This paper focuses on two recent topics in living cationic polymerization of vinyl monomers, i.e., (a) Development of new initiating systems: RCOOH/Lewis acid for vinyl ethers; CH3CH(C6H5)Cl/SnCl4/nBu4NCl for styrene. (b) Synthesis of shape-controlled poly(vinyl ethers): Tri-armed star polymers; Multi-armed spherical polymers. For the RCOOH-based systems, a generalized concept of living cationic polymerization was discussed on the basis of the effects of the counteranions (or R) and Lewis acids (ZnCl2 and EtAlCl2). The CH3CH(C6H5)Cl-based system permitted a truly living cationic polymerization of styrene. The tri- and multi-armed poly(vinyl ethers) included new amphiphilic polymers of unique topology, solubility, etc., all of which were prepared by living cationic polymerization. 相似文献
{η5 -C5H4[CH(CH3)OC(O)CH = CH2])Mn(CO)3, {η5—C5[CH-(CH3)OC(O)C(CH3)=CH2]]Mn(CO)3, and {η5—C5H4[CH(CH3)-OC(O)CH=C(CH3)2])Mn(CO)3 were synthesized (63, 57, and 51%, respectively) from {η5—C5H4[CH(CH3)OH])Mn(CO)3, toluene-sulfonic acid, and the acrylic, methacrylic, and dimethylacrylic acids, and from (η5-C5H4[CH(CH3)OH]}Mn(CO)3, pyridine, and the acrylic, methacrylic, and dimethylacrylic acyl chlorides [26, 48, and 25% (impure), respectively]. No product was obtained when NaH was used as the base in the latter method. The acrylate and methacrylate monomers were bulk homopolymerized at 65°C with AIBN (75% yield, Mn = 88,550 g/mol; 78% yield, Mn = 349,350 g/mol, respectively). The dimethylacrylate did not polymerize under these conditions. The polymers lost vinylcymantrene upon heating to 257 and 279°C, respectively. The polymers did not exhibit a clear Tg but were observed to soften at 85 and 160°C, respectively, and they could be pulled into fibers. 相似文献
Four new mixed‐ring zirconium completes, [CH2 = CH(CH2)n ‐C5H4](RC5H4)ZrCl2 [n = l, R = CH3OCH2CH2(3); n = 2, R = CH3OCH2CH2 (4); n = 2, R=Me3Si (5); n = 2, R = allyl (6)], have been prepared by the reaction of CH2 = CH(CH2)n C5H4ZrCl3, DME[n = l (1); n = 2 (2)] with RC5H4Li. When activated with methylaluminoxane (MAO), the catalytic activities of the above complexes in ethylene polymerization were tested. Complexes 5 and 6 show high activities similar to Cp2ZrCl2. Introduction of methoxyethyl group into Cp‐ligand dramatically decreases the catalytic activities of complexes 3 and 4, which can be overcome by increasing the amount of MAO. For complex 5, the dependence of activity and molecular weight (Mη) on the Al/Zr ratio, the polymerization time (tP), polymerization temperature (TP) and the polymerization solvent volume (V) was investigated. 相似文献
A general procedure, giving high yields for the synthesis of (Ph3P)2Pt(CCR)2 complexes (R = C6H5, C(CH2)CH3, (CH2)6CCH, CH2OH, CH(OH)CH3, CH(OH)C6H5, CH2CH(OH)CH3, C(OH)(CH3)CH3, C6H10OH, C(OH)(CH3)CH2CH3, CH2NHCH3, CH2NHCH2C6H5, CH2N(CH3)2, CH2N(C2H5)2) is reported. On the basis of the low frequency IR spectra a trans structure is proposed for all complexes. UV spectra are also reported. 相似文献
Five-membered cyclic esters of phosphoric acid of the general formula: ? CH2CH(R)OP(O)-(OR′)O? polymerize readily to solid, soluble polymers of high molecular weight without any rearrangement known for various tri- and pentavalent organophosphorus monomers. 1H-, 13C-, and 31P-NMR spectra of polymers confirmed their linear structure: where R is H, with R′ = CH3, C2H5, n-C3H7, i-C3H7; n-C4H9, CCl3CH2, or C6H5, or R is CH2Cl and R′ is C2H5. The use of n-C4H9Li, (C5H5)2Mg, or (i-C4H9)3Al as initiators leads to polymers with Mn = 104–105. 相似文献
