Aliphatic Carbonyl Research Articles

Ionic Liquid as Catalyst and Reaction Medium — A Simple, Efficient and Green Procedure for Knoevenagel Condensation of Aliphatic and Aromatic Carbonyl Compounds Using a Task‐Specific Basic Ionic Liquid.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Ionic Liquid as Catalyst and Reaction Medium – A Simple, Efficient and Green Procedure for Knoevenagel Condensation of Aliphatic and Aromatic Carbonyl Compounds Using a Task‐Specific Basic Ionic Liquid

AbstractThe basic ionic liquid 1‐butyl‐3‐methylimidazolium hydroxide, [bmIm]OH, efficiently catalyzes Knoevenagel condensation without requirement of any organic solvent. A wide range of aliphatic and aromatic aldehydes and ketones easily undergo condensations with diethyl malonate, malononitrile, ethyl cyanoacetate, malonic acid and ethyl acetoacetate. The reactions proceed at room temperature and are very fast (10–30 min). However, the most significant feature of this methodology is the condensation of aliphatic aldehyde with diethyl malonate, which is not very easy to achieve by conventional reagents, and was not addressed adequately in literature providing a general and convenient procedure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Sulfamidation of 2-Arylaldehydes and Ketones with Chloramine-T

[reaction: see text] A series of aliphatic and aromatic carbonyl compounds has been transformed into the corresponding sulfamidated products by means of amine-catalyzed nitrene transfer of chloramine-T. Depending on the residues R, either alpha-sulfamidation in the case of aromatic aldehydes and acetone derivatives or direct sulfamidation at the carbonyl functionality of aliphatic aldehydes has been observed. Applying microwave conditions, good to excellent yields under significantly reduced reaction times could be obtained, thus providing a facile access to alpha,alpha-disubstituted amino acids.

LC−MS Analysis of Carbonyl Compounds and Their Occurrence in Diesel Emissions

Liquid chromatography coupled with atmospheric pressure chemical ionization (APCI) ion trap mass spectrometry (ITMS) is applied to atmospheric aerosol relevant carbonyls. Characterization of positive and negative ion detection mass spectra are presented for 24 model compounds analyzed in their underivatized and O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) oxime forms. The addition of PFBHA derivatization enhanced the detection and sensitivity for many of the carbonyls investigated. For all but five of the carbonyls examined, a pseudomolecular (M + H)+ ion is the base peak in the APCI positive ion mass spectra of PFBHA oxime derivatives and is observed in four of the five exceptions. Application of the evaluated analysis methodology to heavy-duty diesel source emissions facilitated the quantification of 10 aliphatic carbonyls (5 C5-C9 ketones, 4 C6 unsaturated ketones, 1 C6 dicarbonyl) and 14 aromatic carbonyls (1 C9 aldehyde, 5 C8-C13 ketones, 8 C6-C14 quinones). Diesel truck engine emission factors spanning 0.55-540 microg km(-1) were measured for gas- and particle-phase carbonyls. Good agreement was observed for gas-phase emission factors with results obtained by gas chromatography with ITMS.

Ethyl-Branched Aldehydes, Ketones, and Diketones from Caimans (Caiman and Paleosuchus; Crocodylia, Reptilia)

Secretions from the paracloacal glands of alligators (Alligator spp.) and caimans (Caiman spp., Melanosuchus niger, and Paleosuchus spp.) were examined by GC-MS. The secretions of the common caiman (C. crocodilus), the broad-snouted caiman (C. latirostris), the yacare caiman (C. yacare), the dwarf caiman (P. palpebrosus), and the smooth-fronted caiman (P. trigonatus) yielded a new family of 43 aliphatic carbonyl compounds that includes aldehydes, ketones, and beta-diketones with an ethyl branch adjacent to the carbonyl group. The identification of these glandular components and the syntheses and stereochemical investigations of selected compounds are described.

Ultrafast electron diffraction: Excited state structures and chemistries of aromatic carbonyls

