摘要:

The concentration-time relationships of the individual active species in the oligocondensation stage of the reaction of melamine with formaldehyde have been investigated, mainly by electrochemical methods. Based on the reaction equations, a kinetic model of the overall reaction was established and the rate constants were calculated by numerical methods. The results suggest the hydroxy-methylamines are converted to methylene and dimethylene ether bridged compounds by acid- and base-catalyzed reactions, respectively. At pH 7-10 the formation of methylene bridges by base-catalyzed scission of dimethylene ether bridges may occur.

ISSN:0022-233X    

DOI:10.1080/00222338608058497

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The ring-opening polymerization rate of 1-β-cyanoethylazetidine (CA) with 3-hydroxy-1-propanesulfonic acid sultone (HPSS) as an initiator has been investigated in acetonitrile. The polymerization of CA with HPSS proceeded by way of a zwitterion formed by the addition reaction of CA and HPSS. The course of polymerization involved, as an early stage, slow initiation due to the low reactivity of the zwitterion. The propagation constants were obtained as were the enthalpy of activation for propagation (ΔHp* = 12 kcal/mol) and the entropy of activation for propagation (ΔSp* = −31 cal/K·mol).

ISSN:0022-233X    

DOI:10.1080/00222338608058498

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The coordination complexes of o- and p-tolylthioureas with Co(II) and Ni(II) have been synthesized and characterized with the help of elemental analysis, infrared and reflectance spectra, and magnetic and thermogravimetric measurements. The complexes are found to be polymeric in nature with an octahedral geometry. A metal-to-ligand ratio of 1:1 was found in all the complexes except for cobalt(II) bromide where it was 1:2. Coordination of two water molecules per metal atom has been found in all the polymers. Relative thermal stability is also discussed.

ISSN:0022-233X    

DOI:10.1080/00222338608058499

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Optically active N-α-methylbenzylcitraconimide (MBZCI) was prepared from citraconic anhydride and d-α-methylbenzylamine. The polymerizations of MBZCI were carried out with α,α′-azobisiso-butyronitrile (AIBN) in several solvents and in bulk. The specific rotations of the polymers were between 48.6 and 56.7°. The number-average molecular weights for the polymers were 1 400 to 1 900. MBZCI was copolymerized with styrene (ST) and methyl methacrylate (MMA) with AIBN in tetrahydrofuran at 50°C to obtain optically active copolymers. The monomer reactivity ratios of MBZCI (M1) with ST (M2) and MMA (M2) were determined as r1= 0.12, r2= 0.24 in the MBZCI-ST; r1= 0.23, r2= 2.38 in the MBZCI-MMA system. The Q-e values were obtained as Q1= 0.63, e11.07. It was found that all the polymers and copolymers showed a strongly negative circular dichroism (CD) peak at about 258 nm. From the results of chirality of the copolymer, it was concluded that induction of asymmetric carbon atoms into the MBZCI-ST copolymer main chain took place.

ISSN:0022-233X    

DOI:10.1080/00222338608058500

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Coumarin, 3-phenyl, and 3-phenoxy coumarin polymers were prepared by the Perkin reaction of p-xylylene dichloride-salicylaldehyde polymer with acetic anhydride, phenyl acetic acid, and phenoxyacetic acid, respectively. The xanthone polymers were prepared by the Kostanecki reaction on p-xylylene dibromide-salicylic acid polymer with phenol or resorcinol. The flavone polymer were synthesized via chalcone intermediate from p-xylylene dichloride-o-hydroxyacetophenone polymer and benzalde-hyde. All the coumarin, xanthone, and flavone polymer samples were characterized by elemental analyses, by IR spectral studies, by TGA, and by studying their antifungal activities.

ISSN:0022-233X    

DOI:10.1080/00222338608058501

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Radical copolymerization of isobutyl vinyl ether (IBVE) with maleic anhydride (MA) gave 1:1 alternating copolymer in a wide range of monomer composition. IBVE and MA formed a 1:1 donor-acceptor complex which showed an absorption maximum at 273 nm in CHCl3. The equilibrium constant of the complexation was measured to be 0.052 M−1in CCl4at 37°C by NMR, 0.036 M−1in CDCl3at 37°C by NMR, and 0.033 M−1in CHCl3at 23°C by UV. The dilatometrically measured rate of copolymerization in CHCl3at 50°C was a maximum at a feed MA mole fraction of 0.350, 0.405, and 0.435 when the total monomer concentration was 0.5, 1, and 1.5 M, respectively. The Georgiev-Zubov method, based on the reactions of free monomers and the complex, was applied to obtain α = 0.210, β1= 65.6, and β2= 4.42.

ISSN:0022-233X    

DOI:10.1080/00222338608058502

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Alternating copolymerization offers an ideal method for introducing certain pairs of functional groups into copolymer chains in a controlled manner. In a previous paper from this laboratory, a novel copolymer containing alternating imidazole and hydroxamic acid functional groups was reported, and its evaluation as a synthetic enzyme was described. In an extension of this work, the present paper reports the synthesis, characterization, and evaluation of those novel copolymers containing alternating imidazole and phenolic hydroxyl functional groups. The results of this study indicate that “cooperativity” between this pair of functional groups is somewhat restricted, probably for reasons related to the conformation of the copolymer chains or the proximity of the functional groups to the copolymer backbone.

ISSN:0022-233X    

DOI:10.1080/00222338608058503

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0022-233X    

DOI:10.1080/00222338608058496

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor