摘要:

AbstractThe cyclic acetals 1,3‐dioxolane (4a), 1,3‐dioxane (4b), and 1,3‐dioxepane (4c) give in their reactions with the methoxymethyl cation (1) a mixture of two isomeric tertiary oxonium ions: the simple products of cationation5a‐cand the cationated rings6,7,9, enlarged by two atoms. The equilibria for the studied monomers are shifted to the side of the oxonium ions as shown in the reaction schemes 2, 4, 5, and 6 (SbF‐6or SbCIF‐5being the corresponding anions). In the case of4athe equilibrium is displaced almost completely to the enlarged ring6, whereas for the other two cyclic acetals4band4cthe first cationated products5band5cdominate. Application of the dynamic1H NMR method allows the determination of the equilibrium constants of the reactio

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830701

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractD‐N‐(4‐vinylphenyl)carbamoylethylenedioxy(4‐vinylphenyl)borane (1) with D‐glyceric acid as template was copolymerized with technical divinylbenzene by a radical mechanism in the presence of various amounts of acetonitrile as an inert solvent. The resulting differences in the structure and swellability of the polymers are discussed in relation to the specificity of the polymers for the racemic resolution of D,L‐glyceric acid. Some of these polymers were found to be able to bind glyceric acid with high optical enrichment by a covalent amide bond. To prevent the formation of the covalent amide bond during the intake reaction, the amide bond in the monomer is replaced by an ion pair relation. For this intention, the synthesis of an appropriate monomer 4‐vinyltrimethylanilinium 2‐(4‐vinylphenyl)‐1,3,2‐dioxaborolan‐4‐carboxylate (2) and the investigation of the resulti

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830702

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractA series of novel semi‐ladder polymers containing 7H‐benzimidazo[2,1‐a]benzo[d,e]isoquinolin‐7‐on‐3,11‐diyl units in the chain was prepared by one‐step high temperature solution polycondensation of 4,4′‐oxy‐,4,4′‐carbonyl‐, and 4,4′‐sulfonyldi‐1,8‐naphthalenedicarboxylic anhydride (1a‐c) with 2,2′‐diamino‐4,4′‐oxydianiline (2) or 2,2′‐diamino‐4,4′‐hexafluoroisopropylidenedianiline (4). The similarity of the IR and UV spectra of the polymers and the model compounds7a‐cconfirms the presence of the benzimidazobenzoisoquinolinone rings in the polymer chain. All the resulting polymers have excellent thermal stability both in argon and in air. The polymers prepared from4are soluble in

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830703

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractBasic feature of styrene polymerization under the action of 1,3‐bis(1‐lithio‐1‐methylhexyl)‐benzene (1) in the presence of tetrahydrofuran were studied. UV spectra of1and dilithiumpolystyrene in a benzene solution with an without THF were investigated. A comparison of the results of the UV spectra with the data of cryoscopy and viscometric measurements of “living” and deactivated polystyrene allows the conclusion that polystyrene chains propagating on the dilithium catalyst are in m

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830704

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractRing‐opened polymers of racemic and optically active 5,5‐dimethylbicyclo[2.2.1]hept‐2‐ene (6) (5,5‐dimethylnorbornene), with cis double bond contents of 0–100%, were prepared using various Mo‐, W‐, Re‐, Os‐, Ru‐, and Ir‐based olefin metathesis catalysts. The13C NMR spectra of these polymers are interpreted in terms of TH, TT, HH, HT structures (T = tail, H = head, referring to the orientation of the methyl groups), also tt, tc, ct, cc structures (t = trans, c = cis double bonds), and m, r dyads (m = meso, r = racemic, referring to the relative configuration of adjacent cyclopentane rings in the chains). m/r splitting is observed for both the olefinic carbon (C3) and the adjacent ring carbon (C4) in the HH structures of the all‐trans polymer made from racemic monomer using RuCl3as catalyst. All‐cis polymers are fully syndiotactic while all‐trans polymers have 58% isotactic (m) and 42% syndiotactic (r) dyads. A consistent set of substitution parameters is derived, the effect of two methyl substituents on the13C chemical shifts being generally a little less than the sum of the effects o

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830705

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe stereoregularity of poly(α‐methylstyrene)s prepared by anionic initiators was determined from the peak area of α‐methyl proton absorptions and aromatic C1carbon absorptions. Highly syndiotactic polymers were obtained at 0°C in both toluene and tetrahydrofuran (THF). Sodium, potassium, and cesium naphthalenes gave polymers with the same syndiotacticity in THF. The syndiotacticity of polymers prepared by sodium and potassium naphthalenes as catalyst in both toluene and THF decreased at low temperatures. This behavior is similar to that ofo‐methylstyrene andm‐methylstyrene in THF. The stereoregulation mechanism in the anionic polymerization of α‐methylstyrene is discussed and compared with that of polystyrene and ring substituted

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830706

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe polymerization of maleic anhydride initiated by triphenylphosphine was investigated in acetic anhydride as well as in dimethylformamide. It was found that the polymer conversion increases with the increase of the concentration of monomer and initiator and the reaction temperature. It was also found that the rate of polymerization is higher in dimethylformamide than in acetic anhydride under the same set of experimental conditions. The apparent overall activation energy was found to be about 26,4kJ · mol‐1and 39,8 kJ · mol‐1in acetic anhydride and dimethylformamide, respectively. The polymerization rate depends upon the basicity of the initiator as well as on the dielectric constant of the so

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830707

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractCasein‐g‐poly(vinyl acetate) was synthesized using potassium persulfate as initiator. Changes in monomer concentration, initiator concentration, backbone concentration, and temperature were effected. The rate of total conversion of monomer, the rate of homopolymerization and graft copolymerization, the grafting efficiency and the percentage of grafting were calculated. The grafting results were discussed in the light of grafting efficiency and percentage of grafting. They were found to be lower in the case of casein‐g‐poly(vinyl acetate) when compared to those of casein‐g‐poly(buty

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830708

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractPartially acetalisized poly(vinyl alcohol)s with degrees of acetalization between 39 and 60% were prepared by reaction of poly(vinyl alcohol) with 9‐isobutyl‐3‐carbazolealdehyde(5a)or 3‐formyl‐9‐((S)‐2‐methylbutyl)carbazole(5b). Complex formation constants and ε‐values of the charge‐transfer complexes with ethylenetetracarbonitrile, 2,5‐cyclohexadien‐1, 4‐diylidenedimalonodinitrile, 2,4,5,7‐tetranitro‐9‐fluorenone, and 2,4,7‐trinitro‐9‐fluorenone were determined. Circular dicroism measurements of the optically active CT‐comple

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830709

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractA polyazoinitiator obtained from 2,2′‐azoisobutyronitrile (AIBN) and a diol is used to prepare block copolymers according to the Smets procedure. Partial decomposition of the polyazoinitiator in presence of a monomer results in an azogroup‐containing prepolymer. Block copolymers are obtained decomposing the remaining azo groups in presence of a second monomer. Examples investigated are styrene/methyl acrylate, styrene/N‐methyl‐N‐vinylacetamide, methyl acrylate/N‐methyl‐N‐vinylacetamide, 1‐vinyl‐2‐pyrrolidone/acrylonitrile. Homopolymers are produced simultaneously. Up to 70% of block copolymers are formed in these reactions. Block copolymers of styrene/methyl acrylate have hard/soft segmented molecules. It is an elastic material with spherical, cylindrical and lamellar, resp. domain structures, depen

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830710

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY