Classes Of Functional Groups Research Articles

Cover Feature: Isonitrile Photochemistry: A Functional Group Class Coming in from the Cold (Chem. Eur. J. 64/2024)

Cover Feature: Isonitrile Photochemistry: A Functional Group Class Coming in from the Cold (Chem. Eur. J. 64/2024)

Isonitrile Photochemistry: A Functional Group Class Coming in from the Cold.

Starting from a historical background that acknowledges isonitriles as a neglected class of compounds due to their unpleasant smell and hardly controlled reaction conditions with open shell species, the present concept article aims at highlighting the seeds of the modern isonitrile photochemistry. Representative essential transformations achieved via either UV light irradiation or radical initiators at high temperatures are brought into play to draw a parallel with the current literature relying on the exploitation of visible light photochemical methods. Such a comparison points out the potential of this enabling technology to further expand the scope of isonitrile chemistry and the unmet challenges which makes it a very stimulating field.

Carbene-Catalyzed Enantioselective Addition of Sulfinate to Ketones.

A carbene-catalyzed enantioselective addition of sulfinate to ketones between 2-benzoylbenzaldehyde and sulfonyl chloride is disclosed. Up to now, the carbon and heteroatom nucleophiles have effectively undergone catalytic enantioselective addition to carbonyl molecules to introduce functionalities and chirality. Sulfone, as an important class of sulfur-containing functional groups, represents highly valuable motifs in medicines and natural products. It remains undeveloped for the catalytic asymmetric addition of sulfinate to carbonyls. Herein we disclosed the first catalytic enantioselective addition of sulfinate to ketones for the synthesis of sulfones via N-heterocyclic carbene (NHC) catalysis. The sulfonyl chloride behaves both as an oxidant and as a nucleophilic substrate in this carbene-catalyzed process. Experimental studies suggested that the Breslow intermediate can be SET oxidized by sulfonyl chloride to generate the sulfonyl radical. This novel synthetic approach for the asymmetric addition of sulfinate to carbonyls can also be used to modify the commercially available functional molecules.

Alcohol-alcohol cross-coupling enabled by SH2 radical sorting.

Alcohols represent a functional group class with unparalleled abundance and structural diversity. In an era of chemical synthesis that prioritizes reducing time to target and maximizing exploration of chemical space, harnessing these building blocks for carbon-carbon bond-forming reactions is a key goal in organic chemistry. In particular, leveraging a single activation mode to form a new C(sp3)-C(sp3) bond from two alcohol subunits would enable access to an extraordinary level of structural diversity. In this work, we report a nickel radical sorting-mediated cross-alcohol coupling wherein two alcohol fragments are deoxygenated and coupled in one reaction vessel, open to air.

Expert System for Fourier Transform Infrared Spectra Recognition Based on a Convolutional Neural Network With Multiclass Classification.

Fourier transform infrared spectroscopy (FT-IR) is a widely used spectroscopic method for routine analysis of substances and compounds. Spectral interpretation of spectra is a labor-intensive process that provides important information about functional groups or bonds present in compounds and complex substances. In this paper, based on deep learning methods of convolutional neural networks, models were developed to determine the presence of 17 classes of functional groups or 72 classes of coupling oscillations in the FT-IR spectra. Using web scanning, the spectra of 14 361 FT-IR spectra of organic molecules were obtained. Several different variants of model architectures with different sizes of feature maps have been tested. Based on the Shapley additive explanations (SHAP) and gradient-weighted class activation mapping (GradCAM) methods, visualization tools have been developed for visualizing and highlighting the areas of absorption bands manifestation for corresponding functional groups or bonds in the spectrum. To determine 17 and 72 classes, the F1-weighted metric, which is the harmonic mean of the class' precision and class' recall weighted by class' fraction, reached 93 and 88%, respectively, when using data on the position of absorption maxima in the spectrum as an additional source layer. The resulting model can be used to facilitate the routine analysis of spectra for all areas such as organic chemistry, materials science, and biology, as well as to facilitate the preparation of the obtained experimental data for publication.

