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A new efficient solvent-free procedure for the CO cross-coupling between (hetero)aryl halides with phenols, primary alkanols, or (hetero)arylmethanols using Pd2(dba)3/ButBrettPhos ...catalytic system is proposed using 23 examples.
The focus of this study was to examine antisolvent effects, which hold significance in particulate processes, such as crystallization and precipitation. In the first section, an experimental ...investigation revealed that C1–C4 primary alcohols significantly reduced the solubility of potassium dihydrogen phosphate (KDP) in water. The solid–liquid equilibria of KDP solutions were determined using an innovative polythermal method, demonstrating time and labor efficiency compared to the traditional isothermal method while maintaining solubility determination quality. This achievement established an efficient tool for high-throughput solvent screening, a crucial aspect of particulate process development. In addition to the experimental approach, in the second part, the influence of these alcohols on KDP solubility was analyzed using the eNRTL thermodynamics model. The model’s estimated parameters confirmed that the addition of these alcohols induced strong non-ideal behavior in the solutions, altered interactions between solute species and solvent components, and reduced KDP solubility. Under the effects of these alcohols, KDP solubility generally increased with the length of the alkyl chain in the added alcohols, although methanol deviated from this observation. Furthermore, the present work also discussed the limitation of the well-known Bromley’s equation, particularly when applied for KDP in alcohol–water mixed solvents. Consequently, binary and ternary systems consisting of KDP, water, and C1–C4 primary alcohols were successfully modeled using eNRTL. Furthermore, it was determined that the obtained model was insufficient for quaternary systems with a higher alcohol content, particularly when high-order interactions were neglected as in the cases of binary and ternary systems. In short, these investigated alcohols have potential for future applications in the design of particulate processes, with a particular emphasis on antisolvent crystallization.
An efficient multi‐gram scale synthesis protocol of a variety of P,N ligands is described. The synthesis is achieved in a two‐step reaction. First, the amine is deprotonated and subsequently the ...chlorophosphine is added to yield the corresponding P,N ligand. Deprotonation of the amine is normally achieved with n‐BuLi at low temperature, but for the preparation of ligands with a 2,2′‐dipyridylamino backbone and phosphines with a high steric demand KH has to be employed in combination with reaction temperatures of 110 °C for the salt metathesis step. The reaction of two equivalents of a selected P,N ligand with one equivalent of the iridium complex IrCl(cod)2 (cod=1,5‐cyclooctadiene) affords P,N ligand‐coordinated iridium complexes in quantitative yield. X‐Ray single crystal structure analysis of one of these complexes reveals a monomeric five‐coordinated structure in the solid state. The iridium complexes were used to form catalysts for the N‐alkylation of aromatic amines with alcohols. The catalyst system was optimized by studying 8 different P,N ligands, 9 different solvents and 14 different bases. Systematic variation of the substrate to base and the amine to alcohol ratios as well as the catalyst loading led to optimized catalytic reaction conditions. The substrate scope of the developed catalytic protocol was shown by synthesizing 20 different amines of which 12 could be obtained in isolated yields higher than 90%. A new efficient catalyst system for the selective monoalkylation of primary aromatic and heteroaromatic amines with primary aromatic, heteroaromatic as well as aliphatic alcohols has been established. The reaction proceeds with rather moderate catalyst loadings.
The catalytic dehydrogenation of alcohols to carbonyl products is a green sustainable oxidation with no production of waste except for hydrogen, which can be an energy source. Additionally, a ...reusable heterogeneous catalyst is valuable from the viewpoint of process chemistry and water is a green solvent. We have accomplished the palladium on carbon (Pd/C)‐catalyzed dehydrogenation of primary alcohols to carboxylic acids in water under a mildly reduced pressure (800 hPa). The reduced pressure can be easily controlled by the vacuum controller of the rotary evaporator to remove the excess of generated hydrogen, which causes the reduction (reverse reaction) of aldehydes to alcohols (starting materials) and other undesirable side reactions. The present method is applicable to the reaction of various aliphatic and benzylic alcohols to the corresponding carboxylic acids, and the Pd/C could be reused at least 5 times.
Comprehensive Summary
Though alcohol oxidations were considered as well‐established reactions, selecting productive conditions or predicting reaction yields for unseen alcohols remained as major ...challenges. Herein, an auto machine learning (ML) model for TEMPO‐catalyzed oxidation of primary alcohols to the corresponding carboxylic acids is disclosed. A dataset of 3444 data, consisting of 282 primary alcohols and 45 conditions, were generated using high‐throughput experimentation (HTE). With the HTE data and 105 descriptors, a multi‐label prediction was performed with AutoGluon (an open‐source auto machine learning framework) and KNIME (an open‐source data analytics platform). For the independent test of 240 reactions (a full matrix of 20 unseen alcohols and 12 conditions), AutoGluon with multi‐label prediction for yield prediction (AGMP) gave excellent performance. For external test of 1308 reactions (consisting of 84 alcohols and 45 conditions), AGMP still afforded good results with R2 as 0.767 and MAE as 4.9%. The model also revealed that the newly generated descriptor (Y/N, classification of the reaction reactivity) was the most relevant descriptor for yield prediction, offering a new perspective to integrate HTE and ML in organic synthesis.
