Mesityl oxide, hydrogenation

Mesityl oxide hydrogenated 1 hr. with Pd-silk at 30 /90 atm. methyl isobutyl ketone. Y 86%.—The catalyst is particularly suitable for the prepn. of satd. aliphatic aldehydes and ketones from the corresponding unsatd. compounds. F. e. and reductions s. Y. Izumi, Bull. Ghem. Soc. Japan 32, 936 (1959). 

The yield of acetone from the cumene/phenol process is beUeved to average 94%. By-products include significant amounts of a-methylstyrene [98-83-9] and acetophenone [98-86-2] as well as small amounts of hydroxyacetone [116-09-6] and mesityl oxide [141-79-7]. By-product yields vary with the producer. The a-methylstyrene may be hydrogenated to cumene for recycle or recovered for monomer use. Yields of phenol and acetone decline by 3.5—5.5% when the a-methylstyrene is not recycled (21). 

Although the selectivity of isopropyl alcohol to acetone via vapor-phase dehydrogenation is high, there are a number of by-products that must be removed from the acetone. The hot reactor effluent contains acetone, unconverted isopropyl alcohol, and hydrogen, and may also contain propylene, polypropylene, mesityl oxide, diisopropyl ether, acetaldehyde, propionaldehyde, and many other hydrocarbons and carbon oxides (25,28). 

Finally, selective hydrogenation of the olefinic bond in mesityl oxide is conducted over a fixed-bed catalyst in either the Hquid or vapor phase. In the hquid phase the reaction takes place at 150°C and 0.69 MPa, in the vapor phase the reaction can be conducted at atmospheric pressure and temperatures of 150—170°C. The reaction is highly exothermic and yields 8.37 kJ/mol (65). To prevent temperature mnaways and obtain high selectivity, the conversion per pass is limited in the Hquid phase, and in the vapor phase inert gases often are used to dilute the reactants. The catalysts employed in both vapor- and Hquid-phase processes include nickel (66—76), palladium (77—79), copper (80,81), and rhodium hydride complexes (82). Complete conversion of mesityl oxide can be obtained at selectivities of 95—98%. 

Figure 2 illustrates the three-step MIBK process employed by Hibernia Scholven (83). This process is designed to permit the intermediate recovery of refined diacetone alcohol and mesityl oxide. In the first step acetone and dilute sodium hydroxide are fed continuously to a reactor at low temperature and with a reactor residence time of approximately one hour. The product is then stabilized with phosphoric acid and stripped of unreacted acetone to yield a cmde diacetone alcohol stream. More phosphoric acid is then added, and the diacetone alcohol dehydrated to mesityl oxide in a distillation column. Mesityl oxide is recovered overhead in this column and fed to a further distillation column where residual acetone is removed and recycled to yield a tails stream containing 98—99% mesityl oxide. The mesityl oxide is then hydrogenated to MIBK in a reactive distillation conducted at atmospheric pressure and 110°C. Simultaneous hydrogenation and rectification are achieved in a column fitted with a palladium catalyst bed, and yields of mesityl oxide to MIBK exceeding 96% are obtained. 

Mesityl oxide and hydrogen peroxide react initially to form the cycHc hydroxyalkyl alkyl peroxide, a 1,2-dioxolane. Prolonged equiUbration results in formation of the cycHc di(alkylperoxyalkyl) peroxide, 3,3 -dioxybis(3,5,5-trimethyl-l,2-dioxolane) [4507-98-6] (122,138) ... 

Mesityl oxide is produced by the dehydration of acetone. Hydrogenation of mesityl oxide produces methylisobutyl ketone, a solvent for paints and varnishes ... 

Purely parallel reactions are e.g. competitive reactions which are frequently carried out purposefully, with the aim of estimating relative reactivities of reactants these will be discussed elsewhere (Section IV.E). Several kinetic studies have been made of noncompetitive parallel reactions. The examples may be parallel formation of benzene and methylcyclo-pentane by simultaneous dehydrogenation and isomerization of cyclohexane on rhenium-paladium or on platinum catalysts on suitable supports (88, 89), parallel formation of mesityl oxide, acetone, and phorone from diacetone alcohol on an acidic ion exchanger (41), disproportionation of amines on alumina, accompanied by olefin-forming elimination (20), dehydrogenation of butane coupled with hydrogenation of ethylene or propylene on a chromia-alumina catalyst (24), or parallel formation of ethyl-, methylethyl-, and vinylethylbenzene from diethylbenzene on faujasite (89a). 

A Catalytic Distillation Process for the One Step Synthesis of Methyl Isobutyl Ketone from Acetone Liquid Phase Kinetics of the Hydrogenation of Mesityl Oxide... 

The present economic and environmental incentives for the development of a viable one-step process for MIBK production provide an excellent opportunity for the application of catalytic distillation (CD) technology. Here, the use of CD technology for the synthesis of MIBK from acetone is described and recent progress on this process development is reported. Specifically, the results of a study on the liquid phase kinetics of the liquid phase hydrogenation of mesityl oxide (MO) in acetone are presented. Our preliminary spectroscopic results suggest that MO exists as a diadsorbed species with both the carbonyl and olefin groups coordinated to the catalyst. An empirical kinetic model was developed which will be incorporated into our three-phase non-equilibrium rate-based model for the simulation of yield and selectivity for the one step synthesis of MIBK via CD. 