Covalent Adduct Formation between β-Lactoglobulin and Flavor Compounds under Thermal Treatments That Mimic Food Pasteurization or Sterilization.

Thermal processing (e.g., pasteurization and sterilization) is a critical step ensuring the microbial safety of our foods. Previous work from our laboratory has examined the covalent reactions occurring between proteins and a broad selection of flavor compounds under ambient storage temperatures (25-45 °C). However, similar research on reactions of flavor compounds with a protein under thermal processing conditions has not been investigated. In the current study, covalent adduct formation between β-lactoglobulin (BLG) and 46 flavor compounds encompassing 13 different classes of functional groups was investigated under pasteurization and sterilization conditions by UPLC-ESI-QTOF-MS. BLG was chosen as a representative protein for this study because it is structurally well characterized, its molecular weight is well suited for ESI-MS analysis (18.2 kDa), and it is broadly used in the food industry. Schiff base, aza-Michael addition, and disulfide linkages were the main types of covalent interactions occurring across the reactive samples. Among them, isothiocyanates, aldehydes, and thiol-containing compounds were generally very reactive. Increasing the severity of the thermal treatment [high-temperature-short-time (HTST) pasteurization, in-container pasteurization (IC), and ultra-high-temperature (UHT) sterilization conditions] accelerated the reactions of BLG with flavor compounds, which revealed reactivity of three flavor compounds not previously observed to react at room temperature (eugenol, 4-vinyl phenol, and 3-nonen-2-one). Ketones [other than 2-hydroxy-3-methyl-2-cyclopenten-1-one (cyclotene), diketones, and unsaturated ketones], alcohols, acids, alkenes (terpenes), esters, lactones, 3-acetylpyridine, methyl anthranilate, vanillin, 2-methylthiophene, and dimethyl sulfone did not show measurable reactivity with BLG under the thermal processing conditions examined. An overall view of the data shows that the HTST heat treatment (72 °C for 15 s) had the least effect on the extent of reaction while in-container pasteurization conditions (63 °C for 30 min) produced a similar extent of reaction as the UHT (130 °C 30 s) heat treatment. These varying extents of adductation are in reasonable accord with what one might expect, given that the rates of most classes of chemical reactions occurring near ambient temperature increase by a factor of 2-4 for each increase of 10 K in temperature. Unfortunately, our methodology did not permit us to obtain meaningful data using the most aggressive standard sterilization thermal conditions (110 °C for 30 min) because extensive aggregation/coagulation removed essentially all of the BLG protein from the reaction mixtures prior to MS analysis.

Raman Wavelength Conversion in Ionic Liquids

We explore the use of room-temperature ionic liquids (ILs) as Raman wavelength converters. ILs provide an engineerable framework to design suitable liquids for wavelength conversion over a broad spectral range, through careful selection of the molecular structures of the IL anions and cations so that specific characteristics can be obtained, such as a desirable Raman shift, low Brillouin scattering, and good optical transmission in the pump and Stokes wavelengths. Applying such criteria, we demonstrate that 1-ethyl-3-methylimidazolium dicyanamide (EMIM DCA) is an effective medium for conversion of 532-nm pulses from a Q-switched Nd:YAG laser to 603 nm. This corresponds to an approximate 2200 cm−1 shift, which can be used to generate mid-infrared radiation through subsequent difference frequency generation for optical pumping of CO2 lasers. Threefold-higher Raman conversion efficiency is obtained in EMIM DCA compared with water under identical conditions in a proof-of-principle single-pass conversion setup, resulting in an efficient generation of multimillijoule, <6 ns duration, high-quality orange laser pulses in a wavelength region that is difficult to access at high energies. Consequently, we examine ILs representing two other classes of Raman-active functional groups and obtain conversion up to the fifth-order Stokes shift and first anti-Stokes shift. Through the tunable selection of their components and their useful dynamical properties, ILs provide a platform for efficient, simple, and alignment-tolerant high-energy Raman shifting with numerous industrial and technological applications.Received 16 June 2022Accepted 8 December 2022DOI:https://doi.org/10.1103/PhysRevApplied.19.014052© 2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasChemical Physics & Physical ChemistryOptical sources & detectorsStimulated Raman scatteringPhysical SystemsIonic fluidsMoleculesOrganic compoundsTechniquesInfrared techniquesAtomic, Molecular & OpticalCondensed Matter, Materials & Applied PhysicsInterdisciplinary Physics

