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1.
The high molecular weight polymer of α-piperidone, which had been unobtainable with the use of alkali metal, trialkyl aluminum, or Grignard reagent as catalyst, was prepared with M–AlEt3, (where M is alkali metal), MAlEt4 or KAlEt3 (piperidone) as catalyst and N-acyl-α-piperidone as initiator. From the determination of the behavior of the solution viscosity of poly-α-piperidone in m-cresol at 30°C. the value of 0.27 for the Huggins constant was obtained. Examination of the correlation between the number-average molecular weight, determined by endgroup titration, and the intrinsic viscosity gave a somewhat small value for the endgroup COOH. This may be considered due to the consumption of N-acyl-α-piperidone by a propagating polymer in the course of polymerization. The thermal stabilities of the polyamides, nylons 4, 5, and 6, was in the order nylons 6 > 5 > 4 according to differential thermal and thermogravimetric analyses, Poly-α-piperidone, which has a reduced viscosity of 0.7, shows a melting point of 270°C.. which was expected from the zigzag pattern of the correlation between melting points and numbers of CH2 groups for polyamino-acid polymers.  相似文献   

2.
Polymerization of five-, six-, and seven-membered lactams by metallic potassium or MAlEt4 (where M is Li, Na, or K) as a catalyst and N-acyl lactam or diphenylketene as an initiator was carried out at temperatures below 80°C. By using MAlEt4 instead of a metallic potassium catalyst in the polymerization of α-piperidone the propagation was continued until the reduced viscosity of polymer reached a value of 0.9. The polymer obtained has a film-forming ability. The experimental results obtained in the gasometry suggest that MAlEt4 reacts with lactam to form such a complex of the type (where M is Li, Na, or K and X is an ethyl or 2-oxo-alkylene-imine group). The resulting complexes are considered to increase the solubility of catalyst and also to protect the polymer endgroups from side reactions by stabilizing the alkali metal as the complex. In addition, the mode of action of diphenylketene as an initiator was revealed by the facts that the corresponding N-diphenylacetyl lactam was obtained from the reaction of diphenyl ketene with lactam and N-diphenylacetyl lactam itself was useful for the polymerization of α-piperidone.  相似文献   

3.
Low-temperature polymerization of α-pyrrolidone, α-piperidone, and ?-caprolactam was examined by using the salts derived from NaAlEt4 and monomer, sodium lactamates, or the salt derived from AlEt3 and monomer as catalyst and with N-acetyl lactams, ethyl acetate, or lactones as initiator. Sodium lactamate catalyst gave unsatisfactory results in the cases of ethyl acetate or lactones initiators, and gave the following order for the relative efficiency of initiators: N-acetyl lactam > ?-caprolactone ≥ ethyl acetate > β-propiolactone. The polymerization results obtained by the salt from NaAlEt4 catalyst–ethyl acetate initiator system were nearly the same as those with N-acetyl lactam. The increases in the degree of polymerization and in the yield of polymer were observed in case of the salt from NaAlEt4 catalyst-lactone initiator system, particularly in the cases of α-piperidone and ?-caprolactam. Also an incorporation of initiator into polymer chain was observed.  相似文献   

4.
High-temperature polymerization of ?-caprolactam by using the salts derived from MAlEt4 (where M is Li, Na, and K) and monomer as catalyst was carried out. Polymerization occurs at 140–170°C, a temperature at which alkali metal caprolactamate has almost no catalytic activity for initiation. m-Cresol-insoluble polymer was obtained at temperatures lower than 231°C. Formation of a m-cresol-insoluble polymer depends on the polymerization temperature and time, and was observed under conditions where Al(Lac)3 has no catalytic activity. All the polymers obtained by NaAl(Lac)4–n(NHBu)n (n = 1 or 2) at 202°C were soluble in m-cresol. These trends observed in the case of MAl(Lac)4 are considered to be due to initiation by Al(Lac)3, which is a component of the catalyst used.  相似文献   

5.
The catalytic behavior of binary systems derived from AIR3 and alkali metal hydroxide in a molar ratio of 1 to 0.5 in situ for stereospecific polymerization of acetaldehyde was studied for the purpose of preparation of isotactic polyacetal. The polymer obtained can be readily stretched to a film. The polymerization proceeds slowly (in ~20 hr). The polymer yield and stereospecificity of the polymerization by AlEt3–LiOH (1:0.5) catalyst were not significantly changed by the nature of solvent or dilution as far as studied. AlEt3–NaOH, AlEt3–KOH, AlEt3–CsOH, AliBu3–LiOH and AlMe3–LiOH in molar ratios of 1 to 0.5 behaved similarly. AlMe3–NaOH, AlMe3–KOH and AliBu3–NaOH also gave isotactic polymer of high stereoregularity but in lower yields.  相似文献   

