Formation Of Mesityl Oxide Research Articles

Chemical reactivity of the tryptophan/acetone/DMSO triad system and its potential applications in nanomaterial synthesis.

Previously, we reported a novel browning reaction of amino acids and proteins in an organic solvent mixture composed of dimethyl sulfoxide (DMSO) and acetone. The reaction proceeds under surprisingly mild conditions, requiring no heating or additional reactants or catalysts. This present study aimed to investigate the chemical reactivity of the triad reaction system of l-tryptophan/aectone/DMSO. We demonstrated that, in DMSO, l-tryptophan initially catalyzed the self-aldol condensation of acetone, resulting in the formation of mesityl oxide (MO). Furthermore, we showed that the three-component system evolved into a diverse chemical space, producing various indole derivatives with aldehyde or ketone functional groups that exhibited self-assembling and nanoparticle-forming capabilities. We highlight the potential applications in nanomaterial synthesis.

Fluoride adducts of niobium(V): Activation reactions and alkene polymerizations

Fluoride coordination derivatives of niobium(V) were tested for their activation capabilities with respect to acetone and to olefins. Activation of acetone (formation of mesityloxide) was observed with NbF4(OMe). Several fluoride coordination derivatives of niobium(V) of different nature (neutral or ionic) and nuclearity, i.e. NbF5L [L=Et2O, 4, thf, 5 (thf is tetrahydrofuran), MeOH, 6, EtOH, 7], (NbF4L2)(NbF6) [L=dmf, 8 (dmf is dimethylformamide), dme, 9 (dme is dimethoxyethane)], (NbF4L4)(NbF6) [L=thf, 10, Et2O, 11, MeCN, 12], [S(NMe)3][NbF6], 13, NbF4OMe, 1, NbF4OPh, 3), NbF3(OPh)2, 14, NbF2(OPh)3, 15 and NbF2(OEt)3, 16, promoted the polymerization of ethylene using AlMe3-depleted methylaluminoxane as cocatalyst. Highly linear polyethylene was obtained. Compound 3, upon activation with methylaluminoxane, promoted ring-opening metathesis polymerization (ROMP) of norbornene, affording polymers with a slight excess of trans content.

ZnAlFe Mixed Oxides Obtained from LDH Type Materials as Basic Catalyst for the Gas Phase Acetone Condensation

ZnAlFe mixed oxides with high surface area were obtained by the calcination (723 K) of ZnAlFe layered double hydroxides (LDHs). The calcined materials proved as basic catalysts in the gas phase acetone condensation exhibited high activity and high selectivity towards the formation of mesityl oxide.

Synthesis of methyl isobutyl ketone from acetone over metal-doped ion exchange resin catalyst

The kinetics of one-step synthesis of methyl isobutyl ketone from acetone was studied in the presence of the bifunctional commercial ion exchange resin, Amberlyst CH28 over a wide range of temperature, total pressure and catalyst loading in a batch reactor. An activity-based kinetic model is proposed to predict the observed results, with the non-idealities of the liquid phase being described using the UNIQUAC method. Formation of mesityl oxide was found to govern the overall rate of reaction. Low reaction rates were observed at higher conversion, possibly due to a pseudo-equilibrium caused by reversible deactivation of the catalyst as a result of formation of water in the reaction system. Simultaneous removal of water during the course of the reaction may result in an enhanced conversion.

A three-phase nonequilibrium dynamic model for catalytic distillation

A detailed three-phase nonequilibrium (NEQ) dynamic model for simulating batch and continuous catalytic distillation (CD) processes has been developed. In this model, both molar and energy holdups in liquid and vapour phases are taken into account. Multicomponent mass transfer and heat transfer between vapour and liquid phases as well as between liquid and solid (catalyst) phases are described by the Maxwell–Stefan equations. The resulting differential and algebra equations in this model are implemented in gPROMS and C++. The simulation results are in good agreement with the experimental data obtained from the batch and continuous CD processes for the production of diacetone alcohol (DAA) using Amberlite IRA-900 as a catalyst. Sensitivity analysis on the mass transfer and kinetics using the three-phase NEQ dynamic model indicates that the formation of DAA is controlled by solid–liquid mass transfer, whereas the formation of mesityl oxide is kinetically controlled under the simulation conditions.

