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How Are Ketones And Aldehydes Related Apex

Carbanion

Carbanion

Carbanion, any member of a class of organic compounds in which a negative electrical charge is located predominantly on a carbon atom. Carbanions are formally derived from neutral organic molecules by removal of positively charged atoms or groups of atoms, and they are important chiefly as chemical intermediates—that is, as substances used in the preparation of other substances. Important industrial products, including useful plastics, are made using carbanions. The simplest carbanion, the methide ion (CH-3 ), is derived from the organic compound methane (CH4) by a loss of a proton (hydrogen ion, H+) as shown in the following chemical equation: in which the symbols C and H represent, respectively, carbon and hydrogen atoms; the subscripts indicate the numbers of atoms of each kind included in the molecules; the superscript plus and minus signs indicate, respectively, positive and negative charges; and the double arrows indicate that the reaction shown can proceed in either the forward or the reverse direction, a condition known as reversibility. Molecular structures. In discussing the structures of carbanions, one must distinguish between localized and delocalized ions. In the former, the negative charge is confined largely to one carbon atom, whereas, in the latter, it is distributed over several atoms. Localized ions. The simplest localized carbanion is the methide ion (CH-3). It is isoelectronic (it has identical electron configuration) with the neutral molecule ammonia (formula NH3, N being the chemical symbol for the nitrogen atom). The geometry of the methide ion is best represented by a pyramid with the carbon atom at the apex, a structure similar to that of the ammonia molecule. Both structures are shown below: in which the solid lines represent bonds between Continue reading >>

Organocatalytic Asymmetric Α-bromination Of Aldehydes And Ketones

Organocatalytic Asymmetric Α-bromination Of Aldehydes And Ketones

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The Involvement Of Lipid Peroxide-derived Aldehydes In Aluminum Toxicity Of Tobacco Roots

The Involvement Of Lipid Peroxide-derived Aldehydes In Aluminum Toxicity Of Tobacco Roots

Oxidative injury of the root elongation zone is a primary event in aluminum (Al) toxicity in plants, but the injuring species remain unidentified. We verified the hypothesis that lipid peroxide-derived aldehydes, especially highly electrophilic α,β-unsaturated aldehydes (2-alkenals), participate in Al toxicity. Transgenic tobacco (Nicotiana tabacum) overexpressing Arabidopsis (Arabidopsis thaliana) 2-alkenal reductase (AER-OE plants), wild-type SR1, and an empty vector-transformed control line (SR-Vec) were exposed to AlCl3 on their roots. Compared with the two controls, AER-OE plants suffered less retardation of root elongation under AlCl3 treatment and showed more rapid regrowth of roots upon Al removal. Under AlCl3 treatment, the roots of AER-OE plants accumulated Al and H2O2 to the same levels as did the sensitive controls, while they accumulated lower levels of aldehydes and suffered less cell death than SR1 and SR-Vec roots. In SR1 roots, AlCl3 treatment markedly increased the contents of the highly reactive 2-alkenals acrolein, 4-hydroxy-(E)-2-hexenal, and 4-hydroxy-(E)-2-nonenal and other aldehydes such as malondialdehyde and formaldehyde. In AER-OE roots, accumulation of these aldehydes was significantly less. Growth of the roots exposed to 4-hydroxy-(E)-2-nonenal and (E)-2-hexenal were retarded more in SR1 than in AER-OE plants. Thus, the lipid peroxide-derived aldehydes, formed downstream of reactive oxygen species, injured root cells directly. Their suppression by AER provides a new defense mechanism against Al toxicity. Aluminum (Al) is the most abundant metal in the earth's crust and is a major factor limiting plant growth and productivity in acid soils, which cover about 50% of the world's potentially arable land surface (Kochian, 1995; Kochian et al., 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 >>

