Showing papers on "Methyl vinyl ketone published in 2017"

Enantioselective Rauhut-Currier-Type 1,6-Conjugate Addition of Methyl Vinyl Ketone to para-Quinone Methides.

Abstract: An unprecedented Rauhut-Currier-type 1,6-conjugate addition has been developed. With chiral cyclohexane-based phosphine-amide catalyst 3 h, the 1,6-conjugate reaction has been achieved to produce chiral diarylmethine compounds in excellent yields (91-99 %) and enantioselectivities (92-98 % ee).

An experimental study in a jet-stirred reactor and a comprehensive kinetic mechanism for the oxidation of methyl ethyl ketone

Abstract: The first speciation data regarding the oxidation of methyl ethyl ketone (MEK) are presented. Fuel-lean, stoichiometric and fuel-rich mixtures were studied at constant fuel concentration (1000 ppm) in a jet stirred reactor at atmospheric and high pressure (10 atm). A detailed kinetic mechanism is proposed based on theoretical calculations at the G3//MP2/aug-cc-pVDZ level of theory. The new rate constants differ substantially from the estimations employed in the previous MEK submechanism available in the literature, and impact MEK oxidation pathways. The model was tested successfully against these new speciation data and other available data (ignition delay times, flame speeds, pyrolysis species profile). However, some deficiencies in the model were identified concerning methyl ketene and methyl vinyl ketone. Reaction path analyses are used to interpret the results.

Investigation of the reaction of ozone with isoprene, methacrolein and methyl vinyl ketone using the HELIOS chamber.

Abstract: The rate constants for the ozonolysis of isoprene (ISO), methacrolein (MACR) and methyl vinyl ketone (MVK) have been measured using the newly built large volume atmospheric simulation chamber at CNRS-Orleans (France), HELIOS (Chambre de simulation atmospherique a irradiation naturelle d'Orleans). The OH radical yields from the ozonolysis of isoprene, MACR and MVK have also been determined, as well as the gas phase stable products and their yields. The secondary organic aerosol yield for the ozonolysis of isoprene has been tentatively measured in the presence and absence of an OH radical scavenger. The measurements were performed under different experimental conditions with and without adding cyclohexane (cHX) as an OH radical scavenger. All experiments have been conducted at 760 torr of purified dry air (RH < 1%) and ambient temperature (T = 281-295 K). The data obtained are discussed and compared with those from the literature. The use of the HELIOS facility and its associated analytical equipment enables the derivation of kinetic parameters as well as mechanistic information under near realistic atmospheric conditions.

Quantitative Infrared Absorption Spectra and Vibrational Assignments of Crotonaldehyde and Methyl Vinyl Ketone Using Gas-Phase Mid-Infrared, Far-Infrared, and Liquid Raman Spectra: s-cis vs s-trans Composition Confirmed via Temperature Studies and ab Initio Methods

Abstract: Methyl vinyl ketone (MVK) and crotonaldehyde are chemical isomers; both are also important species in tropospheric chemistry. We report quantitative vapor-phase infrared spectra of crotonaldehyde and MVK vapors over the 540–6500 cm–1 range. Vibrational assignments of all fundamental modes are made for both molecules on the basis of far- and mid-infrared vapor-phase spectra, liquid Raman spectra, along with density functional theory and ab initio MP2 and high energy-accuracy compound theoretical models (W1BD). Theoretical results indicate that at room temperature the crotonaldehyde equilibrium mixture is approximately 97% s-trans and only 3% s-cis conformer. Nearly all observed bands are thus associated with the s-trans conformer, but a few appear to be uniquely associated with the s-cis conformer, notably ν16c at 730.90 cm–1, which displays a substantial intensity increase with temperature (70% upon going from 5 to 50 o C). The intensity of the corresponding mode of the s-trans conformer decreases with te...

A laminar flame investigation of 2-butanone, and the combustion-related intermediates formed through its oxidation

