Manganous oxide catalyst

Use the apparatus described in Section 111,72 and adjust the furnace for a working temperature of 400-450°. Although a manganous oxide catalyst gives satisfactory results, thoria is more convenient in practice. 

This is a way to do this procedure without having to use one of those crazy tube furnaces stuffed with thorium oxide or manganous oxide catalyst [21]. The key here is to use an excess of acetic anhydride. Using even more than the amount specified will insure that the reaction proceeds in the right direction and the bad side reaction formation of dibenzylketone will be minimalized (don t ask). 18g piperonylic acid or 13.6g phenylacetic acid, 50mL acetic anhydride and 50mU pyridine are refluxed for 6 hours and the solvent removed by vacuum distillation. The remaining residue is taken up in benzene or ether, washed with 10% NaOH solution (discard the water layer), and vacuum distilled to get 8g P2P (56%). 

Malonic acid, 489, 490 Malononitrile, 428, 434 Mandelic acid, 754, 774 Manganous oxide catalyst, 339 Mannich bases, 910, 911 Mannich reaction, 910, 911, 912, 1012, 1013... 

Modification by such ions like Ca, Mg, Ni, Bi, Cr is proposed for improvement of manganous oxide catalyst [15]. The most effective modifiers are Ca(II) and Mg(II) ions. 

In this process, a mixture of phenylacetic acid and glacial acetic acid is slowly dripped into a Pyrex combustion tube which is filled with pea-sized pumice stones covered with a coating of either thorium oxide or manganous oxide catalyst. This bed of catalyst is heated to a high temperature with a tube furnace and the vapors of phenylacetic acid and acetic acid react on the surface of the catalyst to produce ketones. Three reactions result. 

The complete assembly for carrying out the catalytic decomposition of acids into ketones is shown in Fig. Ill, 72, 1. The main part of the apparatus consists of a device for dropping the acid at constant rate into a combustion tube containing the catalyst (manganous oxide deposited upon pumice) and heated electrically to about 350° the reaction products are condensed by a double surface condenser and coUected in a flask (which may be cooled in ice, if necessary) a glass bubbler at the end of the apparatus indicates the rate of decomposition (evolution of carbon dioxide). The furnace may be a commercial cylindrical furnace, about 70 cm. in length, but it is excellent practice, and certainly very much cheaper, to construct it from simple materials. 

The present research was focused on the study of acetaldehyde oxidation rising air with aqueous mangan acetate catalyst in mechanically stirred tank reactor. 

By passing the vapour of a monobasic acid through a tube containing manganous oxide deposited on pumice and heated to 300-350°, the metallic oxide acting as a catalyst, for example ... 

Neither catalyst showed any evidence of crystalline components by X-ray diffraction. The permanganate on silica gel apparently remains as permanganate. The permanganate on activated carbon appears from the spectrum to have been reduced to Mn02 or to some other hydrous manganic oxide. 

Cyclopentanone has been prepared from adipic acid by distilling the calcium salt,1 heating alone 2 or with acetic anhydride,3 or in the presence of various catalysts such as barium hydroxide,4 thorium oxide,5 manganous oxide,5 uranium nitrate,6 ferrous sulfate 6 and others.7... 

The preparation of ketones by dehydrogenation of secondary alcohols over zinc and copper catalysts and the decarboxylation condensation of acids over manganous oxide or thoria have been adequately covered by standard reference books on catalysis. However, the more complete but equally serviceable catalytic syntheses involving either an aldol or a Tischenko ester type of condensation have been virtually ignored. 

This ketone synthesis was developed further by Ipatieff and by Sabatier, Mailhe, and Senderens. Thoria and manganous oxide proved to be more effective catalysts than the carbonates. The method was extended to higher fatty acids and to the production of mixed ketones. 

Conducting polymers (PANI, PPy and others as well as manganous oxides, perovskite and some other materials are used as non-noble metal catalysts. 

Dehydrogenations of some 2,3-dihydropyrazines to the corresponding pyrazines have been effected as follows 2,3-dimethyI-5,6-dihydro [reflux with potassium hydroxide in ethanol (333) heat in ethylene glycol at 197° (653, 1558) reflux with potassium hydroxide and manganous oxide in ethanol (633a) vapor phase reaction in the presence of a catalyst, such as copper chromite, and clay (472) heat... 

Manganese and cobalt compounds are particularly effective in decomposing hydroperoxides (eqs. (17) and (19)) and hence are frequently used as oxidation catalysts [47]. In spite of their similar abilities in this regard, the results of their use in a given instance can be quite different. Manganous ions are reported to have a pronounced ability to reduce peroxy radicals directly to peroxy anions (eq. (20)) [50] ... 

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