Isomeric Ketones Research Articles

Mechanistic and Synthetic Studies of the Addition of Alkyl Aldehydes to Vinylsilanes Catalyzed by Co(I) Complexes

The mechanistic details of the cobalt-catalyzed intermolecular hydroacylation reaction have been investigated using kinetic, spectroscopic, and crystallographic methods. The Co(I) bisolefin complex 1, [C5Me5Co(C2H3SiMe3)2], was shown to catalyze the addition of a series of alkyl aldehydes (2a−l) to vinylsilanes to give the corresponding ketones with exclusive anti-Markovnikov selectivity under mild conditions. The catalytic cycle exhibits two resting states, complex 1 and a bisalkyl carbonyl complex, [C5Me5Co(CO)(R)(R‘)], 4a−l which are in equilibrium. Kinetic investigations along with low-temperature NMR spectroscopy establish a sensitive balance between resting states during catalysis which is strongly dependent on substrate structure. The turnover-limiting step was established as the reductive elimination of ketone from intermediate 4. Using ferrocenecarboxaldehyde (Fc-C(O)H), 2l, as substrate, the intermediate 4l [C5Me5Co(CO)(Fc)(CH2CH2SiMe3)] was isolated at low temperatures and characterized by X-ray crystallography. Complex 4l was used to study the carbon−carbon bond-forming step directly by thermolysis in the presence of a trapping ligand L (P(OMe)3, PMe3). Kinetic analysis showed competitive ligand dependent and ligand independent pathways for ketone formation. Deuterium scrambling, isomerization of aldehydes prior to ketone formation, and production of isomeric ketones in certain cases establish that complex isomerization processes occur prior to productive ketone elimination from 4. A detailed mechanism accounting for all observations is proposed. Catalyst deactivation was shown to involve primarily decarbonylation to yield [C5Me5Co(CO)]2 and [C5Me5Co(CO)(C2H3SiMe3)]. When excess aldehyde is present, catalytic aldehyde dimerization occurs to give esters.

Use of a Sacrificial Aluminum Anode in the Acylation of Some Olefins

Abstract The acylation of some alicyclic and aliphatic alkenes by the electrochemical generation of a catalyst using a sacrificial aluminum anode was investigated. Substrates were electrolyzed in a dichloromethane solution of an appropriate electrolyte (tetraalkylammonium salts) in the presence of an acylating agent (acetyl chloride or anhydride). Thus, unsubstituted cycloalkenes, namely cyclohexene and cycloheptene, gave by that reaction conjugated ketones, i.e. the corresponding 1-acetylcycloalkenes, as the only unsaturated carbonyl compounds in moderate-to-good yields. Under the same reaction conditions their 1-methyl derivatives gave mixtures of the corresponding conjugated and β,γ-unsaturated isomeric ketones in which unconjugated compounds predominate. In both cases unsaturated ketones were accompanied by different amounts of side products. Terminal aliphatic alkenes (1-hexene, 1-heptene, and 1-dodecene) afforded only conjugated a ketone with a normal skeleton, but in lower yields. The acylation of cyclohexene was studied in more detail, altering the reaction conditions by changing the reaction temperature, the supporting electrolyte, the acylating agent and the electrochemical cell. Mechanistic considerations were made on the basis of the products distribution and some theoretical calculations being made by the MOPAC program package (version 7.0).

Photochemistry and magnetic resonance spectroscopy as probes of supramolecular structures and migration pathways of organic molecules and radicals adsorbed on zeolites

Magnetic resonance, surface area measurements and computational techniques have been integrated to elucidate the supramolecular photochemistry of two isomeric ketones adsorbed on two MFI zeolites (silicalite and ZSM-5) and to demonstrate that common factors proportional to the available external surface area operate to determine the measured parameters in each case.

Thermodynamics of mixtures containing the CO and OH groups. I. Estimation of the DISQUAC interchange coefficients for 1-alkanol + n-alkanone systems

