Cationic polymerization of hydrocarbon monomers induced by complexes of acyl halides with Lewis acids

Murachev, V. B.; Orlinkov, A. V.; Nesmelov, A. I.; Ezhova, E. A.; Byrikhin, V. S.; Akhrem, I. S.

doi:10.1007/bf02496205

Cited by 2 publications

(8 citation statements)

References 7 publications

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“…25 We think that this gives rise to structures depressing additionally the formation of protic superacids such as H + Al 2 Br 7 − , which in principle are active in proton initiation. A confirmation of this proposal is the absence of proton initiation by the addition of an excess (toward carbonyl groups of the polymer) of mixtures HBr with AlBr 3 into the CH 3 COBr·2AlBr 3 /IB/hexane system, whereas in the absence of the acyl complex, the combination of HBr with AlBr 3 promoted rather fast IB polymerization 21. At this temperature (−78 °C), direct chain transfer to the monomer was not found 7.…”

Section: Resultsmentioning

confidence: 77%

“…Some of these data have been published earlier 7–9. 14, 19, 20 Other representative results are shown in Table 3. Indeed, pivaloyl chloride and benzoyl chloride 1:1 adducts show no initiating activity in either solvent.…”

Section: Resultsmentioning

confidence: 79%

“…Some inconsistencies can be explained by factors other than those revealed by NMR spectra analysis. Thus, for example, we explain the decrease in protogenic activity of the acyl bromide CH 3 COBr·2AlBr 3 adduct in hexane by trapping of the protons by the head acetoxy groups of the polymer molecules,21 while the absence of initiating activity for the equimolar mesitoyl complex steins, in our opinion, from the very high nucleophilicity of the AlBr 4 − counterion 20…”

Section: Resultsmentioning

confidence: 87%

“…At this temperature (−78 °C), direct chain transfer to the monomer was not found 7. 9, 14 In contrast, when proton initiation occurs by means of CH 3 COBr·AlBr 3 complex, polymeric chains do not contain the electron donor carbonyl groups, and the polymerization exhibits features of a ‘traditional’ process, ie increasing N and decreasing M n with IB consumption 19…”

Section: Resultsmentioning

confidence: 93%

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Effect of the composition of the initiating complex acyl halides/aluminium bromide on the cationic polymerization of isobutylene

Murachev¹,

Nesmelov²,

Byrikhin³

et al. 2000

Polym. Int.

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Section: Resultsmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 93%

See 2 more Smart Citations

Effect of the composition of the initiating complex acyl halides/aluminium bromide on the cationic polymerization of isobutylene

Murachev¹,

Nesmelov²,

Byrikhin³

et al. 2000

Polym. Int.

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“…9 ~. In addition to reactions leading to the formatiorl of the end C=C bonds or to chain tra.nsfer to.…”

Section: Resultsmentioning

confidence: 99%

Cationic polymerization of hydrocarbon monomers induced by complexes of acyl halides with Lewis acids

Murachev¹,

Evtushenko²,

Nesmelov³

et al. 1997

Russ Chem Bull

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The polymerization of isobutylene in n-hexane at -78 *C under the action of the superacid HBr" 2AIBr 3 as well as acetyl complexes MeCOBr. AIBr 3 and MeCOBr" 2A1Br 3 in the presence of HBr-AIBr 3 and HBr-2AIBr~, respectively, was studied. Unlike the superacid providing a quantitative yield of polyisobutylene (PIB) due to protonogenie initiation, the acetyl complexes suppress the proton initiation. In the presence of a mixture of both complexes with the superacid, only macromolecules with the head acetyl fragments MeC(O) are formed, which is evidence for a carbocationie initiation. The data obtained are explained by trapping of protons by the earbonyl groups to form ionic structures of the [Me--C--PIB][AI~BrT]-type (where PIB is polyisobutylene) and to suppress the ionization II HO* of the superaeids due to the common ion effect.Key words: isobutylene, cationic polymerization; polyisobutylene, molecular weight, terminal groups; Lewis acids.In the previous report, z we have shown that in the course of polymerization of isobutylene (IB) induced by the acyl complexes MeCOBr'AIBr 3 (At-I) and MeCOBr" 2AIBr 3 (At-2) the addition of 2,6-dimethylpyridine (2,6-DMP) suppresses the reactions of chain initiation and transfer involving free protons and retards the elimination of protons from the growing carbocations. The absence of reinitiation by the eliminated protons was also observed when only the cationogenic initiator Ac-2 was used. This results in the almost 100% functionalization (]) of the polymeric molecules by the acetyl head groups MeC(O) (]'c=o ~ 100%) at a sufficiently high content of the tail units with the C=C bonds (]'r ~ 50%) 3.4 formed due to the elimination of protons. In this connection, several questions arise. How is the reinitiation by eliminated protons suppressed when the complex Ac-2 is used? What are potential possibilities of this mechanism for trapping protons? Why is this mechanism not realized in the system with the protonogenic complex Ac-1 ?In order to obtain answers to the questions listed, in this work we studied the polymerization of IB under the action of a mixture of HBr with AIBr 3 in a molar ratio * For Part 7. see ReE 1. of 1 : 2 (protonic superacid) and the complexes Ac-l and Ac-2 in the presence of these mixtures. These results were compared with the data obtained in the absence of additives of HBr. ExperimentalPurification and drying of the starting reagents and solvent (n-hexane), procedures of polymerization in aU-sealed glassware, and methods of isolation and analysis of polymers were described previously. 3-5 The efficiency of initiation (Ein) was calculated as the ratio of molar concentrations of polymeric chains and an initiator. 4 The degree of functionalization of polymers, i.e., the fraction of rnacromolecules with the corresponding functional groups (fC-o, fc--r and fr was calculated from the data of the analysis of the content of the groups mentioned in polymeric samples by IR spectroscopy, ozonization and X-ray fluorescence analysis, and from the numericalmean molecular...

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Cationic polymerization of hydrocarbon monomers induced by complexes of acyl halides with Lewis acids

Cited by 2 publications

References 7 publications

Effect of the composition of the initiating complex acyl halides/aluminium bromide on the cationic polymerization of isobutylene

Effect of the composition of the initiating complex acyl halides/aluminium bromide on the cationic polymerization of isobutylene

Cationic polymerization of hydrocarbon monomers induced by complexes of acyl halides with Lewis acids

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