摘要:

AbstractEsters of diacids and oligo(carboxylic acid)s substituted in α‐position with Li, Na, or K (models of the propagation site in the anionic polymerization of methyl methacrylate (MMA)) were prepared, and their IR spectra were recorded. In the range 1600 – 1800 cm−1, their absorption of the Mt+group in benzene solution was reflected in a band between 1630 and 1645 cm−1, depending on the counterion. In the presence of THF or oftert‐butoxide of the same alkali metal this band appears between 1626 and 1660 cm−1. Coordination of the more remote alkoxycarbonyl group (e.g., in γ‐position) to the counterion is demonstrated by a band near 1712 cm−1; its absorbance is much lower in the presence of THF. In solution, the metalloesters undergo autocondensation, the rate of which increases dramatically with the number of monomeric units. Thus, in benzene at 25 °C ethyl 2‐lithioisobutyrate is stable for more than a week, whereas the half life of dimethyl 2‐lithio‐2,4,4‐trimethylglutarate (Li‐dimer,3b) is<24 h, and the Li‐trimer (5a), Li‐tetramer (5b), and Li‐pentamer (5c) completely decompose in less than 4 min under these conditions. The decomposition may be slowed down by addingtert‐butoxide of the same alkali metal. In THF the decomposition proceeds much more quickly. The properties of models used in this study are compared with those of the propagation site

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830601

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe capability of chloroalkenes to undergo cometathesis with alkenes was investigated with the intention to check the possibility of applying the principle of the synthesis of α,omega;‐difunctional polybutadienes to α,omega;‐dichloropolybutadienes. The results obtained from the analysis of the reaction products resulting from 1,6‐dichloro‐3‐hexene (1)/4‐octene (2) systems and WCl6/EtAlCl2were compared with those obtained from 1‐chloro‐3‐hexene (8) alone,1/1,5‐cyclooctadiène (13), 5‐chloro‐1‐pentene (6)/2, and 1,4‐dichloro‐2‐butene (10)/2systems in the presence of WCl6/EtAlCl2. It was found that it is possible to apply the synthetic principle to α,omega;

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830602

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractPotassium carboxylates and 18‐crown‐6 form initiator systems for the anionic polymerization of oxiranes to afford polyethers with an acyloxy group at one of the chain ends. Because of the slow initiation as compared to the propagation step, the resulting polymers have wide molecular weight distributions (Mw/Mn≈ 4,0). The presence of a small amount of water in the catalysts accelerates the initiation to give polymers with narrow molecular weight distributions (Mw/Mn⩽ 1,2). The polymerization of methyloxirane is accompanied by a significant chain‐transfer reaction to the monomer, especially at high temperatures. Hexamethylcyclotrisiloxane is also polymerized by the same initiators. Furthermore, potassium salts of carboxylic acids initiate the polymerizations in the presence of a cr

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830603

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractA copolymer having reactive primary amino groups was synthesized by the copolymerization of styrene andN‐methyl‐N‐(4‐vinylphenethyl)ethylenediamine (1). Polymerization ofN‐carboxy amino acid anhydrides (NCA's) ofL‐alanine, γ‐benzyl‐L‐glutamate, or β‐benzyl‐L‐aspartate was initiated by the primary amino groups of this copolymer to give a novel polyvinyl‐pol

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830604

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractAmong numerous polymers with cyclic polyethers and non‐cyclic ethers as anchor groups, the condensation resin with dibenzo‐18‐crown‐6 as anchor group (℗‐DB‐18‐C‐6), which can be easily prepared, exhibits the best properties for phase‐transfer catalysis. It catalyses substitution, dichlorocarbene and polymerisation reactions which do not take place at all or only in a low yield without the catalyst. For substitution reaction the highest yields are up to 95% in the liquid phase and up to 70% in the gaseous phase. For chlorocarbene reactions yields up to 76% are reached. For the polymerisation of 2‐pyrrolidone, started by potassium 2‐pyrrolidona