6.
The examination of the reaction between [MgCl2(THF)2], TiCl4(3), AlCl3, AlEt3, AlEt2Cl and the synthesis and isolation of compounds as crystals and resolution of their structure by the X-ray method were the subject of our study. It was expected that these investigations would help to understand the behaviour of MgCl2 towards the transition metal and furnish useful relationships to the structure of catalyst active center and to the polymerization mechanism in TiCl4(3)/MgCl2/AlEt3 system. Our studies have revealed that the main difference between the first and higher generations of Ziegler-Natta catalysts is only the number of active centers.  相似文献   

7.
The NaAl(Lac)4-catalyzed polymerization of ε-caprolactam at the medium temperature range (70–150°C) was investigated. The initiation temperature was observed to decrease to about 100°C in the case of a high concentration (such as 2.0 mole-%) of catalyst. Moreover, in the prolonged polymerization of lactams with KAl(Lac)2Et2 catalyst, in the absence of initiator, the low activity of aluminum lactamate as initiator was observed. In connection with the polymerization of lactams with MAl(Lac)nEt4–n catalyst, the reactivity of MAlEt4 (where M is Na or K) with N-acetyllactams was investigated. The results imply that no consumption of N-acyllactams by the reaction with MAl(Lac)nEt4–n occurs in the course of the low-temperature polymerization of lactams.  相似文献   

8.
The Michael addition of acrylonitrile to the pyrrolidine enamine of 1-(S--phenyl-ethyl)-4-piperidone proceeds with the formation of. a 1:1 mixture of l-(S--phenyl ethyl)-3-(2-cyanoethyl)-4-piperidone diastereomers. A diastereomer isolated in pure form was shown by x-ray diffraction structural analysis to have S-configuration of the new chiral center at C(3) of the piperidone ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp, 1656–1662, December, 1985.  相似文献   

9.
Kinetic studies were carried out on the polymerization of tetrahydrofuran with catalyst systems of aluminum alkyl–epichlorohydrin. As aluminium alkyl species AlEt3, AlEt3–H2O (1:0.1 to 1:1.0), and “oxyaluminum ethyl” were employed. The polymerizations with these catalysts are characterized by a mechanism of stepwise addition without chain transfer or termination, which is expressed by the kinetic relation Rp = Kp[P*] ([M]–[M]e), where [M] and [M]e are the instantaneous and equilibrium concentrations of monomer and [P*] is the concentration of propagating species calculated from the amount and molecular weight of the product polymer. The determination of the rate constant kp for these catalysts has shown that the polymerization rate varied considerably with the change of aluminum alkyl species, i.e., with the water-to-aluminum ratio, but the propagation rate constant itself varied very little. The variation of polymerization rate was, therefore, attributed primarily to the differences in concentration of the propagating species, i.e. the efficiency of the catalyst in forming propagating species. The catalyst efficiency was closely related to the acid strength of the aluminum alkyl species, which was estimated from the magnitude of shift of the xanthone carbonyl band in the infrared spectrum of its coordination complex with aluminum alkyl. The maximal catalyst efficiency was attained at about [H2O]/[AlEt3] = 0.75.  相似文献   

10.
The anionic polymerization of lactams at low temperatures is not governed by thermodynamic equilibrium between the cyclic monomer and the linear polymer. On the basis of our reaction mechanism we propose therefore a new criterion (in contrast to the thermodynamic one) for estimating the chemical polymerizability of lactam: kendo/klactam, where klactam is the rate constant of alkaline hydrolysis of the lactam and kendo that of the endocyclic imide bond in the corresponding N-acyl lactam. The value thus found for α-piperidone and giving the theoretical polymerizability of this lactam accounts, however, only partially for its low polymerizability. Finally, the behavior of α-piperidone derivatives in α-pyrrolidone polymerization, as well as that of α-pyrrolidone and α-piperidone in polymerization in the presence of inorganic salts such as LiCl and LiSCN, shows that the unusually low ability of this lactam to polymerize could be explained in terms of the hydrogen-bond-rich structure of the resulting polymer appearing at a lower stage of conversion than that of other lactams and which might encage the active site situated at the end of the growing chain and thus hinder the access of lactam anion.  相似文献   

