scholarly journals Effect of Reactivity on Kinetics and a Mechanistic Investigation of the Reaction between Dimethyl Acetylenedicarboxylate and 1,3-Dicarbonyl Compounds in the Presence of a Catalyst: A Spectrophotometric Approach

2018 ◽  
Vol 43 (1) ◽  
pp. 79-90 ◽  
Author(s):  
Mahdieh Darijani ◽  
Sayyed Mostafa Habibi-Khorassani ◽  
Mehdi Shahraki
Keyword(s):  
Structural Effect ◽  
Similar Reaction ◽  
Dimethyl Acetylenedicarboxylate ◽  
Dicarbonyl Compounds ◽  
Dicarbonyl Compound ◽  
Rate Determining Step ◽  
Mechanistic Investigation ◽  
Differential Behaviour ◽  
Fourth Step ◽  
Step Step

A kinetic and mechanistic investigation, using conventional UV-Vis spectrophotometry, of the reaction between dimethyl acetylenedicarboxylate (DMAD) and 1,3-dicarbonyl compounds including acetylacetone (ACAC) and dibenzoylmethane (DBM), has been conducted in a methanol environment with triphenylarsine (TPA) acting as a catalyst. Previously, in a similar reaction, triphenylphosphine (TPP) (instead of TPA) had been employed as a reactant (not a catalyst) for the generation of an ylide (final product). In the present work, of significance is the differential behaviour of TPA which, as a catalyst in the reaction environment, leads to a cyclopropane compound. Of other significance is the different behaviours of the two reactants in the kinetics and mechanism of the reaction. In previous work, TPP acted as a weak nucleophile (a reactant), so the first step of the reaction was recognised as the rate-determining step (RDS). Here, TPA reacts as a stronger nucleophile and a catalyst, resulting in the fourth step of the reaction (step4, k4, a proton transfer process) being recognised as the RDS. The reaction followed second-order kinetics. The proposed mechanism was adapted in accord with the experimental results and the steady-state assumption. The results showed that the reaction rate decreases in the presence of DBM, which participates in the second step (step2), compared to ACAC when it is present as another 1,3-dicarbonyl compound (structural effect). In addition, in previous work, the partial order of the reaction with respect to the 1,3-dicarbonyl compound was zero, while it is one in the present work. As a significant result, not only did a change in the structure of one of the reactants (TPA instead of TPP) create a different product, but also the kinetics and reaction mechanism changed. In addition, the reaction is enthalpy-controlled.

Reaction between Chalcones, 1,3-Dicarbonyl Compounds, and Elemental Sulfur: A One-Pot Three-Component Synthesis of Substituted Thiophenes

Synlett ◽  
2018 ◽  
Vol 29 (12) ◽  
pp. 1583-1588 ◽  
Author(s):  
Mehdi Adib ◽  
Saideh Rajai-Daryasarei ◽  
Rahim Pashazadeh ◽  
Mehdi Jahani ◽  
Massoud Amanlou
Keyword(s):  
Elemental Sulfur ◽  
One Pot ◽  
Dicarbonyl Compounds ◽  
Dicarbonyl Compound

A simple and atom-economic synthesis of highly substituted thiophenes is demonstrated. Heating a solution of a chalcone and a ­linear/cyclic 1,3-dicarbonyl compound with elemental sulfur in CH3CN in the presence of NEt3 at 80 °C afforded the corresponding substituted thiophenes in good to excellent yields.

scholarly journals Comparison of Substituting Ability of Nitronate versus Enolate for Direct Substitution of a Nitro Group

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2048 ◽  
Author(s):  
Yusuke Mukaijo ◽  
Soichi Yokoyama ◽  
Nagatoshi Nishiwaki
Keyword(s):  
Nucleophilic Substitution ◽  
Nitro Group ◽  
Conjugate Addition ◽  
Ring Closure ◽  
Dicarbonyl Compounds ◽  
Dicarbonyl Compound ◽  
Direct Substitution ◽  
Electron Withdrawing Group ◽  
Active Methylene

α-Nitrocinnamate underwent the conjugate addition of an active methylene compound such as nitroacetate, 1,3-dicarbonyl compound, or α-nitroketone, and the following ring closure afforded functionalized heterocyclic frameworks. The reaction of cinnamate with nitroacetate occurs via nucleophilic substitution of a nitro group by the O-attack of the nitronate, which results in isoxazoline N-oxide. This protocol was applicable to 1,3-dicarbonyl compounds to afford dihydrofuran derivatives, including those derived from direct substitution of a nitro group caused by O-attack of enolate. It was found the reactivity was lowered by an electron-withdrawing group on the carbonyl moiety. When α-nitroketone was employed as a substrate, three kinds of products were possibly formed; of these, only isoxazoline N-oxide was identified. This result indicates that the substituting ability of nitronate is higher than that of enolate for the direct SN2 substitution of a nitro group.