The rate inhibiting effect of water as a product on reactions catalysed by cation exchange resins: formation of mesityl oxide from acetone as case study

It is known that when water is a product in reactions catalysed by cation exchange resins, it inhibits the reaction rate much more than predicted by the reverse reaction or dilution effects. In this work on the formation of mesityl oxide and water from acetone, the inhibiting effect is ascribed to the preferential association of the catalytically active sites with water. In the derivation of the kinetic model, a Freundlich type adsorption isotherm was used to quantify the number of sites occupied by water. This is combined with a power law expression for the reaction rate per available equivalent acid site. The resultant expression can accurately predict the reaction rate for various initial concentrations of water and mesityl oxide in the acetone. Even when water was initially added to the reaction mixture this model still gave an absolute average error of 5% compared to a 53% error when the same approach was followed but with the more popular Langmuir isotherm to describe site deactivation. The kinetic expression previously proposed for this reaction system by Klein and Banchero also failed when water was added to the reaction mixture and gave an average error of 55%. The procedure used to derive the model is therefore suggested for all cation exchange catalysed reactions where water is one of the products.

Acetone Condensation Reaction on Acid Catalysts

The condensation reaction of acetone on alumina and acid zeolites has been followed by FTIR. Under identical conditions, the reaction rate is faster on alumina, and the condensation goes beyond the formation of mesityl oxide. Zeolites without nonframework aluminum are poor catalysts. On HZSM-5 the reaction is about two orders of magnitude slower than on USY at 105°C. From these data, it appears that Lewis sites, even if they bound acetone less energetically than Brønsted sites, are responsible for the activation of the molecule. On alumina, the reaction would take place between gas phase acetone and acetone adsorbed on Lewis sites. On zeolites with nonframework aluminum and, thus, with Lewis sites, the reaction would involve acetone molecules adsorbed on Brønsted and Lewis sites, the activation occurring on the Lewis site.

The Catalysis of Maghemite and Hematite on the Aldol and the Retro-Aldol Condensation of Acetone

Abstract The catalytic activities of maghemite on the aldol condensation of acetone and on the retro-aldol condensation of diacetone alcohol are found to be higher than those of hematite. Further, the catalytic activity of maghemite on the formation of mesityl oxide is significantly higher than that of hematite. The active sites are considered to be surface hydroxyl groups which behave as a Brønsted base and acid points. Maghemite has more basic surface hydroxyl groups than does hematite, and far more acidic surface hydroxyl groups than does hematite they are sufficiently strong to make its average surface acidity greater than that of hematite. The basic surface hydroxyl groups of maghemite are speculated to be those which bond to the iron ions of the octahedral sites the acidic ones are those of the tetrahedral sites of the spinel lattice of the surface.

Aldol condensation of acetone in the two-phase system solid base-benzene in the presence of benzyltriethylammonium chloride

1. We propose a mechanism for the aldol condensation of acetone in the presence of solid base, explaining the optimum way of forming diacetone alcohol by filling the surface of the base with the diacetone alcohol and acetone anions. 2. Disappearance of the diacetone alcohol from the reaction products after filling the principal centers of the free base was caused by its decomposition under the influence of the acetone anion in the organic phase. 3. The reaction orders for acetone in formation of mesityl oxide and phorone in the presence of solid NaOH are second and third, respectively. 4. We have studied the aldol condensation of acetone in the presence of solid NaOH and benzyltriethylammonium chloride. The formation of diacetone alcohol proceeds in the organic phase as a result of the interaction of the onium alcoholate of diacetone alcohol with acetone, which greatly speeds up the reaction rate. The second order of the reaction with respect to acetone is caused by the limiting step of desorption of the anion of diacetone alcohol inside the organic phase. 5 The role of the benzyldiethylammonium chloride consists of desorption from the surface of the base of the anions of acetone and diacetone alcohol adsorbed on it in the form of ionic pairs, leading to a reduction of the basic properties of the surface of the base.

Reaction of carbonyl compounds in the presence of phase transfer catalysts

1. The rate of alkylation of acetone by prehnylchloride (PC) increases linearly with an increase in the OH− ion activity and the PC concentration. The fact that the reaction appears to be zeroth order with respect to acetone is due to the deprotonation of acetone in the aqueous phase, the result being that the acetone concentration in the 50% NaOH solution is that corresponding to saturation, regardless of the original ketone content of the system. 2. The fact that the rate of alkylation changes with a change in the PC-to-acetone ratio and with the introduction of toluene into the system could be the result of changes in the solubility of the catalyst, or the ion pair, in the organic phase. 3. The differences in the effect of NaOH and KOH on the alkylation reaction have been explained, as has the suppression of PC hydrolysis under two-phase catalysis. 4. The usual temperature effects of the aldol condensation carry over to catalysis in two-phase systems.β-Elimination with the formation of mesityl oxide requires the action of a phase-transfer catalyst.