Polymer-supported bases, 2. Polystyrene-supported 1,8-diazabicyclo[5.4.0]undec-7-ene as reagent in organic syntheses

Polystyrene-supported 1,8-diazabicyclo[5.4.0]undec-7-ene (PDBU) was prepared by the reaction of lithiated 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with chloromethylated or ω-bromoalkylated polystyrene resins. PDBU is effective as reagent for dehydrobromination and esterification. The reactivity of PDBU in dehydrobromination is lower than that of DBU. In the case of esterification, PDBU with 19% ring substitution exhibits almost the same reactivity as DBU. PDBU, regenerated from the hydrobromide salt, can be re-used without decrease in reactivity.     

Preparation and properties of new photo-functional polymers, 1. N-substituted maleimide/styrene copolymers containing pendant para-nitrobenzyl groups

A new photo-functional copolymer was designed by etherification or esterification of poly-[N-(4-hydroxyphenyl)maleimide-co-styrene] or poly[N-(4-carboxyphenyl)maleimide-co-styrene] with p-bromomethylnitrobenzene using 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU) as the base in an aprotic solvent. The chain-stiffening effect of the N-substituted maleimide group provided good thermal stability. It was observed that the photosensitivity of the copolymer is enhanced by the addition of a base like tributylamine.     

Poly(vinyl alcohol) functionalized by chloroacetate groups. Coupling of bioactive carboxylic acids

Poly(vinyl alcohol) (PVAL) functionalized with chloroacetate groups was obtained by reaction of PVAL with chloroacetyl chloride using pyridine as catalyst and N-methyl-2-pyrrolidone as solvent. The structure of the modified polymers was determined by means of IR, ¹H and ¹³C NMR spectroscopies. The coupling of model bioactive carboxylic acids (1-naphthylacetic acid and 6-methoxy-α-methyl-2-naphthaleneacetic acid (naproxen)) to PVAL functionalized with chloroacetate groups was carried out by reaction with their potassium salts or directly in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). High degrees of modification were obtained in the reaction with the potassium salts. However, the esterification reaction is somewhat more efficient in the case of the potassium salt of 1-naphthylacetic acid. The kinetic results were consistent with a second-order reaction, and the activation energy in the reaction with the potassium salt of 1-naphthylacetic acid was found to be 73,2 kJ/mol. The reaction of PVAL with 1-naphthylacetic acid and naproxen in the presence of DBU showed deviation from second-order kinetics, which may be a consequence of some steric effects. The hydrolysis in the heterogeneous phase of PVAL-1-naphthylacetic acid and PVAL-naproxen adducts showed that the release of the bioactive compound from tablets is dependent on the hydrophilic character of the adduct as well as on the pH value of the medium.     

Polymer-supported bases, 4. Macrolide synthesis from ω-bromocarboxylic acids using polymer-supported 1,8-diazabicyclo[5.4.0]undec-7-ene

The macrolactonization of ω-bromocarboxylic acids was carried out in the presence of polystyrene-supported 1,8-diazabicyclo[5.4.0]undec-7-ene. The macrolide yield was found to be a function of the degree of ring substitution and of crosslinking, which governs the effective concentration of the fixed substrate within the polymeric reagent. The effect of the polystyrene matrix on the macrolide yield in the heterogeneous system was discussed by comparison with the corresponding homogeneous reaction.     

Low Temperature Ring‐Opening Polymerization of Diglycolide Using Organocatalysts with PEG as Macroinitiator

Polyglycolide (PGA) is synthesized via ring‐opening polymerization (ROP) of diglycolide using the organocatalysts 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), 1,5‐diazabicyclo[4.3.0]non‐5‐ene, or 1,5,7‐ triazabicyclo[4.4.0]dec‐5‐ene. ROP is carried out at low temperatures ranging from ?20 to 50 °C without adding any alcohol as initiator. All polymers are fully soluble in hexafluoroisopropanol. At ambient temperature number average molecular weights up to 27 000 g mol^?1 are obtained. With DBU the highest molecular weights and conversions are accessible at ?20 °C. Melting temperature and glass transition temperature are independent of PGA molecular weight. Carrying out the reactions in the presence of polyethylene glycol serving as macroinitiator yields polymers with improved thermal stability and lowered melting temperatures.