1-Alkanol + n-alkanone mixtures are treated in terms of the DISQUAC group contribution model, reporting the interaction parameters for hydroxyl–carbonyl contacts. The quasichemical interchange coefficients are independent of the compounds in the mixture; the dispersive interchange coefficients depend on the intramolecular environment of the hydroxyl and (or) carbonyl groups. Mixtures of a given 1-alkanol with isomeric ketones are characterized by the same first dispersive interaction parameter, which is constant from 2-pentanone. This type of system, when including an alcohol up to 1-pentanol, needs different dispersive enthalpic parameters depending on the symmetry of the ketone. In this case, such parameters are constant from 2-pentanone or 3-pentanone. A detailed comparison is presented between DISQUAC results and data available in the literature on vapour–liquid equilibria, VLE (including azeotropic data), molar Gibbs energies, GE, molar excess enthalpies, HE, solid–liquid equilibria, SLE, natural logarithms of activity coefficients, In [Formula: see text] and partial molar excess enthalpies at infinite dilution,[Formula: see text]. For 54 systems, the mean relative standard deviation in pressure is 0.018; for 61 systems, this magnitude in the case of the HE is 0.059. It is noteworthy that the model yields good predictions over a very wide range of temperature for VLE and SLE. HE is also reasonably well represented at different temperatures. Larger discrepancies are encountered, as usual, for partial molar quantities at infinite dilution. Keywords: liquids, mixtures, thermodynamic properties, group contributions.

Cyclocarbonylation of Bicyclic Vinylcyclopropanes – Selective Generation of Seven‐Membered Enones

AbstractThe cyclic vinylcyclopropane 6a reacts at elevated temperatures with iron pentacarbonyl to selectively give the enone 7a in 52% yield. Reducing the reaction time provided the isomeric ketones 7a–b. Partial chromatographic separation of this mixture allowed the complete spectroscopic identification of 7b by 1H NMR. The structure of 7c was determined from selected spectral data of the mixture of 7a and 7c. For comparison, the methyl substituted derivate 6b was subjected to a carbonylation under the above conditions exclusively providing 8 ini 42% yield. A mechanistic rationale for the two different modes of ring opening is presented.

Reinvestigation of the Nazarov cyclization of 1-(3-hydroxypropynyl)cyclododecan-1-ol to bicyclo[10.3.0]pentadec-1(12)-en-13-one

Reinvestigation of the acid-catalyzed cyclization of 1-(3-hydroxypropynyl)cyclododecan-1-ol under the conditions of the Nazarov reaction demonstrated that this conversion yields two isomeric bicyclic ketones, namely, bicyclo[10.3.0]pentadec-1(12)-en-13-one and bicyclo[10.3.0]pentadec-1-en-3-one. The latter compound is thermodynamically less stable.

Synthesis of ferrocenyl-1,2-diketones and related compounds: Crystal and molecular structures of 1,2-diferrocenylethanedione and 1-ferrocenyl-2-(4-biphenylyl) ethanedione

Ferrocenyl-1,2-diketones FcCOCOR, 3, [Fc = (C5H5)Fe(C5H4)] can be prepared by oxidation of acylferrocenes FcCOCH2R or, more efficiently, by oxidation of the isomeric ketones FcCH2COR, 2. The ketones 2 are in turn readily synthesized from the salt (FcCH2PPh3)+I− via the acylated salts [FcCH(COR)PPh3]+I−. The haloacylferocenes FcCOCClx H3−x (x = 1, 2, 3, of which the x = 2 example is synthetically equivalent to a diketone) are synthesized by Friedel—Crafts acylation of ferrocene using CClxH3−xCOCl/AlCl3, but the reaction proceeds via two parallel pathways, one giving the normal acyl derivatives FcCOCClxH3−x and the other giving the reduced products FcCOCClx−1H4−x. Two diketones FcCOCOFc 3b and FcCOCOC6H4Ph 3c have been structurally characterised by single-crystal X-ray diffraction.

Photo-oxidation of n-alkanes in simulated marine environmental conditions

n-Dodecane, n-hexadecane, n-nonadecane, n-eicosane and n-docosane were photo-oxidized in purified and sterilized natural sea water under simulated environmental conditions with anthraquinone as sensitizer. GC and GCMS analyses show the production of all isomeric ketones and alcohols with the same number of carbon atoms as the starting alkane and the formation of minor photoproducts: methylketones, 1-alkenes, 3-substituted-γ-lactones, 1,2-epoxy-alkanes, carboxylic acids, 1,2-disubstituted cyclobutanols, γ-keto-2-alcohols, n-aldehydes, γ-diketones and alkanes. Mechanisms are proposed adn discussed. A generalization of the photo-oxidation degradation pathways of n-alkanes in the marine environment is proposed using these results and some previous works.

Acetylation and benzoylation of ?5,?5-fulvalenedimanganesehexacarbonyl

η5,η5-Fulvalenedimanganesehexacarbonyl (dicymantrenyl) was acetylated and benzoylated by RC(O)Cl+AlCl3 in CH2Cl2, under conditions of the Friedel-Crafts reaction. The reaction involves both nonequivalent positions of the cyclopentadienyl rings to give mixtures of two isomeric ketones. When using an excess of the acetylating mixture, diacetyl derivatives of dicymantrenyl were obtained.