The reaction of tryptophan and derivatives with some 1,3-dicarbonyl compounds

1977 ◽  
Vol 30 (9) ◽  
pp. 2045 ◽  
Author(s):  
JA Maclaren
Keyword(s):  
Condensation Product ◽  
Methyl Esters ◽  
Dicarbonyl Compounds ◽  
Dicarbonyl Compound

Enamine methyl esters are obtained by methylation of the condensation product from a 1,3-dicarbonyl compound with L-tryptophan, or directly from methyl L-tryptophanate and the 1,3-dicarbonyl compound. Protonation of these enamines forms either methyl L-tryptophanate or a tetrahydro-β-carboline derivative (two diastereomers in certain cases), depending on the structure of the dicarbonyl compound. Enamines from 1,3-dicarbonyl compounds and tryptamine yield similar cyclic products on protonation.

The reaction of malononitrile with some β-dicarbonyl compounds

1975 ◽  
Vol 28 (3) ◽  
pp. 581 ◽  
Author(s):  
JW Ducker ◽  
MJ Gunter
Keyword(s):  
Benzene Solution ◽  
Similar Reaction ◽  
Benzene Derivatives ◽  
Dicarbonyl Compounds ◽  
Keto Esters

The reaction of β-keto esters and amides with malononitrile, in the presence of alcohol, has been shown to proceed through cyanocarbon acid and iminopyran intermediates to yield the pyridones (3).With β- diketones, in benzene solution, a similar reaction is accompanied by the formation of δ-lactams(15) and benzene derivatives (16).

scholarly journals Simplified Kinetics and Colour Formation in Sucrose Solutions Based on A-Dicarbonyl Compounds

2007 ◽  
Vol 3 (4) ◽  
Author(s):  
Quido Smejkal ◽  
Thorsten Fiedler ◽  
Tomas Kurz ◽  
Lothar Kroh
Keyword(s):  
Activation Energy ◽  
Maillard Reaction ◽  
Enzymatic Browning ◽  
Dicarbonyl Compounds ◽  
Formation Reaction ◽  
Dicarbonyl Compound ◽  
Reaction Systems ◽  
Dominant Colour ◽  
Sucrose Solutions ◽  
Two Temperature

Colour formation in technical and model sucrose solutions was investigated resulting in a novel kinetic approach of MAILLARD reaction during thermal processing of sugar solutions. Presented results describe new aspects of the non-enzymatic browning reaction (MAILLARD reaction). Two temperature depending pathways of colour formation were found. Both reaction mechanisms are based on the formation of a-dicarbonyl compounds, the key intermediates of colour formation.Discussing temperature dependence of colour formation, a change on MAILLARD reaction mechanism takes place at 100.4 °C. Above this temperature the colour formation is strongly accelerated. Activation energy of the non-enzymatic browning energy for temperatures from 65 ° to 100.4 °C amounts 77 kJ/mol. In this temperature range, D-glucosone is the most important a-dicarbonyl compound for studied reaction systems. Above 100.4 °C, activation energy is equal to 112 kJ/mol and 3-deoxyosone is the dominant colour formation intermediate. Achieved results bridge the gap between the termination step of a MAILLARD reaction –i.e. of colour formation (represented by its activation energy) and intermediates formation (reaction kinetics). In particular, a change of colour formation mechanism with reaction temperature was confirmed by specific formation of two a-dicarbonyl compounds, responsible for MAILLARD reaction in technical sugar solutions.

scholarly journals Flavorings-Related Lung Disease: A Brief Review and New Mechanistic Data

2019 ◽  
Vol 47 (8) ◽  
pp. 1012-1026 ◽  
Author(s):  
Ann F. Hubbs ◽  
Kathleen Kreiss ◽  
Kristin J. Cummings ◽  
Kara L. Fluharty ◽  
Ryan O’Connell ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Lung Disease ◽  
Bronchiolitis Obliterans ◽  
Severe Form ◽  
Biological Molecules ◽  
Airway Epithelial ◽  
Dicarbonyl Compounds ◽  
Dicarbonyl Compound ◽  
Airway Injury ◽  
New Findings