     

Vinylic polymerization of bicyclo[2.2.1]hept-2-ene by Co(II)-catalysis

The vinylic polymerization of bicyclo[2.2.1]hept-2-ene (norbornene) with Co(II) compounds, such as Co(II) stearate, substituted bis(1,3-diketo)cobalt(II), Co(dppe)Cl₂, and the metallocene [η⁵-(C₅Me₅)Co-η²-Cl]₂, in chlorobenzene activated with methylaluminoxane (MAO) is reported. MAO^* synthesized by the hydrolysis of trimethylaluminium in chlorobenzene instead of toluene increases the catalytical activity strongly, and a turn over of 2.7 tons of poly(2,3-bicyclo[2.2.1]hept-2-ene) per mol cobalt per hour was achieved. The polymers obtained are amorphous (WAXS). They show weight-average molecular weights up to M̄_w = 1.5 · 10⁶ and are soluble in chlorobenzene, 1,2-dichlorobenzene, cyclohexane, and decahydronaphthalene.     

Polymerization of bicyclic acetals, 8. Cationic polymerization of 6,8-dioxabicyclo[3.2.1]oct-2-ene

Poly(5,6-dihydro-2H-pyran-2,6-diyloxymethylene) ( 6 ), a new polyacetal having a dihydropyran ring in its repeating unit was prepared by selective ring-opening polymerization of 6,8-dioxabicyclo[3.2.1]oct-2-ene ( 5 ) at temperatures between ?60 and ?90°C in dilute methylene chloride or toluene solutions using boron trifluoride etherate as initiator. The resulting polymers, having a number average molecular weight up to 1,5 · 10⁴, melted at 110 – 130°C and decomposed at ≈ 170°C in air. The isotactic dyad content of the polymers, estimated by ¹³C NMR spectroscopy, was found to be in the range of 70 to 77 mole-%, somewhat lower than that of its saturated analogue, poly(tetrahydropyran-2,6-diyloxymethylene), ( 2 ). The preferred formation of the isotactic sequence along the polymer chain is rationalized in terms of the enantiomer selection by the growing chain end control mechanism as previously proposed for the polymerization of 6,8-dioxabicyclo[3.2.1]octane, ( 1 ).     

Metathesis polymerization of exo,exo-, endo,exo- and endo,endo-5,6-dimethylbicyclo[2.2.1]hept-2-enes; microstructure of the polymers and their hydrogenated products

Polymers of exo,exo-, endo,exo, and endo,endo-5,6-dimethylbicyclo[2.2.1]hept-2-ene monomers were prepared using a selection of eight metathesis catalysts and their structures examined by ¹³C NMR spectroscopy. Tacticities could be determined for the polymers of the endo, endo and endo,exo monomers and for all three hydrogenated polymers. RuCl₃ gave hightrans atactic polymers while ReCl₅ gave high-cis syndiotactic polymers, but WCl₆/Bu₄Sn gave a high-cis atactic polymer of the endo,endo monomer. The endo,exo monomer was unusual in giving polymers of relatively low cis content (fraction of cis double bonds σ_c ≤ 0,3), and with strong exo,endo (XN) bias except in the case of RuCl₃. The parallel with the head, tail (HT) biased polymers of 1-methylbicyclo[2.2.1]hept-2-ene is noted. Polymers of the exo,exo and endo,endo monomers have a blocky cis/trans double bond distribution at moderate cis content. The results are discussed in terms of a mechanism involving propagation by metal-carbene, metal-carbene-olefin and metallacyclobutane complexes.     

The ring-opening metathesis polymerization of (±)-5-endo-methoxynorborn-2-ene. Microstructure of the polymers

The title monomer (±)-5-endo-methoxynorborn-2-ene ((±)-5-endo-methoxybicyclo[2.2.1]-hept-2-ene, 1 ) was polymerized by Ru-, W-, Ir-, Re- and Mo-based metathesis catalysts to yield polymers with cis contents ranging from 10% to 48%. An assignment of the ¹³C NMR spectra was made. No significant head-tail bias was observed and no splitting due to tacticity could be positively identified.     