The photophysics and photochemistry of molecules with complex electronic structures, such as aromatic carbonyls, involve dark structures of radiationless processes. With ultrafast electron diffraction (UED) of isolated molecular beams it is possible to determine these transient structures, and in this contribution we examine the nature of structural dynamics in two systems, benzaldehyde and acetophenone. Both molecules are seen to undergo a bifurcation upon excitation (S(2)). Following femtosecond conversion to S(1), the bifurcation leads to the formation of molecular dissociation products, benzene and carbon monoxide for benzaldehyde, and benzoyl and methyl radicals for acetophenone, as well as intersystem crossing to the triplet state in both cases. The structure of the triplet state was determined to be "quinoidlike" of pipi(*) character with the excitation being localized in the phenyl ring. For the chemical channels, the product structures were also determined. The difference in photochemistry between the two species is discussed with respect to the change in large amplitude motion caused by the added methyl group in acetophenone. This discussion is also expanded to compare these results with the prototypical aliphatic carbonyl compounds, acetaldehyde and acetone. From these studies of structural dynamics, experimental and theoretical, we provide a landscape picture for, and the structures involved in, the radiationless pathways which determine the fate of molecules following excitation. For completeness, the UED methodology and the theoretical framework for structure determination are described in this full account of an earlier communication [J. S. Feenstra et al., J. Chem. Phys. 123, 221104 (2005)].

Supercritical fluid assisted impregnation of indomethacin into chitosan thermosets for controlled release applications

Supercritical carbon dioxide (sc-CO 2) was used to impregnate indomethacin (a non-steroidal anti-inflammatory drug) into chitosan thermosets for the preparation of controlled release formulations. The products were analyzed by a range of methods including powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of the experimental temperature and pressure of the sc-CO 2 on the thermal behavior of chitosan–indomethacin drug composites (DCs) was investigated via differential scanning calorimeter (DSC). The interaction of chitosan and indomethacin after impregnation was then studied by Fourier transform infrared (FTIR) and Raman spectroscopy, respectively. Our results suggest that the supercritical fluid impregnation process results in indomethacin being amorphously dispersed within the chitosan matrix. FTIR data suggest that the aliphatic carbonyl group of indomethacin interacts with the NH 2 group of the chitosan backbone. In vitro dissolution studies (via UV–vis spectroscopy) reveal that the dissolution rate of indomethacin substantially increases after processing in sc-CO 2, particularly, under the experimental conditions 20.7 MPa and 70 °C.

A Simple Synthesis of Oximes

The conversion of alicyclic and aliphatic carbonyl compounds as well as aromatic aldehydes into the corresponding oximes (up to quantitative yields) was achieved by simply grinding these reactants, hydroxylamine hydrochloride and sodium hydroxide without solvent. However, this procedure was unsuccessful in the case of aromatic ketones. In this case it was necessary to add silica gel as a catalyst.

Distribution coefficients of aliphatic alcohols, carbonyl compounds and esters between air and Carboxen/polydimethylsiloxane fiber coating

Lower aliphatic carbonyl compounds, esters and alcohols were found in open atmosphere, as well as in volatiles of microorganisms, living plants and leaf litter. Quantitative determination of their emissions into the gas phase with the aid of solid phase microextraction (SPME) requires the knowledge of their distribution coefficients K fg between fiber coating and gas phase. This paper reports the results of experimental determination of K fg values for 17 volatiles belonging to the above-mentioned classes of organic compounds. Mixed Carboxen/polydimethylsiloxane stationary phase, which proved to be effective during SPME determination of more volatile pollutants, was chosen as the fiber coating. Values K fg were determined at temperature range 15–30 °C, which permitted the dependence between log K fg and T −1 to be determined. Distribution coefficients for 23 other compounds from the same homologue series were calculated using two-parameter empirical equation, where physico-chemical parameters of compounds (boiling temperature, linear temperature programmed retention index) served as descriptors.

Volatile constituents from flowers, leaves, bark and wood ofPrunus mahaleb L.

Volatile constituents from air-dried flowers, leaves, stem-bark and wood of Prunus mahaleb L. (Rosaceae) were isolated by steam-distillation and analysed using GC and GC–MS; 130 components were identified. Aliphatic hydrocarbons, alcohols, carbonyls, fatty acids, terpenes, C13-norisoprenoids and phenylpropane derivatives were detected. Coumarin was identified as the main component of the bark volatiles (34.1%). Hexadecanoic acid was the main component in the wood (46.0%), and was also present in the leaves (17.8%) and bark (9.3%). n-Alkanes, heneicosane (22.1%) and octacosane (13.0%) were identified as the main components in the flowers, while eicosane was detected in the wood (12.9%). Phytol was identified in the leaves (5.1%). Dodecanoic, tetradecanoic and linoleic acids were present in all samples among the major components. The contents of volatile compounds were 340.0 mg/kg (flowers), 64.6 mg/kg (leaves), 41.0 mg/kg (bark) and 6.6 mg/kg (wood). Copyright © 2005 John Wiley & Sons, Ltd.