Abstract: 2-butanone (methyl ethyl ketone) is a recently identified high-octane, next-generation biofuel candidate, synthesized through microbiological pathways from biomass. Its high octane number (RON = 117), low boiling point (80 °C), and relatively high vapor pressure (10.8 kPa at 20 °C) make 2-butanone a potentially good candidate for use in spark-ignition engines. The flame structure and species formed in 2-butanone combustion are of interest when further considering this compound for use as a fuel. To this end, the present study has, for the first time, quantitatively measured species profiles within a fuel-rich (ϕ = 1.6) laminar premixed flat flame of 2-butanone. Two experiments which used different facilities and measurement techniques were combined to provide a cross comparison of the measured species. One experiment was performed using electron ionization (EI) molecular-beam mass spectrometry (MBMS), and the second relied on synchrotron-generated vacuum ultraviolet (VUV) photoionization (PI) MBMS. Quantitative mole fraction profiles for about 45 species were obtained from the two independent experiments that are found to be in good agreement. The experiments have identified the formation of a number of toxic oxygenated intermediates, such as methyl vinyl ketone (MVK), acetaldehyde, and formaldehyde. In addition, the measurements have also provided quantitative species profiles for a number of soot precursor species, the concentrations of which are notably low. These measurements provide useful validation targets for the further development of detailed chemical kinetic models. As a first test, an existing 2-butanone model was examined against the experimental data with the main aim to identify elements of the model that may need improvement.

Poly(Methyl Vinyl Ketone) as a Potential Carbon Fiber Precursor

Abstract: Given their increasing importance in a variety of applications, the preparation of carbon fibers with well-defined chemical structures and innocuous byproducts has garnered a growing interest over the past decade. We report the preparation of medium molecular weight poly(methyl vinyl ketone) (PMVK) as a potential carbon fiber precursor material which can easily undergo carbonization via the well-known, acid-catalyzed aldol condensation with water as a sole byproduct. Rheological studies further show that PMVK (MW ∼ 50 kg/mol) exhibits excellent physical and thermal properties for the spinning of single and multifilament fibers and easily produces carbon yields of 25% at temperatures as low as 250 °C. Analysis of the carbonized product also suggests a more defect-free structure than commercially available carbon fibers.

Conformational Landscape and Torsion–Rotation–Vibration Effects in the Two Conformers of Methyl Vinyl Ketone, a Major Oxidation Product of Isoprene

Abstract: Methyl vinyl ketone is the second major oxidation product of isoprene, and as such an important volatile organic compound present in the troposphere. In the present study, quantum chemical calculations coupled to high-resolution millimeter-wave spectroscopy have been performed to characterize the ground and first excited vibrational states of the two stable conformers. Equilibrium structures, internal rotation barriers, and relative energies have been calculated at the MP2 and M062X levels of theory. Experimental molecular parameters have been obtained that model the rotational and torsional structures, including splitting patterns due to the internal rotation of the methyl group. For the most stable antiperiplanar (s-trans) conformer, the set of parameters obtained for the ground state should be useful to further model IR spectra up to room temperature. By combining theoretical and experimental data, we obtained a relative energy value of 164 ± 30 cm–1 in the gas phase between the more stable antiperipla...

Synthesis of functionalized alkyl substituted benzoquinones by Rh-catalyzed additions of boronic acids

Abstract: A general synthetic route to γ-oxo alkyl or α-hydroxy benzyl 2-substituted benzoquinones has been developed through a one-pot Rh-catalyzed C–C bond formation/oxidative demethylation sequence from 2,5-dimethoxy aryl boronic acids and several electron deficient alkenes or aldehydes. The process allows rapid access to functionalized benzoquinones under very mild conditions and good yields. We disclose the first example of a Rh-catalyzed 1,4-addition reaction of benzoquinonyl boronic acid to methyl vinyl ketone and other conjugate acceptors, which allows the direct synthesis of 2-(γ-functionalized alkyl) substituted benzoquinones.

A Nucleophilic Activation of Carboxylic Acids by Proline: Oxa-Michael Addition to Methyl Vinyl Ketone under Solvent-Free Conditions

Abstract: A serendipitous nucleophilic activation of carboxylic acids by proline helped to achieve a direct hydrocarboxylation of methyl vinyl ketone at 60 °C under solvent-free conditions. A variety of carboxylic acids were used successfully in this oxa-Michael addition, affording useful 4-acyloxy-2-butanones in moderate yields. The reactions are carried out under solvent-free conditions, and the products are isolated in high purity by a simple work-up procedure without any need for column chromatographic purification, imparting a green quotient to the protocol. A heterodimeric non-covalent interaction between the amino acid and the carboxylic acid appears to be the most plausible mechanistic interpretation for the nucleophilic activation; additionally, the possible activation of the Michael acceptor by iminium ion formation presents an interesting case of proline acting as a bifunctional catalyst.

