摘要:

AbstractAn alternative method for the preparation of the cyclic dimer3of 2‐pyrrolidone is presented, which is based on hydrolysis of 1‐(1‐pyrrolin‐2‐yl)‐2‐pyrrolidone (4,x=y= 3), and some physicochemical properties of4and its hydrolytical products

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890101

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe anionic polymerization of 2‐pyrrolidone (PD) was initiated with the potassium salt of PD at 30–50°C and accelerated with the followingN‐iminolactams (NIL): 1‐(1‐pyrrolin‐2‐yl)‐2‐pyrrolidone(1), 1‐(1‐azacyclohept‐1‐en‐2‐yl)‐2‐pyrrolidone(2), 1‐(1‐azacyclonon‐1‐en‐2‐yl)‐2‐pyrrolidone(4), 1‐(1‐azacyclohept‐1‐en‐2‐yl)‐1‐ azacycloheptan‐2‐one(3)and 1‐(phenyliminomethyl)‐2‐pyrrolidone(5). The polymerizations exhibit formal kinetics of zero order with respect to the monomer with substantially differing apparent rate constants depending on the type of NIL used. The same limit conversions are attained in a

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890102

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe anionic polymerization of ϵ‐caprolactam (CL), initiated with the sodium or potassium salt of CL, was shown to be accelerated with 1‐(1‐pyrrolin‐2‐yl)‐2‐pyrrolidone(1), 1‐(1‐azacyclohept‐1‐en‐2‐yl)‐2‐pyrrolidone(2), 1‐(1‐azacyclonon‐1‐en‐2‐yl)‐2‐pyrrolidone(3), 1‐(1‐azacyclohept‐1‐en‐2‐yl)‐1‐azacycloheptan‐2‐one(4)and 1‐(phenyliminomethyl)‐2‐pyrrolidone(5), both above the below the melting temperature of the polymer (150‐230°C). Th

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890103

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe anionic polymerization of 2‐pyrrolidone was accelerated with 1‐(1‐pyrrolin‐2‐yl)‐2‐pyrrolidone(1), labelled with nuclide15N. The incorporation of1into the polymer was followed by the change of isotope concentration, and the apparent rate constants were derived for some elementary reactions in the investigated polyreaction. The interchange reaction between1and monomer was also measured.1can be considered a slow activator, each molecule incorporating into the polymer being the precursor of a

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890104

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractA new catalytic complex was developed by reacting 1,1‐diphenylethylene with metallic calcium and submitting the resulting derivative [designated as (Ar)2Ca] to chemical modifications with 1‐chloro‐2,3‐epoxypropane (epichlorohydrin; ECh). From these reactions a series of (Ar)2Ca · x ECh catalysts resulted differing by the mole ratio ECh/Ca. A value of 0,7 was found to be the optimal one with regard to the catalytic efficiency of polymerizing epichlorohydrin. The poly(epichlorohydrin)s (PECh), obtained with yields of 46, 5 to 82, 4%, are distinguished by their chlorine content and cover a range of molar masses from 0,35 · 105to 2,23 · 105g/mol. The catalysts were characterized by elemental analyses and thermogravimetry. According to X‐ray patterns, PECh obtained by means of (Ar)2Ca · 0,7 ECh as catalyst displayes no crystallinity like PECh prepared in the presence of appropriate alum

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890105

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe free‐radical terpolymerization of maleic anhydride, styrene, and acrylic monomers such as acrylonitrile, methyl acrylate and methyl methacrylate was studied. The alternating copolymerization of maleic anhydride with styrene was found to be favored in those systems. Contrary to theoretical predictions, maleic anhydride is more reactive than styrene in ternary systems. The relative reactivity of the acrylic monomers studied was found to decrease in the order: methyl methacrylate ≥ methyl acrylate>acrylonitrile. In the presence of a Lewis acid, such as ZnCl2or C2H5AlCl2, the relative reactivity of acrylic monomers increases and at the respective complexing agent concentration the copropagation of the acrylic monomer with styrene can dominate. On the basis of the results obtained, some aspects of the mechanism of alternating propagation in systems comprising an electron‐donor monomer and two electron‐acceptor monomers are di

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890106

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractFree‐radical polymerizations of several aliphatic and aromaticN‐substituted vinyl carbonates are described. The bulk polymerization was initiated at 35°C with di‐tert‐butylcylohexyl peroxydicarbonate yielding high‐molecular‐weight poly(vinyl carbonate)s. The structure of these polymers was examined by FTIR spectroscopy and the molecular weight by GPC. The effects of the substituents on the physical properties of the resulting polymers were studied. A comparison of the properties with those of similar compounds described in the literat

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890107

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe reaction mechanism of the redox initiation system persulfate/N,N,N′,N′‐tetramethyl‐ethylenediamine (TMEDA) was studied by spin trapping technique and ESR spectra. The free radical (CH3)2NCH2CH2(CH3)NCH ˙2(1)is one of the initial free radicals responsible for the initiation of the vinyl polymerization in addition to the sulfate free radical (HO3SO˙). The result of amino end group analysis confirmed the fact that the free radical1initiates vinyl polymerization and becomes the end group of the resulting polymers. The effect of TMEDA concentration on the final percentage of conversion of acrylamide polymerization and on the molecular weights of the resulting polymer were also studied. An initiation mechanism w

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890108

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper describes a re‐examination of the kinetics and molecular weights formed in the zwitterionic polymerization of butyl cyanoacrylate by triphenylphosphine (Ph3P) and pyridine (Py) in THF, and an extension to include the solvents, diethyl ether (Et2O), dimethoxyethane (DME) and hexane. In THF, the previously observed kinetics were confirmed, yielding evidence for absence of termination, and values for rate constants for initiation (ki) and propagation (kp) with substantial agreement between the values for Kpobtained from both systems. At 20°C, the mean value found forkpin THF was 3 · 105l · mol−1· s−1; in Et2O, some 10 times lower, and in hexane, 10 times lower again. The temperature dependence ofkpin THF was confirmed to be extremely low and anomalous; in Et2O rather greater and near‐normal, corresponding to an energy of activation of ca. 5 kcal · mol−1. A correction procedure enabled the large experimental scatter in thekpvalues to be reduced sufficiently to reveal trends downwards at higher concentrations of propagating species, i.e. evidence for their dissociation on dilution. In Py‐initiated polymerizations, excess of pyridinium salts did not depresskp; evidence that the propagating species are preponderately paired ions, not free. It is concluded that at 20°C these species are mainly ‘tight’ ion‐pairs in all solvents, and remain so in Et2O at all temperatures down to −80°C. In THF, over this temperature range, there is increasing solvation producing an increasing proportion of more reactive ‘solvent‐separated’ ion‐pairs. The molecular weights produced under all conditions were high (Mnusually 1 to 3 · 106). Those produced by high concentration of Ph3P did not conform to theory; others followed the ‘no‐termination’ theory as modifie

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890109

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe coupling reaction of ampicillin with the polysaccharide xanthane in DMSO, using dicyclohexylcarbodiimide as activator, was studied. To find the conditions for maximum yield a regression equation was established, describing the dependence of the yield of coupling product on the reaction parameters (drug/support mole ratio, activator/support mole ratio and duration), starting from an experimental, centrated rotable complex, second order program. The coupling product was spectroscopically characterized and the in vitro release rate of ampicillin in a weakly basic medium was established along with the determination of its antimicrobiological activity.

ISSN:0025-116X    

DOI:10.1002/macp.1988.021890110

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY