Some new examples of cationic polymerization

Synthesis and properties of cis-and trans-methoxyvinyl chloride (MVC) are described. Both of these monomers can be polymerized with cationic initiators. From the ¹³C-NMR spectra it was concluded, that poly-(trans-MVC) is mainly threo-diisotactic. Copolymerization of cis-MVC with for instance trans-MVC or styrene or 1,3-dioxolane is also described. The ring-opening polymerization of 2-phenyl-2-oxazoline under different conditions was investigated. The molecular weights, determined by light-scattering and GPC are in the range between 10 000 and 350 000. A[η] -M- equation was derived. By hydrolysis with hydrochlorid acid high molecular weight poly(iminoethylene) was obtained. The ring-opening polymerization of 1-azabicyclooctane [4.2.0] (conidine) with different catalysts as well as the properties of the polymers were studied in detail. By means of a “mixed-mechanism technique” well defined styrene-conidine diblock copolymers are available.     

Durch Nachbargruppenbeteiligung induzierte (1,2)-Chlorwasserstoff-Eliminierung aus ionisiertem 2-(β-Chloräthyl)- benzoesäuremethylester

By using deuterium labelled compounds and collisional activation spectra the mechanism of the unusually intensive HCl elimination from 2-(β-chloroalkyl)benzoic acid methyl ester as well as the structure of the product ion have been elucidated. It can be shown that the structure of the stable ion (lifetime τ～10?5 s) is best represented by 2-vinyl benzoic acid methyl ester whereas the reactive ion (lifetime τ<10^?6 s) at least partially rearranges to a cyclic ion. The hydrogen chloride elimination from 2-(β-chloroalkyl)benzoic acid is apparently a simple 1,2 process. A closer examination reveals that the reaction represents a further example of an unusual neighbouring group participation of the ester function.     

Zur Darstellung von Cyclophosphaten,Cyclophosphatophosphonaten, Diphosphonaten und Diphosphiten in Harnstoffschmelzen

Preparation of Cyclophosphates, Cyclophosphatophosphonates, Diphosphonates, and Di-phosphites in Urea Melts Ammonium cyclotriphosphate (NH₄)P₃O₉, ammonium cyclotetraphosphate [P^IV? P^IV ? O? ]₂, ammonium cyclotriphosphatophosphonates Ammonium organyldiphosphonates And ammonium diphosphites are prepared in high yields on heating acidic phosphates, phosphonates, and phosphites in urea or urea/ammonium nitrate melts. The mechanism of the dehydration of phosphorus compounds containing POH groups in molten urea is discussed.     

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.     

On the Statistical Nonliving Nature of the Cationic Ring‐Opening Copolymerization of Oxetane with Tetrahydropyran

The copolymerization system of oxetane and tetrahydropyran is reinterpreted with the aid of computer simulations. The original claim that this system is a “living” and/or controlled pseudoperiodic copolymerization 1 is not confirmed by the simulation results. It is suggested that the formation of branched oxonium cations and the statistical nature of THP incorporation are the reasons for the observed discrepancies between the simulation results and experimental data.

     

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.     

Synthesis and Self‐Assembly of Amphiphilic Diblock Copolymers using a Fluorescently Labeled N‐Alkoxyamine Initiator

Summary: An initiator for nitroxide mediated ‘living’ free radical polymerization was prepared with a fluorescent tag attached to the initiating alkyl radical terminus. This was used to synthesize amphiphilic poly(acrylic acid)‐block‐polystyrene diblock copolymers, which self assembled in a tetrahydrofuran/buffer solution to form structures that are visible by fluorescence.

     

Darstellung neuer Spiro-Alkoxy-cyclophosphazatriene

Preparation of New Spiro-Alkoxy-Cyclophosphazatrienes New spiro-Alkoxy-cyclophosphazatrienes of the general formula are described. The preparation of the substances and their mass spectroscopic data are reported.     

