Asymmetric induction in the copolymerization of (–)-3-(β-styryloxy)menthane with styrene

Asymmetric induction in the copolymerization of (–)-3-(β-styryloxy)menthane (1) with styrene was investigated. The copolymers obtained in the presence of BF₃ · OEt₂ are optically active. The absolute value of the specific rotation of the copolymers was found to be higher than that of the homopolymeric mixture, whatever the composition. After ether cleavage reaction of the copolymers, the products are still optically active. The result suggests that an asymmetric induction takes place in the polymer main chain.     

Polyadditions of diisocyanatodiketenes, 3-(ω-isocyanatoalkyl)-4-(ω-isocyanatoalkyliden)-2-oxetanones,and polymeranalogous reactions with the resulting polymers

Reactions of diisocyanatodiketenes, 3-(ω-isocyanatoalkyl)-4-(ω-isocyanatoalkylidene)-2-oxetanones (3a–c) , with oligomeric diols (4 or 5) as well as 1,4-butanediol afforded linear polyurethanes containing reactive diketene moieties. From these poly(diketene-urethane)s polymeranalogues products were prepared by reaction with ethanol, ammonia, water or acetic acid. The resulting polyurethanes containing ß-ketoester, ß-ketoamide or keton moieties were characterized by IR spectroscopy, viscosimetry, differential scanning calorimetry and size exclusion chromatography. The properties of the products based on diols 4 or 5 are mainly determined by the oligomeric diols, whereas the (modified) diisocyanate part has a great influence e.g. on the thermal behaviour of the polyurethanes.     

Poly(2-[α-3H]vinylpyridine 1-oxide)

Poly(2-vinylpyridine 1-oxide), when injected into animals, counteracts the pathogenic effects of inhaled silica dust. To study its distribution in the cells, a specifically labelled polymer has been synthesised by reducing 2-acetylpyridine with tritium, dehydrating, polymerising then oxidizing the polyvinyl product. Some of the tritium (17%) enters the aromatic ring by exchange and there is a small loss of tritium by exchange with solvents. At the stage of reduction, there is preference for C? T bond formation rather then C? H.     

The rôle of carbocations in cationic polymerization (polycondensation) of π-, σ-, and n-donor monomers

The rôle of carbocations in cationic polymerizations is discussed, differentiating σ- (i.e. alkene and arene), π- (i.e. alkane) and n-donor (i.e. ether, sulfide, nitrogen compound) monomers as the reactive nucleophiles. The mechanism of the initiation step in alkene polymerization is evaluated considering both protic (i.e. coinitiator containing) and aprotic systems. The aluminum bromide catalyzed polymerization of isobutylene, as an example, can involve besides the conjugate protic acid, bromoalanation intermediates in aprotic media, which, however, themselves rapidly can undergo elimination, forming HBr in the originally acid free system. The involvement of dialkylhalonium ions in alkyl halide solvent systems is also of substantial interest and may explain increasing deactivation in the order RI>RBr>RCl. Oxidative polycondensation of π-donor arenes (such as benzene) and σ-donor alkanes (such as methane) is discussed in the context of the general carbocation concept, involving trivalent carbenium ion intermediates in the former and pentacoordinated carbonium ions in the latter case, as the reactive alkylating agents responsible for the ionic propagation reactions. n-Donor monomers, such as ethers, sulfides or miscellaneous nitrogen compounds, undergo polymerization via nucleophilic displacement reactions on the polarized carbocationic sites of intermediate alkylated or protonated onium ions.     

Synthesis of 3′,5′-bis(morpholinomethyl)-4′-hydroxy- and 3′,5′-bis(4-methyl-1-piperazinylmethyl)-4′-hydroxymethacrylanilide. Copolymerization and metal ion binding properties of monomers and copolymers

4′-Hydroxymethacrylanilide was modified by Mannich reaction with morpholine/formaldehyde and 1-methyl-piperazine/formaldehyde, respectively. The interaction of the resulting monomers 3 and 4 and their corresponding copolymers with acrylamide ( 5 and 6 ) with Cu^{2 +} ions was studied by photometric methods. Incorporation of the aminomethylated phenol derivatives 3 and 4 in an acrylamide-methylene diacrylamide network system was performed to yield a product which selectively adsorbs Cu²⁺ in the presence of Ni²⁺, Co²⁺, Cd²⁺ and Ca²⁺ ions.     

