Isobutene polymerization initiated by [CP*TiMe<sub>2</sub>]<sup>+</sup> in the presence of a series of novel, weakly coordinating counteranions
Bibliographic record
Abstract
Abstract The highly electrophilic borane B(C 6 F 5 ) 3 reacts with n ‐octadecanol ( n ‐C 18 H 37 OH) and n ‐octadecanethiol ( n ‐C 18 H 37 SH) to form the 1:1 adducts ( n ‐C 18 H 37 EH)B(C 6 F 5 ) 3 (E = O or S). The latter are acidic and react with Cp*TiMe 3 in methylene chloride and toluene to give methane and the complexes [Cp*TiMe 2 ][( n ‐C 18 H 37 E)B(C 6 F 5 ) 3 ], which are very good initiators for the carbocationic polymerization of isobutene (IB) from −40 to −20 °C. High conversions to high molecular weight polyisobutene (PIB) in methylene chloride and moderate conversions to high molecular weight PIB in toluene are observed and are consistent with the anions [( n ‐C 18 H 37 E)B(C 6 F 5 ) 3 ] − being very weakly coordinating. Although polymerization in methylene chloride is too rapid for the temperature to be controlled, polymerization in toluene is slower, and the temperatures can be controlled so that Arrhenius‐type plots of the logarithm of the number‐average molecular weight versus T −1 = 1/T may be obtained. Activation energies for the degree of polymerization in these polymerization reactions and similar polymerizations carried out with n ‐C 18 H 37 EH:borane ratios of 1:2 and with the activators [Ph 3 C][B(C 6 F 5 ) 4 ] and Al(C 6 F 5 ) 3 range from −11 to −27 kJ mol −1 , values comparable to those for most conventional IB polymerization initiators. However, the values of the weight‐average and number‐average molecular weights are unusually high for the temperatures used, and this is consistent with current theories of the role of weakly coordinating anions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3302–3311, 2002
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.002 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".