11.
Copolymerization of ethylene with mixtures of linear α-olefins C6–C36 in the presence of two heterogeneous Ziegler–Natta catalysts, δ-TiCl3–AlEt3 and TiCl4/MgCl2–AlEt3, at 90°C was studied by the GC method, and reactivity ratios for all paris ethylene–α-olefin were estimated from the data on olefin consumption in the reactions. In the case of the δ-TiCl3–AlEt3 system, the r2 value decreases from ca. 0.05 for 1-decene to ca. 0.02 for α-C22H44 and then remains approximately constant. This change is similar to the dependence of the modified steric parameter ESC of the olefin alkyl group on the size of the alkyl group. In the case of the supported TiCl4/MgCl2–AlEt3 system a similar variation of r2 with the length of the alkyl group were observed but the absolute values of r2 were six to ten times lower than those for the first catalytic system.  相似文献   

12.
T. Fujii  S. Yoshifuji 《Tetrahedron》1970,26(24):5953-5958
In order to explain the difficulty in hydrolysing the lactam linkage of 1-benzyl-2-oxo-5-ethyl-4-piperidineacetic acid (XIV) under acid conditions, several model compounds such as 1-benzyl-2-piperidone (X), 1-benzyl-5-ethyl-2-piperidone (XI), 1-benzyl-4-ethyl-2-piperidone (XII) and 1-benzyl-2-oxo-4-piperidineacetic add (XIII) were prepared and their hydrolysis in boiling 6N HCl was studied. For each of the lactams, the hydrolysis was found to proceed to an equilibrium as shown in Table 1. Substituents at the 4- and 5-positions of the piperidone ring seemed to favour the ring form in the equilibrium between piperidones (X-XIV) and ω-amino acid hydrochlorides (type XV).  相似文献   

13.
The effects of hydrogen in ethylene polymerization and oligomerization with different bis(imino)pyridyl iron(II) complexes immobilized on supports of type MgCl2/AlEtn(OEt)3–n have been investigated. Hydrogen has a significant activating effect on polymerization catalysts containing relatively bulky bis(imino)pyridyl ligands, but this is not the case in ethylene oligomerization with a catalyst containing relatively little steric bulk in the ligand. It was found that the presence of hydrogen in the latter system led to decreased activity and an overall increase rather than a decrease in product molecular weight, indicating deactivation of active species producing low molecular weight polymer and oligomer. Decreased formation of vinyl‐terminated oligomers in the presence of hydrogen can therefore contribute to the activating effect of hydrogen in ethylene polymerization with immobilized iron catalysts, if it is assumed that hydrogen activation is related to chain transfer after a 2,1‐insertion of a vinyl‐terminated oligomer into the growing polymer chain. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4054–4061, 2007  相似文献   

14.
The polymerization of styrene with VOCl3 in combination with AlEt3 and with Al(i-Bu)3 in n-hexane at 40°C. has been investigated. The rate of polymerization was found to be second order with respect to monomer in both systems. With respect to catalyst the rate of polymerization was first order for VOCl3–AlEt3 and second order for VOCl3-Al(i-Bu)3 systems. The activation energies for VOCl3–AlEt3 and VOCl3–Al(i-Bu)3 systems were 7.37 and 11.25 kcal./mole, respectively. The molecular weight of polystyrene in the AlEt3 system was considerably higher than that in the Al(i-Bu)3 system. The valence of vanadium obtained by a potentiometric method showed that the catalyst sites in the AlEt3 system are different in nature from those in the Al(i-Bu)3 system. The effect of diethylzinc as a chain-transfer agent in the AlEt3 system was also studied.  相似文献   

15.
The polymerization of vinyl chloride was carried out by using a catalyst system consisting of Ti(O-n-Bu)4, AlEt3, and epichlorohydrin. The polymerization rate and the reduced viscosity of polymer were influenced by the polymerization temperature, AlEt3/Ti(O-n-Bu)4 molar ratios, and epichlorohydrin/Ti(O-n-Bu)4 molar ratios. The reduced viscosity of polymer obtained in the virtual absence of n-heptane as solvent was two to three times as high as that of polymer obtained in the presence of n-heptane. The crystallinity of poly(vinyl chloride) thus obtained was similar to that of poly(vinyl chloride) produced by a radical catalyst. It was concluded that the polymerization of vinyl chloride by the present catalyst system obeys a radical mechanism rather than a coordinated anionic mechanism.  相似文献   