Polymere kryptanden, 1

The synthesis of a vinyl group containing cryptand, 18-vinyl-5,6-benzo-4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacos-2-ene ( 8 ), was developed. Gel type copolymers with different polarities of the matrix were obtained from 8 and styrene or 8 and 1-vinyl-2-pyrrolidone, crosslinked with 1,4-divinylbenzene. A copolymer with 4,4'-divinylbiphenyl as crosslinking agent was prepared in a macroporous form. The ability of the different copolymers to form complexes with the alkali metal cations as well as the selectivity of the copolymers towards these cations were investigated.     

Novel Network Polymeric Phthalocyanines: Synthesis and Characterization

Summary: New p‐xylylenebis‐(oxa‐thia‐propan) bridged metal‐free and metallophthalocyanine polymers were synthesized. The metal‐free phthalocyanine polymer ( 3 ) was prepared by the reaction of a tetranitrile monomer with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in pentanol. Ni‐ and Co‐phthalocyanine polymers were prepared by reaction of the tetranitrile compound with the chlorides of Ni(II ) and Co(II ) in quinoline. Cu‐ and Zn‐phthalocyanine polymers were prepared by the reaction of the tetranitrile compound with the acetates of Cu(II ) and Zn(II ) and DBU in amyl alcohol. Yellow PbO and Fe(CO)₅ were used to prepare Pb‐ and Fe‐analog polymers, respectively. The Co‐phthalocyanine polymer was also prepared using ethylene glycol instead of quinoline in the presence of the catalyst ammonium molybdate. ( 3 ) was chemically doped with iodine. The electrical conductivities of the polymeric phthalocyanines measured as gold sandwiches were found to be 10⁻⁹–10⁻⁷ S · cm⁻¹ in a vacuum and in argon. The electrical conductivity of iodine doped metal‐free phthalocyanine ( 3a ) was found to be approximately 57 times higher than that of the undoped version. The extraction ability of ( 3 ) was also evaluated in THF using transition metal picrates, such as Ag¹⁺, Hg²⁺, Pb²⁺, Cd²⁺, Cu²⁺ and Zn²⁺. The extraction affinity of ( 3 ) for Ag¹⁺ was found to be highest in the heterogeneous phase extraction experiments. All the novel compounds were characterized using elemental analysis, UV‐Vis, FT‐IR, NMR and MS spectral data and DSC.

Synthesis of new network polymeric phthalocyanines.     

Polymerisation durch [3+2]-cycloaddition, 2. Reaktionen von hexafluoracetonazin mit substituierten diolefinen

Hexafluoroacetone azine reacts with esters of 1,6-heptadien-4-ol to form polymers 1 containing 4,4,8,8-tetrakis(trifluoromethyl)-1,5-diazabicyclo[3.3.0]octan-2,6-diyl groups linked with trimethylene chains with acyloxy side groups. Due to these ester functions the polymers are completely soluble in common solvents. DSC measurements proved these polymers to be partly crystalline.     

ω-Chloro-α-olefins as co- and termonomers for the synthesis of functional polyolefins

This paper deals with the use of ω-chloro-α-olefins as monomers for the synthesis of chloro-functional homo-, co- and terpolyolefins in the presence of (IVb) metallocene/MAO catalytic systems. Two ω-chloro-α-olefins, 11-chloroundec-1-ene and 5-chloropent-1-ene, were tested. It was found that only the functional olefin containing the longer aliphatic spacer between the alkene function and the halide polymerizes readily in the presence of the rac-Et(Ind)₂ZrCl₂/MAO catalyst. The drastic influence of the reaction solvent on the chloro-olefin reactivity and (co)polymerization behavior is examined and discussed. Finally, the terpolymerization of 11-chloroundec-1-ene with ethylene and propene is investigated. In a second part, the quantitative preparation, by derivatization of 11-chloroundec-1-ene units, of functional polyolefins bearing benzoate, hydroxy or azido functions as side groups is described. The corresponding functional polymers are characterized by IR and ¹H NMR spectroscopy.     

