Complexation of cyclodextrins with nicotinamide and N-(hydroxymethyl)nicotinamide in aqueous solution

Complex formation of α- and β-cyclodextrins with biologically active nicotinamide and Nhydroxymethylnicotinamide (nicodine) was studied by calorimetry and ¹H NMR spectroscopy. Cyclodextrins showed a weak complexing ability toward nicotinamide and nicodine: 1: 1 enthalpy-stabilized host-guest complexes were formed in aqueous solution at 298.15 K. Nicotinamide and nicodine molecules appeared inside the macrocycle cavity of cyclodextrins, but interaction between their polar side-chain groups with the outer surface of cyclodextrins cannot be ruled out. Thermodynamic parameters of the complexation process were calculated, and a mechanism was proposed for the observed interaction. The results were compared with those obtained previously for the complexation of cyclodextrins with nicotinic acid.     

Radical polymerization of benzyl N-(2,6-dimethylphenyl)itaconamate

The polymerization of benzyl N-(2,6-dimethylphenyl)itaconamate (BDMPI) with benzoyl peroxide (BPO) in N,N-dimethylformamide (DMF) was studied kinetically by ESR. The polymerization rate (R_p) at 70°C was given by R_p = k[BPO]^0.78[BDMPI]^1.1. The overall activation energy of polymerization was determined to be 83.7 kJ/mol. The number-average molecular weight of poly(BDMPI) was in the range of 1500–2000 by gel permeation chromatography. From the ESR study, the polymerization system was found to involve ESR-observable propagating radicals of BDMPI under practical polymerization conditions. Using the polymer radical concentration by ESR, the rate constants of propagation (k_p) and termination (k_t) were determined in the temperature range of 50–70°C. The k_p value seemed dependent on the chain-length of propagating radical. The analysis of polymers by the MALDI-TOF mass spectrometry suggested that most of the resulting polymers contain the dimethylamino terminal group. The copolymerization of BDMPI (M₁) and styrene (M₂) at 50°C in DMF gave the following copolymerization parameters; r₁ = 0.49, r₂ = 0.26, Q₁ = 1.2, and e₁ = +0.63. The thermal behavior of poly(BDMPI) was examined by dynamic thermogravimetry and differential scanning calorimetry. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1891–1900, 1997     

Synthesis and polymerization of N-(ethylene)-phthalimidyl acrylate

N-(Ethylene)phthalimidyl acrylate was synthesized starting from phthalimide or phthalic anhydride using two different routes. Free radical or anionic polymerization of the ester resulted in low-molecular-weight polymers.     

Preparation and polymerization of some N-(dialkylaminoalkyl)acrylamides

A series of N-(dialkylaminoalkyl)acrylamides was synthesized by reductive amination of N-(1,1-dimethyl-3-oxobutyl)acrylamide (diacetone acrylamide) and by the reaction of either an alkenylamine or an amino alcohol with acrylonitrile. These monomers homopolymerize and copolymerize readily to form high molecular weight products. The solubility of the monomers and their homopolymers in water ranges from soluble to insoluble at room temperature. The insoluble materials can be quaternized readily to produce water-soluble products. The solubility of the homopolymers in water decreases with increasing temperature. Glass transition and decomposition temperatures of the homopolymers are reported.     

Effects of poly(2-vinylpyridine) as a template for the radical polymerization of methacrylic acid—III. Influence of monomer concentration

The template polymerization of methacrylic acid along atactic poly (2-vinylpyridine) was studied calorimetrically at various monomer concentrations from 0.1 to 9.0 M in DMF; the concentration of the P2VP template was fixed at 0.4 base M. Azobisisobutyronitrile and bis(p-tert-butylcyclohexyl)peroxydicarbonate were used as initiators at concentrations of 0.1 and 0.01 M, respectively. The temperature was 30°. The results could be well described by a generalized kinetic model in which the effect of preferential adsorption of monomer by the template, this adsorption being assumed to be of the Langmuir type, has been taken into account, i.e. the model incorporates propagation along the template not only by picking-up monomer from the surrounding solution (mechanism II) but also by zipping-up pre-adsorbed monomer (mechanism I).     

Untersuchungen zur Silicationenkonstitution in N-(2)Hydroxyethyl- und N-(2)Hydroxypropylpyridiniumsilicatlösungen. Bildung von N-(2)Hydroxypropylpyridiniumsilicathydrat

Investigations on the Silicate Ion Constitution in N-(2)hydroxyethyl- and N-(2)hydroxypropylpyridinium Silicate Solutions Crystallization of N-(2)hydroxypropylpyridinium Silicate Hydrate In N-(2)hydroxyethyl- and N-(2)hydroxypropylpyridinium silicate solutions are present mainly double three-ring and double four-ring silicate ions. With increasing concentration their molar ratio shifts in direction to double four-ring silicate. Simultaneously the amount of the low-condensed silicates decreases. An increasing concentration of the alkali hydroxide destroys the double ring cages. From solutions of N-(2)hydroxypropylpyridinium silicate with molar ratios of the pyridinium base to silicon dioxide of 0.5 to 2 and from solutions with a certain amount of alkali hydroxide an acid- N-(2)hydroxypropylpyridinium-double-four-ring silicate hydrate is obtained by crystallization.     