Ketones in hydrothermal petroleums and sediment extracts from Guaymas Basin, Gulf of California

The polar compound (NSO) fractions of seabed petroleums and sediment extracts from the Guaymas Basin hydrothermal system have been analyzed by gas chromatography and gas chromatography-mass spectrometry. The oils were collected from the interiors and exteriors of high temperature hydrothermal vents and represent hydrothermal pyrolysates that have migrated to the seafloor by hydrothermal fluid circulation. The downcore samples are representative of both thermally unaltered and thermally altered sediments. The survey has revealed the presence of oxygenated compounds correlated with samples exhibiting a high degree of thermal maturity. Several homologous series of related ketone isomers are enriched in the interiors of the hydrothermal vent samples or in hydrothermally-altered sequences of the downcore sediments (DSDP Holes 477 and 481A). The n-alkanones range in carbon number from C 11 to C 33 with a C max from 14 to 23, distributions that are similar to those of the n-alkanes. The alkan-2-ones are usually in highest concentrations, with lower amounts of 3-, 4-, 5-, 6-, 7- (and higher) alkanones, and they exhibit no carbon number preference (there is an odd carbon number preference of alkanones observed for downcore samples). The alkanones are enriched in the interiors of the hydrothermal vent spires or in downcore hydrothermally-altered sediments, indicating an origin at depth or in the hydrothermal fluids and not from an external biogenic deposition. Minor amounts of C 13 and C 18 isoprenoid ketones are also present. Simulation of the natural hydrothermal alternation process by laboratory hydrous pyrolysis techniques provided information regarding the mode of alkanone formation. Hydrous pyrolysis of n-C 32H 66 at 350°C for 72 h with water only or water with inorganic additives has been studied using a stainless steel reaction vessel. In each experiment oxygenated hydrocarbons, including alkanones, were formed from the n-alkane. The product distributions indicate a reaction pathway consisting of n-alkanes and α-olefins as primary cracking products with internal olefins and alkanones as secondary reaction products. Hydrous pyrolyses of Messel shale spiked with molecular probes have been performed under similar time and temperature constraints to produce alkanone distributions like those found in the hydrothermal vent petroleums.

Unstabilized diazo derivatives from carbohydrates. Application to the synthesis of 2-deamino-tunicamine and products related to C-disaccharides

We applied a new synthetic method to C-disaccharides to obtain 2-deamino-tunicamine, the 2-hydroxy analogue of tunicamine, which is the main nucleus of tunicamycin antibiotics. 6-Deoxy-6-diazo-1:2,3:4-di-O-isopropylidene-D-galactopyranose was synthesized and reacted with methyl 2,3-O-isopropylidene-β-D-ribopentonodialdo-1,4-furanoside, to obtain a mixture of ketone and an epoxide with C-disaccharide structures. The epoxide was obtained in a reasonably good yield and full stereoselectivity, and was reduced to protected 2-deamino-tunicamine. Reduction of the ketone isomer, yielded the 7-epimer of 2-deamino-tunicamine. This is the first reported instance of an epoxy-C-disaccharide, the primary interest of which lies in its potential inhibition of glycosidase enzymes.

Reactions of 2,3-epoxypolyfluoroalkanes with triethylamine

The reactions of 2,3-epoxyperfluoro- and 2,3-epoxy-ω-hydropolyfluoroalkanes with excess triethylamine at elevated temperatures yield secondary alcohols, which are the reduction products of intermediate isomeric ketones. Ring-opening occurs preferentially from the side of the less bulky trifluoromethyl group in all compounds except 2,3-epoxy-6-hydroundecafluorohexane.

Fragmentation reactions of the trimethylsilyl adducts of C6 ketones

AbstractThe unimolecular (metastable ion) and collision‐induced fragmentation reactions of the trimethylsilyl cation adducts of six C6 ketones have been studied by tandem mass spectrometry. A major unimolecular fragmentation channel involves regeneration of the trimethylsilyl cation; other fragmentation channels involve elimination of (CH3)3SiOH, C5H10, C4H8 and C3H6 from the adduct ions. Some mechanistic detail has been obtained from a study of the adducts with deuterium‐containing ketones, and the reactions observed are compared with the fragmentation reactions of the protonated ketones. Collision‐induced dissociation (CID) of the adduct ion results in predominant formation of (CH3)3Si+. However, in the high energy (6 keV) CID new minor reaction channels, involving elimination of alkanes, CH4 to C4H10, become accessible. It is concluded that tandem mass spectrometry of the trimethylsilyl adducts provides only limited ability to distinguish between isomeric ketones.