Iodine catalyzed synthesis of α,α'‐bis(substituted benzylidene)‐1‐carbethoxy‐4‐piperidone

A facile and efficient method for the preparation of α,α′‐bis(substituted benzylidene)‐1‐carbethoxy‐4‐piperidone is described using iodine as a catalyst in acetonitrile. The reaction proceeds rapidly at room temperature, giving high yields of products.     

Effect of gegen ion in cationic polymerization and copolymerization of trioxane

p-Chlorophenyldiazonium hexafluorophosphate has been reported to be a superior catalyst for cationic polymerization and copolymerization of trioxane as compared to boron trifluoride dibutyl etherate (BF₃·Bu₂O)¹. In the present investigation the effect of anions derived from elements in Group VA, AsF and SbF, has been ascertained. It has been concluded that p-chlorophenyldiazonium hexafluoroarsenate is also a superior catalyst to boron trifluoride dibutyletherate (BF₃·Bu₂O), while p-chlorophenyl-diazonium hexafluoroantimonate is inferior. Copolymers with the highest polymer yield (>95%) and molecular weight (intrinsic viscosity = 4 to 5) were obtained with Simple dependences on catalyst concentration have been observed to hold for a wide catalyst concentration range ([M]/[C]) = (1 to 20) × 10⁵: For the same relationships hold. However, the polymer yield (75%) and molecular weights (intrinsic viscosity ?1) are considerably lower while the extent of chain transfer is higher. Furthermore, the polymerization proceeds with explosive violence. The quantitative aspects resulting from polymerization, for the most part, can be interpreted in terms of the extent of dissociation of the propagating ions.     

Post‐Synthesis Functionalization of (Meth)acrylate Based Monoliths via Electron Beam Triggered Graft Polymerization

Porous polymeric monoliths were prepared via electron beam triggered free radical polymerization of (meth)acrylates. Post‐synthesis functionalization of these supports was accomplished via electron beam initiated free radical graft polymerization of methacryloyl‐substituted NHC precursors. The grafted precursors were converted into the corresponding copper complexes. Cu‐loadings were between 1.3 mg · g⁻¹ and 1.5 mg · g⁻¹. These supported catalysts were used in selected CO hydrosilylation and cyanosilylation reactions using a continuous flow setup.

     

Structure‐Transport Relationship of Dendritic Core‐Shell Nanocarriers for Polar Dyes

TriPEGylated functionalized dendritic poly(ethylene imines) were synthesized and their transportation properties for rose Bengal (up to 50 guests per dendrimer) were evaluated. A critical aggregation concentration was observed, demonstrating the formation of aggregates among the dendrimers. The structure‐activity relationships show that their encapsulation capacities were dependent linearly on the density of the PEG shell, either as PEG length or degree of functionality, which confirmed that the PEG chains play a predominant role in the encapsulation process. It further gives some insights that the guest molecules appeared to be predominantly located in the PEG shell rather than in the core.

     

Studies on Radical Cations I. Molecular and electronic structure of [3]radialene cation produced by γ-irradiation in condensed phase

γ-Irradiation of tris (methylidene)-cyclopropane (‘[3]radialene’) 1 in a rigid electron scavenging matrix (butylchoride/i-pentane, 1:1) at 77 K leads to formation of its molecular cation 1 ⁺. Slight softening of the matrix by a temperature increase of 3–5 K results in formation of a newly absorbing species, tentatively assigned arising from structrral relaxation of 1 ⁺ by π-bond rotation:      

Mass spectrometric studies of organophosphorus compounds: III—Remarkable migration of chalcogen on electron impact of organophosphorus compounds

The mass spectra of several dibenzo (d.f)-1,3,2,-dioxaphosphorepines of the type where X=0, S, Se and R=2,2′-biphenylylene, have been studied. Dibenzochalcogen ions [RX]⁺˙ stemming directly from [M]⁺˙ were observed with high intensities, indicating specific migration of X from phosphorus to carbon with simultaneous destruction of the dioxaphosphorepine ring. Simple cleavage of P? Y as usually observed in similar organophosphorus compounds is not a common process here.     