N-(5,6,7-Trihydroquinolin-8-ylidene)arylaminonickel dichlorides as highly active single-site pro-catalysts in ethylene polymerization

A series of N-(5,6,7-trihydroquinolin-8-ylidene)arylamine ligands was synthesized and fully characterized by NMR, IR spectroscopy and elemental analysis. Dimeric N-(5,6,7-trihydroquinolin-8-ylidene)arylaminonickel dichlorides were prepared and examined by IR spectroscopy and elemental analysis, and the molecular structures of the representative nickel complexes were determined by the single crystal X-ray diffraction. On treatment with various alkylaluminiums, all the title complexes exhibited highly active, single-site active behavior for ethylene polymerization producing polyethylene (PE) waxes. The catalytic systems using the co-catalysts diethylaluminium chloride (Et(2)AlCl) or methylaluminoxane (MAO) were investigated in detail, and the molecular weights and distributions of the PEs obtained were found to significantly rely on the nature of the different ligands present and reaction parameters such as the molar ratios of Al/Ni, reaction temperature and reaction time.     

Group‐transfer polymerization of cyclic trimethylsilyl dienolate as a new monomer

This communication reports the group‐transfer polymerization of a cyclic trimethylsilyl dienolate, 2‐(trimethylsilyloxy)furan ( 1 ), initiated with benzaldehyde. The polymerization proceeded in the presence of a tetrabutylammonium salt as the catalyst in THF solvent at 0–50°C. The product was isolated as an ethyl acetate insoluble fraction after acidic work‐up. The structure of the product polymer was determined by means of ¹H NMR, ¹³C NMR, and IR spectroscopy to be polylactone 3 . The mechanism of the polymerization can be explained by a Michael‐type addition of 1 onto the propagating end.     

Synthesis and polymerization of multiallyl monomer in matrix of poly(methacryloyl chloride)

By reacting poly(methacryloyl chloride) (PMKC) with allyl amine, a multiallyl monomer in PMKC matrix has been obtained. Free-radical polymerization of multiallyl monomer in diluted solutions at a concentration of 12 g/L multiallyl monomer occurs partly along ordered allyl units in the matrix and results in ladder-type branched polymers. The polymers obtained are soluble in alcohols, DMF, DMSO and have unreacted allyl double bonds. The structures of multiallyl monomer and homopolymer have been found on the basis of elemental analysis, IR and ¹H-NMR spectra and an examination of the products of hydrolysis. The effect of the reaction of degradative chain transfer on the structure of the polymer obtained has been discussed.     

Poly[N-(2-hydroxypropyl)methacrylamide]—I. Radical polymerization and copolymerization

The radical polymerization of N-(2-hydroxypropyl)methacrylamide was investigated kinetically. The hydrophilic character of the polymerization medium was found to affect the rate of decomposition of the initiator [2,2′-azobis(methyl isobutyrate)] and the course of primary radical termination. The presence of the -OH group in the alkyl group attached to the nitrogen atom leads to an increase in the molecular weight of the polymer in comparison with polymers of N-alkyl methacrylamides. This phenomenon was interpreted in terms of the possibility of a polymeranalogous transesteramidation and of an increased possibility of transfer to monomer and polymer. The copolymerization parameters of N-(2-hydroxypropyl)methacrylamide (M₁) with methyl methacrylate and styrene were determined; in the first case, r₁ = 0·84 ± 0·05, r₂ = 0·66 ± 0·07; in the second case, r₁ = 0·53 ± 0·08, r₂ = 1·72 ± 0·19.     

Poly(terephthalic acid anhydride) as a latent monomer in polybenzoxazole synthesis

High molecular weight poly(p-phenylenebenzobisoxazole) (PBO) was prepared from poly(terephthalic acid anhydride) (PTAA) and 1,3-diamino-4,6-dihydroxybenzene dihydrogenchloride in polyphosphoric acid (PPA). PTAA may react directly with the o-aminophenol groups to form benzoxazoles or react with PPA to generate terephthalic acid (TA) of very small particle size, which dissolves readily in PPA. PTAA provides the advantages of bypassing the requirement of small particle size TA, reducing the amount of water liberated by half, and possibly providing faster kinetics in PBO synthesis. © 1994 John Wiley & Sons, Inc.