The kinetics of the spontaneous, proton- and Al<sup>III</sup>-catalysed hydrolysis of 1,5-anhydrocellobiitol Models for cellulose depolymerization in paper aging and alkaline pulping, and a benchmark for cellulase efficiency
Bibliographic record
Abstract
The kinetics of the spontaneous, proton- and Al III -catalysed hydrolyses of the C1O4′ bond in 1,5-anhydrocellobiitol have been measured at elevated temperatures (125.0220.0 °C). Data for the first two processes extrapolate to the expression k = (8.6 ± 2.1 × 10 16 ) + (1.4 ± 0.2 × 10 9-pH ) s 1 at 25 °C. These room-temperature figures were used to model cellulose depolymerization by the af Ekenstam equation. The spontaneous process is too slow to contribute to loss of paper strength on aging, and even the acid-catalysed process is significant only below ~pH 4.0. However, the spontaneous hydrolysis readily accounts for the reduction of cellulose degree of polymerization (DP) during alkaline (e.g., kraft) pulping of cellulose fibres. Efficient electrophilic catalysis by Al III was observed at 150.0 °C in 0.1 mol/L succinate buffers of room temperature pH 3.05 and 3.35 (k 2 = 8.1 ± 0.4 × 10 3 and 4.2 ± 0.2 × 10 3 (mol/L) 1 s 1 , respectively). The apparent activation energy of the Al III -catalysed process was 31 ± 4 kJ mol -1 , lower than that of the proton-catalysed path, suggesting the electrophilic catalysis increases in importance as the temperature approaches ambient. Consequently, it appears that the culprit in the impermanence of “rosin-alum” -sized paper is Al III , directly acting as a Lewis acid, not the Al III hydration sphere as a Brønsted acid. Conservation measures should either address this or be generic (e.g., low-temperature storage). Key words: cellulose, hydrolysis, kraft pulping, paper conservation, rosin-alum sizing.
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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 | 0.000 | 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) | 0.000 | 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".