Regio‐ and stereoselectivity in the Paternò‐Büchi reaction on furan derivatives

The photochemical coupling reaction between 2,3‐dihydrofuran and benzaldehyde was studied by using DFT/B3LYP/6 − 31G + (d, p) method. The regiocontrol of the attack of the benzaldehyde on the double bond is related to the different stabilities of the biradical intermediates. The endo stereoselectivity of the reaction depends on the superposition between HSOMO and LSOMO in the biradical intermediate. In the photochemical reaction between furan and benzaldehyde also the regiocontrol depends on the relative stability of the possible biradical intermediates. The exo stereoselectivity of the coupling reaction depends on the superposition between the HSOMO and LSOMO of the biradical intermediate. The reaction of chiral phenylglyoxylates with furan gave the corresponding adducts with de = 15–95%. The stereocontrol can be explained considering the energy gap between the biradical intermediates in the coupling reaction. When the reaction was performed in the presence of zeolite, the diastereoisomeric excess increased. The reaction of benzoin and 2‐phenylpropiophenone with furan gave the cycloadduct with high diastereocontrol. All the products were obtained with de > 98%. The Paterrnò‐Büchi reaction between 2‐furylmethanols with aromatic carbonyl compounds also showed high regio‐ and stereocontrol. On the contrary, when 5‐methyl derivatives were used, a lack of regiocontrol was observed. Furthermore, with aliphatic carbonyl compounds, no diastereoselectivity was observed. These results were explained assuming the attack of the excited carbonyl compound on the same side as the hydroxyl group, through the formation of a hydrogen bond or of a complex. This type of attack gave the biradical intermediate in preferential conformations. The relative energies of these conformers account for the observed diastereoselectivity.

Synthetic Scope and Mechanistic Studies of Ru(OH)x/Al2O3‐Catalyzed Heterogeneous Hydrogen‐Transfer Reactions

Three kinds of hydrogen-transfer reactions, namely racemization of chiral secondary alcohols, reduction of carbonyl compounds to alcohols using 2-propanol as a hydrogen donor, and isomerization of allylic alcohols to saturated ketones, are efficiently promoted by the easily prepared and inexpensive supported ruthenium catalyst Ru(OH)x/Al2O3. A wide variety of substrates, such as aromatic, aliphatic, and heterocyclic alcohols or carbonyl compounds, can be converted into the desired products, under anaerobic conditions, in moderate to excellent yields and without the need for additives such as bases. A larger scale, solvent-free reaction is also demonstrated: the isomerization of 1-octen-3-ol with a substrate/catalyst ratio of 20,000/1 shows a very high turnover frequency (TOF) of 18,400 h(-1), with a turnover number (TON) that reaches 17,200. The catalysis for these reactions is intrinsically heterogeneous in nature, and the Ru(OH)x/Al2O3 recovered after the reactions can be reused without appreciable loss of catalytic performance. The reaction mechanism of the present Ru(OH)x/Al2O3-catalyzed hydrogen-transfer reactions were examined with monodeuterated substrates. After the racemization of (S)-1-deuterio-1-phenylethanol in the presence of acetophenone was complete, the deuterium content at the alpha-position of the corresponding racemic alcohol was 91%, whereas no deuterium was incorporated into the alpha-position during the racemization of (S)-1-phenylethanol-OD. These results show that direct carbon-to-carbon hydrogen transfer occurs via a metal monohydride for the racemization of chiral secondary alcohols and reduction of carbonyl compounds to alcohols. For the isomerization, the alpha-deuterium of 3-deuterio-1-octen-3-ol was selectively relocated at the beta-position of the corresponding ketones (99% D at the beta-position), suggesting the involvement of a 1,4-addition of ruthenium monohydride species to the alpha,beta-unsaturated ketone intermediate. The ruthenium monohydride species and the alpha,beta-unsaturated ketone would be formed through alcoholate formation/beta-elimination. Kinetic studies and kinetic isotope effects show that the Ru-H bond cleavage (hydride transfer) is included in the rate-determining step.

A Novel Method for the Synthesis of Dichloroalkenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Catalyzing Henry reactions in chloroaluminate ionic liquids

Henry reactions can be accelerated in chloroaluminate room temperature ionic liquids. The choloroaluminates with higher compositions of organic species of the chloroaluminates prove to be more efficient rate promoters than the ones with lower organic species in catalyzing Henry reactions, involving both aliphatic and aromatic carbonyl compounds. The ionic liquids can be recycled five times to offer good yields.

Nickel‐Catalyzed Addition of Dimethylzinc to Aldehydes Across Alkynes and 1,3‐Butadiene: An Efficient Four‐Component Connection Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Candidate Analog for Carbonaceous Interstellar Dust: Formation by Reactive Plasma Polymerization

Carbonaceous compounds are a significant component of interstellar dust, and the composition and structure of such materials is therefore of key importance. We present 1.5‐15 � m spectra of a plasma-polymerized carbonaceous material produced in radio-frequency discharge under low pressure, using C2H2 as a precursor component. The infrared spectra of the resulting spheroidal carbonaceous nanoparticles reveal a strong aliphatic band (3.4 � m feature), weak OH and carbonyl bands, and traces of aromatic compounds, all characteristics identified with dust in the diffuse interstellar medium of our Galaxy. The plasma polymerization process described here provides a convenient way to make carbonaceous interstellar dust analogs under controlled conditions and to compare their characteristics with astronomical observations. Here we focus on a comparison with the IR spectra of interstellar dust. The IR spectrum of carbonaceous dust in the diffuse interstellar medium is characterized by a strong 3.4 � m

Nickel-Catalyzed Addition of Dimethylzinc to Aldehydes across Alkynes and 1,3-Butadiene: An Efficient Four-Component Connection Reaction

In the presence of 10 mol % of Ni(acac)(2), four components comprising Me(2)Zn, alkynes, 1,3-butadiene, and carbonyl compounds combine in this order in 1:1:1:1 ratio to furnish (3E,6Z)-octadien-1-ols 1 in good yields. Similarly, the coupling reaction of Me(2)Zn, 1,omega-dienynes 5, and carbonyls furnishes 1-alkylidene-2-(4'-hydroxy-(1'E)-alkenyl)cyclopentanes and -cyclohexanes 6 and their oxygen and nitrogen heterocycle derivatives in good yield and an excellent level of 1,5-diastereoselectivity with respect to the cycloalkane methine carbon and the OH-bearing carbon of the C2 side chain. The reaction is completed in most cases within 1 h at room temperature under nitrogen, tolerates an ester, a hydroxy, an allyl and propargyl ethers, an allylamino, and a pyridyl functionalities, and accommodates a variety of aromatic and aliphatic alkynes and carbonyls (aldehydes and ketones).

Size Distributions of Organic Functional Groups in Ambient Aerosol Collected in Houston, Texas Special Issue ofAerosol Science and Technologyon Findings from the Fine Particulate Matter Supersites Program

The size distributions of aliphatic carbon, carbonyl, and organonitrate functional groups in ambient aerosol were determined at three sites during an air quality field study conducted during August and September 2000, in Houston, Texas. Samples were collected using a Hering low-pressure impactor and were analyzed, in transmission mode, using Fourier transform infrared spectroscopy. The submicron fractions of the samples exhibited patterns seen in other urban areas. Carbonyl and organonitrate group absorbances showed maxima in the 0.05–0.26 μm and the 0.5–1.0 μm size fractions, and based on these absorbances appear to be primarily due to secondary organic aerosol. Aliphatic carbon absorbances in the submicron aerosol showed maxima in the 0.076–0.12 μm size fraction and the 0.5–1.0 μm size fraction. Weak correlation between ozone concentrations and aliphatic carbon absorbances suggest that some of these aliphatic functional groups are due to primary emissions. For the supermicron aerosol, all three functional groups exhibit maxima in the 2–4 μm size fraction. These coarse size fractions observed in Houston were not observed in similar samples collected in Los Angeles. In addition, some of the aerosol samples collected in Houston display organic functional group concentrations, especially for organonitrates, that are significantly higher than the median concentrations. Samples with very high organic functional group concentrations had molar ratios of carbonyl and organonitrate functional groups that are suggestive of either primary emissions or secondary organic aerosol formation processes that are not commonly observed in other urban areas.

A novel method for the synthesis of dichloroalkenes

A novel convenient method for the synthesis of dichloroalkenes was developed. The method involves catalytic olefination of hydrazones of aliphatic carbonyl compounds with bromo(trichloro)methane.

Analysis of Aliphatic and Aromatic Carbonyl Compounds in Ambient Air by LC/MS/MS

A sensitive liquid chromatograph/tandem mass spectrometric technique (LC/MS/MS) was applied to determine aliphatic and aromatic carbonyl compounds in ambient air. Traces of the carbonyl compounds were sampled by passing through a Sep-Pak DNPH-silica cartridge. Their derivatives were thus eluted with acetonitrile, separated by reversed-phase liquid chromatography and determined by quadrupole tandem mass spectrometry in an atmospheric pressure chemical ionization (APCI) mode with multiple reaction monitoring (MRM). The detection limits (DL) of the carbonyl compounds were 0.8 - 15 ng/m3. A number of the carbonyl compounds were detected at n.d.- 14 microg/m3 levels. The precursor ion scanning analysis was applied to identify the unknown compounds.