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830605

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractN‐Ethylaziridine (1) was polymerized in water with HCl as initiator and copolymerized withN‐(2‐hydroxyethyl)aziridine (2). Rapid propagation and termination reactions were observed. The maximum yield increases with the initiator concentration, whereas the molecular weight decreases. This is due to the difference in basicity between the tertiaryN‐atoms of the two monomers and the tertiary and the terminal secondaryN‐atoms of the polymers, which causes tranfer and termination reactions. Macrocycles with a side chain on a quaternaryN‐atom are formed. During the copolymerization, the more basic1is preferentially incorporated into the copolymer chain. The copolymerization parameters can be estimated roughly on the basis of basicity considerations: r1>1; r2<1. The ratio of the rate constants (propagation to termination) is lower for1than for2. This is due to the fact that the basicity difference between the monomer and the tertiaryN‐atoms of the polymer is higher for1than for2. By reaction of thionyl chloride with the copolymers the desired hydrochlorides of theN‐(2‐chloroethyl) derivatives are obtained. The neutralisation with alkali did not result the free bases, since the products formed are rather due

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830606

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe polyamides3–5were synthesized from α,ω‐diamino‐substituted oligo(oxyethylene)s (1) and bis‐chlorides of dicarboxylic acids (2). As copolymers with defined sequences they contain up to five oxyethylene units per repeating unit. Hereby properties like solubility, thermal stability and complexing ability towards alkali metal cations are i

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830607

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

Abstractp‐Cresol and eight oligo[(hydroxyphenylene)methylene] compounds1b–eand4a–dcould be esterified with good yields with acryloyl chloride or propionyl chloride, respectively, in the presence of triethylamine. The simple and multiple acrylates and propionates were characterized by determination of their molar masses, elemental analyses, hydrogenation of the CC double bonds in the acrylate groups, and by their IR‐ and UV‐spectra. No steric hindrance could be ascertained. Acrylates with more than three phenolic units in their molecules were found to have a range of melting, whereas all the propionates possess sharp melting points. This can be explained by polymerization of the acrylates which proceeds at room temperature without changing the appearance of the sample. The decadic molar absorption coefficients from the UV‐spectra of the different homologous series were found to be proportional to the number of the phenolic units in thei

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830608

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractAs a model reaction for the homogeneous cationic polymerization of vinyl ethers,cis‐ethyl vinyl ether‐β‐d(1a) was reacted with 1,1‐diethoxyethane in presence of BF3O(C2H5)2as a catalyst. The steric structures of the adducts, mainly 1,1,3‐triethoxybutane‐2‐d(3a) and 1,1,3,5‐tetraethoxyhexane‐2, 4‐d2(4a, equivalent to the dimer) were determined by means of1H NMR spectroscopy, taking into account the conformational characteristics based on energy calculation. The predominant stereoisomer of3awas proved to be theerythro‐form. The assignments of the methylene proton resonances toerythro‐ andthreo‐configurations were applied to the analysis of the spectra of4awhich enabled us to elucidate the molecular aspects of the opening of the double bond and the mode of approach of the monomer to the cationic reactive site. It was also concluded that the stereospecific reaction might be attributed to the repulsive forces between the ethoxy group of vinyl ether and that of the carbonium i

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830609

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractStyrene homologues (styrene, α‐methylstyrene, and β‐methylstyrene) were copolymerized with oxygen to produce optically active copolymers in the presence of a chiral Co(II) (Schiffbase) complex. The absolute configuration of the carbon atom in the copolymer chain was determined by hydrogenolysis of the copolymer to phenylethanediol derivatives. In the cases of styrene and α‐methylstyrene, (R)‐(+)‐1‐phenylethanediol and (R)‐(+)‐2‐phenyl‐1,2‐propanediol were preferentially formed, respectively. In the reaction of β‐methylstyrene, the preferential formation of (1S, 2R)‐(−)‐ and/or (1R, 2R)‐(−)‐1‐phenyl‐1,2‐propanediol was observed. The chiral Co(II) (Schiff‐base) complex seems to stabil

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830610

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY