Carbonyl Components Research Articles

Separation of Aldehydes and Reactive Ketones from Mixtures Using a Bisulfite Extraction Protocol.

The purification of organic compounds is an essential component of routine synthetic operations. The ability to remove contaminants into an aqueous layer by generating a charged structure provides an opportunity to use extraction as a simple purification technique. By combining the use of a miscible organic solvent with saturated sodium bisulfite, aldehydes and reactive ketones can be successfully transformed into charged bisulfite adducts that can then be separated from other organic components of a mixture by the introduction of an immiscible organic layer. Here, we describe a simple protocol for the removal of aldehydes, including sterically-hindered neopentyl aldehydes and some ketones, from chemical mixtures. Ketones can be separated if they are sterically unhindered cyclic or methyl ketones. For aliphatic aldehydes and ketones, dimethylformamide is used as the miscible solvent to improve removal rates. The bisulfite addition reaction can be reversed by basification of the aqueous layer, allowing for the re-isolation of the reactive carbonyl component of a mixture.

The effect of biosilver nanoparticles on different bacterial strains’ metabolism reflected in their VOCs profiles

The use of silver nanoparticles has become in recent years a growing interest for many researchers, due to their bacteriostatic and bactericidal properties and synergetic effects when they are used together with antibiotics, for an increased efficiency and less adverse reactions in the treatment of bacterial infections. Gas chromatography coupled with mass spectrometry (GC-MS), which is considered ‘the golden standard’ in chemical analysis, has proven to be a reliable instrument, perfectly suitable for clinical analysis. In this work, three bacterial strains, Escherichia coli (E. coli), Klebsiella oxytoca (K. oxytoca) and Staphylococcus saccharolyticus (S. saccharolyticus) were treated with biosilver nanoparticles (bioAgNPs). Headspace and GC-MS analysis was used for the detection of volatile metabolites. We observed decreased amounts of alcohols and carbonyl components (mainly ketones) in K. oxytoca and S. saccharolyticus bacteria incubated with silver. In contrast, biosilver nanoparticles added to E. coli increased the amount of VOCs, mainly hydrocarbons and alcohols. Our results have successfully demonstrated that the treatment of bacterial strains with bioAgNPs has a direct influence on their VOC profiles, by modifying the number of metabolic markers. Connected with this, the inhibition of bacteria is supposed, and consequently both the bacteriostatic and/or bactericidal effects of bioAgNPs on all three bacterial strains investigated were revealed.

Synthesis of Block Copolymers Based on a Macroinitiator and 2,4-Toluene Diisocyanate

The effect of the reaction medium and synthesis temperature on the polyaddition of 2,4-toluene diisocyanate to a macroinitiator representing a potassium-substituted block copolymer of propylene and ethylene oxides is revealed. Factors affecting the polyaddition accompanied by the opening of isocyanate groups via the carbonyl component are the use of catalytic amounts of acidic compounds, water in combination with trimethylamine, and maintenance of fairly low temperatures. The dielectric properties and static electrical conductivity of polymers obtained under different reaction conditions are studied. It is shown that the preferential formation of polyisocyanates of the acetal nature and, thus, block copolymers with their participation can be responsible for change in the electrophysical properties of the polymers.

Reductive Etherification via Anion-Binding Catalysis

Reductive condensations of alcohols with aldehydes/ketones to generate ethers are catalyzed by a readily accessible thiourea organocatalyst that operates in combination with HCl. 1,1,3,3-tetramethyldisiloxane serves as a convenient reducing reagent. This strategy is applicable to challenging substrate combinations and exhibits functional group tolerance. Competing reductive homocoupling of the carbonyl component is suppressed.

Pyrolysis process using a bench scale high pressure thermobalance

The influence of the pressure and other operating conditions such as particle size, sweep gas flow and initial sample weight on the cellulose pyrolysis process using a bench scale plant high pressure thermobalance was evaluated. The particle size and the sweep gas flow did not have a great influence on the pyrolysis process. Nevertheless, initial sample weight altered the thermochemical behavior of the pyrolysis process. Moreover, a comparison of the values of the kinetic parameters obtained from pyrolysis experiments performed at lab and bench scale was established. On the other hand, the morphology, the presence of functional groups, the surface area, the proximate analysis and elemental analysis of the chars obtained were studied. Moreover, the evolved gases from the pyrolysis performed at different pressures were also analyzed. An increase of pressure led to both a decrease in the temperature at which pyrolysis took place and an increase in the char yield. Furthermore, the higher the pressure, the higher the porosity, the lower the pores size and the higher the occurrence of alkanes and carbonyl components in the resulting chars were. Finally, the gas released analysis from the pyrolysis process by mass spectrometry showed that high pressures promoted the CH4 and CO2 formation, the H2 yield being practically negligible.

A novel approach to the assessment of aerospace coatings degradation: The HyperTest

Protecting an aircraft from the extremes of environments during service begins at the interface between topcoat and environment. The topcoat considered here is an aliphatic polyurethane (PU) based matte coating. This paper examines the degradation of the PU topcoat through the use of a novel HyperTest which combines ultra-violet (UV) and ozone as the degradation method. To benchmark the technique against accepted accelerated testing methods, QUV was used and samples were tested between two and 56 days. For The HyperTest, samples were degraded at increments between one to 120 minutes. X-ray photoelectron spectroscopy (XPS) determined that 56 days of UV exposure was equivalent, in terms of the extent of the chemical degradation of the topcoat, to one to two minutes of UV/ozone (UV/O3) exposure. There was a significant increase in carbonyl component with increasing oxygen concentration for samples treated with The HyperTest, whereas no clear degradation trend was observed for the samples exposed to UV alone. After 60 minutes of UV/O3 exposure a steady-state mechanism is established as the oxidative decomposition of the PU coating. The proposed degradation mechanism of the PU topcoat, through UV/O3 exposure, is the reaction of atomic oxygen with the polymer matrix/binder through hydrogen abstraction producing a hydroxyl group. This further decomposes to produce a carbonyl component observed in the XPS analysis. The products of degradation are simple volatile molecules such as CO2 and H2O for both testing methods used here. However, the efficient nature of The HyperTest, requiring only minutes to degrade samples as shown here, proves it to be a viable complementary technique to established methods of laboratory accelerated testing.

Efficient Synthesis of Spirooxindole-Fused 3-Thiazoline Derivatives by a One-Pot Asinger-Type Reaction

A one-pot, three-component reaction has been developed and successfully employed for the synthesis of biologically relevant, highly functionalized spirooxindole-fused 3-thiazoline derivatives. Starting from ammonia, three mercapto carbonyl components and a series of substituted isatins, products were obtained in good yields (24 examples), by following a simple and rapid protocol. The obtained thiazolines proved to be optimal substrates for further transformations, including the three-component Ugi–Joullié reaction.

From Cyclic CF3-ketimines to a Family of Trifluoromethylated Nazlinine and Trypargine Analogues.

An efficient (one- and two-step) synthesis of trifluoromethylated derivatives of the natural alkaloids nazlinine, trypargine, and homotrypargine was elaborated. Trifluoromethyl-substituted 5-7-membered cyclic imines were used as a masked carbonyl component in the Pictet-Spengler reaction with various tryptamines. As a result, this approach opens access to a family of alkaloid-like compounds bearing a CF3 group at position 1 of tetrahydro-β-carboline.

ChemInform Abstract: Synthesis and Chemical Reactions of the Steroidal Hormone 17α‐Methyltestosterone.

Structural modifications of natural products with complex structures like steroids require great synthetic effort. A review of literature is presented on the chemistry of the steroidal hormone 17α-methyltestosterone that is approved by Food and Drug Administration (FDA) in the United States as an androgen for estrogen-androgen hormone replacement therapy treatment. The analog also offers special possibilities for the prevention/treatment of hormone-sensitive cancers. The testosterone skeleton has important functionalities in the molecule that can act as a carbonyl component, an active methylene compound, α,β-unsaturated enone and tertiary hydroxyl group in various chemical reactions to access stereoisomeric steroidal compounds with potent activity. In addition, microbiological methods of synthesis and transformation of this hormone are presented.

Scandium triflate-catalyzed selective ring opening and rearrangement reaction of spiro-epoxyoxindole and carbonyl compounds

Scandium triflate-catalyzed reactions between spiro-epoxyoxindole and carbonyl compounds have been disclosed. Furthermore, an unprecedented rearrangement takes place to yield alkylidene oxindoles when aromatic aldehydes are used as carbonyl components.

Structures and packing of ferrocenylmethyl methacrylate and ferrocene-1,1'-diylbis(methylene) dimethacrylate.

