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How Are Ketones And Aldehydes Related Apex

Comprehensive 2d Gc With Tof-ms Detection: Study Of Pyrolytic Bio-oil Of Kraft Mill Residues

Comprehensive 2d Gc With Tof-ms Detection: Study Of Pyrolytic Bio-oil Of Kraft Mill Residues

ARTICLE Candice S. FacciniI; Isadora Dalla VecchiaII; Desyrre RibeiroI; Claudia A. ZiniI; Elina B. CaramãoI,* IPós-Graduação em Química IIPós-Graduação em Ciências dos Materiais, Laboratório de Química Analítica Ambiental e Oleoquímica (LAAO), Instituto de Química, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre-RS, Brazil ABSTRACT Brazil is a great manufacturer of Eucalyptus pulp and has experienced important improvements in the environmental management in the last decades. However, there are still opportunities for alternative uses of pulp mill residues, which may result in higher added value products. Qualitative and semi-quantitative characterizations of bio-oil composition of three pulp mill residues (Eucalyptus sawdust, digester residue and wastewater treatment sludge) were performed using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GC×GC/TOF-MS). The best pyrolysis conditions achieved for the digester residue were applied to the other residues and similar bio-oils were obtained for sawdust and digester residue, while sludge rendered a more complex pyrolysate. The advantages of GC×GC/TOF-MS for this specific application are presented, as well as the potential of bio-oil components for important industrial applications. Keywords: comprehensive two-dimensional gas chromatography, bio-oil, pyrolysis, pulp and paper residues, time-of-flight RESUMO O Brasil é um grande fabricante de celulose de eucalipto e experimentou progressos importantes na gestão ambiental nesta área nas últimas décadas. Entretanto, ainda há oportunidades para usos alternativos dos resíduos dessas fábricas, que podem resultar em produtos de maior valor agregado. As caracterizações qualitativa e semi- Continue reading >>

Aucl3-catalyzed Benzannulation: Synthesis Of Naphthyl Ketone Derivatives From O-alkynylbenzaldehydes With Alkynes

Aucl3-catalyzed Benzannulation: Synthesis Of Naphthyl Ketone Derivatives From O-alkynylbenzaldehydes With Alkynes

Abstract The reaction of o-alkynylbenzaldehydes 1 and alkynes 2 in the presence of a catalytic amount of AuCl3 in (CH2Cl)2 at 80 °C gave naphthyl ketone products in high yields. The AuCl3-catalyzed formal [4 + 2] benzannulation proceeds most probably through the coordination of the triple bond of 1 to AuCl3, the formation of benzo[c]pyrylium auric ate complex via the nucleophilic addition of the carbonyl oxygen atom, the Diels−Alder addition of alkynes 2 to the auric ate complex, and subsequent bond rearrangement. Similarly, the AuCl3-catalyzed reactions of o-alkynylacetophenone and o-alkynylbenzophenone with phenylacetylene afforded the corresponding naphthyl ketone products in good yields. Continue reading >>

Allergic Asthma Exhaled Breath Metabolome: A Challenge For Comprehensive Two-dimensional Gas Chromatography

Allergic Asthma Exhaled Breath Metabolome: A Challenge For Comprehensive Two-dimensional Gas Chromatography

Allergic asthma represents an important public health issue, most common in the paediatric population, characterized by airway inflammation that may lead to changes in volatiles secreted via the lungs. Thus, exhaled breath has potential to be a matrix with relevant metabolomic information to characterize this disease. Progress in biochemistry, health sciences and related areas depends on instrumental advances, and a high throughput and sensitive equipment such as comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC-ToFMS) was considered. GC×GC-ToFMS application in the analysis of the exhaled breath of 32 children with allergic asthma, from which 10 had also allergic rhinitis, and 27 control children allowed the identification of several hundreds of compounds belonging to different chemical families. Multivariate analysis, using Partial Least Squares-Discriminant Analysis in tandem with Monte Carlo Cross Validation was performed to assess the predictive power and to help the interpretation of recovered compounds possibly linked to oxidative stress, inflammation processes or other cellular processes that may characterize asthma. The results suggest that the model is robust, considering the high classification rate, sensitivity, and specificity. A pattern of six compounds belonging to the alkanes characterized the asthmatic population: nonane, 2,2,4,6,6-pentamethylheptane, decane, 3,6-dimethyldecane, dodecane, and tetradecane. To explore future clinical applications, and considering the future role of molecular-based methodologies, a compound set was established to rapid access of information from exhaled breath, reducing the time of data processing, and thus, becoming more expedite method for the clinical purposes. Continue reading >>

Fragrance Sample? Aldehydes And Ketones

Fragrance Sample? Aldehydes And Ketones

Formaldehyde and acetone are immediately associated with nail hardeners and nail enamel remover. In chemical terms, these substances belong to the substance class of aldehydes and ketones - which are well-known molecules in cosmetic products like e.g. preservatives, perfumes or essential oils. Aldehydes and ketones are oxygen-containing hydrocarbons and can be found in abundance either in natural surroundings but also in combination with chemical processes. They are formed with the oxidation of alcohol for instance. The low molecular molecules are used in cosmetic products because of their flowery notes and solvent characteristics. Aldehydes and ketones also are known for their chemical reactivity which is the reason for a strong antimicrobial activity. Formaldehyde is not equipped with an agreeable fragrance though, as a matter of fact even in small concentrations it has quite a disagreeable pungent and acrid smell that irritates eyes and respiratory tract. Due to the high reactivity of formaldehyde with nitrogen-containing substances like proteins respectively amino acids, it is used as a disinfecting agent and preservative. formaldehyde Since formaldehyde has meanwhile been classified as a carcinogenic substance, its use in cosmetic products is subject to strong restrictions (KVO - German Cosmetic Decree): "Every finished product containing formaldehyde and those that release formaldehyde are subject to be labeled "containing formaldehyde" as far as the concentration of formaldehyde in the finished product exceeds 0.05 %." Nail hardeners may contain concentrations of about 5 % though. Once applied on the nails it cross-links with the protein structures of the keratin in the nails similar to cross-linkage processes in plastics manufacturing. Formaldehyde use declining Continue reading >>

How Are Aldehydes And Ketones Alike?

How Are Aldehydes And Ketones Alike?

Both aldehydes (R-CHO) and ketones (R-CO-R') are called carbonyl compounds as they have the electron-withdrawing carbonyl group (C=O) in their molecules. On reduction both these classes of compounds yield respective alcohols. Aldehydes are converted to primary alcohols, and ketones to secondary alcohols. Both aldehydes and ketones undergo addition reactions at the CO group with compounds such as NH3, NH2OH, HCN and NaHSO3. On treatment with PCl5, the oxygen atom of the CO group gets replaced by chlorine, and they form dichloro compounds of the types R-CHCl2 and R-CCl2-R' respectively. Both undergo self-condensation in the presence of alkalis. Both acetaldehyde and acetone (and other methyl ketones) form iodoform with iodine and alkali. Aldehydes on oxidation are converted to carboxylic acids with same number of carbon atoms. Though ketones resist oxidation, they can be oxidised by strong oxidising agents like chromic acid to carboxylic acids containing lesser number of carbon atoms, as the molecule gets ruptured at the CO group. One major difference between aldehydes and ketones is that the former have distinct reducing properties. Aldehydes reduce Tollen's reagent to metallic silver, and Fehling's solution to red cuprous oxide. Continue reading >>

Final Report: New Chemical Analysis Tools For Aromatic Hydrocarbons

Final Report: New Chemical Analysis Tools For Aromatic Hydrocarbons

EPA Grant Number: R829415E02 Title: New Chemical Analysis Tools for Aromatic Hydrocarbons Investigators: Campiglia, Andres D. , Borgerding, Anthony J. , Swenson, Orven F. Institution: North Dakota State University Main Campus , University of North Dakota EPA Project Officer: Hunt, Sherri Project Amount: $499,105 RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (2000) RFA Text | Recipients Lists Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research) Objective: Our Science and Engineering Environmental Research (SEER) project was a focused, multidisciplinary, multi-institutional approach to developing new analysis methodology for an important class of organic contaminants: the aromatic hydrocarbons. Specifically, the research proposed in the SEER section led to improved methodology for the selective chemical analysis of polycyclic aromatic hydrocarbons (PAHs), the BTEX compounds (benzene, toluene, ethylbenzene, and the xylenes), and the halogenated benzene compounds. Summary/Accomplishments (Outputs/Outcomes): Dr. Borgerding funded four undergraduate students who performed various projects related to the aromatic selective laser ionization detector (ArSLID). These projects included studies to determine the degree of improvement in selectivity and sensitivity offered for aromatic compounds with various substituent groups. A new gas chromatography (GC) detector was created that is comparatively sensitive and far more selective for aromatic compounds than the traditional photoionization detector. The detection means is multiphoton ionization at atmospheric pressure. The ionization source in these experiments is a diode-pumped passively Q-switched microchip laser operating at 266 nm. Experiments were conducted with the detec Continue reading >>

Annulative Π-extension (apex): Rapid Access To Fused Arenes, Heteroarenes, And Nanographenes

Annulative Π-extension (apex): Rapid Access To Fused Arenes, Heteroarenes, And Nanographenes

Abstract The annulative π-extension (APEX) reaction has the potential to have a tremendous impact on the fields of materials science and bioimaging, as well as on the pharmaceutical/agrochemical industries, since it allows access to fused aromatic systems from relatively simple aromatic compounds in a single step. Typically, an APEX reaction facilitates a one-pot π-extension without the need to prefunctionalize the aromatic compounds. This advantageous feature is extremely useful for tuning and modifying molecular properties in the last step of a synthesis. In this Review, the progress and applications of APEX reactions of unfunctionalized arenes and heteroarenes are described. Continue reading >>

Organocatalytic Asymmetric Α-bromination Of Aldehydes And Ketones

Organocatalytic Asymmetric Α-bromination Of Aldehydes And Ketones

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Organocatalytic Asymmetric Α-bromination Of Aldehydes And Ketones

Organocatalytic Asymmetric Α-bromination Of Aldehydes And Ketones

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Modifying Electron Transfer Between Photoredox And Organocatalytic Units Via Framework Interpenetration For Β-carbonyl Functionalization

Modifying Electron Transfer Between Photoredox And Organocatalytic Units Via Framework Interpenetration For Β-carbonyl Functionalization

Modifying electron transfer pathways is essential to controlling the regioselectivity of heterogeneous photochemical transformations relevant to saturated carbonyls, due to fixed catalytic sites. Here we show that the interpenetration of metal–organic frameworks that contain both photoredox and asymmetric catalytic units can adjust the separations and electron transfer process between them. The enforced close proximity between two active sites via framework interpenetration accelerates the electron transfer between the oxidized photosensitizer and enamine intermediate, enabling the generation of 5πe− β-enaminyl radicals before the intermediates couple with other active species, achieving β-functionalized carbonyl products. The enriched benzoate and iminium groups in the catalysts provide a suitable Lewis-acid/base environment to stabilize the active radicals, allowing the protocol described to advance the β-functionalization of saturated cyclic ketones with aryl ketones to deliver γ-hydroxyketone motifs. The homochiral environment of the pores within the recyclable frameworks provides additional spatial constraints to enhance the regioselectivity and enantioselectivity. Catalytic synthesis methods that work under ambient atmosphere with benign reaction environments and clean energy have been a major goal in synthetic chemistry1. Of the essential structural motifs that are frequently found in pharmaceutical, material, agrochemical, and fine chemicals, the carbonyls play a pivotal role as powerful building blocks in broad areas of synthetic organic chemistry2,3,4. The functionalization of carbonyls, one of the most fundamental transformation in organic synthesis, has evolved to a range of widely used organic reactions and synthetic protocols5. While direct α-car Continue reading >>

Microbial Volatile Organic Compounds (mvoc's)

Microbial Volatile Organic Compounds (mvoc's)

Hello, I hope you're enjoying spring and doing well. Attached are articles by Karen Abella Santo-Pietro and Gregorio Delgado, regarding MVOC's and Nigrospora respectively, that I hope you'll find interesting and useful. With best wishes, Dave Gallup Volatile Organic Compounds (VOC's) are chemicals with low molecular weights, high vapor pressure and low water solubility. These chemical characteristics allow VOC's to easily evaporate into the air or "off-gas". VOC's can be produced through industrial or biological processes. In the industrial setting, VOC's are commonly used or are created as by-products in the manufacture of paints, pharmaceuticals, refrigerants, petroleum fuels, household cleaners, and other products. VOC's can also be produced by microorganisms such as fungi and bacteria. During metabolism, microbes can produce these chemicals, specifically called Microbial Volatile Organic Compounds (MVOC's). This article will concentrate on MVOC's, as opposed to industrially produced VOC's, and their relevance in the indoor air quality setting. Microbial Volatile Organic Compounds (MVOC's) are composed of low molecular weight alcohols, aldehydes, amines, ketones, terpenes, aromatic and chlorinated hydrocarbons, and sulfur-based compounds, all of which are variations of carbon-based molecules. MVOC's have a very low odor threshold, thus, making them easily detectable by smell. They often have strong odors and are responsible for the odious smells ("old cheese", dirty socks" or "locker room") associated with mold and bacterial growth. MVOC's are products of the microbes' primary and secondary metabolism. In primary metabolism, the organism breaks down food in the environment to extract nutrients needed for the maintenance of cell structures and, in the process, creates Continue reading >>

Acetone Peroxide

Acetone Peroxide

Acetone peroxide is an organic peroxide and a primary high explosive. It is produced by the oxidation of acetone to yield a mixture of linear monomer and cyclic dimer, trimer, and tetramer forms. The trimer is known as triacetone triperoxide (TATP) or tri-cyclic acetone peroxide (TCAP). Acetone peroxide takes the form of a white crystalline powder with a distinctive bleach-like odor (when impure) and can explode if subjected to heat, friction, static electricity, strong UV radiation or shock. As a non-nitrogenous explosive, TATP has historically been more difficult to detect, and it has been used as an explosive in several terrorist attacks since 2001. History[edit] Acetone peroxide (specifically, triacetone triperoxide) was discovered in 1895 by Richard Wolffenstein.[2] Wolffenstein combined acetone and hydrogen peroxide, and then he allowed the mixture to stand for a week at room temperature, during which time a small quantity of crystals precipitated, which had a melting point of 97 °C.[3] In 1899 Adolf von Baeyer and Victor Villiger described the first synthesis of the dimer and described use of acids for the synthesis of both peroxides.[4] Baeyer and Villiger prepared the dimer by combining potassium persulfate in diethyl ether with acetone, under cooling. After separating the ether layer, the product was purified and found to melt at 132–133 °C.[5] They found that the trimer could be prepared by adding hydrochloric acid to a chilled mixture of acetone and hydrogen peroxide.[6] By using the depression of freezing points to determine the molecular weights of the compounds, they also determined that the form of acetone peroxide that they had prepared via potassium persulfate was a dimer, whereas the acetone peroxide that had been prepared via hydrochloric acid wa Continue reading >>

Laminin Targeting Of A Peripheral Nerve-highlighting Peptide Enables Degenerated Nerve Visualization

Laminin Targeting Of A Peripheral Nerve-highlighting Peptide Enables Degenerated Nerve Visualization

Abstract Target-blind activity-based screening of molecular libraries is often used to develop first-generation compounds, but subsequent target identification is rate-limiting to developing improved agents with higher specific affinity and lower off-target binding. A fluorescently labeled nerve-binding peptide, NP41, selected by phage display, highlights peripheral nerves in vivo. Nerve highlighting has the potential to improve surgical outcomes by facilitating intraoperative nerve identification, reducing accidental nerve transection, and facilitating repair of damaged nerves. To enable screening of molecular target-specific molecules for higher nerve contrast and to identify potential toxicities, NP41’s binding target was sought. Laminin-421 and -211 were identified by proximity-based labeling using singlet oxygen and by an adapted version of TRICEPS-based ligand-receptor capture to identify glycoprotein receptors via ligand cross-linking. In proximity labeling, photooxidation of a ligand-conjugated singlet oxygen generator is coupled to chemical labeling of locally oxidized residues. Photooxidation of methylene blue–NP41-bound nerves, followed by biotin hydrazide labeling and purification, resulted in light-induced enrichment of laminin subunits α4 and α2, nidogen 1, and decorin (FDR-adjusted P value < 10−7) and minor enrichment of laminin-γ1 and collagens I and VI. Glycoprotein receptor capture also identified laminin-α4 and -γ1. Laminins colocalized with NP41 within nerve sheath, particularly perineurium, where laminin-421 is predominant. Binding assays with phage expressing NP41 confirmed binding to purified laminin-421, laminin-211, and laminin-α4. Affinity for these extracellular matrix proteins explains the striking ability of NP41 to highlight deg Continue reading >>

Peptide Synthesis Resins

Peptide Synthesis Resins

Linkers and Synthesis Resins The core resins, by themselves, have limited utility as peptide synthesis resins. Peptides can be cleaved from Merrifield resin and MBHA resin in good yield only with strong acid and are seldom used with Fmoc-amino acids. Peptides attached to aminomethyl resin can not be removed without destroying or seriously damaging the peptide. The cleavage properties of the resins can be modified by permanently attaching suitable linkers. By manipulating the structure of the linker, resins ranging from extremely acid labile to base labile can be prepared. Using linkers additionally allows preparation of resins with special applications such as DHP resin utilized as a solid phase support for alcohols or Weinreb resin utilized for preparing aldehydes and ketones. PAM resin is widely used for solid phase synthesis of peptides utilizing the Boc strategy. The numerous Boc deprotection reactions with trifluoroacetic acid (TFA) required in the synthesis of large peptides leads to significant losses of peptide from Merrifield resin.1 PAM resin provides better stability to TFA,2 but the finished products are harder to cleave. Since typical cleavage conditions require a strong acid such a HF, this resin has found limited use in solid phase organic chemistry.3 Wang resin is the most widely used solid phase support for acid substrates. The linker attached to the polystyrene core is a 4-hydroxybenzyl alcohol moiety.4 The linker is bound to the resin through a phenyl ether bond and the substrate is generally attached to the linker by a benzylic ester or ether bond. This linkage has good stability to a variety of reaction conditions, but can be readily cleaved by moderate treatment with an acid, generally trifluoroacetic acid. Impurities can form if a portion of the l Continue reading >>

Efficient Hydrogenation Of Ketones And Aldehydes Catalyzed By Well-defined Iron(ii) Pnp Pincer Complexes: Evidence For An Insertion Mechanism

Efficient Hydrogenation Of Ketones And Aldehydes Catalyzed By Well-defined Iron(ii) Pnp Pincer Complexes: Evidence For An Insertion Mechanism

Go to: Introduction The catalytic reduction of polar multiple bonds via molecular hydrogen plays a significant role in modern synthetic organic chemistry. This reaction is excellently performed by many transition metal complexes containing noble metals such as ruthenium, rhodium, or iridium.1 However, the limited availability of precious metals, their high price, and their toxicity diminish their attractiveness in the long run, and more economical and environmentally friendly alternatives have to be found. In this respect, the preparation of well-defined iron-based catalysts of comparable activity would be desirable.2 Iron is the most abundant transition metal in the earth’s crust and is ubiquitously available. Accordingly, it is not surprising that the field of iron-catalyzed hydrogenations of polar multiple bonds is rapidly evolving, as shown by several recent examples.3−7 It is interesting to note that many of these hydrogenations involve ligand–metal bifunctional catalysis (metal–ligand cooperation);8 that is, the complexes contain electronically coupled hydride and acidic hydrogen atoms as a result of heterolytic dihydrogen cleavage that may be transferred to polar unsaturated substrates in an outer-sphere fashion or may be transferred via hydride migration (inner-sphere mechanism). An effective way of bond activation by metal–ligand cooperation involves aromatization/dearomatization of the ligand in pincer-type complexes. In particular, pincer ligands in which a central pyridine-based backbone is connected with −CH2PR2 and/or −CH2NR2 substituents were shown to exhibit this behavior.9 This has resulted in the development of novel and unprecedented iron catalysis where this type of cooperation plays a key role in the heterolytic cleavage of H2.4 In the Continue reading >>

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