摘要:

AbstractCoordination polymers,\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \rlap{--} (MtL\rlap{--} )}_{\rm n} $\end{document}were synthesized by condensation of bis(salicylaldehydo)‐metal(II) (metal = Co, Ni, and Cu) with diamines (1, 4‐diaminobenzene and 4,4′‐diaminobiphenyl). Their composition, structure, thermal stability, and physical properties were investigated by analytical, magnetic, spectral (IR and DRS), the thermogravimetric studies. It was found that in the bis(salicylaldehydo)metal(II)‐chelates, two salicylaldehyde molecules are linked to each metal ion through the oxygen atoms of the phenolic and aldehydic groups and in the polymeric complexes the nitrogen atoms of the amino groups replace the aldehyde oxygens. The diamine molecule is thus acting as a bridging unit between two salicylaldehydometal(II) units, forming structures1and2. The polymers obtained from 4,4′‐diaminobiphenyl (2a−c) are thermally more stable than those from 1, 4‐diaminobenzene (1a−c), the order of thermal stability in both cases being Ni(II)>Cu(II)>Co(II). Co(II) and Cu(II)‐complexes are paramagnetic, whereas Ni(II)‐complexes are diamagnetic. The reflectance spectra along with the magnetic data suggest a square planar structure for Cu(II) and Ni(II)‐complexes, and a tetrahedral one

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830301

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe nature of alkali derivatives of acetone (ADA) and active centres (AC) in the anionic polymerization of isopropenyl methyl ket one (IMK) was studied by means of IR spectroscopy. Solutions of ADA and of the AC of IMK in tetrahydrofuran show a characteristic absorption at 1560 – 1610 cm−1, due to the stretching vibrations of the delocalized isopropenyl oxide group. Two kinds of equimolar complexes are formed between acetone and ADA, depending on the nature of the counterion (Li+, Na+, K+, Cs+). The same interaction is observed between the AC of oligo (IMK) and the carbonyl group of the last but one monomeric unit (penultimate effe

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830302

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractPrevious Kinetic studies of the emulsion polymerisation of the three component system acrylonitrile (A) — styrene (S) — methyl acrylate (M) have shown that S is much more reactive than A and M, which have practically the same reactivities. As a consequence, in batch process a large copolymer composition drift is observed versus conversion. To avoid this damageable drift, two techniques were investigated, to get homogeneous macromolecules. (1) Application of the well known “semi‐continuous technique” which appeared not to be totally satisfactory, since the initial batch polymer fraction generally has a composition different from the further polymer when the monomer feed is added under starving conditions; a mixture of various macromolecules is the result. (2) The use of the composition controlled reactor, developed in this laboratory, which consists in a continuous monitored readjustment of monomer feed composition. However, due to the heterogeneous medium of an emulsion copolymerization, the copolymer exerts a small chemical heterogeneity which may be practically negligible at high monomer/water ratio. It is finally proposed that a thermodynamic approach might overcome such a behaviour and insure an actual control of the copolymer co

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830303

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe interaction of Ni[P(OR)3]4(R = C2H5or C6H5) with chlorinated rubber (CR) of CCl4is studied. The results of the polymerization of methyl methacrylate (MMA) initiated by the system CR or CCl4Ni[P(OR)3]4depend on the order in which the reagents are introduced. Trialkylphosphite, tetrakis(trialkylphosphite) nickel and the products resulting from the reaction of CCl4or CR with Ni[P(OR)3]4are characterized by31P NMR. From this study, it appears that the initiation of polymerization by the system chlorinated compound‐nickel derivative does not involve the formation of free phosphite, which is at variance with previously reported assumption.1H NMR study supports these resu

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830304

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe reaction of a diisocyanate and an asymmetric aliphatic‐aromatic diacid containing a preformed imide group was studied in order to obtain polyamide‐imides. It is shown in this paper that combined1H and13C NMR spectrometry will permit the quantitative evaluation of the proportions of head‐tail, head‐head, tail‐tail additions, provided the content of urea in the polymer is low. In order to obtain unequivocal assignments and to thoroughly characterize the NMR spectra of the polymer, several model compounds resembling the polymer backbone were synthesized. A model polymer was synthesized with the same purpose, and its1H and13C NMR spectra fully assigned. Unexpected chemical functions in the polymer, like urea and carboxylic acid, can also be easily detected and quantifi

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830305

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe polycondensation of 4,4′‐methylenediphenylisocyanate and 6‐(4‐carboxyphthalimido)‐hexanoic acid was studied under different conditions in order to establish the influence of factors such as temperature, catalyst, stoichiometric disbalance, and addition order of reactants on the molecular weight and the chemical composition of the final polyamide‐imide. All these factors proved to influence the extent of possible side reactions that lead to undersirable functions, the main ones being urea functions that locate within the polymer backbone. Other side‐reactions proposed to explain the formation of acylureas or biurets did not take place in appreciable extent since these functions could not be detected by NMR spectroscopy. Therefore, particular emphasis was made to prevent the formation of urea by changing the polycondensation conditions. A first attempt to clarify the regularity degree of the polymers (amounts of head to tail and head to head addition) by1H NMR spectroscopy

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830306

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractIn the asymmetric addition of hydrogen cyanide to benzaldehyde to give mandelonitrile, a cyanohydrin, the highest enantiomeric excess (e.e.) ever reported (90%) was obtained with (2d) whereas the corresponding linear dipeptide gave a very low e. e. This high e. e. decreased with the reaction time, because of the racemization of the product. All cyclic dipeptides used containing an (S)‐histidine residue preferred the (R)‐product. A scheme for the interaction between the catalyst and the reactants to give the (R)‐product is pro

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830307

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe direction of the oxirane ring opening in the polymerization of styrene oxide by sodium methoxide was determined on the basis of the structure of the products obtained. The oxirane ring opening was found to occur almost exclusively in β‐position. This result was compared with a model reaction, i.e. the methanol addition to styrene oxide in the presence of sodium methoxide. In the model reaction the oxirane ring opening occurred to ca. 35% in α‐position and to ca. 65% in β‐

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830308

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe13C NMR spectra ofN‐acetyl‐D‐glucosamine (1) and chitobiose (2), monomer and dimer of chitin, were assigned and used to assign the13C NMR spectra of chitin in lithium thiocyanate and in LiCl/dimethylacetamide solutions. The dissolution of chitin in formic acid was studied. IR,13C and1H NMR spectra show that dissolution occurs by a reaction of formic acid with chitin with the formation of formyl chitin as a statistical derivative of chitin.13C NMR spectra of diformyl‐ and diacetylchitin were also assigned to characterize these regular p

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830309

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractTurbidimetric results obtained with the ternary systemsN,N‐dimethylformamide/cyclohexane/polystyrene,N,N‐dimethylformamide/cyclohexane/polybutadiene, methanol/cyclohexane/polystyrene, methanol/cyclohexane/poly(ethylene glycol) are reported. These results show that a very small quantity of polymer changes drastically the demixing curve of the two partially mixed liquids. The displacement of the heterogeneous region starts from the domain of the critical point of the two liquids and becomes more significant in the domain of compositions of the two liquids rich in the poor solvent of the polymer. A qualitative explanation of this phenomenon is attempted based on the theory of the isorange lines of two partially miscible liqu

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830310

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY