Hybrid Systems: Synthesis and Supramolecular Organization

Versatile synthetic methods towards a variety of thiophene‐nucleobase hybrid systems are reported. Adenine‐ and thymine‐based modified nucleosides characterized by a bithiophene unit linked to the C5′ or C8 position through an ethylenamino or an ethylensulfanyl bridge were synthesized and successfully polymerized in the presence of FeCl₃. The self‐organization properties of the pure polymers as well as their mixtures ‐ with complementary nucleobases ‐ were investigated by means of optical microscopy and AFM in cast film showing complex supramolecular structures resulting from the interplay of multiple intermolecular interactions.

     

[2, 3] Sigmatropic Rearrangements on Lithiation of Some Allyl Sulfides. Preliminary communication

In five cases, [2,3] sigmatropic rearrangement of the type has been observed.     

Deformation of methylenecyclopropane in solution: NMR study in the nematic phase at 240 and 400 MHz

The NMR spectrum of methylenecyclopropane oriented in two nematic phases has been measured at 240 and 400 MHz. Ratios of the proton-proton distances have been obtained. These values are compared with those deduced from the structure of the molecule in the gaseous state; they suggest an increase of the ethylenic angle in the nematic phase.     

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.     

Structure of the tetramer of α-methylstyrene

The structure of the tetrameric dianion formed by α-methylstyrene in tetrahydrofuran by reaction with sodium has been examined. Mass spectral, NMR, infrared, and kinetic data all indicate that the structure is rather than the structure which had previously been assumed for this species.     

Flash Photolysis of 2,4,6-Trinitrotoluene Solutions

Flash photolysis of 2,4,6-trinitrotoluene solutions (TNT) indicates a photochemically induced isomerization leading to the aci-quinoid isomer with an absorption maximum at 460 nm in nonpolar solvents, or the conjugate base of the aci-quinoid isomer with absorption maxima at 500, 540, and 630 nm in polar solvents. Both species, the quinoid isomer and the conjugate base, have transient existence and their identification was based on detailed spectroscopic and kinetic studies presented here. The magnitude of the negative charge on the transient conjugate base was determined with salt effect experiments and found to be equal to unity.     

Living cationic polymerization of 2-chloroethyl vinyl ether: Kinetics,mechanism and application to polymer synthesis

The cationic polymerization of 2-chloroethyl vinyl ether initiated by HI/weak Lewis acid (I₂ or ZnI₂) systems has been studied from both a kinetic-mechanistic and a synthetic viewpoint. At low temperature and in toluene as solvent, the polymerization proceeds via a living process and the kinetic order with respect to monomer varies according to the nature of the Lewis acid activator. This behaviour can be explained by the coordination of the Lewis acid with both the monomer and the chain-end, the latter leading to a strong activation of the -I bond towards monomer insertion. The living polymerization obtained from divinylether precursors leads to -I ended telechelics, and their transformation into dihydroxytelechelic oligomers has been performed. The chemical modification of chloroalkyl side groups by phase transfer catalysis allows the attachment of specific groups without consumption of-OH ends.     

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.     

Oxazolidines versus schiff bases

The formation of oxazolidines from propionaldehyde and aliphatic β-aminoalcohols is complicated by the appearance of appreciable amounts of unsaturated Schiff bases. The simple Schiff base, often the dominant species when aromatic aldehydes react with amines, could not be detected in the present aliphatic systems. We conclude that in aliphatic systems the order of stability is and . The gem-dimethyl group α to nitrogen stablizes the heterocyclic ring remarkably.     

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.     

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.     

Thermal decomposition of azoisopropane. II. Secondary decomposition processes

The thermal decomposition of azoisopropane (AIP) was studied in the presence of various quantities of propylene in the temperature and pressure intervals 498–553 K and 3.33–5.33 kPa. The inhibition functions relating to formation of the products were determined; these proved a good basis for interpretation of the formation of the secondary decompositon products of AIP. The experimental data support the conception that the βμ radical—radical reaction occurs. The product of this is not stable; its decomposition is one of the sources of the secondary products. The ratio of the rate constants was determined for the following reactions:      

Liquid-crystal polymers with tolan units

A new series of liquid-crystal polymers containing main-chain mesogenic units is reported. The general repeating unit is where n = 4, 5, 6, 7, 8, 10, or 12.     

Polymerization of alkoxyallenes by transition-metal catalysts

The structure of polymers obtained by polymerization of methoxyallene and ethoxyallene with transition-metal catalysts depends on the catalyst employed. Rapid polymerization at 0°C through the unsubstituted double bond occurred with π-allylnickel halides, NiCl₂/AlEt₃ and CoCl₂/AlEt₃, yielding polymers with the structure Typical Ziegler–Natta catalysts (TiCl₄, VOCl₃ or FeCl₃ with AIEt₃) gave polymers mainly with the structure although some of the structural units were probably present as well. Polymers having conjugated double bonds were prepared with PdCl₂, [(π-allyl)PdCl]₂, and PdCl₂(C₆H₅CN)₂ as catalysts. Palladium iodide produced polymers with all three of the above structural units present. Polymerization occurred more slowly with these palladium catalysts. A preliminary examination of the effect of variation of solvent, ligand, co-catalyst, and temperature on the rate and structure of the polymers obtained with the palladium catalysts is reported.