Addition reactions of polymers containing pendant cyclic iminoethers with thiols,carboxylic, thiocarboxylic and sulfinic acids

Poly[1-(2-oxazoline-2-yl)ethylene] ( 2a ), poly[1-(5-methyl-2-oxazoline-2-yl)ethylene] ( 2b ), poly[1-(4,4-dimethyl-2-oxazoline-2-yl)ethylene] ( 2c ), poly[1-(4,4-dimethyl-5,6-dihydro-4H-1,3-oxazine-2-yl)ethylene] ( 2d ), and poly[1-(4,4,6-trimethyl-5,6-dihydro-4H-1,3-oxazine-2-yl)ethylene] ( 2e ) were synthesized with high yields by radical polymerization, using AIBN as initiator. Polymer 2a was found to be soluble in water and in organic solvents such as methanol, acetone, chloroform and benzene, polymer 2b in hot water and in the same organic solvents, and polymers 2c and 2d are insoluble in cold and hot water. However, polymers 2d and 2e are soluble in diethyl ether and hexane. Addition reactions of polymers 2a–e with carboxylic acids and thiols were investigated. Reactions of polymer 2a with acetic acid, benzoic acid and cinnamic acid at 110°C for 10 h proceeded with 57–74 mol-% conversion in DMF, NMP and DMSO, and reactions with benzenethiol and thiobenzoic acid quantitatively under the same reactions conditions. Reactions of polymers 2b and 2c with carboxylic acids proceeded with 4–36 mol-% conversion, and with benzenethiol and thiobenzoic acid with 80–96 mol-% conversion. From the results the following order of reactivities of these polymers may be suggested: 2a ? 2d > 2e > 2b > 2c . According to their higher nucleophilicity, the reactivities of benzenethiol and thiobenzoic acid towards the pendant 2-oxazoline ring are much higher than those of carboxylic acids.     

Versatile,Highly Controlled Synthesis of Hybrid (Meth)acrylate–Polyester–Carbonates and their Exploitation in Tandem Post‐Polymerization–Functionalization

The use of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) as a mild catalyst for the ring‐opening polymerization (ROP) of the pharma‐friendly and biodegradable monomer lactide and a functionalizable tert‐butyloxycarbonyl (BOC)‐protected cyclic carbonate is explored. Successful and controlled ROP is demonstrated when employing a series of labile‐ester (bis)(meth)acrylate initiators to produce macromonomers suitable for a range of post‐polymerization modifications. Importantly, the use of DBU ensured retention of the BOC group of the carbonate monomer during the polymerization, thus facilitating the production of highly functionalizable hybrid materials unobtainable using the more reactive triazabicyclodecene (TBD). Subsequently, a variety of short homo‐ and copolymers are synthesized with good control over material properties and final polymer composition. Successful attainment of these short copolymers confirm that DBU can overcome the previously observed limitations of TBD related to its kinetic competition between ROP and transesterification side‐reactions under these reaction conditions. Furthermore, the fidelity of the hydroxyl and (meth)acrylic end groups are maintained as confirmed by a series of secondary tandem reactions. The macromonomers are also utilized in reversible addition?fragmentation chain‐transfer polymerization (RAFT) polymerization for the production of amphiphilic block or random copolymers with a hydrophilic comonomer, poly(ethyleneglycol)methacrylate. The amphiphilic copolymers produced via the tandem RAFT reaction demonstrate the ability to self‐assemble into monodisperse nanoparticles in aqueous environments.     

Synthesis and characterization of new cardo polyamide-imides containing ether and tricyclo[5.2.1.02, 6]decane groups

A new cardo diimide-dicarboxylic acid, 8,8-bis[4-(4-trimellitimidophenoxy)phenyl]tricyclo-[5.2.1.0^{2, 6}]decane (BTPTD), containing an ether linkage and a tricyclo[5.2.1.0^{2, 6}]decane group was synthesized by condensation reaction of 8,8-bis[4-(4-aminophenoxy)phenyl]tricyclo[5.2.1.0^{2, 6}]decane with trimellitic anhydride. A series of new cardo polyamide-imides were prepared by direct polycondensation of BTPTD with various aromatic diamines in N-methyl-2-pyrrolidinone (NMP) using triphenyl phosphite and pyridine as condensing agents. The polymers were produced with high yield and moderate to high inherent viscosities, i. e., of 0.73–1.36 dL·g^–1. Nearly all polymers are readily soluble in polar aprotic solvents such as NMP, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, dimethyl sulfoxide as well as less polar solvents such as pyridine, γ-butyrolactone, and tetrahydrofuran. These polymers were solution-cast from DMAc solution into transparent, flexible, and tough films except for polymers 4 a and 4 b . Wide-angle X-ray measurement revealed that all polymers were amorphous. These polyamide-imides have glass transition temperatures between 250–290°C and 5% weight loss temperatures in the range of 445 to 491 and 462 to 490°C in nitrogen and air atmosphere, respectively. The polymer films have a tensile strength range of 77 to 87 MPa, an elongation at break range of 3 to 9%, and a tensile modulus range of 2.2 to 2.8 GPa.     

