Manganese recrystallization

Hydroxyandrosta-4,6-dien-3-one. A suspension of 42 g of crude androsta-4,6-diene-3j ,17j -diol in 2000 ml of chloroform is treated with 250 g of activated, manganese dioxide. The mixture is then shaken vigorously for 15 min in a stoppered flask. The mixture is filtered and the manganese dioxide washed well with chloroform in order to elute material which initially remains adsorbed on the solid phase. The filtrate is concentrated to a pale yellow, crystalline residue. Recrystallization from acetonitrile gives 38 g (90%) of 17/ -hydroxyandrosta-4,6-dien-3-one as plates mp 211-214°. 

A solution of 11.2 g of potassium permanganate in 100 ml of warm water was added drop-wise to a well stirred solution of 10 g of 2-(4-chlorophenyl)-3-methyl-4-metathiazanone in 50 ml of glacial acetic acid. The temperature was kept below 30°C with external cooling. An aqueous sodium bisulfite solution was then added to remove the manganese dioxide. The thick whitish oil which separated was taken up in chloroform and the extract was washed with water. Removal of the chloroform by distillation in vacuo yielded an oily residue which solidified. The solid was recrystallized from isopropyl alcohol to give 5 g of the product, 2-(4-chlorophenyl)-3-methyl-4-metathiazanone-1,1-dioxide, MP 116.2° to 118.6°C (corr.). 

Preparation of 2-Cyc/opropy/methy/amino-5-Ch/orobenzophenone To a solution of 315 g (1.09 mols) of 2-cyclopropylmethylamino-5-chloroDenzhydrol in 4 liters of benzene is added 453.6 g (5.22 mols) of manganese dioxide, freshly prepared according to the method of Attenburrow et al, J.C.S. 1952, 1104. The mixture is then refluxed for VA hours, filtered, and the filtrate evaporated under vacuum. The reddish residue is recrystallized from 510 ml of 90% acetone-10% water, giving 181 g of pure 2-cyclopropylmethylamino-5-chloro-benzophenone, MP 79° to 80°C (58% yield). Upon concentration of the mother liquor a second crop of 2-cyclopropylmethylamino-5-chlorobenzophenone weighing 34.1 g and melting at 76.5°-78°C are obtained. 

In the Amoco process, p-xylene is oxidized at 200 °C under 15-20 atm in acetic acid and in the presence of a catalyst consisting of a mixture of cobalt acetate (5% weight of the solution), manganese acetate (1%) and ammonium bromide. Owing to the highly corrosive nature of the reaction mixture, special titanium reactor vessels are required. One of the main difficulties of this process is to remove the intermediate oxidation products such as p-toluic acid or p-carboxybenzal-dehyde which contaminate TPA obtained by precipitation from the reaction medium. A series of recrystallization and solvent extraction apparatus is required to obtain fiber grade TPA with 99.95% purity. The overall yield in TPA is ca. 90% for a 95% conversion of p-xylene. 

A mixture of this material with 500 ml of toluene and 30 g of manganese dioxide was heated to reflux for IV2 hours. The manganese dioxide was separated by filtration over Celite. The filtrate was evaporated and the residue was crystallized from ether to yield 8-chloro-6-(2-fluorophenyl)-l-methyl-4H-imidazo[l,5-a][l,4]benzodiazepine, melting point 152°C to 154°C. The analytical sample was recrystallized from methylene chloride/hexane. 

Bis[tetrakis(l-pyrazolyl)borato]manganese(II) is a white crystalline solid, melting, after recrystallization from toluene... 

Marble is formed from carbonate sediments, the most common of which is limestone. It is composed mostly of calcite. Pure marble is white, but it is easily stained by impurities such as iron oxide (red or brown) or manganese oxide (black). When the grains of calcite in limestone are exposed to heat and pressure, the mineral recrystallizes, forming a dense mass of inter-grown crystals. This makes marble stronger and slightly more dense than its parent rock. 

Solutions of 1.98 g. of manganese(II) chloride tetrahydrate (0.01 mol) and 3.68 g. of tetraethylammonium chloride monohydrate (0.022 mol) in 10 ml. of hot absolute ethanol are filtered and mixed, and the mixture is boiled for one minute. The pale green crystals are collected on a sin-tered-glass filter and dried in vacuo. Further crystals are obtained by evaporation of the mother liquor to about one-half the initial volume. The yield is nearly 4 g. The deliquescent crystals are recrystallized most conveniently from a 60 40 methanol-absolute ethanol mixture. The solution is evaporated nearly to dryness to recover the product. The yield is 3.6 g. (79%). Anal. Calcd. for [NEt4]2[MnCl4] C, 42.0 H, 8.8 N, 6.1 Cl, 31.0 Mn, 12.0. Found C, 42.3 H, 8.8 N, 6.5 Cl, 30.9 Mn, 12.2. 

Tetrahalocobaltate(II) salts are prepared in a manner similar to that used for the manganese compounds. The chloro and bromo derivatives are recrystallized from absolute ethanol, the solutions being evaporated to obtain the crystals. 

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