Photoredox-Mediated Deoxygenative Alkylation of DNA-Tagged Alkenes with Activated Alcohols.

DNA-encoded library (DEL) screens have become a key technology to find small molecule binders to biological targets for drug discovery applications. The development of new DNA-compatible chemistries to expand the accessible DEL chemical space is imperative to enhance screen success across broad target classes and modalities. Additionally, reactions that use commonly available building blocks as well as those that enable the fsp3 of library members to be increased would have high impact for accessing diverse drug-like structures. Herein, we report a DNA-compatible Giese-type addition of nonstabilized C-centered radicals generated by the deoxygenation of preactivated alcohols into on-DNA olefins. Although alcohols have been historically underused as a building block class within DEL synthesis, their activation to a xanthate enables Csp3-Csp3 coupling to furnish sp3-rich products. This reaction is compatible with multiple classes of functional groups, does not damage the DNA tag, and is suitable for use in DEL productions.

Direct Reaction of Nitroarenes and Thiols via Photodriven Oxygen Atom Transfer for Access to Sulfonamides.

Sulfonamide is a common motif in medicines and agrochemicals. Typically, this class of functional groups is prepared by reacting amines with sulfonyl chlorides that are presynthesized from nitro compounds and thiols, respectively. Here, we report a novel strategy that directly couples nitro compounds and thiols to form sulfonamides atom- and redox-economically. Mechanistic studies suggest our reaction proceeds via direct photoexcitation of nitroarenes that eventually transfers the oxygen atoms from the nitro group to the thiol unit.

Factors influencing hydrogen peroxide versus water inclusion in molecular crystals.

Hydrate formation is often unavoidable during crystallization, leading to performance degradation of pharmaceuticals and energetics. In some cases, water molecules trapped within crystal lattices can be substituted for hydrogen peroxide, improving the solubility of drugs and detonation performance of explosives. The present work compares hydrates and hydrogen peroxide solvates in two ways: (1) analyzing structural motifs present in crystal structures accessed from the Cambridge Structural Database and (2) developing potential energy surfaces for water and hydrogen peroxide interacting with functional groups of interest at geometries relevant to the solid state. By elucidating fundamental differences in local interactions that can be formed with molecules of hydrogen peroxide and/or water, the analyses presented here provide a foundation for the design and selection of candidate molecules for the formation of hydrogen peroxide solvates.

Rhodium-Catalyzed Decarboxylative Michael Reaction of Coumarin-3- Carboxylic Acids with N-heterocycles Triggered by C-H Bond Functionalization

Rhodium-catalyzed hydrocarbon bond activation of N-heterocycles and decarboxylative Michael addition with coumarin-3-carboxylic acids has been well achieved. Various N-heterocycles substituted 3,4-dihydrocoumarin could be easily provided with excellent chemo- and regioselectivity in good to excellent yields. A class of functional groups on N-heterocycles and coumarin-3-carboxylic acids is compatible with this process. A stoichiometric amount of Zn(OAc)2 is necessary for the high yield of products.