Synthesis and Crosslinking of Polyethers with Ethynylphenyl Pendant Groups

Polyepibromohydrin (A) and poly[(6‐bromo‐1‐hexyl) glycidyl ether] (B) were synthesized from precursor monomers using a coordinative ionic catalyst. These brominated polymers were chemically modified using 1,8‐diazabicyclo[5.4.0]‐7‐undecene to catalyze the substitution of the bromine atom by p‐ethynylbenzoic acid. A quantitative modification was reached. Linear polyethers with ethynyl side chain undergo a process of thermal crosslinking that leads to thermostable polymers. Isoconversional kinetic analysis was applied to DSC data and the dependencies of the activation energies on the conversion degrees were obtained. The degree of modification was shown to influence the crosslinking process.     

Polymere mit dem zentralatom eines makrocyclus in der hauptkette, 3.Polykondensationsreaktionen mit zinnkomplexen des meso-tetraphenylporphins,phthalocyanins und hemiporphyrazins

Dihydroxy(meso-tetraphenylporphino)tin ( 1b ), dihydroxy(phthalocyanino)tin ( 1d ), and dihydroxy(hemiporphyrazino)tin ( 1f ) react with bivalent phenols to afford polymers of type B . With 1,2-ethanediol and 1b low molecular compound 3 is obtained, which eliminates 1,2-ethanediol to give poly[oxyethyleneoxy(meso-tetraphenylporphin)stannandiyl] ( 4 ). Dehydration of the dihydroxy compounds 1b, 1d, 1f leads to polymers of type C . The IR-spectra of the prepared compounds are discussed; thermogravimetric and semiconductive measurements (σ_298K≈10^?6?10^?16Ω^?1cm^?1) are described and compared with the analogous complexes of germanium.     

Polymerisation von fulvenen, 3. Strukturbeweis für kationische polyfulvene durch vergleich mit modellverbindungen

The structure of cationic poly(6,6-dimethylfulvene) ( 2a ) has been confirmed by synthesis of 4 model compounds 6, 7, 8, 9 and comparison of the spectral data with those of the polyfulvene. 5-Isoproylidenetricyclo[5.2.1.0^2.6]dec-3-ene ( 6 ) shows the same sensitivity towards oxygen as 2a . The reaction of 6 with oxygen yields a 1:1-copolymer, for which structure 10 has been proved by means of spectroscopic methods.     

Redox polymerization of 2-hydroxyethyl methacrylate, 2. Kinetics,mechanism and solvent effect using manganese triacetate/cyanoacetic acid as the redox system

Polymerization of 2-hydroxyethyl methacrylate (HEMA) initiated by the redox system manganese triacetate (Mn)(III)/cyanoacetic acid (CAA) was investigated kinetically in DMF and in HOAc/water (80 : 20 v/v). Monomer (M) conversion was followed gravimetrically. Polymerization was carried out at 31°C and at 41°C. The rate of polymerization R_p in DMF is expressed by the equation, R_P, ∝ [M]^1,4 [Mn(III)]^0,4 [CAA]^0,4. In HOAc/water, the polymerization exhibited a strong dependence on the concentration of Mn(III). That is, at low concentrations of Mn(III), the rate variations are [M]^1,0, [CAA]^0,5 and [Mn(III)]^0,5, while at high Mn(III) concentration the polymerization rates are independent of [Mn(III)] and vary as a function of [M]^1,5 and [CAA]^0,5. Enhanced oxidation of the primary radicals by Mn(III) at higher concentrations has been elicited to explain the observed orders. The degree of polymerization was found to increase with increase in concentrations of monomer and decrease in concentrations of CAA and Mn(III). The polymerization rates as well as the molecular weights of the polymers are higher in HOAc/water than in DMF. The enhanced polymerization rates have been attributed to the increased propagation and the reduced termination rates.