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Search for "kinetics" in Full Text gives 371 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides
Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142
- nm. There is a secondary evolution occurring with a time constant of approximately 60 ps resulting in a long-lived feature existing beyond the 5 ns window of the ultrafast experiment. In toluene (Figure 4b), the spectral features at early times are different; however, the kinetics at 654 nm are the
- same between solvents suggesting that the initial features dominating the spectra at 250 fs in MeCN are present in toluene. The (Cyc-DMBI)2 exhibits faster decay kinetics (Figure 4c) than (N-DMBI)2 under the same experimental conditions. The spectral shape is similar to the late time spectra of the (N
Selectivity control towards CO versus H2 for photo-driven CO2 reduction with a novel Co(II) catalyst
Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129
- ). The reaction kinetics was evaluated in photocatalytic systems containing 0.025 mM of 1, since the amount of produced CO should be sufficient to be detected by GC-BID, even after a very short time from starting the reaction. As shown in Figure 5, in the first four hours, the formation of CO presents a
Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity
Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121
- , reacts more rapidly than any of the other dimers with VII via “electron-transfer-first”. Crystal structures show rather long central C–C bonds for 1b2 (1.5899(11) and 1.6194(8) Å) and 1h2 (1.6299(13) Å). Keywords: benzoimidazole; crystal structure; kinetics; n-dopant; reduction; Introduction Electrical
- spin resonance [14] or using dissociation and dimerization barriers from reaction kinetics and variable scan-rate electrochemistry, respectively [54]) and where F is the Faraday constant. Similarly, at least for cases where the reactive hydrides of 1H derivatives are ultimately lost as H2, the strength
- of 1H dopants is given by: where ΔGdiss(1H) is the free-energy change for dissociation of 1H to 1• and H• (again, not discussed in this work), and ΔGdiss(H2) the free-energy change for dissociation of dihydrogen. The values of E(1+/1•) are also relevant to the kinetics of steps in doping reactions
Cyclodextrins permeabilize DPPC liposome membranes: a focus on cholesterol content, cyclodextrin type, and concentration
Beilstein J. Org. Chem. 2023, 19, 1570–1579, doi:10.3762/bjoc.19.115
- the effect of the CD concentration on the SRB release for a specific membrane composition, while the horizontal reading of the tables highlights the impact of CHOL content on the permeability of membranes at various intervals of time. The SRB release kinetics for blank liposomes (untreated with CDs
Synthesis of ether lipids: natural compounds and analogues
Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96
Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light
Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82
- additional reaction pathway is proposed in which the incorporated oxygen on the heteroatoms originates from water. Furthermore, the addition of certain additives enhances productivity by affecting kinetics. The industrial potential is demonstrated by conveniently transferring the batch protocol to continuous
- resulted in a significant reduction in kinetics and selectivity (Table 1, entry 3). Other more green and biobased solvent alternatives, such as ethanol [36], can effectively replace the acetonitrile (for the complete scope of solvents, please consult Supporting Information File 1, Table S2), but reaction
- increase the concentration from 0.06 M to 0.6 M (Table 1, entry 7) maintaining approximately the same reaction time, while further concentration increase resulted in substantially slower kinetics (see Supporting Information File 1, Table S2). When performing the reaction in the dark or under visible light
Photoredox catalysis harvesting multiple photon or electrochemical energies
Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81
- transfer. Second-order kinetics analyses revealed that rapid charge recombination (e.g., kCR (PC1•−) = 2.6 × 108 M−1 s−1) is a significant deactivation pathway in the generation of the key intermediate. This deactivation by back electron transfer taking place in the Marcus-inverted region of electron
The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads
Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79
- unlikely to be detected in ns-TA spectra due to its transient character (the lifetime of this state is short, its concentration is too low to be detected by ns-TA spectroscopy) [67][68]. The monoexponential decay kinetics indicate that the 3LE and 3CS state are in good equilibrium, i.e., the spin–vibronic
- studies, in which both the 3CS and 3LE states were observed, and the two transient species decay with the same kinetics. In polar solvents, however, the CS state energy decreases sharply, yet, the 3LE state energy does not change, thus, although a long-lived 3CS state was found in ACN (τCS = 140 ns), no
Linker, loading, and reaction scale influence automated glycan assembly
Beilstein J. Org. Chem. 2023, 19, 1015–1020, doi:10.3762/bjoc.19.77
- attractive to produce more material in a single AGA run, but might suffer from insufficient mixing [27][28], causing slower kinetics [29], temperature gradients [30], and precipitation [31]. We set off to study the effect of these parameters on the AGA of three different glycan sequences (Figure 2). In an
C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis
Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43