Electroactive metallocene polymers are of interest due to the possibility that they offer a muscle-like response, and in gel systems very large volume changes are possible. The ferrocenyl moiety exhibits physical and electrochemical stability of the neutral and oxidized forms and could be a candidate for use as the redox-active group in these materials. The title compounds, [Fe(C5H5)(C10H11O2)], (I), and [Fe(C10H11O2)2], (II), comprise a typical ferrocene core with coplanar and approximately eclipsed cyclopentadienyl (Cp) rings. In (I), there is a single methyl methacrylate substituent, with the other Cp ring unsubstituted. In (II), a methyl methacrylate substituent on each Cp ring completes the structure. In both compounds, there is an s-trans geometry of the vinyl and carbonyl components of the methacrylate group. Inversion dimers formed through C-H...O contacts dominate the crystal packing of both molecules. Weak C-H...π(ring) contacts and, in the case of (I), an unusual C-H...π(alkene) contact further stabilize the structures.

Synthesis of rigid tryptophan mimetics by the diastereoselective Pictet-Spengler reaction of β³-homo-tryptophan derivatives with chiral α-amino aldehydes.

The Pictet-Spengler (PS) cyclizations of β(3)-hTrp derivatives as arylethylamine substrates were performed with L-α-amino and D-α-amino aldehydes as carbonyl components. During the PS reaction, a new stereogenic center was created, and the mixture of cis/trans 1,3-disubstituted 1,2,3,4-tetrahydro-β-carbolines was obtained. The ratio of cis/trans diastereomers depends on the stereogenic centre of used amino aldehyde and the size of substituents. It was confirmed by 1H and 2D NMR (ROESY) spectra. The conformations of cyclic products were studied by 2D NMR ROESY spectra. Products of the PS condensation after removal of protecting group(s) can be incorporated into a peptide chain as tryptophan mimetics with the possibility of the β-turn induction.

Three Solvent‐Free Catalytic Approaches to the Acetal Functionalization of Carbohydrates and Their Applicability to One‐Pot Generation of Orthogonally Protected Building Blocks

AbstractThree alternative protocols were developed to carry out the selective installation of acetal groups on carbohydrates and polyols under mildly acidic, solvent‐free conditions. One protocol is based on a diol/aldehyde condensation at room temperature, with an acetolysis process serving for the activation of the carbonyl component. A second approach is based on an orthoester‐mediated activation of the carbonyl component at high temperature. The third protocol is instead entailing a transacetalation mechanism. Combination of these methods allows a wide set of acetal‐protected building blocks to be accessed in short times under very simple experimental conditions working under air. The scope of the latter two approaches was also extended to unusual one‐pot synthetic sequences leading to concomitant Fischer glycosidation/acetal protection of reducing sugars.magnified image

Cross-selectivity in the catalytic ketonization of carboxylic acids

A mixture of acetic and 2-methylpropanoic (isobutyric) acids representing non-branched and branched acids, respectively, was catalytically converted to a mixture of ketones in a set of statistically designed experiments (DOE). The selectivity toward the cross-ketonization product was analyzed depending on (a) temperature within 300–450°C range, (b) molar fraction of each acid in the mixture, from 10% to 90%, and (c) liquid hourly space velocity (LHSV) within 2–12h−1, and compared against the selectivity toward two symmetrical ketones. Six metal oxide catalysts were tested and ranked on their ability to yield the cross-product as opposed to the self-condensation product. The catalysts were based on either the anatase form of titania or monoclinic form of zirconia and treated with either KOH or K2HPO4. The titania catalyst treated by KOH outperformed all other catalysts by providing the cross-selectivity above the statistically expected binomial distribution. The criterion for having a high cross-selectivity in the decarboxylative ketonization is formulated mathematically as the separation of roles of two acids, one being a more active enolic component, and the other being the preferred carbonyl component. According to the suggested criterion, the less branched acetic acid reacts as both the preferred carbonyl and enolic component with untreated catalysts. Therefore, untreated catalysts promote selective formation of the symmetrical ketone, acetone, thereby decreasing the selectivity to the cross-ketone. After alkaline treatment, both the anatase form of titania and monoclinic form of zirconia increase the isobutyric acid participation as the carbonyl component. Acetic acid remains as the preferred enolic component with all treated catalysts, thus increasing the selectivity toward the cross-product in the ketonization of a mixture of carboxylic acids. The condition for achieving a high cross-selectivity by polarizing roles of the two reactants can be extended to other types of cross-condensations.