Ketones in a Proterozoic dolerite sill

A dolerite sample from the Middle Proterozoic McArthur Basin in northern Australia has solid bitumen on fracture surfaces and liquid hydrocarbon fluid inclusions in secondary calcite mineralization. The extract of this sample is rich in polar compounds and contains an unusual and novel series of saturated ketone isomers, including homologous series of n-alkan-2-ones and n-alkan-3-ones, together with a complicated series of branched mid-chain ketones. These ketone isomers were identified by the monitoring of diagnostic mass chromatograms, including those due to rearrangement ions. n-Alkanes are only three to four times more abundant than the ketones. The n-alkan-2-ones have a similar distribution to the n-alkanes and may have been formed by the pyrolysis and β-oxidation of carboxylic acids, followed by decarboxylation of the resultant β-keto acids. The n-alkan-3-ones and the mid-chain isomers have a distribution which is biased towards the low molecular weight isomers, probably due to the pyrolysis of a different kerogen moiety, perhaps alkyl chains cross-linked by ether groups. Ketones are known to occur when oil shales are pyrolysed and in hydrothermal oil, so by analogy the natural pyrolysis of kerogen in the fine-grained sediments by the dolerite sill resulted in the generation of liquid products (predominantly n-alkanes and ketones) which were preserved as hydrocarbon-bearing fluid inclusions and as solid bitumen in a fracture.

An integrated analytical approach for determining the origin of solid bitumens in the McArthur Basin, northern Australia

An integrated analytical approach using petrological, geochemical and isotopic techniques has been used to determine the origin of solid bitumens in the Middle Proterozoic Roper Group, McArthur Basin, northern Australia. Sandstone and dolerite samples, which in hand specimen contain dark material believed to be solid bitumens, were examined from six wells. Under ultraviolet illumination, non-fluorescent solid bitumens can be distinguished from two generations of crude oil, one of lower maturity (orange fluorescence), the other of higher maturity (white fluorescence). Other petrographic observations indicate that the precursor hydrocarbons to the solid bitumens and the subsequent charges of crude oil postdate all diagenetic clay and quartz cementation. Geochemical analyses indicate that many of the sandstones contain both an aliphatic-rich oil and solid bitumen, mixed in varying proportions, thus corroborating the petrological results. On the basis of n-alkane distributions, the oil appears to have two 3ubtly-different source inputs, one of which is typified by a greater proportion of high molecular weight n-alkanes which have a slight even carbon-number predominance and an isotopically lighter aliphatic hydrocarbon fraction. One sandstone sample contains solid bitumen in a fracture which is characterized by a high abundance of asphaltenes, polar compounds and sulphur and may have formed by deasphalting of a precursor oil. The solid bitumens recovered from fractures in dolerite sills were formed by thermal processes which in one sample resulted in an unusual series of ketone isomers. However most solid bitumens, particularly where present in the coarser sandstones, are related to the generation of secondary porosity. The large proportion of unresolved complex mixture, the lack of n-alkanes and the isotopically heavier aliphatic hydrocarbon fractions of samples containing predominantly solid bitumens indicate that bitumen formation occurred mainly by biodegradation of a precursor oil.

Gas‐phase unimolecular chemistry of ethyl butyl ketone cations

AbstractMass spectra of the four isomeric ethylbutyl ketones, C2H5CO‐n‐C4H9 (1), C2H5CO‐iso‐C4H9 (2), C2H5CO‐sec‐C4H9 (3) and C2H5 CO‐t‐C4H9 (4), are reported. The structure of the fragment ions produced from precursors of both high and low internal energy were identified by collision experiments in a six‐sector mass spectrometer. Metastable molecular ions 1+˙ and 2+˙ behave identically in expelling CH3˙, C3H6 and C2H5˙ to produce the same fragment ions: [C2H5C(OH)CHCHCH3]+, [C2H5C(OH)CH2]+˙ and a mixture of [CHOHCHCHC2H5]+ and [CHOHCHC(CH3)2]+, respectively. The key isomerization step between 1+˙ and 2+˙ is a 1,2‐enol–olefin shift. Metastable molecular ions 3+˙ and 4+˙ give essentially ethene and ethyl losses, respectively; the fragment ions are [C2H5C(OH)CHCH3]+˙ and [t‐C4H9CO]+. Keto–enol isomerization also occurs to a significant extent for ions 1+˙ and 2+˙ and 3+˙. In contrast, 1,2‐ or 1,3‐ethylhydroxycarbene migrations are only marginal processes.