Synthetic routes for the preparation of 3-alkyl-6-phenyl-4(3H)-pteridinones 6 and their corresponding 8-oxides 5 (R = CH3, C2H5, (CH2)2CH3, (CH2)3CH3, CH(CH3)C2H5, CH(CH3)2 and CH(C2H5)CH2OCH(OC2H5)2 are described and their reactivities towards xanthine oxidase from Arthrobacter M-4 are determined. Only the 3-methyl derivative of 6-phenyl-4(3H)-pteridinone and its 8-oxide i. e. 6a and 5a are found to be substrates although their reactivities are still very low. Oxidation takes place at C-2 of the pteridinone nucleus. All the 3-alkyl derivatives are less tightly bound to the enzyme than 6-phenyl-4(3H)-pteridinone. Introduction of the N-oxide at N-8 considerably lowers the binding of the substrates. Inhibition studies have revealed that 3-methyl-6-phenyl-4(3H)-pteridinone ( 6a ) is a non-competitive inhibitor with a Ki-value of 47 μM and the 3-ethyl derivative ( 6b ) an uncompetitive one with a Ki-value of 19.6 μM. 相似文献
Cyclopentadienyl cobalt complexes (η5‐C5H4R) CoLI2 [L = CO,R=‐COOCH2CH=CH2 (3); L=PPh3, R=‐COOCH2‐CH=CH2 (6); L=P(p‐C6H4O3)3, R = ‐COOC(CH3) = CH2 (7), ‐COOCH2C6H5 (8), ‐COOCH2CH = CH2 (9)] were prepared and characterized by elemental analyses, 1H NMR, ER and UV‐vis spectra. The reaction of complexes (η5‐C5H4R)CoLI2 [L= CO, R= ‐COOC(CH3) = CH2 (1), ‐COOCH2C6H5(2); L=PPh3, R=‐COOC (CH3) = CH2 (4), ‐COOCH2C6H5 (5)] with Na‐Hg resulted in the formation of their corresponding substituted cobaltocene (η5‐C5H4R)2 Co[R=‐COOC(CH3) = CH2 (10), ‐COOCH2C6H5 (11)]. The electrochemical properties of these complexes 1–11 were studied by cyclic voltammetry. It was found that as the ligand (L) of the cobalt (III) complexes changing from CO to PPh3 and P(p‐tolyl)3, their oxidation potentials increased gradually. The cyclic voltammetry of α,α′‐substituted cobaltocene showed reversible oxidation of one electron process. 相似文献
2,4-Bismethylthio-1,3,2,4-dithiadiphosphetane 2,4- disulfide, IIa, is prepared from 0,0-dimethyldithiophosphoric acid, Ia, and P4S10 at 160°C. 2,4-Bis(4-phenoxyphenyl)-1,3,2,4- dithiadiphsophetane 2,4-disulfide, IIc, and 2,4-bis(4-phenylthiolophenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, IId, are prepared at l60°C from P4 S10 and diphenylether and diphenylsulfides, respectively. Carboxylic acids RCOOH(R = CH3 C2H5, n-C3H7, n-C4H9, C6H5CH2, C6H8) react with compound Ia at 130°C to give the corresponding methyl dithioesters. Carboxylic acids RCOOH (R = C6H8-CH2, C6H8) react with compound Ib at 200°C for 15 min to give the corresponding ethyl dithioesters, while low boiling acids (R = CH3, C2H8, n-C3H7) yielded mixtures of the corresponding ethyl dithioester and ethyl carboxylate. Carboxylic acid chlorides RCOCl (R = ClCH2, C2H5, t-C4H5 C6H5CH2, C6H5, P-NO2C6H4) react with compound IIa at 80°C to give the corresponding methyl dithioesters in good yields. S-Substituted thioesters react with IIC at 85°C to give the corresponding dithioesters in good yields. Dihydro2(3H)-furanone, VI, and 5-methyl-2(3H)-furanone, VII, react with IIa at 80°C; to dihydro-2(3H)-thiophenethione, VIII and 2,2'-dithiobis(5-methyl thiophene),IX, respectively. Also XI reacts with IIa,IIc, and IId to give VIII in nearly quantitative yields. 相似文献