A Cascade Aza‐Cope/Aza‐Prins Cyclization Leading to Piperidine Derivatives

AbstractThe cascade aza‐Cope/aza‐Prins cyclization of homoallylamines to give substituted piperidines has been explored. The use of glyoxalic acid as the carbonyl component afforded bicyclic structures as a result of the internal carboxylate anion trapping the intermediate cation. The unimolecular bis‐, tris‐, and tetrakis(homoallylamine)s efficiently delivered the appended bis‐, tris‐ and tetrakis(piperidine‐4‐ol)s (tripod and crucifix shape, respectively) as new entities. The latter compound served as an excellent ligand in the Suzuki–Miyaura cross‐coupling reaction to synthesize incrustoporin.

Microplasma pen designs for surface chemical pattern fabrication

Introduction: Surface engineering approaches have been investigated to control cell responses in vitro . Surface chemistry impacts greatly on cell responses. Amines mimic the natural biological environment and are therefore widely used for these investigations. Chemical patterning allows the presentation of defined surface regions controlling cell attachment and morphology. Designer interactions can be fabricated between discrete cell populations. This is increasingly important within the field of regenerative medicine as researchers are striving to mimic complex cellular architectures. Current surface chemical patterning methods are, however, limited in this capacity because of multistep and time-consuming methodologies. Objectives: Here we present the use of plasma pens for direct-writing defined chemical regions. Cell response to these areas has been assessed, showing a capacity to control cell attachment and directional morphology. Materials and methods: A fluoropolymer was etched via helium radio frequency plasma (9W; 13.56MHz); allylamine was also polymerized in the plasma. Surfaces were characterized by water contact angles (WCA) and Raman microscopy. HEK293 cells were cultured over the chemically modified surfaces at 37°C in media containing 10% fetal calf serum, 1% Glu and 1% penicillin/streptomycin. Results: Helium plasma-treated regions were hydrophilic compared with the surrounding hydrophobic areas, having WCAs of ≈ 15° and ≈ 112°, respectively. Defined patterns were visualized by wettability maps and Raman microscopy. Plasma-treated regions were devoid of polymeric groups, also apparent in surrounding fluorocarbon regions, indicating plasma etching had taken place. Edges of the chemical pattern showed a higher proportion of carbonyl component, indicating localized oxidization. Cells were found to attach well to plasma-treated regions, elongating along the length of the pattern edge. Conclusions: Surface chemical patterning can be achieved by direct-write using a plasma pen. These regions can be tuned to control cell attachment and elongation. Acknowledgements: We thank the College of Medicine, Imam Muhammad ibn Saud Islamic University for student scholarship support to carry out this project at Keele University.

Formation of Poultry Meat Flavor by Heating Process and Lipid Oxidation

Flavor is an important factor in the acceptance of food. Flavor of poultry meat is naturally formed through a specific process of heating, where various chemical reactions complex occurred among nonvolatile precursors in fatty tissue or in lean tissue. The main flavor in the form of volatile and nonvolatile components play a major influence on the acceptance of various processed meat, especially the taste. Removal of sulfur components decreases meat flavor (meaty), while removal of carbonyl compounds decrease the specific flavor and increases common flavor of the meat. Poultry meat has a fairly high fat content that easily generates lipid oxidation. Lipid oxidation in poultry meat is a sign that the meat was damaged and caused off odor. Addition of antioxidants in the diet can inhibit lipid oxidation in the meat. Lipids interaction with proteins and carbohydrates is unavoidable during the thermal processing of food, causing the appearance of volatile components. The main reaction in meat flavor formation mechanism is Maillard reaction followed by Stecker reaction and degradation of lipids and thiamine. They involve in the reaction between carbonyl and amine components to form flavor compounds, which enhance the flavor of poultry meat. Key words: Flavor, off flavor, poultry meat, lipid oxidation, antioxidant

ChemInform Abstract: Convenient Access to Novel Functionalized Pyrazino[1,2‐b]isoquinolin‐6‐one and Diazepino[1,2‐b]isoquinolin‐7‐one Scaffolds via the Cushman Multicomponent Reaction Followed by Post‐Condensation.

AbstractThe synthesis is based on Cushman multicomponent reaction, wherein aryl glyoxals are used as the carbonyl component for the first time.