Green Polymer Chemistry: Microwave‐Assisted Single‐Step Synthesis of Various (Meth)acrylamides and Poly(meth)acrylamides Directly from (Meth)acrylic Acid and Amines

Summary: Various (meth)acrylamides were synthesized in good yields directly from (meth)acrylic acid and an amine using microwave irradiation in a solvent‐free environment. Under the applied conditions the (meth)acrylic function is preserved. Furthermore, the addition of an initiator like 2,2′‐azoisobutyronitrile (AIBN) to the starting mixture leads directly to poly(meth)acrylamides in a single step.

General reaction scheme for the formation of poly(meth)acrylamides from the microwave‐assisted reaction of (meth)acrylic acid and various amines.     

Towards Chiral Microporous Soluble Polymers—Binaphthalene‐Based Polyimides

Recently, intrinsically microporous polymers have received increased interest in research. Contrary to currently commercially used microporous materials, e.g., zeolithes or polymer networks, they can be dissolved, processed and further functionalised. Microporous poly(imide)s are especially interesting, as they are chemically and thermally resistant to decomposition up to high temperatures. In this paper, we report for the first time on a chiral poly(imide) which is intrinsically microporous and soluble in common solvents. After analysing the structure of the polymer, its pore system is characterised via its ability to adsorb nitrogen, argon, hydrogen and carbon dioxide. Furthermore, the chiral polymer is compared with its racemic counterpart, illustrating the special role of an organised superstructure.

     

Isomérie Polyédrique dans des Spirophosphoranes Possédant le Groupement P?H

We have studied the temperature dependence of NMR spectra of six spirophosphoranes of the general formula: Experimental data show intramolecular isomerism which was explained by pseudo-rotation mechanism (Berry, Lit. 1). In all cases except one we also observed tautomerism between spirophosphorane and phosphite forms.     

Nuclear magnetic resonance spectra and structure of some alkyl vinyl sulphides

The NMR spectra of eight alkyl vinyl sulphides have been analyzed and the parameters compared with those obtained from an analogous series of oxygen derivatives. It is shown that a definite parallelism exists between chemical shifts and H? H coupling. Difference in absolute values have been explained by mesomeric interaction involving the ability of sulphur to accommodate a decet of electrons in its valence shell. By analogy with alkyl vinyl ethers, it is possible to predict a similar correlation between the spectral characteristics and relative reactivity of vinyl sulphides in cationic polymerization.     

Pyrrolopyrimidine nucleosides VII. A study on electrophilic and nucleophilic substitution at position six of certain pyrrolo[2,3-d] pyrimidine nucleosides

A study involving the reactivity of the pyrrolo[2,3-d] pyrimidine ring system at position 6 with another exocyclic group (CN or -NH₂) already residing at C5 has established that hydrogen and bromine are susceptible to electrophilic and acid-catalyzed nucleophilic substitution, respect-tively. In one instance a strong nucleophile (hydrazine) gave nucleophilic substitution at position 6 which was followed by a reaction with the o-nitrile group to afford the tricyclic nucleoside 4,5-diamino-8-(β-D-ribofuranosyl)pyrazolo[3′, 4′ :5,4] pyrrolo[2,3-d] pyrimidine (4).     

A Simple Method to Fabricate a Conductive Polymer Micropattern on an Organic Polymer Substrate

Summary: Under UV irradiation plus a photomask, a hydrophilic/hydrophobic hybrid polymer surface is created by sandwiching an ammonium persulfate solution between two polymer films. It is demonstrated that an effective conductive PANI micropattern can be fabricated on such a wettability patterned surface. For PET, a stable negative micropattern could be formed directly by the selective deposition of PANI onto the hydrophobic region. Alternatively, for PP or PI, direct deposition of PANI is non‐selective, however, the PANI layer remains preferentially on the hydrophilic region by peeling off the PANI layer on the hydrophobic region to form a positive micropattern.

Schematic illustration of the procedure used for the formation of a conducting polymer (PANI) micropattern on a wettability patterned polymer substrate.