Aliphatic Carbonyl Research Articles

FTIR measurements of functional groups and organic mass in aerosol samples over the Caribbean

An aircraft-based aerosol concentrator consisting of three virtual impactors in series has been used to collect particles for Fourier transform infrared (FTIR) transmission spectroscopy on stretched Teflon filters. Submicron atmospheric aerosol samples were collected near St. Croix aboard the National Center for Atmospheric Research C-130 aircraft during the passing efficiency of a low-turbulence inlet project. FTIR identified sulfate, ammonium, silicate, and organic functional groups, and a four-solvent rinsing procedure separated these functional groups into fractions of increasing hygroscopicity. The Caribbean aerosols contained 0.01– 1.6 μg m −3 of Si, indicative of African mineral dust at all altitudes, with higher Al/Ca ratios in the boundary layer. Organic compounds were present in high and low dust conditions with estimated total organic mass varying from 0.8– 4 μg m −3 during the project. Aliphatic carbon and carbonyl carbon were quantified at concentrations of up to 4 and 0.8 μg m −3 , respectively, and were summed to calculate organic carbon and organic mass (OM) concentrations. Sequential solvent rinsing with repeated FTIR analysis revealed that 60–90% of OM in the free troposphere was hygroscopic, with hydrophobic organic compounds accounting for 20–50% of OM in the marine boundary layer.

Metal‐Promoted Variants of the Passerini Reaction Leading to Functionalized Heterocycles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Additions of water, hydroxide ions, alcohols and alkoxide ions to carbonyl and azomethine bonds

In this review are discussed equilibria involved in nucleophilic additions of H2O, HO - , ROH, and RO - (where R is an alkyl) to compounds containing carbonyl and azomethine bonds. These reactions result in a formation of covalent bonds between the heteroatom of the nucleophile and the carbon of the carbonyl double bond. After a brief summary of reactions resulting in additions to aliphatic carbonyl compounds, attention is paid to additions to benzaldehydes and formyl aromatic heterocycles. Equilibria involving additions to pyridoxal and some related compounds are dealt with in some detail. Discussion of additions of stated nucleophiles to azomethine bonds is practically restricted to additions to C=N bonds in heterocyclic rings. The reactivity of nucleophiles in such additions depends on the number of heteroatoms (in particular nitrogen) in the attacked ring, as well as on the number and position of substituents in such rings. In polynuclear compounds the reactivity depends on the number and kind of annelled rings, on the number and mutual position of heteroatoms and on the kind, number and position of substituents. In particular additions to pyrimidines, quinazolines, 1,2,4- and 1,3,5-triazines, pteridines and other heterocycles with four nitrogens, as well as 8-azapurines are mentioned.

A new entry to β-hydroxyphosphonates: the SmI 2-mediated reaction of diethyl iodomethylphosphonate with carbonyl compounds

In the presence of samarium iodide α-halophosphonates react with aliphatic carbonyl compounds (aldehydes and ketones) to afford β-hydroxyphosphonates in fairly good yields under neutral and mild conditions. Lower yields are obtained with aromatic carbonyl compounds.

Reductive Amination of Aliphatic Carbonyls using Low–valent Titanium Reagent: A Convenient Route to free Primary Amines

A simple procedure for reductive amination of aliphatic carbonyls, giving direct access to free primary amines using low–valent titanium (LVT) reagent has been reported.

Copolyesters of hydroxyphenylalkanoic acids: synthesis and thermal properties of poly{(4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate]} and poly{(3‐bromo‐4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate

AbstractCopolyesters of 8‐(3‐hydroxyphenyl)octanoic acid (HPOA), a monomer with kink and flexible segment derived from cardanol, and 4‐hydroxybenzoic acid (HBA) or its brominated derivative, 3‐bromo‐4‐hydroxybenzoic acid (BrHBA), were synthesized by acidolysis melt polycondensation of the in situ generated acetoxyderivative in the presence of magnesium acetate as catalyst by a one‐pot method and characterized. The formation of the copolyester was confirmed by elemental analysis, FTIR and 1H NMR spectroscopy. These polymers were highly insoluble in most solvents except highly polar solvents, such as trifluoroacetic acid. The inherent viscosities of the soluble polymers were in the range of 0.8–1.1 dlg−1. The thermal and phase behaviour of the copolyesters were studied by DSC and polarized light microscopy. Poly{(4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate]} with 50 mole% of HPOA showed a birefringent melt with opalescence and a worm‐like texture of a nematic phase. The effect of bromine substitution in the analogue poly{(3‐bromo‐4‐oxybenzoate)‐co‐[8‐(3‐oxyphenyl)octanoate]} was evident when it showed a lower transition with minimum 45% Br‐HBA at 225 °C showing enhanced melt processability. These copolymers, with hydrolytically degradable aliphatic carbonyl group and better crystallinity compared to poly(hydroxyalkanoate)s, are interesting in possible biomedical applications.© 2002 Society of Chemical Industry

Ambient air measurement of acrolein and other carbonyls at the Oakland-San Francisco Bay Bridge toll plaza.

Interest in ambient concentrations of acrolein and other alpha,beta-unsaturated aldehydes and dicarbonyls (e.g., crotonaldehyde, methyl glyoxal, glyoxal, malonaldehyde (malondialdehyde)) is growing because either they exist at high levels in motor vehicle emissions or they arise from photooxidation of other hydrocarbons emitted from mobile sources. In addition, their mutagenic, genotoxic, or carcinogenic properties are well-established, and the results of a dispersion-modeling study regarding the health risks posed by the 188 hazardous air pollutants in California attributes the highest noncancer risk to exposure to acrolein. Such modeling studies, conducted by the U.S. Environmental Protection Agency (U.S. EPA), also predict median ambient air concentrations of acrolein higher than 0.06 microg/m3, the chronic inhalation reference exposure level stipulated by the California Office of Environmental Health Hazard Assessment in counties surrounding the Oakland-San Francisco Bay Bridge. We measured acrolein and other potentially toxic carbonyls in air sampled at the San Francisco Bay Bridge toll plaza during rush hour traffic, which may be considered a "worst case scenario" for outdoor airborne carbonyls. We identified 36 carbonyls in the sample extracts, including 14 saturated aliphatic carbonyls, six unsaturated carbonyls, four aromatic carbonyls, six dicarbonyls, and six hydroxy carbonyls. Structural information to support tentative identification of carbonyls and hydroxycarbonyls was obtained by using a method that involves O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and PFBHA/bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization in concert with gas chromatography/ion trap mass spectrometry. Most notably, we report for the first time the presence of malonaldehyde in the ambient atmospheric environment. A relatively linear relationship between retention time and the molecular weight of the derivatives was established to assist in obtaining structural information about chemicals for which authentic standards are not readily available. Levels of acrolein exceeded the California reference exposure level during morning rush hour traffic. The measured values, however, were significantly lower than estimates of county-wide average acrolein concentrations predicted by a U.S. EPA modeling study based on 1996 data. Successful regulatory efforts such as the introduction of reformulated gasoline, together with the advancement of new catalysts and fleet turnover throughout the 1990s, are likely to account for part of the gap between our determination and the 1996 levels.

Metal-promoted variants of the Passerini reaction leading to functionalized heterocycles.

[reaction: see text]. The effect of replacing the Brønsted acid in classic Passerini reactions with a mild Lewis acid has been studied. Triggered by metal-promoted silylation, condensations of aliphatic or aromatic carbonyl compounds with appropriately substituted isonitriles capable of neighboring group donation afford alpha-hydroxyamides, substituted oxazoles, and other useful heterocycles.

Morphology and structures of polypropylene-aliphatic polyketone blends

Aliphatic polyketone (PK) contains both non-polar aliphatic units and polar carbonyl groups, which make it an ideal and unique candidate for modifying non-polar polymer systems containing purely alkyl chains,such as polyalkenes. A new polymer blend system based on polypropylene (PP) and aliphatic polyketone has been prepared; PP-PK blends containing 5 and 8 wt-% PK were prepared by the melt blending method. The morphology and structures of the blends were characterised using SEM, DSC, WAXS, FTIR, and TGA. The SEM study indicates that the blends are immiscible in this composition range. They have typical island-sea morphology and the size of the droplets increases as the PK concentration increases. On the fractured surfaces of the blend samples some droplets are partially connected to the matrix, which implies that the interface between the two phases has relatively high strength. The DSC study shows that the blending significantly reduces the crystallinity of both PP and PK. The WAXS result indicates that the crystal size of PP along the b axis is largely reduced in the blends, which implies that a small amount of PK chains may have been incorporated into the matrix,interrupting the growth of the PP crystals. Both FTIR and TGA studies suggest that there are chemical reactions between PP and PK during compounding, which may contribute to the partial miscibility and to the relatively strong interface observed.

Diastereoselective synthesis of substituted 1,3,6-triazabicyclo[3.1.0]hexanes

A general method was developed for the synthesis of substituted 1,3,6-triazabicyclo[3.1.0]hexanes via intramolecular aminomethylation of the NH group of the diaziridine ring by the reactions of 3-aminomethyl-1,3-dimethyldiaziridine with aliphatic, aromatic, and heteroaromatic carbonyl compounds. These reactions with aldehydes proceeded diastereoselectively to form mixtures of two racemates, viz., 1R*,2R*,5R*,6R* and 1R*,2S*,5R*,6R*, in a ratio of (3—20) : 1, the predominant diastereomer being isolated in all cases. The reactions with symmetrical ketones gave rise exclusively to the (1R*,5R*,6R*) racemate. The predominant diastereomer 1R*,2R*,5R*,6R*-2-(2-bromothien-5-yl)-1,3,6-triazabicyclo[3.1.0]hexane crystallized as a conglomerate. The structure of one of its enantiomers was established by X-ray diffraction analysis.

PINACOLBORATAMETHYL- ENETRIPHENYLPHOSPHONIUM IODIDE, A NEW METHYLENE TRANSFER REAGENT

ABSTRACT The title compound is easily prepared and reacts with various aldehydes and ketone. The reagent is compatible with free hydroxy groups. Yields with various aldehydes and ketones are in 50–>99% range. Both aliphatic, aromatic and unsaturated carbonyls react.

On-Road Measurement of Carbonyls in California Light-Duty Vehicle Emissions

Emissions of carbonyls by motor vehicles are of concern because these species can be hazardous to human health and highly reactive in the atmosphere. The objective of this research was to measure carbonyl emission factors for California light-duty motor vehicles. Measurements were made at the entrance and exit of a San Francisco Bay area highway tunnel, in the center bore where heavy-duty trucks are not allowed. During summer 1999, approximately 100 carbonyls were identified, including saturated aliphatic aldehydes and ketones, unsaturated aliphatic carbonyls, aliphatic dicarbonyls, and aromatic carbonyls. Concentrations were measured for 32 carbonyls and were combined with NMOC, CO, and CO2 concentrations to calculate by carbon balance emission factors per unit of fuel burned. The measured carbonyl mass emitted from light-duty vehicles was 68 +/- 4 mg L(-1). Formaldehyde accounted for 45% of the measured mass emissions, acetaldehyde 12%, tolualdehydes 10%, benzaldehyde 7.2%, and acetone 5.9%. The ozone forming potential of the carbonyl emissions was dominated by formaldehyde (70%) and acetaldehyde (14%). Between 1994 and 1999, emission factors measured at the same tunnel for formaldehyde, acetaldehyde, and benzaldehyde decreased by 45-70%. Carbonyls constituted 3.9% of total NMOC mass emissions and 5.2% of NMOC reactivity. A comparison of carbonyl emissions with gasoline composition supports previous findings that aromatic aldehyde emissions are related to aromatics in gasoline. Carbonyl concentrations in liquid gasoline were also measured. Acetone and MEK were the most abundant carbonyls in unburned gasoline; eight other carbonyls were detected and quantified.

Studies on the mechanism of B(C(6)F(5))(3)-catalyzed hydrosilation of carbonyl functions

The strong organoborane Lewis acid B(C(6)F(5))(3) catalyzes the hydrosilation (using R(3)SiH) of aromatic and aliphatic carbonyl functions at convenient rates with loadings of 1-4%. For aldehydes and ketones, the product silyl ethers are isolated in 75-96% yield; for esters, the aldehydes produced upon workup of the silyl acetal products can be obtained in 45-70% yield. Extensive mechanistic studies point to an unusual silane activation mechanism rather than one involving borane activation of the carbonyl function. Quantitative kinetic studies show that the least basic substrates are hydrosilated at the fastest rates; furthermore, increased concentrations of substrate have an inhibitory effect on the observed reaction rate. Paradoxically, the most basic substrates are reduced selectively, albeit at a slower rate, in competition experiments. The borane thus must dissociate from the carbonyl to activate the silane via hydride abstraction; the incipient silylium species then coordinates the most basic function, which is selectively reduced by [HB(C(6)F(5))(3)](-). In addition to the kinetic data, this mechanistic proposal is supported by a kinetic isotope effect of 1.4(5) for the hydrosilation of acetophenone, the observation that B(C(6)F(5))(3) catalyzes H/D and H/H scrambling in silanes in the absence of substrate, computational investigations, the synthesis of models for proposed intermediates, and other isotope labeling and crossover experiments.

Effective synthesis of 1,2-di-, 1,2,3-tri-, 1,2,3,3-tetraalkyldiaziridines and 1,5-diazabicyclo[3.1.0]hexanes

A versatile single-step procedure was proposed for the synthesis of the title compounds by the interaction of equimolar amounts of aliphatic carbonyl compounds, primary aliphatic amines and N -chloroalkylamines in an aprotic organic solvent in the presence of potassium carbonate.