The liquid phase kinetics of the selective hydrogenation of mesityl oxide in acetone were studied for the purpose of developing a robust kinetic model to be integrated into an existing non-equilibrium rate-based model for the simulation of the CD process for MIBK production. A typical concentration versus time profde is illustrated in Figure 2. MIBK was produced with veiy high selectivity with essentially all of the MO converted to MIBK. Products from the... 

The solid base catalysed aldol condensation of acetone was performed over a CsOH/Si02 catalyst using a H2 carrier gas. The products observed were diacetone alcohol, mesityl oxide, phorone, iso-phorone and the hydrogenated product, methyl isobutyl ketone. Deuterium tracer experiments were performed to gain an insight into the reaction mechanism. A mechanism is proposed. 

The aldol condensation of acetone to diacetone alcohol is the first step in a three-step process in the traditional method for the production of methyl isobutyl ketone (MIBK). This reaction is catalysed by aqueous NaOH in the liquid phase. (3) The second step involves the acid catalysed dehydration of diacetone alcohol (DAA) to mesityl oxide (MO) by H2S04 at 373 K. Finally the MO is hydrogenated to MIBK using Cu or Ni catalysts at 288 - 473 K and 3- 10 bar (3). 

The reaction mechanism is shown in Figure 4 and is adapted from work by Fiego et al. [9] on the acid catalysed condensation of acetone by basic molecular sieves. The scheme has been modified to include the hydrogenation of mesityl oxide to MIBK. The scheme begins with the self-condensation of acetone to form diacetone alcohol as the primary product. The dehydration of DAA forms mesityl oxide, which undergoes addition of an addition acetone to form phorone that then can cyclise, via a 1,6-Michael addition to produce isophorone. Alternatively, the mesityl oxide can hydrogenate to form MIBK. 

Butyne-l,4-diol has been hydrogenated to the 2-butene-diol (97), mesityl oxide to methylisobutylketone (98), and epoxides to alcohols (98a). The rhodium complex and a related solvated complex, RhCl(solvent)(dppb), where dppb = l,4-bis(diphenylphosphino)butane, have been used to hydrogenate the ketone group in pyruvates to give lactates (99) [Eq. (15)], and in situ catalysts formed from rhodium(I) precursors with phosphines can also catalyze the hydrogenation of the imine bond in Schiff bases (100) (see also Section III,A,3). 

Mesitylene, production from acetone, 1 164 Mesityl oxide, 14 589-590 characteristics of, 16 337 hydrogenation, 16 337-338 hydrogen peroxide treatment of, 16 338 Z-menthol from, 24 520 production of, 16 336-337 production from acetone, 1 164, 174 Mesogenic diols, 25 460 Mesogenic molecules, solids of, 15 82 Mesogens, 24 53, 54 Mesomixing, 16 683 Mesomorphic behavior, 24 53-54 Mesomorphic phase transitions, 15 102 Mesomorphism, 15 81. See also Liquid crystalline materials Mesophase pitch-based carbon fiber, 26 734-735... 

In the second step, the diacetone alcohol is dehydrated (the -OH group and a hydrogen atom are clipped off) to form mesityl oxide. The dehydration is done by mixing the diacetone alcohol with the water-loving catalyst sulfuric acid at 212 250 F,... 

In the third step, the mesityl oxide is hydrogenated (hydrogen added) to MIBK by heating it to the vapor stage at 300—400°F and passing it over a copper or nickel catalyst at 50-150 psi in the presence of hydrogen. 

A biphasic system consisting of the ionic liquid [BMIM]PF6 and water was used for the epoxidation reactions of a, 3-unsaturated carbonyl compounds with hydrogen peroxide as an oxidant at room temperature 202). This biphasic catalytic system compared favorably with the traditional phase transfer catalysts. For example, under similar conditions (15°C and a substrate/NaOH ratio of five), the [BMIM]PF6/H20 biphasic system showed a mesityl oxide conversion of 100% with 98% selectivity to oc, 3-epoxyketone, whereas the phase-transfer catalyst with tet-rabutylammonium bromide in a CH2CI2/H2O biphasic system gave a conversion of only 5% with 85% selectivity. 

The pilot scale experiments were carried out in a CD column 23 ft (7 m) tall with a total packing height of 16 ft (4.9 m) and a 1 (2.54 cm) nominal I.D. The column is made of 316 SS and consists of 5 sections that are connected by flanges. Two 2 ft (0.6 m) sections located above a 9 ft (2.7 m) stripping section and below a 3 ft (0.9 m) rectification section, were used as the reaction zones, which contained the catalyst. The non-reactive sections were filled with i inch (0.64 cm) Intalox saddles. In the first experiment for which mesityl oxide was synthesized from acetone, the two sections were filled with 130 mL of Amberlyst-15, that had been swelled in 2-propanol for 24 hours, in wire mesh bundles. In the second experiment in which MIBK was synthesized from acetone, the top section and the top half of the bottom section contained 135.0 mL of Amberlyst-15 in wire mesh bundles that had been swelled in acetone for over 24 hours. The bottom half of the bottom section, immediately below the Amberlyst 15, was filled with 50.1 g of a commercial Pd/AlzOs catalyst (Aldrich 20,574-5). The hydrogenation catalyst was reduced ex situ in hydrogen at 350°C for 3 hours and was transferred to the CD column under a nitrogen blanket. 

In the first experiment, Amberlyst-15, a strongly acidic cation exchange resin, was used as a catalyst to synthesize mesityl oxide, the precursor of MIBK, from acetone without hydrogenation. The effects of acetone feed rate, reboiler duty and reaction temperature on the mesityl oxide productivity and product distribution were investigated. Preliminary results of this experiment are outlined in Table 1. 

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