Methylation catalysts

Methylamines are produced from the vapor reaction of methanol with ammonia over a siUca—alumiaa catalyst. Methyl esters result from the reaction of methanol with the corresponding organic or inorganic acid as shown, eg, for methyl methacrylate. 

Mixtures of ethylene and aluminium chloride, initially at 30-60 bar, rapidly heat and explode in presence of supported nickel catalysts, methyl chloride or... 

Alkyl groups differ as to ease of elimination. When 5-methyl-5-ethyl-l,3-cyclohexadiene is reacted over a sodium-organosodium catalyst, methyl groups are eliminated more easily than ethyl groups (B ). 

For example, with the Co-I-PPh catalyst, methyl acetate reacts with synthesis gas to form ethyl acetate. All of the primary and secondary alcohols tested (C thru C ) decompose during long-term operation. The major decomposition products include aldehydes, alkyl iodides, and ethers. Ketones are readily hydrogenated and the resulting alcohols decompose. Good solvents in terms of stability are diphenyl ether and alkanes. The acetaldehyde rate is somewhat low (1.8 M/hr) in diphenyl ether, and the selectivity is low in alkanes. In addition, these solvents do not have good solubility properties, especially in product refining. 

Raney nickel catalyst. Methyl a-D-glucopyranoside was fully deu-terated at carbon atoms 2, 3, 4, and 6, to afford 71, by treatment with... 

The binder itself (Genpol A-20 polyester resin, styrene and methyl acrylate) was combined with the necessary polymerization catalyst (methyl ethyl ketone peroxide) and an accelerator (cobalt octoate or naphthenate). 

Methyl Ester A fatty ester formed when organically derived oils are combined with methanol in the presence of a catalyst. Methyl ester has characteristics similar to petroleum-based diesel motor fuels. 

A way to counteract the effect of harmful impurities in alkylchlorides is to introduce substances which would be adsorbed on the active centres of contact mass at the initial stage of synthesis, thus opposing undesirable chemisorption and harmful substances fouling the catalyst. Methyl- or ethylchlorosilanes were found to be active substances of the kind moreover, their ability to activate contact mass grows in the following sequence ... 

Spent acid alkylation catalyst methyl methacrylate catalyst... 

The carbonyl ir-bond has been found to add chemo- and regio-selectively across the alkenic ir-bond of ketenes. Thus diphenylketene readily reacts with benzoquinone to yield a stable [2 + 2] adduct (equation 1). With an excess of diphenylketene the bis-adduct is formed, which decomposes into tetraphe-nylquinodimethane and carbon dioxide (equation 2). With the less stable ketene, thermal [2 + 2] cycloadditions are observed with highly electrophilic carbonyl compounds (equation 3). With unactivated aldehydes and ketones, yields are much lower due to a faster oligomerization of the ketene reagent. However, in the presence of a Lewis acid catalyst, most aldehydes or ketones form P-lactones with ketene (equation 4). Cycloadditions with ketones usually require more active catalysts than with aldehydes. The catalyzed reaction of ketene with methyl vinyl ketone is chemoselective, yielding a 10 1 ratio of [2 + 2] versus [4 + 2] adducts (equation 5). In the absence of catalyst, methyl vinyl ketone reacts with ketene to give exclusively the [4 + 2] adduct. 

Heterogeneous catalytic hydrogenation of the methyl esters of a-keto acids over modified metal catalysts other than nickel have been studied using a cinchonidine-modified platinum catalyst. " Methyl pyruvate and methyl benzoylformate were hydrogenated to form methyl (R)-lactate and (R)-mandelate with high ee (81-84%). 

Fry has used a similar system for the enzymatic reduction of pyruvate to L-lactate. In this case, the one-electron transfer redox catalyst, methyl viologen, and the lipoamide dehydrogenase are coimmobilized within a Nafion cation-exchange layer on the surface of a reticulated vitreous carbon electrode. As production enzyme, L-lactate dehydrogenase (LDH) was employed [48], which was later stabilized considerably in the form of cross-... 

Nguyen JV, Jones CW (2005) Recyclable polymerization catalysts methyl methacrylate polymerization with sihca-supported CuBr-bipyridine atom transfer radical polymerization catalysts. J Catal 232 276... 

Catalyst for 1,4-Grignard addition. With cuprous bromide as catalyst, methyl-magnesium bromide reacts with A < -octalone-2 exclusively by 1,4-addition to give 9-methyl-cH-decalone-2."... 

With this catalyst, methyl palmitate afforded palmityl alcohol in 78% yield on hydrogenation at 175° for 3 hrs. Aldehydes and ketones were hydrogenated at room temperature with catalyst that had been activated by heating it at 100° under hydrogen pressure. The same activation can be effected by refluxing the catalyst in cyclohexanol for 4 hrs. during this time 11% of cyclohexanone is formed. Cholestane-3/3-ol, refluxed in xylene with three times its weight of Adkins catalyst (HJS 2), affords cholestane-3-one in moderate yield. 

Phenol readily couples with diazonium salts to yield coloured compounds. The latter can be nsed for the photometric detection of phenol as in the case of diazotized 4-nitroaniline. Sahcylic acid (2-hydroxybenzoic acid) can be prodnced by the Kolbe-Schmitt reaction (stndied by the density functional method ) from sodinm phenolate and carbon dioxide, whereas potassium phenolate gives the para compound. Alkylation and acylation of phenol can be carried out with aluminium chloride as catalyst methyl groups can also be introduced by the Mannich reaction. Diaryl ethers can only be produced under extreme conditions. 

In contrast to asymmetric hydrogenation, examples of stereoselective reduction of functionalized ketones are rare. Scheme 43 illustrates the highly enantioselec-tive reduction of methyl benzoylformate in 2-propanol containing KOH using a catalyst prepared in situ from [RhCl(CgHjo)]2 and (S,S)-3 [101]. With the same catalyst, methyl pyruvate is reduced in 5% optical yield. 

Fig. 19. Proposed transition state assembly for catalyst 13 catalyst-methyl crotonate complex...

Best results are attained with ketones having a second group capable of coordination to the catalyst. Methyl acetylacetate is reduced in 77% e.e. with a chiral complex of Rh and CAMP. Hy ogenation of open-chain a-keto-esters in the presence of Rh(l) com-... 

A solution of methacrolein in methanol and aqueous soda solutions were continuously oxidized by O2 at 5 bar and 80 °C in a reactor packed with Pd-Bi/ Si02-Mg0-Al203 catalyst. Methyl methacrylate was obtained with 90.8 % selectivity at 63.4 % conversion [93]. 

The tertiary alkyl halides react vigorously and, in the case of amyl chloride, can alkylate phenols without the intervention of a catalyst. Methyl iodide is used in the preparation of such methylated products as Pinaverdol and other sensitizing dyes, which possess a pentavalent nitrogen. 

Volatile organics are destroyed via combustion that converts oxygenated organics into carbon oxides and water over a heterogeneous catalyst. Methyl bromide is an ozone-depleting chemical, and it is subjected to additional treatment, where methyl bromide is converted into carbon dioxide, H2O, and NaBr. 

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