Acetone, catalysis

Ketones with labile hydrogen atoms undergo enol acetylation on reaction with ketene. Strong acid catalysis is required. If acetone is used, isoptopenyl acetate [108-22-5] (10) is formed (82—85). Isopropenyl acetate is the starting material for the production of 2,4-pentanedione (acetylacetone) [123-54-6] (11). 

The most widely used process for the production of phenol is the cumene process developed and Hcensed in the United States by AHiedSignal (formerly AHied Chemical Corp.). Benzene is alkylated with propylene to produce cumene (isopropylbenzene), which is oxidized by air over a catalyst to produce cumene hydroperoxide (CHP). With acid catalysis, CHP undergoes controUed decomposition to produce phenol and acetone a-methylstyrene and acetophenone are the by-products (12) (see Cumene Phenol). Other commercial processes for making phenol include the Raschig process, using chlorobenzene as the starting material, and the toluene process, via a benzoic acid intermediate. In the United States, 35-40% of the phenol produced is used for phenoHc resins. 

The samples were examined before and after catalysis by SEM (Phihps XL 20) and HREM by both a JEOL 200 CX operating at 200 kV and a JEOL 4000 EX operating at 400 kV. The specimens for TEM were either directly glued on copper grids or dispersed in acetone by ultrasound, then dropped on the holey carbon grids. 

The use of A -enol ethers as substrates for dehydrogenation is often attractive. Aqueous acetone at room temperature gives yields ranging from 70 to 88% other systems with acid catalysis have also been used, e.g. ... 

Goi. As noted previously, an a-chlorine atom renders a ring-nitrogen atom very weakly basic. Cyanuric chloride (5) is a very weak base both because s-triazines are of low basicity and because each of the ring-nitrogen atoms is alpha to two chlorine atoms. Hence, this compound should be insensitive to acid catalysis or acid autocatalysis and this has been observed for the displacement of the first chlorine atom with alcohols in alcohol-acetone solution and with water (see, however. Section II,D,2,6). 

Oxepin has also been converted photochemically to phenol in 74% yield. This reaction occurs under irradiation conditions by which benzene oxide is excited to a triplet state, e.g. by irradiation in acetone as solvent.207 A rare example for a nucleophilic catalysis of the aromatization of an oxepin/benzene oxide to a phenol has been reported for /err-butyl oxepin-4-carboxylate which undergoes a rearrangement reaction in the presence of trimethylamine to give a mixture of /m-butyl 3-hydroxybenzoate (94%) and 4-hydroxybenzoate (6%).243... 

Base catalysis is another area which has received a recent stimulus from developments in materials science and microporous solids in particular. The Merk company, for example, has developed a basic catalyst by supporting clusters of cesium oxide in a zeolite matrix [13]. This catalyst system has been developed to manufacture 4-methylthiazole from acetone and methylamine. 

The Hock process includes the oxidation of cumene by air to hydroperoxides using large bubble columns and the cleavage of the hydroperoxide via acid catalysis, which is reaction [OS 82]. This process is used for the majority of world-wide phenol production and, as a secondary product, also produces large quantities of acetone [64]. Phenol is used, e.g., for large-scale polymer production when reacted in a polycondensation with formaldehyde. 

Feedstock Reactions Catalyst References Acetone Condensation-hydrogenation (bifunctional catalysis) Pd on sulfonated PS-DVB [6] Methanol, Raffinate II Condensation, hydrogenation Pd on sulfonated PS-DVB [61] Dioxygen dissolved in water Hydrogenation Pd on sulfonated PS-DVB [8]... 

A different type of catalysis is observed using proline as a catalyst.166 Proline promotes addition of acetone to aromatic aldehydes with 65-77% enantioselectivity. It has been suggested that the carboxylic acid functions as an intramolecular proton donor and promotes reaction through an enamine intermediate. 

For the main isotopic species the following mechanism (Figure 5) has been proposed for the production of MO, MIBK, phorone and isophorone from acetone base catalysis under a deuterium stream. A similar mechanism can be invoked for the less common isotopic species. 

In general base catalysis, bases other than eOH are involved. Thus in the base catalysed bromination of acetone (c/. p. 295) in an acetate buffer it is found that,... 

A literature procedure whereby bromopyrimidine is oxidised by excess peroxy-acetic acid in acetone, with sulfuric acid catalysis, was being scaled up. The crude product from the fourth batch at two molar scale was filtered out and allowed to dry to dry in the sintered glass funnel over the weekend. An explosion occurred when it was scraped out to complete purification on the Monday. This was considered due to acetone peroxides, which had probably concentrated locally by wicking or sublimation. 

Erdelyi, B., Szabo, A., Birincsik, L. and Hoschke A. (2004) Process development of methylenedioxyphenyl-acetone chiral bioreduction. Journal of Molecular Catalysis B, Enzymatic, 29 (1-6), 195-199. 

Hydride transfer from [(bipy)2(CO)RuH]+ occurs in the hydrogenation of acetone when the reaction is carried out in buffered aqueous solutions (Eq. (21)) [39]. The kinetics of the reaction showed that it was a first-order in [(bipy)2(CO)RuH]+ and also first-order in acetone. The reaction proceeds faster at lower pH. The proposed mechanism involved general acid catalysis, with a fast pre-equilibrium protonation of the ketone followed by hydride transfer from [(biPy)2(CO)RuH]+. 

The kinetics and mechanism of the ketone-bisulfite addition were studied by the use of the polarographic technique (Rao Salunke, Reaction Kinetics and Catalysis Letters 26 273, 1984).The specific rate was found to depend on pH. For an equimolar solution of bisulfite and acetone in a deaerated solution of potassium hydrogen phthalate buffer containing potassium iodide as the... 

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