Oxygen-containing bicyclic monoterpenes.1H,13C and17O NMR Spectroscopic and X-ray diffraction studies of seven oxidation products of (+)-3-carene

Seven oxidation products of (1S,6R)-(+)-3,7,7-trimethylbicyclo[4.1.0]hept-3-ene [naturally abundant terpene, (+)-3-carene)]1; (1S,6R)-3,7,7-trimethylbicyclo[4.1.0]hept-3-en-2-one (3-caren-2-one)2, (1S,6R)-3,7,7-trimethylbicyclo[4.1.0]hept-3-en-5-one (3-caren-5-one)3, (1S,6R)-3,7,7-tri-methylbicyclo[4.1.0]hept-3-ene-2,5-dione (3-carene-2,5-dione)4, (1S,3S,4R,6R)-(+)-3,7,7-trimethylbicyclo[4.1.0]heptene 3,4-trans-oxide (trans-3,4-epoxy-3-carene)5, (1S,3R,4R,6R)-3,7,7-trimethylbicyclo[4.1.0]heptane-3-exo-4-endo-diol (carane-3-exo-4-endo-diol)6 and (1S,2R,4R,5R)-1-methyl-4-exo-(1-hydroxy-1-methylethyl)bicyclo[3.1.0]hexan-2-endo-ol 7 and (1S,6R)-3-endo-7,7-trimethylbicyclo[4.1.0]heptan-4-one (trans-4-caranone)8 have been obtained by oxidation with tert-butylchromate, selenium dioxide, hydrogen peroxide and peracetic acid. The 1H, 13C and 17O NMR spectra of the purified oxidation products have been recorded and assigned. In addition to C,H-COSY spectra, the 1J(C,H) coupling constants were especially useful in 13C NMR spectral assignment. The differentiation between isomeric ketones 2 and 3 is based on a clear difference in the 13C NMR shifts of the double bond methyl. The stereochemical structure elucidation of oxide 5 is based on lanthanide shift reagent [Eu(dpm)3] induced effects. For ketone 8, molecular mechanics (MM) calculations and comparison of experimental and theoretical 3J(H,H) coupling constants are needed for a final structure elucidation. The assignment of 17O NMR lines of diols 6 and 7 is based on literature values. The crystal structures and absolute configurations of pure enantiomers of diols 6 and 7 have been determined by X-ray diffraction. Crystal data: a= 7.659(2), b= 10.804(3), c= 25.509(4)A, orthorhombic, space group C 2221, Z= 8 (6) and a= 8.076(4), b= 8.836(2), c= 12.487(3)A, orthorhombic, space group P212121, Z= 4 (7).

The Shape-Selective Acylation of 2-Methoxynaphthalene, Catalyzed by Zeolites Y, Beta and ZSM-12

The Friedel-Crafts acylation of 2-methoxynaphthalene (2MN) was investigated using zeolites USY, Beta and ZSM-12 as catalysts under batch conditions at 100 and 180 °C. Two ketone isomers, 1-acetyl-2-methoxynaphthalene (1AC) and 2-acetyl-6-methoxynaphthalene (2AC) were produced; the selectivity of the reaction could be influenced by the zeolite used. USY produced only the 1AC isomer whereas Beta and ZSM-12 produced both. Selective synthesis of 2AC was achieved by optimization of the reaction conditions using zeolite Beta as the catalyst. It was also observed that the 1AC ketone is unstable in contact with acid zeolite catalysts and undergoes protiodeacylation, a reaction previously only observed in the presence of strong mineral acids.

Durch Säuren katalysierte Öffnung eines Epoxids und Reaktionen der Produkte an Kieselgel / Acid Catalyzed Alcoholysis of an Epoxide and Reactions of Products on Contact with Silica Gel

The alcoholysis of epoxide 1 in acidic methanol leads to various products; one of these — hydroxymethoxyketone 7 — rearranges to the isomeric ketone 14 on contact with silica gel.

The interaction of polyfluorinated bis(fluorosulfato)carbonyl compounds with nucleophiles

The action of LiCl or LiBr on polyfluorinated bis(fluorosulfato)- carbonyl compounds leads to substitution of one FSO 3-group, predominatingly in α-position and simultaneous formation of second carbonyl function: ▪ (I,II) R=(CF 3) 2CF;Z(I)=OCH 3;Z(II)=C 2F 5; Hal=Cl,Br Depending on reaction condition(I) interacts with CsF to formate diketoester(III) or epoxide (IV); ketone (II) is transformed into the mixture of isomeric ketones (V–VI). In DMF media(II) gives oxirane (VII),which dimerizes in the cours of reaction. Triketone (VIII) was obtained by reaction of (II) with MeOH and subsequent make up with H 2S0 4. ▪