Ferric chloride oxidation

Aside from their extensive use in metaHacarborane chemistry, the dicarboUide anions are important intermediates in the synthesis of other carborane compounds. For example, aqueous ferric chloride oxidation of the 1 anion results in the 10-vertex cage nido- b ()-(Z, 2 (H8) and the... 

Dihalogenation of oxindole followed by alkaline hydrolysis of the 3,3-dihalooxindole has been applied to the synthesis of some isa-tins.66,126,136 137b A number of oxindoles have been treated with nitrous acid to give isatin-3-oximes.100,138 Reduction of the oximes to 3-aminooxindoles followed by ferric chloride oxidation gave isatins.100,138 When this sequence was applied to 7-azaoxindole, the azaisatin 33 was... 

The ferric chloride oxidation of bis(2-mercaptoethyl) sulfide 204 afforded the 1,2,5-trithiepine 44, which upon oxidation with one mole of OT-chloroperoxybenzoic acid afforded 1,2,5-trithiepine-l-sulfoxide 130 chemoselectively (Scheme 45). 

Ferric chloride oxidizes a,a -unsubstituted pyrroles to pyrrole blacks 101,102 if substituted with electron-withdrawing groups, pyrroles withstand oxidation quite well.102... 

By this method, 1-bromonaphthalene affords 1-naphthonitrile in 94% yield after refluxing for 4 hrs. with pyridine as solvent the reaction mixture is heated in an oil bath at 215-225° for 15 hrs., and the yield is 82-90%. Efficient procedures for liberating the nitrile from the cuprous halide complex involve pouring the brown reaction mixture into an aqueous solution of ferric chloride (oxidizes Cu+ to Cu ", which forms no complex), ethylenediamine (forms complexes with Cu+ and Cu " ), or sodium cyanide (forms soluble sodium cuprocyanide). The higher-boiling N-methyl-2-pyrrolidone (b.p, 202°) is also satisfactory, but is more expensive. 

Only a very few 4,4 -bis(2-pyrazolin-5-ones) linked by a double bond have been prepared. The parent compound of this series, 4-(3-methyl -1 -phenyl - 5 - oxo - 2 - pyrazolin - 4-ylidene)-3-methyl-l-phenyl-2-pyrazolin-5-one (XXII-D), is known as pyrazole blue.323,807,809,816, 1090,1091 was so nameci by Knorr because of its great resemblance to indigo blue. All these compounds are strongly colored. The usual synthesis is by ferric chloride oxidation of monomeric 2-pyrazolin-5-ones (eq. 61)296,809 or by oxidation of the corresponding bis compounds... 

Figure 3.20 Proposed mechanisms for ferric chloride oxidative polymerizations of thiophenes.

Ferric chloride oxidation of D-galactose i -(p-chlorophenyl)thiosemi-carbazone yielded the 1,3, -thiadiazole derivative (4 4), the sugar chain on which could be reduced to a formyl group by periodate... 

Aqueous ferric chloride oxidation of the triphenolic phenethylisoquinoline 17a provided a 6% yield of the homoproaporphine... 

PT film has also been prepared by treating thiophene with FeCls solution in anhydrous CHCI3, a method known as ferric chloride oxidative polymerization [37]. 

Hydrochloric acid should not be used for acidifying the alkaline solution since the yellow colour, due to the ferric chloride formed, causes the Prussian blue to appear greenish. For the same reason, ferric chloride should not be added—as is frequently recommended a sufficient concentration of ferric ions is produced by atmospheric oxidation of the hot alkaline solution. The addition of a little dfiute potassium fluoride solution may be advantageous in assisting the formation of Prussian blue in a readily filterable form. 

Isopropylidene or benzylidene 2-hydrazinoselenazole derivatives can be converted to highly colored 2.2 -dioxo-A-3,3 -biselenazol-5,5 -inylidene-bis-hydrazones (Table X-11) by oxidation with ferric chloride and hydrogen peroxide i33). 