A Haxpes Study on Solid Electrolyte Interphase Formed on a Carbon Negative Electrode

Solid electrolyte interphase (SEI) formed on a carbon negative electrode plays an important role in supporting the reversible Li ion intercalation phenomena during charge and discharge treatments. Since the chemical and electrochemical conditions of the electro-lyte/electrode interface change during electrochemical lithiation and delithiation reactions, the structure of the SEI might change even after the formation of the SEI by the initial charge and discharge treatments, although details of the reaction mechanism remain unknown. We, therefore, investigated the behavior of the SEI of a carbon negative electrode during electrochemical lithiation and delithiation reactions by using Hard X-ray photoelectron spectroscopy (HAX-PES) technique. Lithiated and delithiated carbon anodes were prepared by using a coin-type cell with Li metal. The carbon anode was a composite graphite (active agents, carbon black, PVDF) coated on Cu foil. The electrolyte was 1 M LiPF6 in ethylene carbonate / diethyl carbonate (EC / DEC) in a 1:1 volume ratio. After charge and discharge, the cell was disassembled and the anode was then retrieved, washed with dimethyl carbonate repeatedly in an argon-filled glovebox (<1 ppm H2O, <1 ppm O2). The anodes were transferred from the glovebox to UHV measurement chamber without exposing to the air by using special transfer systems. The HAXPES measurements were carried out at the BL46XU beamline at SPring-8. The photon energy of incident x-rays was 8 keV. Figure 1 shows C 1s HAXPES spectra for the lithiated graphite anodes with the state of charge (SOC) 0%, 50%, 100% after twice charge and discharge cycles. The spectra were fitted with six singlets centered at 283.5eV (Peak 1), 284.6 eV (Peak 2), 285.5 eV (Peak 3), 287 eV(Peak 4), 289 eV(Peak 5) and 290.5 eV(Peak 6). Peak 1 can be assigned to lithiated carbon LixC. Peak 2 can be assigned to hydrocarbons for lithium alkyl carbonate (LAC), the organic materials of SEI and PVDF binder. The carbonyl components for the LAC are observed as Peak 3, Peak 4, and Peak 5. Peak 6 can be associated with a organofluorine component for the PVDF binder and a carbonate component for the Li2CO3, a inorganic material of SEI. LixC was observed in the C 1s HAXPES spectra with all SOC conditions, whereas this peak wasn’t observed in the C 1s XPS spectra with Al K-α incident x-rays for the lithiated graphite anodes with SOC 50%, 100% after twice charge and discharge cycles (the C 1s XPS spectra were not shown). This result indicates that the probing depth of HAXPES (hν = 8keV) is larger than thickness of SEI, thus HAXPES detected whole SEI and a part of the LixC exists underneath SEI formed on all the lithiated graphite anodes in the depth direction. HAXPES technique allows us to analyze the variation of the chemical composition of SEI depending on electrochemical lithiation and delithiation reactions. Table 1 shows the concentration ratio of LixC, LAC, and Li2CO3 depending on SOC determined by the C 1s HAXPES spectra. The ratio of LixC decreases up to SOC 100%, while those of LAC, and Li2CO3 increases up to SOC 100%. This variation shows the structural behavior of the SEI during electrochemical lithiation reactions after the formation of the SEI by the initial charge and cycles: SEI continues growth and dissolution even after stable state is established. Acknowledgement The synchrotron experiments were carried out on beamline BL46XU at Spring-8 with approvals from Japan synchrotron radiation institute (JASRI) (Proposal nos. 2013A1234)[1] H. Hori, M. Shikano, H. Kobayashi, S. Koike, H. Sakaebe, Y. Saito, K. Tatsumi, H. Yoshikawa, and E. Ikenaga J. Power. Sources, 242, 844 (2013).[2] P. Verma, P. Maire1, and P. Novak, Electrochim. Acta., 55, 6332 (2010). [3] K. Xu and Arthur V. Cresce, J. Mater. Chem., 21, 9849 (2011).

Synthesis of arylmethylidene(ethylidene)furanones

The data on the methods of synthesizing arylmethylidene(ethylidene) derivatives of 3H-furan-2-ones and related compounds based on the heterocyclization of different acids and their functional derivatives as well as the condensation of heterocyclic compounds with carbonyl components, are systematized in the review.