Phenol Removal from Aqueous Solution by Adsorption Technique Using Coconut Shell Activated Carbon

Adsorption is one of the simplest techniques with low economic requirements. Coconut shell is an abundant agriculture waste which is inexpensive and easy to be obtained in Malaysia. This agriculture waste was transformed to activated carbon via 600°C of carbonization and zinc chloride activation. The ability of coconut shell-based activated carbon to remove phenolic compounds from aqueous solutions was evaluated. From the experiment, the equilibrium time for the adsorption of phenol onto coconut shell-based activated carbon is 120 minutes. The effect of the operating parameters, such as contact time, initial concentration, agitation speed, adsorbent dosage, and pH of the phenolic solution were studied. Adsorption kinetics models (pseudo-first-order, pseudo-second-order, and Elovich equation) and isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) were used to fit the experimental data.Pseudo-second-order was found to be the best fitted kinetics model to describe the adsorption of phenol on coconut shell-based activated carbon. While the equilibrium experiment data was well expressed by the Temkin isotherm model, The maximum adsorption capacity is determined as 19.02 mg/g, which is comparatively lower than the previous research. Meanwhile, 92% of removal efficiency was achieved by a dosage of 10g/L. Meanwhile, the adsorption of phenol by activated carbon was more favorable under acidic conditions. The favourable isotherm behavior was indicated by the dimensionless separation factor. The functional group and compound class of activated carbon before and after the experiment were determined through the analysis of Fourier-transform infrared (FTIR) spectroscopy.

A lumped kinetic model for high-temperature pyrolysis and combustion of 50 surrogate fuel components and their mixtures

Wide distillation fuels (WDF) and gasoline/diesel blends have been proposed as new fuel formulations for advanced combustion engines. Recent studies have shown that multi-component gasoline and diesel surrogate mixtures can accurately mimic the distillation curve, functional group or hydrocarbon class distribution, average molecular weight, and other combustion properties of real fuels. This work presents an updated decoupling methodology to construct a 50-component fuel model, which consists of a skeletal sub-mechanism for large hydrocarbon components present in gasoline, jet and diesel fuels, a reduced C5-Cn mechanism, and a detailed C0-C4 mechanism. The entire model contains 156 species and 1132 reactions. The chemical classes covered include n-alkanes, iso-alkanes, cyclo-alkanes and alkylbenzenes. Compared with the comprehensive detailed kinetic modeling approach, the present methodology largely reduces the model size due to the use of skeletal fuel mechanisms. Compared with the traditional decoupling methodology, our approach increases the model accuracy since it contains a detailed C0-C4 mechanism instead of a reduced C2-C3 mechanism. The present model was validated against experimental targets at high temperatures, including the pyrolysis and oxidation speciation data and global parameters such as ignition delay times and laminar flame speeds from 30 pure fuel components and 12 fuel mixtures. In general, the present model performs well against these experimental data, suggesting this methodology is a suitable approach for developing accurate kinetic models for multi-component fuels. Future work will extend the present framework to predict low-temperature combustion chemistry of multi-component fuels.

Covalent Adduct Formation Between Flavor Compounds of Various Functional Group Classes and the Model Protein β-Lactoglobulin.

The formation of covalent bonds between 47 flavor compounds belonging to 13 different classes of functional groups and β-lactoglobulin (BLG) has been evaluated using electrospray ionization protein mass spectrometry. Covalent bond formation was determined by the appearance of ions in the mass spectra corresponding to BLG + flavor molecule(s). The observed processes for covalent bond formation were Schiff base, Michael addition, and disulfide linkages. Some reactions resulted in protein cross-linking. Aldehydes, sulfur-containing molecules (especially thiols), and functional group-containing furans were the most reactive flavor components. The thiol-containing compounds cleaved one or both electrophilic disulfide linkages in BLG to form disulfide linkages and the sulfides formed covalent bonds with the free cysteine group. Ketones were generally stable, but α-diketones (e.g., diacetyl) were reactive. Some bases (e.g., pyrazines and pyridines) were interactive, while the nucleophilic allylamine was reactive. Hydrocarbons, alcohols, acids, esters, lactones, and pyrans did not give observable levels of adduct formation within the period studied. The formation of covalent bonding (flavor protein) is potentially responsible for the loss of flavor, limiting the shelf-life of many foods.