Synthesis of New Aliphatic Carbonyl Derivatives with Palladium (II) Catalyst

Bis-alkoxylcarbonylation of dicyclopentadiene (DCPD) with carbon monoxide and a variety of alcoholsin the presence of palladium (II) catalyst and copper (II) salt as reoxidant have been studied andtricyclo [5.2.1.02, 6] dec-3-ene-8, 9-diester (TCDE) and tricyclo [5.2.1.02, 6] dec-3-ene-8, 9-dicarboxylic anhydride (TCDA) successfully were obtained for the first time. It is found that the double bond in the norboranenering can selectively be diesterified without affecting double bond in the cyclopentene ring, to obtain TCDE in good yield. When lower alcohols such as methanol and n-butanol are used, TCDE is obtainable in a highyield, however, branched alcohols such as sec-butanol or cyclohexanol and higher alcohol such as n-decanol gave TCDE in a yield ranging from 66% to 61%. Tert-alcohols such as tert-butanol or tert-amyl alcohol gave TCDA exclusively. It is the first example showing the selectively directly diesterifying one of the double binds in the DCPD.

N-Bromosuccinimide (NBS), an Efficient Reagent for the Conversion of 1,3-Oxathiolanes to Carbonyl Compounds

Various types of 1,3-oxathiolanes of aromatic and aliphatic carbonyl compounds, including those obtained from α,β-unsaturated aldehydes were efficiently converted to the corresponding carbonyl compounds in the presence of NBS (0.4-0.9 equiv.) under mild reaction conditions. The method was also effectively applied to the chemoselective deprotection of 1,3-oxathiolanes in the presence of 1,3-dioxolanes.

A Comparative Study of Some Values of ionization constants of Oximes and Phenolic Acids Derived fromِ Aliphatic and Aromatic Carbonyl Compounds

A Comparative Study of Some Values of ionization constants of Oximes and Phenolic Acids Derived fromِ Aliphatic and Aromatic Carbonyl Compounds

ChemInform Abstract: Facile Synthesis of Silyl Enol Ethers by Mg‐Promoted Coupling of Aliphatic Carbonyl Compounds with Trimethylsilyl Chloride.

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Molecular Electrostatics for Exploring Complexes of Carbonyl Compounds and Hydrogen Fluoride

The negative-valued molecular electrostatic potential (MESP) minima (Vmin) observed in the substituted carbonyl molecules are found to be a sensitive measure for the analysis of the electronic charge perturbations due to the substituents. MESP topography of eight monosubstituted aliphatic carbonyl molecules (HCOR: R = H, F, Cl, CN, OH, SH, NH2, CH3, CF3, NO2) [following Bobadova-Parvanova, P.; Galabov, B. J. Phys. Chem. A 1998, 102, 1815] is carried out at the HF-SCF/6-31G** level for assessing this scheme. The Vmin values are seen to clearly reflect the changes due to the electron donating/withdrawing substituents. The electrostatic potential for intermolecular complexation (EPIC) model is used for predicting the possible hydrogen-bonded structures of the carbonyl molecules with the hydrogen fluoride. These complexes are further optimized at the HF-SCF/6-31G** level of theory. An excellent linear correlation is obtained with EPIC energy and the corresponding optimized interaction energy of the complex. ...

Liquid Chromatography Analysis of Carbonyl (2,4-Dinitrophenyl)hydrazones with Detection by Diode Array Ultraviolet Spectroscopy and by Atmospheric Pressure Negative Chemical Ionization Mass Spectrometry

The (2,4-dinitrophenyl)hydrazones of carbonyls are separated by liquid chromatography and detected by ultraviolet spectroscopy (diode array detector) and by atmospheric pressure negative chemical ionization mass spectrometry. Results are presented for 78 carbonyls including 18 1-alkanals (from formaldehyde to octadecanal), 16 other saturated aliphatic carbonyls (5 C(4)-C(7) aldehydes and 11 C(3)-C(9) ketones), 16 unsaturated aliphatic carbonyls (9 C(3)-C(11) aldehydes and 7 C(4)-C(9) ketones), 13 aromatic carbonyls (including hydroxy- and/or methoxy-substituted compounds), 10 C(2)-C(10) aliphatic dicarbonyls, 3 aliphatic carbonyl esters, and 2 other carbonyls. Isomers were observed for α,β-unsaturated ketones and saturated carbonyls that bear other oxygen-containing substituents, e.g. methoxyacetone, 2-furaldehyde, and the 3 carbonyl esters. For all but two of the carbonyls studied, the base peak in the negative APCI mass spectrum was the M - 1 ion (NO(2))(2)C(6)H(3)NN [Formula: see text] CR(1)R(2) (R(1) = H for aldehydes), where M is the molecular mass of the carbonyl (2,4-dinitrophenyl)hydrazone derivative. The dicarbonyls 2,4-pentanedione and succinic dialdehyde reacted with DNPH to yield predominantly other products. Concentrations measured by ultraviolet spectroscopy (peak area) and by mass spectrometry (abundance of M - 1 ion) were in good agreement. Applications described include the measurement of 34 C(1)-C(18) carbonyls at levels of 0.015-14 parts per billion (ppb) in urban air and the identification of carbonyls at ppb concentrations as reaction products in laboratory studies of the atmospheric oxidation of unsaturated organic compounds.