Molecular Motions in the Supramolecular Complexes between Poly(ε‐caprolactone)‐Poly(ethylene oxide)‐Poly(ε‐caprolactone) and α‐ and γ‐Cyclodextrins

The structure and molecular motions of the triblock copolymer PCL‐PEO‐PCL and its inclusion complexes with α‐ and γ‐cyclodextrins (α‐ and γ‐CDs) have been studied by solid‐state NMR. Different cross‐polarization dynamics have been observed for the guest polymer and host CDs. Guest–host magnetization exchange has been observed by proton spin lattice relaxation T₁, proton spin lattice frame relaxation T_1ρ and 2D heteronuclear correlation experiments. A homogeneous phase has been observed for these complexes. Conventional relaxation experiments and 2D wide‐line separation NMR with windowless isotropic mixing have been used to measure the chain dynamics. The results show that for localized molecular motion in the megahertz regime, the included PCL block chains are much more mobile than the crystalline PCL blocks in the bulk triblock copolymer. However, the mobility of the included PEO block chains is not very different from the amorphous PEO blocks of the bulk sample. The cooperative, long chain motions in the mid‐kilohertz regime for pairs of PCL‐PEO‐PCL chains in their γ‐CD channels seem more restricted than for the single PCL‐PEO‐PCL chains in the α‐CD channels, however, they are not influencing the more localized, higher frequency megahertz motions.     

4-(α,α-dimethylbenzyl)phenyl methacrylate, 1. Synthesis and crystal structure

4-(α,α-dimethylbenzyl)phenyl methacrylate ( 1 ) was prepared by reaction of 4-(α,α-dimethylbenzyl)phenol and methacryloyl chloride in ether. By careful crystallization from ether large monoclinic crystals could be obtained with the following crystal data: a = 6,622 (2) Å, b = 12,578 (2) Å, c = 9,892 (3) Å, β = 99,86° (3), D_c = 1,147 g · cm^?3, V = 811,1 ų, M = 280,4, λ = 0,7107 Å, μ = (Mo K_α) = 0,7 cm^?1, F(000) = 300, space group P2₁, Z = 2. Attempts to polymerize the monomer (m.p. 46–48°C) by γ-irradiation at ambient temperature gave only a small amount of a crosslinked product.     

Synthetic Antigens as Immunogens: Part IV. Specificity of Antisera Developed to Gal β1-3(GlcNAc β1-6)GalNAc and GlcNAc βl-6GalNAc

Antisera to the chemically synthesized trisaccharide, Gal β1-3(GlcNAc β1-6)GalNAc, and disaccharide, GlcNAc β1-6GalNAc, were developed using the diazophenyl bovine serum albumin derivatives. The binding specificity of the antisera were analyzed by enzyme immunoassays with structurally related, chemically synthesized oligosaccharides. The anti-trisaccharide antibody showed no reactivity to T antigenic structures which bear the Gal pl-3GalNAc moiety. The immunodominant area of the Gral β1-3(GlcNAc β 1-6)GalNAc was contained in the GlcNAc β1-6GalNAc region of the molecule. The reactivity pattern of the anti-trisaccharide antibody, although directed to the disaccharide, did not exactly duplicate the reactivity pattern of the anti-disaccharide.     

The production of 3aα-H-4α-(3′-propionic acid)-5α-hydroxy-7aβ-methylhexahydro-1-indanone-δ-lactone by Nocardia restricta mutants

Two mutants of Nocardia restricta breakdown androst-4-ene-3,17-dione into 3aα-H-4α-(3′-propionic acid)-5α-hydroxy-7aβ-methylhexahydro-l-indanone-δ-lactone. The metabolic intermediates formed are very different in each mutant. One uses certain aromatic compounds very slowly. A degradation pathway for steroids by Nocardia restricta has been proposed.     

Asymmetric radical polymerization of (–)-3-p-menthyl sorbate

The radical polymerization of (–)-3-p-menthyl sorbate ( 2 ) was performed with azoisobutyronitrile (AIBN) as an initiator in benzene at 50°C. The chiral (–)-menthyl group in the resulting poly- 2 was removed by hydrolysis in potassium hydroxide solution to give optically active poly(sorbic acid), indicating that an asymmetric induction took place during the polymerization. It was concluded from the results of ozonolysis and optical rotatory dispersion measurements on the poly(sorbic acid) that the asymmetry was induced only at 1-position of the monomeric unit in the poly- 2 main chain.