Reversible decomposition of mono(α-hydroxy)phosphines and their reaction with α,β-unsaturated aldehydes
Bibliographic record
Abstract
The mono(α-hydroxy)phosphines R 2 PCH(OH)R′ (R = Ph, R′ = H, Et, CH 2 Ph, Ph, p-X-C 6 H 4 ; R = cyclohexyl, R′ = Ph) are prepared under solvent-free conditions by a 1:1 reaction of Ph 2 PH with the appropriate aldehyde, and their stabilities (with respect to reversible dissociation into reactants), studied in DMSO, Et 2 O, and MeOH, increase with decreased basicity of the hydroxyphosphine; for example, for the Ph 2 PCH(OH)C 6 H 4 -p-X phosphines, stability decreases in the order: X = CN > Cl > F > H > Me > OMe. A 1:1 room-temperature reaction of the (α-hydroxy)phosphines (except for R′ = H) with cinnamaldehyde in DMSO slowly yields the known mono- and di-phosphines Ph 2 PCH(Ph)CH 2 CHO (4a) and Ph 2 PCH(Ph)CH 2 CH(PPh 2 )OH (10a), and the corresponding R′CHO aldehyde. In MeOH, the sequentially formed intermediates, PhCH=CHCH(OH)PPh 2 , PhCH(OH)CH=CHPPh 2 , and Ph 2 PCH(Ph)CH=CHOH, were detected en route to 4a and 10a. Reaction of cinnamaldehyde with Ph 2 PCH 2 OH gives 4a and the hemiacetal Ph 2 PCH 2 OCH 2 OH formed from the reactant hydroxyphosphine with the co-product formaldehyde. Reactions carried out in MeOH are faster because of the formation of hemiacetals from the phosphine-containing aldehyde products; thus, 4a is seen as Ph 2 PCH(Ph)CH 2 CH(OMe)(OH), which on dissolution in Et 2 O, reverts to the aldehyde. The reaction rates and equilibrium concentrations of the various species depend on the R′ group of the reactant phosphine; the rates of consumption of the hydroxyphosphines in the reactions with cinnamaldehyde decrease in the order: Ph 2 PCH(OH)Ph > Ph 2 PCH(OH)Et > Ph 2 PCH(OH)CH 2 Ph >> Ph 2 PCH 2 OH. The reactivity pattern of Ph 2 PCH(OH)Ph with sinapaldehyde [3,5-(OMe) 2 -4-OH-cinnamaldehyde] in DMSO follows that seen for cinnamaldehyde. Reaction of Ph 2 PH with cinnamaldehyde in DMSO affords 4a and 10a via the same intermediates seen with the Ph 2 PCH(OH)R′ reagents, but these latter reactions are thought to occur via direct attack on cinnamaldehyde by the hydroxyphosphine rather than via Ph 2 PH.
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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".