Cationic polymerization of hydrocarbon monomers under the effect of complexes of acyl halides with lewis acids 3. Polymer chain initiation and breaking in hexane at -78?C

Nesmelov, A. I.; Orlinkov, A. V.; Murachev, V. B.; Akhrem, I. S.; Byrikhin, V. S.; Zubov, V.P.

doi:10.1007/bf00958835

Cited by 2 publications

(9 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The acetyl bromide equimolar CH 3 COBr·AlBr 3 complex demonstrates only protogenic activity because the macromolecules obtained do not contain CO groups. As shown in previous papers,7, 9, 14 the 1:2 complexes CH 3 COBr·2AlBr 3 and C 6 H 5 COCl·2AlBr 3 in hexane behave only as cationogen initiators.…”

Section: Resultssupporting

confidence: 66%

“…Let us now compare the predictions with the experimental data provided by an analysis of the head acyl fragments in the macromolecules (Table 2). Some of these data have been published earlier 7–9. 14, 19, 20 Other representative results are shown in Table 3.…”

Section: Resultsmentioning

confidence: 77%

“…Our previous studies7–9 confirmed that some complexes of acyl halides with aluminium bromide RCOX· n AlBr 3 (when X = Cl, Br; n = 1, 2) can initiate the polymerizaton of isobutylene (IB), while the composition of the complex (nature of R and value of n ) significantly influences both the initiation mechanism and the whole polymerization process.…”

Section: Introductionmentioning

confidence: 63%

“…In the second case, M n of the polymers increases almost linearly with monomer conversion, while a number of polymer chains ( N ) and I eff remain virtually constant 7. 9, 14 In this respect, the processes are similar to living ones. However, an analysis of our polymeric samples at different conversions showed that part of the active centres decayed during polymerization, due to proton elimination 7.…”

Section: Resultsmentioning

confidence: 88%

See 3 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.

View full text Add to dashboard Cite

Section: Resultssupporting

confidence: 66%

Section: Resultsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 63%

Section: Resultsmentioning

confidence: 88%

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.

View full text Add to dashboard Cite

“…z, 3 we have shown that cationic polymerization of isobutene (IB) in n-hexane at -78 ~ initiated by the acyl complex MeCOBr. z, 3 we have shown that cationic polymerization of isobutene (IB) in n-hexane at -78 ~ initiated by the acyl complex MeCOBr.…”

mentioning

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

Self Cite

View full text Add to dashboard Cite

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...

show abstract

Cationic polymerization of hydrocarbon monomers under the effect of complexes of acyl halides with lewis acids 3. Polymer chain initiation and breaking in hexane at -78?C

Cited by 2 publications

References 6 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

Contact Info

Product

Resources

About