Study of the Synchrotron Photoionization Oxidation of 2-Methylfuran Initiated by O(3P) under Low-Temperature Conditions at 550 and 650 K

Abstract: The O(3P)-initiated oxidation of 2-methylfuran (2-MF) was investigated using vacuum-ultraviolet synchrotron radiation from the Advanced Light Source at Lawrence Berkeley National Laboratory. Reaction species were studied by multiplexed photoionization mass spectrometry at 550 and 650 K. The oxygen addition pathway is favored in this reaction, forming four triplet diradicals that undergo intersystem crossing into singlet epoxide species that lead to the formation of products at m/z 30 (formaldehyde), 42 (propene), 54 (1-butyne, 1,3-butadiene, and 2-butyne), and 70 (2-butenal, methyl vinyl ketone, and 3-butenal). Mass-to-charge ratios, photoionization spectra, and adiabatic ionization energies for each primary reaction species were obtained and used to characterize their identities. In addition, by means of electronic structure calculations, potential energy surface scans of the different species produced throughout the oxidation were examined to further validate the primary chemistry occurring. Branching f...

Mechanism and kinetics for the reactions of methacrolein and methyl vinyl ketone with HO2 radical

Abstract: The high-level theoretical study on the reactions of methacrolein and methyl vinyl ketone with hydroperoxyl radical was carried out using the M06-2X method in conjunction with the 6-311+G(2df,2pd) basis sets. For the two reactions, all possible addition and abstraction channels initiate from the reactant complexes. The most favorable reaction channel is the concerted addition of the terminal O atom of HO2 radical to the aldehyde-C (or carbonyl-C) and H-transfer from HO2 to the aldehyde-O (or carbonyl-O) forming the α-hydroxyalkenylperoxy radical. For the methacrolein + HO2 and methyl vinyl ketone + HO2 reactions, the calculated rate constants decrease as the temperature increases from 200 K to 500 K, and at 298 K, they are 1.34 × 10−14 and 2.56 × 10−14 cm3 molecule−1 s−1, respectively. The calculated results are close to the previous theoretical and experimental observations for the reactions of HO2 radical with formaldehyde, acetaldehyde, and acetone.

Fabrication and photodegradable properties of chitosan-g-poly(methyl vinyl ketones) nanoporous microspheres

Abstract: Chitosan (CS) is a well-known natural polysaccharide with good biocompatibility and biodegradability. Graft copolymerization of poly (methyl vinyl ketone) (PMVK) onto chitosan was conducted by free...

Method for preparing raspberry ketone under catalysis of multi-sulfonic functionalized ionic liquid

Abstract: The invention discloses a method for preparing raspberry ketone under the catalysis of multi-sulfonic functionalized ionic liquid. According to the method, phenol and methyl vinyl ketone are used as raw materials and the multi-sulfonic functionalized ionic liquid is used as a catalyst for selective catalytic synthesis of raspberry ketone. The ionic catalyst has the advantages of high acid value, low synthesis cost, good catalysis efficiency and reaction activity at room temperature compared with conventional ionic catalysts.

Photocatalytic Carbon – Carbon Bond Formations with Visible Light

Abstract: The presented work deals with visible light photoredox catalysis. Different reactions, e. g. photocatalytic conjugate additions and oxidative Mannich reactions were investigated and an immobilizable photoredox catalyst was developed. In the first project the yield and scope of a photocatalytic conjugate addition between a tert. amine and an enone was increased. The influence of different additives and new photoredox catalysts on the reaction was investigated. The yield could be improved to up to 93%. Also new suitable amines to conduct the reaction were discovered. Besides irradiation of the solution in snap cap vials, the reaction was also performed using a mircoreactor system. In the second project a photocatalytic way to functionalize γ-butyrolactones was investigated and established. Up to 28% yield where obtainable when TBS-furan, trimethylaniline and [Ir(ppy)2(dtbbpy)]PF6 as photoredoxcatalyst were mixed and irradiated without degassing in a micro reactor. Also a photocatalytic method to open a pyrrole derived cyclopropane and functionalize it with methyl vinyl ketone in an unprecedented way was developed. However, currently only one example of this transformation is known. Further substrates have to be discovered. As final project a photoredox catalyst based on [Ir(ppy)2(dtbbpy)]PF6 was developed that can be immobilized on silica particles. The novel catalyst exhibited nearly the same photochemical properties as unfunctionalized catalyst and could be immobilized on silica particles in up to 35 µmol/g. The immobilized catalyst was employed in deoxygenation reactions and could be recycled for four consecutive runs.

Method for preparing important Suvorexant intermediate

Abstract: The invention belongs to the technical field of medicines and relates to a method for preparing an important intermediate {2-[(5-chlorobenzoxazole-2-yl)-(3-one-butyl)-amino]ethyl}-tert-butyl carbamate. A highly toxic product methyl vinyl ketone is substituted by a compound with low toxicity, and due to catalytic reactions of DBU, LDA, NaHMDS, KHMDS and the like, a compound of a formula (3) can be obtained at high yield of 90% or higher. Moreover, the HPLC (high performance liquid chromatography) content of the crude product reaches 99.5% or higher, and the method disclosed by the invention is suitable for industrial production.