HCl gas reacts with metal oxides to form chlorides, oxychlorides, and water. Therefore, all the steel equipment should be pickled to remove the oxide scales before it is put in service. Because oxidi2ing agents in the HCl gas such as oxygen or chlorine significantly affect the corrosion rate, it is essential that the operating temperature of the steel equipment be kept below the temperature (316°C) at which ferric chloride is vapori2ed from the metal surface. 

Oxidi ng Solutions. In many leaching processes the mineral must be oxidized, as for instance, in the leaching of copper sulfides by ferric sulfate or ferric chloride solutions. 

Oxidative coupling of aromatic compounds via the SchoU reaction has been appHed successhiUy to synthesise a polyarylethersulfone (18). High molecular weight polymer was obtained upon treating 4,4 -di(l-naphthoxy)diphenylsulfone and 4,4 -di(l-naphthoxy)ben2ophenone with ferric chloride. Equimolar amounts of the Lewis acid are required and the method is limited to naphthoxy-based monomers and other systems that can undergo the SchoU reaction. 

Chromic acid, permanganic acid, and ferric chloride do not oxidize sulfamic acid. 

Neutral aqueous salt solutions react slowly with tin when oxygen is present but oxidizing salt solutions, such as potassium peroxysulfate, ferric chloride and sulfate, and aluminum and stannic chlorides dissolve tin. Nonaqueous organic solvents, lubricating oils, and gasoline have Httle effect. 

Chemical Properties. The most significant chemical property of L-ascorbic acid is its reversible oxidation to dehydro-L-ascorbic acid. Dehydro-L-ascorbic acid has been prepared by uv irradiation and by oxidation with air and charcoal, halogens, ferric chloride, hydrogen peroxide, 2,6-dichlorophenolindophenol, neutral potassium permanganate, selenium oxide, and many other compounds. Dehydro-L-ascorbic acid has been reduced to L-ascorbic acid by hydrogen iodide, hydrogen sulfide, 1,4-dithiothreitol (l,4-dimercapto-2,3-butanediol), and the like (33). 

The most suitable oxidizing agent is potassium ferricyanide, but ferric chloride, hydrogen peroxide ia the presence of ferrous salts, ammonium persulfate, lead dioxide, lead tetraacetate or chromate, or silver and cupric salts may be useful. Water mixed, eg, with methanol, dimethylformamide, or glycol ethers, is employed as reaction medium. 

Cadmium Hydroxide. Cd(OH)2 [21041-95-2] is best prepared by addition of cadmium nitrate solution to a boiling solution of sodium or potassium hydroxide. The crystals adopt the layered stmcture of Cdl2 there is contact between hydroxide ions of adjacent layers. Cd(OH)2 can be dehydrated to the oxide by gende heating to 200°C it absorbs CO2 from the air forming the basic carbonate. It is soluble ia dilute acids and solutions of ammonium ions, ferric chloride, alkah haUdes, cyanides, and thiocyanates forming complex ions. 

Ethers. In the presence of anhydrous agents such as ferric chloride (88), hydrogen bromide, and acid chlorides, ethers react to form esters (see Ethers). Esters can also be prepared from ethers by an oxidative process (89). With mixed sulfonic—carboxyhc anhydrides, ethers are converted to a mixture of the corresponding carboxylate and sulfonate esters (90) ... 

Polymerization of ethylene oxide can occur duriag storage, especially at elevated temperatures. Contamination with water, alkahes, acids, amines, metal oxides, or Lewis acids (such as ferric chloride and aluminum chloride) can lead to mnaway polymerization reactions with a potential for failure of the storage vessel. Therefore, prolonged storage at high temperatures or contact with these chemicals must be avoided (9). 

Thymoquinone has been prepared directly from thymol by sulfonating and oxidizing the sulfonation mixture with manganese dioxide or potassium dichromate the same process has been successfully applied to carvacrol. The oxidation of sa ts of aminothymol with dichromate, ferric chloride, or nascent bromine also leads to satisfactory yields of thymoquinone. The above procedure is based on the observation that the diazonium salt obtained from aminothymol is almost quantitatively con-... 

---