A machine learning model for TEMPO‐catalyzed alcohol oxidation was developed, superior prediction accuracy was achieved and unprecedented attention on multi‐label prediction of organic chemistry reactions was attracted.
A variety of 4‐substituted 2,2,6,6‐tetramethylpiperidyl‐1‐oxy (TEMPO) derivatives has been screened for their ability in the oxidation of primary alcohols to the aldehydes with dioxygen under mild ...conditions. An evaluation of the efficiency of these 4‐substituted TEMPO derivatives in the alcohol oxidation may allow an insight into the effect of the structural variations of TEMPO on the oxidation of alcohols, which should facilitate catalyst design and screening efforts. Based on the screening results of 4‐substituted TEMPO derivatives, the catalyst comprised of 4‐acetamido‐TEMPO, iron chloride and sodium nitrite, has been developed for the highly efficient oxidation of a wide range of primary alcohols including primary aliphatic alcohols to the corresponding aldehydes under mild conditions.
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•New copper(I) catalysts for the aerobic oxidation of primary alcohols.•Ligand detachment activates the copper(I)-catalyst.•Quantitative yields are obtained of benzaldehyde in 1 ...h.•High (96%) yields are obtained of octanal.
We report here new copper(I)-Schiff base complexes for the selective oxidation of primary alcohols to aldehydes under ambient conditions (with 2,2,6,6-tetramethylpiperdine-N-oxyl (TEMPO), N-methylimidazole (NMI), ambient air, acetonitril and RT). Particularly, the copper(I) complex bearing N-(4-fluorophenyl)-1-(furan-2-yl)methanimine (L2) showed high activity in the series and gave near- quantitative yields in the oxidations of benzyl alcohol (99% yield in 1 h) and 1-octanol (96% yield in 24 h). Based on the X-ray structure determination, the complex has a square pyramidal coordination accomplished by two L2 ligands and bromide as a counter anion. The oxidation reactions were monitored with UV–vis and in situ ATR-IR spectroscopy to study the changes in the catalytic structure and to elucidate the catalytic properties and the mechanistic details. Accordingly, detachment of one of the L2 ligands from the complexes is related to the oxidation activity.
Catalytic transfer hydrogenation (CTH) with alcohols has been increasingly employed as effective tool for biomass upgrading, however, relying predominantly on secondary alcohols. Herein, for the ...first time skeletal CuZnAl catalysts were employed for the activation of a primary alcohol, ethanol, for the hydrogenation 5‐hydroxymethylfurfual (HMF) to 2,5‐bis(hydroxymethyl)furan (BHMF) under a mild condition. The catalysts were extensively characterized to reveal the structure characteristics and surface compositions. Over 90 % yield of BHMF were obtained over the optimal CuZnAl‐0.5 catalyst at the reaction temperatures of 100–120 °C. Reaction kinetics indicated a competitive adsorption between HMF and ethanol on the catalyst surface, with the activation of ethanol being the rate‐determining step (apparent activation energy Ea=70.9 kJ mol−1). Preliminary adsorption investigation using combined attenuated total reflectance infrared spectroscopy and density functional theory calculation proposed a η2‐(O,O)‐aldehyde, furoxy perpendicular configuration of HMF on catalyst surface. The catalyst was further applied to the CTH of various aldehydes to the corresponding alcohols with high yields, demonstrating the broad applicability of the current system.
Transfer hydrogenation: A facilely prepared skeletal CuZnAl catalyst is found to be active for primary alcohol activation for catalytic transfer hydrogenation, efficiently converting biobased 5‐hydroxymethylfurfural (HMF) to 2,5‐bis(hydroxymethyl)furan (BHMF) with up to 92 % yield under a mild condition of 100–120 °C.
The first organic–inorganic lacunary polyoxometalate catalytic oxidation system with H
2
O
2
as an oxidant for the preparation of aliphatic carboxylic acids from primary alcohols has been developed. ...This new catalytic system not only exhibits good catalytic activity with high selectivity toward acids, but also satisfactorily resolves the separation of the catalyst for reuse.
Graphical Abstract
Herein we report a protocol for novel palladium‐catalyzed cross‐coupling reactions of sustainably produced primary furfuryl alcohols with arylboronic acids to deliver 5‐arylfurfuryl alcohols and ...2,5‐diaryl furans. Hammett plot analysis suggested that the reaction mechanism involved aromatization‐driven cleavage of the carbon−carbon bond of a furan oxonium ion intermediate. This protocol provides a simple, practical way to transform 5‐hydroxymethylfurfural into useful compounds.
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