Anthraquinone benzaldehyde oxidation

Also important is the choice of a suitable redox system for the indirect electroreaction of particular substrates. For instance, toluene can be oxidized with Mn(III) or Ce(IV) to benzaldehyde, whilst with Cr(VI) benzoic acid is obtained. On the other hand, anthraquinone is commercially prepared from anthracene by employing chromic acid oxidation. 

Anthraquinone vat dyes containing a thia-zole ring include C.I. Vat Yellow 2, the synthesis of which is shown in Fig. 13.125. In this case, at least two approaches are possible. In the first, 2,6-diaminoanthraquinone is condensed with benzotrichloride in the presence of sulfur and the initial product is oxidized without isolation to give the target dye. Alternatively, the starting diamine can be chlorinated and converted to the corresponding dithiol (47). At this point condensation with benzaldehyde followed by oxidation (e.g. air or dichromate) gives the dye. 

Simulated solar radiation of anthracene in aqueous media has been reported by Mallakin et al. to produce more than 20 photoproducts consisting of anthraquinones, benzoic acids, benzaldehydes, and phenols as determined by HPLC [ 11 ]. Photochemical oxidation of some of the anthraquinones formed initially (Scheme 2) has been attributed to the formation of secondary products observed in this process (not shown). However, no independent studies of anthraquinone photolysis under the same conditions were carried out to confirm the proposed hypothesis. 

The selective oxidation of toluene has been studied over a number of catalysts based on metal oxides, with the U/Mo oxide system being one of the most achve and selective[50, 51]. The main products in the oxidation of toluene, excluding the non-oxidative coupling products, were benzaldehyde, benzoic acid, maleic anhydride, benzene, benzoquinone, CO and CO2. Under the same reachon condihons toluene may also yield coupling products such as phthalic anhydride, methyldi-phenylmethane, benzophenone, diphenylethanone and anthraquinone, as shown by Zhu and coworkers [51]. A range of different uranium-based oxides were tested [51] and the results obtained are shown in Table 13.4. 

Under the reaction conditions used, a U3O8 catalyst demonstrated appreciable selective oxidation activity. The best results, in terms of both activity and selectivity to benzaldehyde, were obtained with the mixed oxides with U Mo atomic ratios in the range 8 2 to 9 1. The maximum yield of benzaldehyde was 40 mol%. On the other hand, antimony-based uranium oxides were not found to be effective as catalyst for this reaction. U—Mo and Bi—Mo mixtures also exhibited promising activity and selectivity to benzaldehyde. Bi—Mo and Bi—Mo—P—Si catalysts were also tested. Qualitahvely there was little difference between the product distributions from the two catalysts. The major products formed were benzaldehyde, benzene and carbon oxides, as well as traces of anthraquinone and benzoic acid. 

V. Catalysts.—Electrolytic oxidation reactions are often facilitated by the presence of catalysts capable of existing in two valence stages examples of such oxygen carriers are cerium, chromium, manganese and vanadium ions. Their action is probably similar to that previously described for hydrogen carriers. These catalysts have been used to facilitate the oxidation of toluene to benzaldehyde or benzoic acid, of toluene sulfonamide to saccharin, and of anthracene to anthraquinone. 

The relative proportions in which the products, chiefly benzaldehyde, benzoic acid, and anthraquinone, are obtained depends in a large measure on the temperatures to which the reaction mixture of toluene vapor and air is subjected. High temperatures, together with rapid rates of flow as well as high temperatures and mild catalysts, are conducive to bai-zaldehyde formation. With vanadium pentoxide catalysts oxidation of... 

Allylic oxidation, for example, of cyclohexene to 2-cyclohexenone, and oxidative cleavage of styrene to benzaldehyde are readily accomplished with oxygen such reaction systems contain ALhydrox3fphthalimide and l,4-diamino-2,3-dichloro-9,10-anthraquinone. Aldehydes are converted into carboxylic acids with Pd/C, KOH and catalytic amounts of NaBH4 in the air. Very similar conditions (K2CO3 instead of KOH) are described for oxidation of benzylic and allylic alcohols. ... 

The products of toluene oxidation, chiefly benzaldehyde, benzoic acid, maleic acid, and anthraquinone, are obtained in proportions that depend upon catalyst, temperature, oxygen ratio, and time of contact. High temr pieratures, mild catalysts, and short times of contact promote the formation... 

Ammonium nitrate Ammonium nitrite Ammonium oxalate Ammonium salicylate Ammonium sulfate Ammonium sulfide Ammonium sulfite Ammonium thiosulfate Amyl acetate Amyl alcohol Amyl chloride Amyl mercaptan Amyl naphthalene Amyl nitrate Amyl nitrite Amyl phenol Aniline hydrdochloride Aniline sulfate Aniline sulfite Animal fats Animal oils Anthraquinone Antimony sulfate Antimony tribromide Antimony trichloride Antimony trioxide Aqua regia Arsenic oxide Arsenic trichloride Arsenic trioxide Arsenic trisulfide Ascorbic acid Barium carbonate Barium chlorate Barium chloride, aqueous Barium cyanide Barium hydroxide Barium iodide Barium nitrate Barium oxide Barium peroxide Barium salts Beet sugar liquors Benzaldehyde Benzene... 

In their study utiHzing vanadium oxide catalysts in the 1950s, Mars and van Kre-velen investigated the oxidation ofbenzene to benzoquinone, maleic anhydride, CO2, CO, and H2O, toluene to benzaldehyde and benzoic acid, naphthalene to naphthoquinone and phthalic anhydride, and anthracene to anthraquinone and phthalic anhydride. 

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