Catalytic acetalization reaction

PRATT, H. R. C. Trans. Inst. Chem. Eng. 25 (1947) 43. Continuous purification and azeotropic dehydration of acetonitrile produced by the catalytic acetic acid-ammonia reaction. 

This tethered ferrocenyl-based Pd complex on MCM-41 (17) was then used for the catalytic amination reaction between cinnamyl acetate and benzylamine (40 °C, THF) [59]. In this case, confinement of the catalyst results in profound changes in regio- and enantioselectivity. When the homogeneous equivalent is used to catalyze the reaction, the straight chained derivative is the sole product. Similar results (only 2% of the branched product) were obtained when the catalyst was tethered to the surface of the non-porous silica Cabosil. When tethered inside the pores of MCM-41 a major change occurred in that now the branched product accounts for about 50% and a change in e.e. from 49% e.e. when anchored to the Cabosil support to +99% when anchored inside the MCM-41 pore could be observed. If the catalyst s chirality was reversed in the MCM-41 immobihzed case, so was the chirality of the product (measured at 93% e.e.) [60]. 

While the research in the direction of the CH activation had its advances, the central problem is still not solved. There is no selective and efficient catalytic functionalization reaction known for unactivated sp CH bonds. Only a small number of systems have been published that are capable of functionalizing methane cataly tically [113-115], many of them dealing with the direct carbonylation to acetic acid [116-119]. 

However, little has been reported about the acidic and catalytic properties of S04 /Zr02-Si02. In this paper, S04 /Zr02-Si02 nanocrystalline catalysts were prepared by a chemical method. The structure, acidic properties and catalytic activity of the catalysts were investigated by using X-ray diffraction (XRD), IR, DTA, Hammett indicators and catalytic esterification reaction of acetic acid with glycerin. 

An important modern example of homogeneous catalysis is provided by the Monsanto process in which the rhodium compound 1.4 catalyses a reaction, resulting in the addition of carbon monoxide to methanol to form ethanoic acid (acetic acid). Another well-known process is hydro-formylation, in which the reaction of carbon monoxide and hydrogen with an alkene, RCH=CH2, forms an aldehyde, RCH2CH2CHO. Certain cobalt or rhodium compounds are effective catalysts for this reaction. In addition to catalytic applications, non-catalytic stoichiometric reactions of transition elements now play a major role in the production of fine organic chemicals and pharmaceuticals. 

Monsanto acetic acid synthesis 4), and the hydroformylation or 0X0 reaction (5). A key mechanistic step in catalytic carbonylation reactions is the migration of an alkyl group onto an adjacent carbonyl ligand. This reaction involves the formation of a new carbon-carbon bond and has been termed a carbonyl insertion reaction since a CO ligand has been formally inserted into the transition metal-carbon (r-bond. Because of the industrial and commercial importance of these catalytic reactions, the search for stoichiometric systems in which this step can be observed directly has been, and still is, one of great endeavor. 

Allylic substitutions. Substitution of pronucleophiles with allylic acetates under neutral conditions uses (dbajjPd -PhjP as the catalytic system reactions can also be carried out in perfluorinated solvents. Carbonates derived from y-hydroxy-a,p-unsaturated... 

As described above, decarboxylation of carboxylic acids gives a variety of products depending on the reaction conditions and substrates used. In the presence of a catalytic amount of copper(II) acetate reaction of carboxylic acids with lead tetraacetate affords olefins in good yields (Scheme 13.58) [77]. 

Condensation of acetophenone with AT in DMF and catalytic acetic acid (Scheme 13) leads to dihydro TP 49 and byproduct 50 that in the presence of hydrochloric or phosphoric acid becomes the main product (92DOK801). It seems to originate from the hypothetical intermediate 48 by reaction with the solvent DMF. 

Kobayashi s group37 developed a new enantioselective synthesis of Cis phytosphingosine using catalytic asymmetric aldol reactions as a key step (Scheme 23). The key catalytic aldol reaction of acrolein with the ketene silyl acetal 148 derived from phenyl a-benzyloxyacetate was carried out by using tin(II) triflate, chiral diamine 149, and tin(II) oxide. The desired aldol product... 

Trost proposed the following mechanism to account for these catalytic transformations. Reaction of the palladium catalyst with 377 generates jt-alkene palladium complex 378. Palladium removes the allylic hydrogen, with expulsion of the acetate moiety to generate the Jt-allyl palladium complex (379). Attack of a nucleophile at Ca leads to 380, with expulsion of the PdL2 species, whereas attack at Cb leads to 381. Palladium coordinates on the face of the alkene distal to the acetate (distant from the acetate Ca rather than Cb). Palladium displaces acetate with inversion (378 - 379). When the nucleophile displaces the palladium, a second inversion occurs at Ca or Cb, whichever is less sterically hindered, to give a net retention of configuration for the conversion 377 - 380 and/or 381. 

During adsorption of methyl ethyl ketone in the presence of oxygen, some catalytic surface reactions occur (Figure 22.1.17). The reaction products are acetic acid, di-acetyl, and presumably also di-acetyl peroxide. Di-acetyl has an intensive green coloration and a distinctive odor. Important for the heat balance of the adsorber is... 

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