Unusual monodentate binding of a C-NONOate ligand in the nitrosyl complex (OEP)Ru(NO)(η1-ONN(t-Bu)O)

The recent discovery of the C-NONOate moiety ([X{N2O2}]−; diazeniumdiolate) as a new class of siderophore functional group necessitates further examination of its coordination chemistry. The bidentate η2-O,O binding mode of the C-NONOate moiety is well-established. We have synthesized and characterized, by X-ray crystallography, the first monodentate η1-O binding mode of a C-NONOate group to any metal, namely that of (OEP)Ru(NO)(η1-ONN(t-Bu)O). The compound exhibits an irreversible first oxidation in CH2Cl2 at a Pt electrode. Protonation with triflic acid results in the formation of N2O, presumably from the direct protonation of the C-NONOate ligand.

Stem and leaf functional traits allow successional classification in six pioneer and non-pioneer tree species in Tropical Moist Broadleaved Forests

More than half of the tropical forests are secondary forests that are undergoing a highly dynamic interplay of forest succession of uncertain outcome. Vegetation models can help predict forest trajectory but require simplifying the high biodiversity of these forests into a few distinct classes of functional or successional groups. The classification of tree species by successional groups has traditionally relied on qualitative criteria such as life span, or on parameters that are difficult to measure on mature trees in the field, like photosynthetic activity, in particular in tropical forests. Hence, quantitative traits that can be easily measured in a number of species may provide more accurate classification thresholds. The present study identifies quantitative anatomical and biochemical traits of leaf and stem of six species that are useful for classification of successional groups in the Tropical Moist Broadleaved Forest (TMBF) of south-eastern Brazil. Consistent with assumed fast growth and high light requirements of pioneers the investigated pioneer species presented higher stem glucose content (600%), larger vessel elements (162%), greater stomatal density (72%) and higher chloroplastic pigments concentrations (90%) than non-pioneer species. By contrast, non-pioneers were characterized by larger mesophyll cells (70%) and higher cell wall polymers concentrations (65–100%) in leaf and stem. The biggest differences between pioneer and non-pioneer species were observed in leaf blade thickness, followed by vessel lumen diameter, and stem lignin. We provide research laboratories a variety of different tools that they can use as a guideline to accurately assess the successional class of tree species in the TMBF of south-eastern Brazil.

Electrically Driven N(sp2)–C(sp2/3) Bond Cleavage of Sulfonamides

Sulfonamides are a privileged class of functional groups in medicinal chemistry and an important class of protecting groups in organic synthesis. We report the discovery and development of unexpect...

Methyl Anion Affinities of the Canonical Organic Functional Groups.

Calculated methyl anion affinities are known to correlate with experimentally determined Mayr E parameters for individual organic functional group classes but not between neutral and cationic organic electrophiles. We demonstrate that methyl anion affinities calculated with a solvation model (MAA*) give a linear correlation with Mayr E parameters for a broad range of functional groups. Methyl anion affinities (MAA*), plotted on the log scale of Mayr E, provide insights into the full range of electrophilicity of organic functional groups. On the Mayr E scale, the electrophilicity toward the methyl anion spans 180 orders of magnitude.

High Intensity Functional Exercise Group Class for Acute Rehabilitation

High Intensity Functional Exercise Group Class for Acute Rehabilitation

Synthesis of anti-vicinal diboronates from diarylethynes and B2pin2

Anti-vicinal diboronates were fabricated from easily available diarylethynes and B2pin2 via a base-catalyzed domino-borylation-protodeboronation (DBP) strategy under transition-metal-free conditions. Under the standard conditions, reactants with a range of different classes of functional groups on the rings, such as MeO, MeS, CF3O, Me2N, TMS, I, Br, Cl, F, and the thiophene ring, were tolerated. Downstream transformation of the vicinal diboronates provided a facile pathway for obtaining vicinal diols by mild oxidation with NaBO3, and a new deuteriation technique was developed in order to acquire 1,2-diarylethanes-1,2-d2 and 1,2-diarylethanes-1,1,2,2-d4. The new deuteriation strategy developed in this study may provide a new research direction for deuteriation chemistry.