Methyl benzoate, oxidation

Hydrogenolyses of carboxylic acids and esters to the corresponding aldehydes seems very attractive due to their simplicity. Copper chromites are the most widely used catalysts.15 Raney copper and zinc oxide-chromium oxide have also been used for this process.16-18 The hydrogenolysis of methyl benzoate to benzaldehyde was studied on various metal oxides at 300-350°C. ZnO, Zr02 and Ce02 presented high activities and selectivities (Scheme 4.8). 

Generally, primary aliphatic alcohols are oxidized to their respective aldehydes, secondary aliphatic and aromatic alcohols to the corresponding ketones, and allyl and benzyl alcohols to their carboxylic acid or carboxylate ions. For instance, 2-propanol, acetaldehyde, and methyl-benzoate ions are oxidized quantitatively to acetone, acetate, and terephtalate ion respectively, while toluene is converted into benzoate ion with an 86% yield. Controlling the number of coulombs passed through the solution allows oxidation in good yield of benzyl alcohol to its aldehyde. For diols,502 some excellent selectivity has been reached by changing the experimental conditions such as pH, number of coulombs, and temperature. 

Triphenylcarbinol has been obtained by the reaction between phenylmagnesium bromide and benzophenone,1 methyl benzoate, or phosgene 8 by action of phenylsodium upon benzophenone, benzoyl chloride, ethyl chlorocarbonate, or ethyl benzoate 4 by hydrolysis of triphenylchloromethane 5 and by oxidation of tri-phenylmethane.6... 

Figure 1.1 XRD patterns for different manganese oxides before and after pretreatment in H2 at 420°C [17]. The top three traces correspond to the original Mn02, Mn2Os, and Mn304 solids used in these experiments, while the bottom three were obtained after H2 treatment. It can be seen here that the catalysts are all reduced to the same MnO phase regardless of the nature of the starting material. It was inferred that MnO is the actual working catalyst in all cases, hence the similarity in methyl benzoate hydrogenation activity obtained with all these MnO solids. (Reproduced with permission from Elsevier.)...

The deuterium content can be determined by reaction of the deuterated diazomethane with benzoic acid-O d in anhydrous ether followed by analysis of methyl benzoate for deuterium content either by n.m.r. spectrometry or by mass spectrometry. The benzoic acid-O-d is prepared by heating a mixture of 48.6 g. (0.216 mole) of benzoic anhydride (obtained from Aldrich Chemical Company, Inc.), 0.10 g. (0.0009 mole) of anhydrous sodium carbonate, and 7.0 g. (0.35 mole) of deuterium oxide to 90° for 2 hours. The resulting mixture is distilled at atmospheric pressure in a short-path still fitted with a receiver protected from atmospheric moisture by a drying tube. After removal of a forerun, b.p. 100-101°, the benzoic... 

Results of the previously described semiquantitative method of analysis, applied to methyl enters, are reported in Table V. Yields of products eluting before methyl benzoate have not been included in this table since these should be included in the results presented in Table III. Total yield of methyl esters was largest in the neutral oxygen oxidation, slightly lower under alkaline oxygen oxidation, and substantially lower in acidic oxygen, nitric acid, and alkaline nitrobenzene oxidations. The differences in yields may be attributed in a large part to three major peaks phthalate, a component at a relative retention time of 0.490, and benzoate. 

Magnesium, 12, 48 Malononitrile, 10, 66 Malonylurea, see Barbituric acid Mercuration, 12, 46, 54 Mercuric chloride, 12, 54 Mercuric oxide, 12, 44 Mercury di-/3-naphthyl, 12, 46 Mesaconic acid, 11, 74 Mcsitylene, 11, 24, 67 Methylamine, 12, 38 Methylamine hydrochloride, 10, 112 Methyl -amyI ketone, 10, 60 M ethylation of thiourea, 12, 52 Methyl benzoate, 10, 51 Methyl chloride, 10, 32, 36 Methylene bromide, 10, 112... 

Bis[4-methoxyphenyl] tellurium, obtained from 4-methoxybenzene and tellurium tetrachloride and reduction of the resultant bis[4-methoxyphenyl] tellurium dichloride, was converted to methyl 4-methoxybenzoate in 99% yieldh Methyl benzoate was similarly obtained from diphenyl tellurium in yields higher than 90%. These reactions can be carried out with catalytic amounts of palladium(II) chloride when copper(II) chloride is used as an oxidant f... 

Both oxidation steps are reported to yield 95 % of the desired product, resulting in an overall yield of approximately 90 % from p-xylene to DMT. The major side product of the Witten process is methyl benzoate (from decarboxylation of intermediates) with radical coupling products accounting for heavy ends from production. 

Usually the C-0 single bond in esters is cleaved at the acyl-0 bond, whereas examples of cleavage at the other point in esters have been reported. An electron-rich iron(O) complex produced on reductive elimination of naphthalene from a hydrido(naphthyl)iron complex undergoes oxidative addition reaction with methyl benzoate to give a methyliron benzoate complex (Eq. 22) [63]. 

Benzocyclopropenone (3a) was formed as a reactive intermediate on photochemical decomposition of the lithium salt of 3-tosylamino-l,2,3-bcnzotriazin-4(3//)-one in methanol 3-chlorobenzocyclopropenone (3b) was formed analogously. Further reaction of the ketone 3a with methanol produced methyl benzoate as the main product. Additional evidence for the occurrence of benzocyclopropenone as reactive intermediate resulted from the oxidation of... 

The reactions were conducted in a custom-made 0.5 x 2.0 in screw-capped stainless steel vial and milled with an 0.250 in aluminum oxide ball-bearing in a Spexx certiprep mixer/mill 8000 M for approximately 17 h. Various para-substituted aryl methyl benzoates were reduced using a 5 1 ratio of lithium chloride sodium boro-hydride. At the conclusion of the reaction, the products were washed with 10% HC1 and the remaining solids were dried over a Hirsch funnel. Liquid products were isolated by extraction from a minimal amount of ethyl acetate. 

Alper et al.97,98 immobilized palladium-modified PAMAM-like dendron complexes onto silica for carbonylation of iodobenzene in MeOH to generate methyl benzoate under low pressures of CO at 100°C. Product yields were high overall and the catalyst could be recycled 4 5 times without significant loss of activity. This type of PAMAM-type dendron-Pd complex was also used for the oxidation of terminal alkenes to generate methyl ketones under mild conditions 99 oxidative selectivity toward the terminal versus internal double bonds was also determined. 

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