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 >>

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 >>

Proactive Repellent And Camp Perimeter Defense Against Apex Predators

Proactive Repellent And Camp Perimeter Defense Against Apex Predators

BACKGROUND BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION This disclosure describes a proactive repellent and camp perimeter defense against apex predators. In an implementation, the proactive repellent is a liquid agent tuned to the particularly sensitive olfactory senses of apex predators. The example repellent is aversive to apex predators, which find the repellent distressing, threatening, repugnant, or sickening. In an implementation, the example repellent contains ingredients to catch the attention of the apex predator, while also providing olfactory aversion signals to the predator. In an implementation, the example repellent also has very low toxicity. The example repellent may also be made from environmentally safe compounds. FIG. 1 shows an example area 100, a campsite to be proactively protected by the example repellent 102 from an apex predator 104. In an implementation, the example repellent 102 can be applied around the area 100 to be proactively protected via delivery methods such as by spray, aerosol, gel, stream, or squirt apparatuses, or by foam, cloth, gauze, sponge, wick, or swab applicators. The repellent 102 then dries, emitting odors and chemicals in both liquid and dried states. Artifacts containing or covered with the example proactive repellent 102 may also be cards, tubes, sticks, balls, beads, gels, granules, stakes, and so forth, soaked, sprayed, exposed to, or impregnated with the example repellent 102, and spaced apart from each other to create a protective boundary around the campsite or other area 100. The example repellent 102 does not have to stay liquid, but may dry on the artifact, emitting repellent odors and chemicals. In an implementation, the artifacts may come pre-packaged, and previously exposed to the example repellent 102

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 >>

Organic Chemistry/ketones And Aldehydes

Organic Chemistry/ketones And Aldehydes

Aldehydes () and ketones () are both carbonyl compounds. They are organic compounds in which the carbonyl carbon is connected to C or H atoms on either side. An aldehyde has one or both vacancies of the carbonyl carbon satisfied by a H atom, while a ketone has both its vacancies satisfied by carbon. 3 Preparing Aldehydes and Ketones Ketones are named by replacing the -e in the alkane name with -one. The carbon chain is numbered so that the ketone carbon, called the carbonyl group, gets the lowest number. For example, would be named 2-butanone because the root structure is butane and the ketone group is on the number two carbon. Alternatively, functional class nomenclature of ketones is also recognized by IUPAC, which is done by naming the substituents attached to the carbonyl group in alphabetical order, ending with the word ketone. The above example of 2-butanone can also be named ethyl methyl ketone using this method. If two ketone groups are on the same structure, the ending -dione would be added to the alkane name, such as heptane-2,5-dione. Aldehydes replace the -e ending of an alkane with -al for an aldehyde. Since an aldehyde is always at the carbon that is numbered one, a number designation is not needed. For example, the aldehyde of pentane would simply be pentanal. The -CH=O group of aldehydes is known as a formyl group. When a formyl group is attached to a ring, the ring name is followed by the suffix "carbaldehyde". For example, a hexane ring with a formyl group is named cyclohexanecarbaldehyde. Aldehyde and ketone polarity is characterized by the high dipole moments of their carbonyl group, which makes them rather polar molecules. They are more polar than alkenes and ethers, though because they lack hydrogen, they cannot participate in hydrogen bonding like 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 >>

14.9: Aldehydes And Ketones: Structure And Names

14.9: Aldehydes And Ketones: Structure And Names

Identify the general structure for an aldehyde and a ketone. Use common names to name aldehydes and ketones. Use the IUPAC system to name aldehydes and ketones. The next functional group we consider, the carbonyl group, has a carbon-to-oxygen double bond. Carbonyl groups define two related families of organic compounds: the aldehydes and the ketones. The carbonyl group is ubiquitous in biological compounds. It is found in carbohydrates, fats, proteins, nucleic acids, hormones, and vitamins—organic compounds critical to living systems. In a ketone, two carbon groups are attached to the carbonyl carbon atom. The following general formulas, in which R represents an alkyl group and Ar stands for an aryl group, represent ketones. In an aldehyde, at least one of the attached groups must be a hydrogen atom. The following compounds are aldehydes: In condensed formulas, we use CHO to identify an aldehyde rather than COH, which might be confused with an alcohol. This follows the general rule that in condensed structural formulas H comes after the atom it is attached to (usually C, N, or O). The carbon-to-oxygen double bond is not shown but understood to be present. Because they contain the same functional group, aldehydes and ketones share many common properties, but they still differ enough to warrant their classification into two families. Here are some simple IUPAC rules for naming aldehydes and ketones: The stem names of aldehydes and ketones are derived from those of the parent alkanes, defined by the longest continuous chain (LCC) of carbon atoms that contains the functional group. For an aldehyde, drop the -e from the alkane name and add the ending -al. Methanal is the IUPAC name for formaldehyde, and ethanal is the name for acetaldehyde. For a ketone, drop the -e from t 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 >>

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 >>

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 >>

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 >>

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