- compared to [Ru3(CO)12] at 200 °C (Table 1, entries 3 and 4). This can be attributed, as mentioned above, to the slightly faster reaction kinetics of the [Ru3(CO)12] catalyst compared to that of comp1. Nevertheless, the better solubility of comp1 in toluene allows to get around the problems of
- as (pre)catalyst. These Ru(0) aggregates are therefore active, but the reaction kinetics are slower. While this observation is not a strict confirmation of our hypothesis regarding the formation of a monometallic complex, it is still consistent with it. Second optimization with a continuous flow
- to ring tension, gave endo product 2f with an isolated yield of 49%. On the other side, disubstituted vinylsilanes proved to be ineffective, certainly because of the steric hindrance of the double bond decreasing the kinetics of the hydroruthenation step. We also wanted to extend this alkylation
Dipeptide analogues of fluorinated aminophosphonic acid sodium salts as moderate competitive inhibitors of cathepsin C
Beilstein J. Org. Chem. 2023, 19, 434–439, doi:10.3762/bjoc.19.33
- analogues of fluorinated aminophosphonic acid sodium salts 9, 11 with phenylalanine at the N-terminus and evaluated their inhibitory activity against bovine cathepsin C. Inhibition kinetics were carried out at 37 °C for 10 minutes in acetate buffer at pH 5. Changes in product concentration versus time were
Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis
Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30
- domestica Borkh.) on the basis of antioxidant properties and radical scavenging kinetics [27][60][61]. However, only few studies have been published on the discrimination of CD-based complexes using multivariate statistical analysis. They are especially related to the retention behavior of various
Recommendations for performing measurements of apparent equilibrium constants of enzyme-catalyzed reactions and for reporting the results of these measurements
Beilstein J. Org. Chem. 2023, 19, 303–316, doi:10.3762/bjoc.19.26
- concentrations of species in complex reaction mixtures at equilibrium. Thus, values of K and K′ are used to determine the practicality of using a reaction to manufacture a substance and for process optimization in bioengineering applications. These values can also be used in the analysis of the kinetics of
- ′. Nevertheless, the half-time to reach equilibrium can be estimated by assuming Michaelis–Menten kinetics. Thus, when the substrate and product concentrations are below their respective Michaelis constants (KM and KP, respectively), one finds that Here, [enzyme] is the concentration of the enzyme and kcat,for
- constants and certain enzyme kinetics parameters via the Haldane relationships. These relationships are discussed in references [10][36] and, in fact, values of K′ have been obtained for a fair number of enzyme-catalyzed reactions by measuring rates of reaction and obtaining the enzyme kinetic parameters
Investigation of cationic ring-opening polymerization of 2-oxazolines in the “green” solvent dihydrolevoglucosenone
Beilstein J. Org. Chem. 2023, 19, 217–230, doi:10.3762/bjoc.19.21
- polymerization process. Further work will be necessary to establish whether a living polymerization can be achieved by additional adjustments. Keywords: 2-alkyl-2-oxazolines; matrix-assisted laser desorption/ionization mass spectrometry; nuclear magnetic resonance; polymerization kinetics; Introduction
- polymerization of MeOx, there was no improvement when the initiator salt EtOxMeOTf was introduced directly. The molar mass of the resulting PMeOx remained much lower than expected with a broad molar mass distribution. The comparison of the polymerization kinetics using MeOTf and EtOxMeOTf requires a comparison
- time for [M]0/[I]0 = 20 and 50 show a linear pseudo first-order kinetics, indicating a constant number of propagating species during polymerization. The increase of the [M]0/[I]0 ratio up to 200 leads to increased reaction time and, unexpectedly, a decreased apparent polymerization rate (Figure 7a). A
Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry
Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15
- benefits from the leaving group ligation at the latest stages of the cross coupling. This is particularly interesting since it can hamper the usual decomposition of the iron catalyst, which tends to afford unreactive reduced aggregates at the end of the catalytic transformation, when the coupling kinetics
Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors
Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14
- cancer; camptothecin; 3D spheroid; cyclodextrin; oral nanoparticle; release kinetics; Introduction Cancer is still one of the most common, highly variable and fatal diseases worldwide. Therefore, studies are continuing to develop effective/innovative and more flexible treatments for various types of
- over 48 hours in order to clearly elucidate the release kinetics (Figure 1). An in vitro release study was carried out at 0–2 hours in simulated gastric fluid (SGF), 2–5 hours in simulated intestinal fluid (SIF), then in simulated colonic fluid (SCoF) settings till the completion of the experiment in
- assessments of this topic [9]. Release kinetics study The in vitro release profiles of CPT-loaded amphiphilic cyclodextrin nanoparticles were fitted with a variety of kinetic models, and the release mechanisms, which are illuminating markers for novel drug delivery systems, were mathematically investigated
Preparation of β-cyclodextrin/polysaccharide foams using saponin
Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7
- coronavirus vaccine chitosan–saponin coatings have been developed to study its immunogenic potential [32]. A complexation between saponin and cyclodextrins (native or derivative) is possible [33], and the resulting release kinetics is appropriate for the creation of new saponin-based drugs [34]. Their
Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies
Beilstein J. Org. Chem. 2022, 18, 1346–1354, doi:10.3762/bjoc.18.140
- ; imine; kinetics; pro-fragrance; Schiff base; Introduction The fragrance and flavor industry is one of the most intensively developing sectors of the chemical industry. Encapsulation techniques are widely used in both food and cosmetic industries to control the delivery of the encapsulated guest
- example of flavor compounds. The imine bond was chosen for its relative stability; on the other hand, it can be readily hydrolyzed forming the starting non-volatile amine and releasing the aldehyde. The kinetics of the aldehyde release was studied by 1H NMR techniques in buffers with different pH values
Make or break: the thermodynamic equilibrium of polyphosphate kinase-catalysed reactions
Beilstein J. Org. Chem. 2022, 18, 1278–1288, doi:10.3762/bjoc.18.134
- substrate/product ratio is an important parameter for kinetics and for the reaction equilibrium, as it defines how much conversion will be achieved [25]. For acetate kinase a conversion of at least 90% using stoichiometric amounts of ADP and acetylphosphate was reported [26]. The reaction of pyruvate kinase
- is generally reached very quickly. This effect is experimentally observed – it is shown in the literature that kinetics should be expressed based on the thermodynamic activity of the enzyme [56]. The enzyme activity coefficients were not taken into account in the present work, which does not allow
- drawing conclusions from the concentration-based kinetics presented in Figure 6 and the activity-based consideration of the equilibrium constants yielding the results in Figure 5. Nevertheless, the experimentally observed difference in velocity agrees with the described kinetic “preference” of PPK2 for
Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor
Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115
- efficiency of the nickel cycle in metallaphotoredox reactions. It is therefore not surprising that a larger acceleration of the reaction kinetics in flow versus batch was observed for the C–O coupling as opposed to the C–S coupling. Conclusion In summary, we developed a packed-bed reactor for
Automated grindstone chemistry: a simple and facile way for PEG-assisted stoichiometry-controlled halogenation of phenols and anilines using N-halosuccinimides
Beilstein J. Org. Chem. 2022, 18, 999–1008, doi:10.3762/bjoc.18.100
- of mechanochemistry, Toda et al.’s “grindstone chemistry” [48] has also been proved as a useful technique for various organic transformations [49]. It is generally carried out by hand-grinding which is not only a labor-intensive process but also raises some concerns on the reaction kinetics
- through p-position leading to the formation of the thermodynamically stable halo derivative via a σ-complex formation. The high concentration of substrates and reagents in the close proximity in this solvent-less process and grinding force could be the other reasons for the fast reaction kinetics. The
- observed in the case of salicylic acids or anthranilic acids leading to 2,4,6-trihalo derivatives when 3 equiv of NXS were used. PEG-400 plays a key role for faster reaction kinetics and to afford better regioselectivity. Almost exclusive p-selectivity was observed for the aromatic substrates with free
Palladium-catalyzed solid-state borylation of aryl halides using mechanochemistry
Beilstein J. Org. Chem. 2022, 18, 855–862, doi:10.3762/bjoc.18.86
- faster reaction kinetics than those under conventional solution-based conditions because of the high concentration; further, the experimental operations can be carried out in air. Considering these achievements, including our recent success in solid-state cross-coupling chemistry, we envisioned that this
Structural basis for endoperoxide-forming oxygenases
Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71
- showed similar reaction kinetics and verruculogen productivity to those of wild type FtmOx1. Interestingly, the Y68F variant generated an unidentified product, which was recently determined to be 26-hydroxyverruculogen [75]. Based on these observations, they proposed an alternative reaction mechanism. In
Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies
Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70
- further catalyzes this reaction, complete conversions with low carbon formation could be obtained at low flow rates. At higher flow rates, reaction kinetics was the limiting factor. Later, it was found that by doping the alloy with small amounts of copper, almost complete conversion (95%) could be
Shift of the reaction equilibrium at high pressure in the continuous synthesis of neuraminic acid
Beilstein J. Org. Chem. 2022, 18, 567–579, doi:10.3762/bjoc.18.59
- recycling steps, and were characterized regarding the reaction kinetics (initial rate) and scalability (different lab scales) in a batch reactor. The reaction kinetics were studied in a continuous flow reactor. A high-pressure circular reactor (up to 130 MPa) was applied for the investigation of changes in
- under investigation [9][10][11]. For this study, the enzymatic synthesis was chosen for its simple reaction sequence (Figure 1) and high selectivity. Different research groups already described the reaction kinetics of the epimerase and aldolase at ambient pressure [5][8]. In this study, the rate
- kinetics [16][17][18], in enantiomeric excess [19], in stability [20], or in the position of the equilibrium [17][21]. State of the art for high-pressure research is the use of pressurized batch reactors [22][23]. Since continuous production and suitable reactors are receiving more attention [24], and some
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