Acceleration of the methanolysis of phosphate diesters promoted by La(OTf)<sub>3</sub> The analysis of non-integer pH/rate profiles resulting from changes in metal ion speciation
Bibliographic record
Abstract
In a previous publication (A.A. Neverov and R.S. Brown. Inorg. Chem. 40, 3588 (2001)) we reported very effective catalysis of the methanolysis of some phosphate diesters (methyl p-nitrophenyl phosphate (1), bis(p-nitrophenyl) phosphate (2), and diphenyl phosphate (3)) promoted by La 3+ , and noted a general observation that the plots of logk cat vs. [Formula: see text]pH had non-integer gradients. In this report the origins of that behaviour are studied and analyzed through determination of the speciation of La 3+ ( OCH 3 ) n , (La 3+ ) 2 ( OCH 3 ) m , (La 3+ ) 2 :phosphate:( OCH 3 ) y forms in solution as a function of [Formula: see text]pH. Potentiometric titrations of solutions of La(OTf) 3 in methanol at low (<1 × 10 4 mol/L) and high (>1 × 10 3 mol/L) concentration were analyzed through fits of the data to various models to provide speciation diagrams of the various La 3+ forms in the absence of phosphate. Titrations of La 3+ in the presence of diphenyl phosphate were also analyzed to provide speciation diagrams for phosphate bound forms. The kinetic data for the La 3+ catalyzed methanolysis of 1 were analyzed through fitting the kinetic data at low and high [La 3+ ] as a function of [Formula: see text]pH to a linear combination of the individual kinetic contributions of each species. Overall the data are best analyzed in the low [La 3+ ] domain as resulting from methoxide attack on a transient complex of phosphate bound to La 3+ ( OCH 3 ) 0,1 . In the high [La 3+ ] domain the data fit two kinetically equivalent processes involving either a spontaneous decomposition of (La 3+ ) 2 :1 :( OCH 3 ) 2,3,4,5 or external methoxide attack on (La 3+ ) 2 :1 :( OCH 3 ) 1,2,3,4 . Key words: lanthanides, phosphate diester, methanolysis, kinetics, speciation, metal ion catalysis of methanolysis, DNA model methanolysis.
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".