Hydrogenation of natural rubber in the presence of OsHCL(CO)(O<sub>2</sub>)(PCY<sub>3</sub>)<sub>2</sub>: Kinetics and mechanism
Bibliographic record
Abstract
Abstract The homogeneous catalyst precursor, OsHCl(CO)(O2)(PCy3)2, was utilized for the hydrogenation of natural rubber to convert the unsaturated structure to a saturated form, providing an alternating ethylene‐propylene copolymer. A detailed kinetic investigation was carried out by monitoring the amount of hydrogen consumption during the reaction using a gas‐uptake apparatus. 1H NMR spectroscopy was used to determine the final olefin conversion to the hydrogenated product. Kinetic data, collected according to a statistical design framework, defined the influence of catalyst and polymer concentration, hydrogen pressure, and reaction temperature on the catalytic activity. The kinetic results indicated that the hydrogenation rate exhibited a first‐ shifted to zero‐order dependence on hydrogen at lower hydrogen pressure, which then decreased toward an inverse behavior at pressures higher than 41.4 bar. The hydrogenation was also observed to be first‐order with respect to catalyst concentration, and an apparent inverse dependence on rubber concentration was observed due to the impurities in the rubber. The hydrogenation rate was dependent on reaction temperature, and the apparent activation energy over the temperature range of 125–145°C was found to be 122.76 kJ/mol. Mechanistic aspects of the hydrogenation of natural rubber in the presence of OsHCl(CO)(O2)(PCy3)2 were proposed on the basis of the observed kinetic results. The addition of some acids and certain nitrogen containing materials showed an effect on the hydrogenation rate. The thermal properties of hydrogenated natural rubber indicated that the thermal stability increased with increasing % hydrogenation of the rubber. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4499–4514, 2006
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 machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".