16.
It was found that structurally isomeric polymers were formed by the ring-opening polymerization of β-(2-acetoxy ethyl)-β-propiolactone with (EtAlO)n and Et(ZnO)2ZnEt catalysts; that is, the Al catalyst catalyzed normal polymerization which led to poly-β-ester and the Zn catalyst formed isomerized poly-β-ester as the main product. The polymer structure was determined by nuclear magnetic resonance (NMR), T1-value, thermal decomposition product, and (Tg). The NMR studies for the monomer–catalyst systems indicated that the Al catalyst interacted predominately with the lactone group, whereas the Zn catalyst interacted with the side-chain ester group. These site-selective interactions could be related to the difference in the stereoregulation by the two catalysts during the poly(β-ester)-forming polymerization process.  相似文献   

17.
Some new TiCl4/Crown ether complexes were synthesized and used as polymerization catalysts with AlEt3 or AlEt2Cl as cocatalyst for the stereospecific polymerization of 1,3-butadiene. As with most of the nucleophilic ligands the addition of crown ethers to Ziegler–Natta catalytic systems results in a decrease of the polymer conversion. But the Al/Ti molar ratio appears to be less critical for the complexed systems than for the uncomplexed ones. The presence of the crown ether in the surroundings of the catalytic sites presumably protects them from an excess of the organoaluminum cocatalyst. The side groups of the crown ether do not influence the microstructure of the polybutadiene obtained but they change the activity of the catalytic systems. Thus, the electron-donating effect of the macrocyclic ligands seems to be less important than the sterical effect due to the rigidity and to the hole size of the crown ether.  相似文献   

18.
Epoxides, propylene oxide in particular, were polymerized by a catalyst system consisting of AlEt3–metal soap, to high molecular weight polyethers in high conversion. Carboxylic acid salts of Ti, V, Cr, Zr, Mo, Co, and Ni, transition metals of groups IV–VIII in the Periodic Table, were most preferable. Metal salts of stearic, octanoic, lauric and naphthenic acid were examined as catalyst components and proved to be very active for the polymerization of epoxides when used with an organoaluminum compound such as AlEt3 or AlEt2Cl. Copolymerization of propylene oxide and allyl glycidyl ether was successfully carried out with an AlEt3–Zr octoate catalyst.  相似文献   

19.
The polymerization of isobutyl vinyl ether by the VCln–AIR3 system was carefully studied. The vanadium components were prepared by the reaction between VCl4 and AlEt3 or n-BuLi as a reducing agent. VCl3·LiCl and VCl2·2LiCl are the effective catalysts for the stereospecific polymerization of isobutyl vinyl ether. When VCl3·LiCl is combined with AlR3, a new catalytic system is formed. The effect of the preparative conditions of the various vanadium component in the AlR3–VCln system shows that the effective vanadium component is trivalent. In the polymerization by VCl3·LiCl–Al (i-Bu)3 system, a change of the polymerization mechanism may occur at Al(i-Bu)3/VCl3·LiCl ratio at around 5. When the ratio is lower than 5, a cationic polymerization by VCl3·LiCl takes place predominantly, while at ratios higher than 5, it is suggested that the polymerization proceeds by means of a VCl3·LiClA–Al(i-Bu)3 complex by a coordinated anionic mechanism. The polymers obtained by these catalysts are highly crystalline. Styrene was also polymerized by using the same catalysts. VCl3·LiCl and VCl3·LiCl–THF complex yielded amorphous polymer by cationic polymerization. When VCl3·LiCl was combined with 6 mole-eq of Al(i-Bu)3, the resulting polystyrene was highly crystalline and had an isotactic structure, while the VCl2·2LiCl–Al(i-Bu)3 (1:6) system yielded traces of polymer of extremely low stereoregularity. The results indicate that the effective vanadium component at Al/V ≧ 6 is trivalent and that the mechanism is a coordinated anionic one.  相似文献   

20.
The relationship between stereoregularity and polymerization conditions of α-methylstyrene has been studied by means of NMR spectra. The effects of solvents and various Freidel-Crafts catalysts have been investigated. The stereoregularity of poly-α-methylstyrene increased with increased polymer solubility in the solvent used and with decreasing polymerization temperature. This behavior is completely different from the stereospecific polymerization of vinyl ethers and methyl methacrylate in homogeneous systems. This may be due to the strong steric repulsion exerted by the two substituents in the α-position of α-methylstyrene. For example, with BF3 · O(C2H5)2 as catalyst at ?78°C., atactic polymer is obtained in n-hexane, a nonsolvent for α-methylstyrene, whereas highly stereoregular polymer is produced in toluene or methylene chloride, good solvents for the polymer. However, the polarity of the solvent and the nature of the catalyst hardly affect the stereoregularity of the polymer.  相似文献   

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