Liaison hydrogène des arylamines : compétition des sites π et N
Bibliographic record
Abstract
An IR study, in the region of OH stretching, of a reference hydrogen-bond donor, 4-fluorophenol, hydrogen bonded to primary, secondary, and tertiary arylamines differently substituted on the ring and on the nitrogen, shows the formation of two kinds of 1:1 complexes in CCl 4 solution: an OH···π and an OH···N hydrogen-bonded complex. The IR method gives only access to a global complexation constant K t . A method is proposed for separating K t into a K π component for hydrogen bonding to the π system and a K N component for hydrogen bonding to the nitrogen atom. This method is validated by comparing the estimated K π and K N values to theoretically calculated descriptors of basicity: the nitrogen lone pair orientation towards the aromatic ring, the molecular electrostatic potentials around the nitrogen and the π cloud, and the enthalpy of hydrogen bonding of hydrogen fluoride with the π system of selected arylamines. The main electronic and steric factors governing the competition between π and N sites are analysed. The strongest π and N bases among the arylamines are julolidine and Tröger's base, respectively. Triphenylamine and diphenylamine, which are nitrogen Brønsted bases, become π bases in hydrogen bonding. Moreover, there is no correlation between the pK HB and the pK BH+ scales of basicity of arylamines. The use of the pK BH+ scale is therefore not recommended in hydrogen-bonding studies.Key words: hydrogen bonding, arylamines, pK HB scale, competition of π and N hydrogen-bonded sites.
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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) | 0.002 | 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".