Benzyl acetone synthesis method

Abstract: The present invention provides a benzyl acetone synthesis method, which comprises: (1) adding a catalyst and first part of benzene to a reactor, and uniformly stirring at a temperature of -5-35 DEG C; and (2) adding the mixture of methyl vinyl ketone and second part of benzene to the reactor of the step (1), carrying out a reaction for 1-5 h at a temperature of -5-35 DEG C, carrying out water washing, recovering benzene, and distilling to obtain the benzyl acetone. According to the present invention, the intermediate link is eliminated, the operation is simple, the reaction time is short, the energy consumption for the temperature control is saved, and the raw materials are easy to obtain so as to further reduce the production cost.

Synthesis method of 5-benzyl-2-tert-butyl-8-oxo-2,5-diazaspiro[3,5]nonanyl-2,5-dicarboxylic acid

Abstract: The invention relates to a synthesis method of 5-benzyl-2-tert-butyl-8-oxo-2,5-diazaspiro[3,5]nonanyl-2,5-dicarboxylic acid. The technical problem of no industrial synthesis routes is mainly solved. The method comprises the following steps: carrying out a reflux reaction on methyl vinyl ketone and phthalimide in an ethyl acetate and methanol mixed solvent to obtain a compound 1; carrying out a reflux reaction on the compound 1 in toluene to convert ketone into a compound 2; carrying out a reflux reaction on the compound 2 and hydrazine hydrate in methanol to obtain a compound 3; reacting the compound 3 with tertbutyloxycarbonyl protected azetidinone to obtain a compound 4; and carrying out a reaction under an acidic condition to remove ethyl ketal from the compound 4, and carrying out amino group protection to obtain the target compound 5-benzyl-2-tert-butyl-8-oxo-2,5-diazaspiro[3,5]nonanyl-2,5-dicarboxylic acid. The compound obtained in the invention is a medicine intermediate.

Solid-supported MPV reaction catalyst, preparation method and application thereof to production of nerol and geraniol

Abstract: The invention discloses a solid-supported MPV reaction catalyst. The catalyst is of a structure based on a styrol/methyl vinyl ketone copolymer skeleton, and the structure is shown in the specification. A wavy line denotes repeated styrol/methyl vinyl ketone segmented copolymer structure units, each styrol/methyl vinyl ketone segmented copolymer structure unit is shown in the specification, n is equal to 17 to 27, and the weight-average molecular weight of the catalyst is 3000 to 5000. Polystyrene-methyl vinyl ketone is obtained by adopting a copolymerization method of styrol and methyl vinyl ketone, then a hydroxyl polymer is obtained under the effect of reducing agents such as sodium borohydride, and finally the solid-supported aluminum alkoxide structure catalyst is obtained through reaction with aluminum powder. The catalyst is applied to citral selective hydrogen transfer so as to generate nerol and geraniol, the reaction selectivity is greater than 99%, and the yield reaches up to 95%. After the reaction is completed, the catalyst is recycled through filtering, and the activity is not decreased obviously after ten times of recycling.

Method for preparing methyl vinyl ketone through continuous dehydration of butanone alcohol

Abstract: The invention discloses a method for preparing methyl vinyl ketone through continuous dehydration of butanone alcohol The method comprises the following steps that after crude butanone alcohol and acid are mixed to be uniform, the mixture enters a film evaporator, the mass concentration of the acid is 2-25%, and the volume ratio of the acid to the crude butanone alcohol is 1:(40-180); under heating of the film evaporator and the effect of acid, the dehydration generation boiling point of butanone alcohol is lower than that of methyl vinyl ketone, the methyl vinyl ketone generated through the reaction is rapidly evaporated inside the film evaporator and separated from the liquid butanone alcohol and acid mixture, the outlet temperature of the film evaporator is controlled to be 100-200 DEG C, and the time spent by the butanone alcohol and acid mixture from entrance to exit of the film evaporator is controlled to be 4-60 s; then, the product is condensed and recycled through a gas-liquid separator and a condenser

Urea hydrochloride compositions and associated methods

Abstract: Disclosed is a method for treating a system, the method comprising providing a composition comprising HCl, urea, complex substituted keto-amine-hydrochloride, at least one alcohol selected from the group consisting of isopropyl alcohol and propargyl alcohol, an ethoxylate, and at least one ketone selected from the group consisting of methyl vinyl ketone, acetone, and acetophenone; and inserting the composition into at least one of an oil well and a gas well.