Benzenesulfonyl chloride with primary and secondary amines in aqueous media Unexpected high conversions to sulfonamides at high pH
Bibliographic record
Abstract
We have determined pHyield profiles under pseudo-first-order conditions of the reactions of benzenesulfonyl chloride with a set of primary and secondary water-soluble alkylamines, and have found with certain amines, such as dibutylamine, a profile taking the form of a sigmoid pH–yield curve with relatively high yields of the sulfonamide persisting with increasing basicity up to and including 1.0 mol/L sodium hydroxide. This behaviour is quantitatively accounted for by invoking, in addition to the usual second-order reaction of the sulfonyl chloride with the amine, two third-order terms (i) one first-order in sulfonyl chloride, amine and hydroxide anion, and (ii) another first-order in sulfonyl chloride and second-order in the amine. The importance of the third-order terms correlates approximately with the total number of alkyl carbon atoms in the amine, and this in turn is regarded as related to the hydrophobic character of the amine. Experiments to test this picture included: (i) observation of a bell-shaped curve with bis(2-methoxyethyl)amine, (ii) in the reaction of dibutylamine in THF–H2O (1:1), and also (iii) in the reaction of dibutylamine in 1.0 mol/L tetrabutylammonium bromide, and (iv) increase in the contributions of the third-order terms in 1.0 mol/L aqueous sodium chloride. Preparative reactions with dibutylamine, 1-octylamine, and hexamethylenimine in 1.0 mol/L aqueous sodium hydroxide with a 5% excess of benzenesulfonyl chloride gave, respectively, 94%, 98%, and 97% yields of the corresponding sulfonamides. Key words: sulfonyl chlorides, primary and secondary amines, pHyield profiles, organic synthesis in water, hydrophobic effects.
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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 | 0.001 |
| 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".