Flavorings-related lung disease is a potentially disabling and sometimes fatal lung disease of workers making or using flavorings. First identified almost 20 years ago in microwave popcorn workers exposed to butter-flavoring vapors, flavorings-related lung disease remains a concern today. In some cases, workers develop bronchiolitis obliterans, a severe form of fixed airways disease. Affected workers have been reported in microwave popcorn, flavorings, and coffee production workplaces. Volatile α-dicarbonyl compounds, particularly diacetyl (2,3-butanedione) and 2,3-pentanedione, are implicated in the etiology. Published studies on diacetyl and 2,3-pentanedione document their ability to cause airway epithelial necrosis, damage biological molecules, and perturb protein homeostasis. With chronic exposure in rats, they produce airway fibrosis resembling bronchiolitis obliterans. To add to this knowledge, we recently evaluated airway toxicity of the 3-carbon α-dicarbonyl compound, methylglyoxal. Methylglyoxal inhalation causes epithelial necrosis at even lower concentrations than diacetyl. In addition, we investigated airway toxicity of mixtures of diacetyl, acetoin, and acetic acid, common volatiles in butter flavoring. At ratios comparable to workplace scenarios, the mixtures or diacetyl alone, but not acetic acid or acetoin, cause airway epithelial necrosis. These new findings add to existing data to implicate α-dicarbonyl compounds in airway injury and flavorings-related lung disease.

Nazarov cyclisations initiated by DDQ-oxidised pentadienyl ether: a mechanistic investigation from the DFT perspective

2018 ◽  
Vol 16 (46) ◽  
pp. 9021-9029 ◽  
Author(s):  
Ali Gouranourimi ◽  
Antony Chipman ◽  
Rasool Babaahmadi ◽  
Angus Olding ◽  
Brian F. Yates ◽  
...  
Keyword(s):  
Hydride Transfer ◽  
Nazarov Cyclization ◽  
Rate Determining Step ◽  
Mechanistic Investigation

The rate determining step for such a Nazarov cyclization is direct hydride transfer from pentadienyl ether to the oxygen of DDQ.

Facile synthesis of 1,4-diketones via three-component reactions of α-ketoaldehyde, 1,3-dicarbonyl compound, and a nucleophile in water

2018 ◽  
Vol 20 (6) ◽  
pp. 1367-1374 ◽  
Author(s):  
Jian Yang ◽  
Fuming Mei ◽  
Shitao Fu ◽  
Yanlong Gu
Keyword(s):  
Facile Synthesis ◽  
Dicarbonyl Compounds ◽  
Dicarbonyl Compound ◽  
Catalyst Free

Three-component reactions of alkylglyoxals, 1,3-dicarbonyl compounds, and a nucleophile were performed under aqueous and catalyst-free conditions, which produced 1,4-diketone scaffolds in a straightforward way.

scholarly journals Full Kinetics and a Mechanistic Investigation of the Green Protocol for Synthesis of β-Aminoketone in the Presence of Saccharose as a Catalyst by a One-Pot Three-Component Reaction

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Sayyed Mostafa Habibi-Khorassani ◽  
Malek Taher Maghsoodlou ◽  
Mehdi Shahraki ◽  
Sadegh Talaie Far ◽  
Mir Rasul Mousavi
Keyword(s):  
Reaction Mechanism ◽  
Rate Constant ◽  
Order Rate Constant ◽  
Second Order ◽  
One Pot ◽  
Green Protocol ◽  
Order Rate ◽  
Rate Determining Step ◽  
Mechanistic Investigation ◽  
Three Component Reaction

For the first time, in a green protocol, an investigation of the kinetics and mechanism of the reaction between benzaldehyde 1, 4-chloroanilinne 2, and acetophenone 3 compounds in the presence of saccharose as a catalyst was performed for generating β-aminoketone. For determining the kinetic parameters, the reaction was monitored by using the UV/Vis spectrophotometry technique. The second order rate constant (k1) was automatically calculated by the standard equations contained within the program. In the studied temperature range, the second order rate constant (ln k1, ln k1/T) depended on reciprocal temperature that was in good consistent with Arrhenius and Eyring equations, respectively. These data provided the suitable plots for calculating the activation energy and parameters (Ea, ΔG‡, ΔS‡, and ΔH‡) of the reaction. Furthermore, useful information was obtained from studying the effects of solvent, concentration, and catalyst on the reaction mechanism. The results showed that the first step of the reaction mechanism is a rate determining step (RDS). The obtained experimental data and also the steady state assumption confirmed the proposed mechanism.

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