VI Oxide Chloride

Molybdenum oxytetrachloride has been prepared in limited quantities by several methods, most of which give low yields 

Molybdenum oxytetrachloride is a dark green crystalline compound with a melting point of 100 to 101°. Infrared absorption (KBr disk) has been used to establish the absence of OH and HjO in verification of the anhydrous state. A broad band appears in the 970-cm. region and reveals molyb-denum-to-oxygen bonding. The oxychloride reacts with thoroughly dried Nujol so that satisfactory infrared spectra cannot be obtained with this as a dispersion medium. When exposed to light, molybdenum oxytetrachloride forms a brown film on the surface of the ampule. Since this film is not formed when the ampules are stored in the dark, molybdenum oxytetrachloride is concluded to be photosensitive. 

---

Mo OjCls -(V, VI)-oxid-chlorid s 417,14 loslich. Mit vicl Wasser Dlauer Nieder schlag. 

Moissanite, see Silicon carbide Molybdenite, see Molybdenum disulfide Molybdite, see Molybdenum(VI) oxide Molysite, see Iron(III) chloride Montroydite, see Mercury(II) oxide Morenosite, see Nickel sulfate 7-water Mosaic gold, see Tin disulfide Muriatic acid, see Hydrogen chloride, aqueous solutions... 

Ammonia, anhydrous Mercury, halogens, hypochlorites, chlorites, chlorine(I) oxide, hydrofluoric acid (anhydrous), hydrogen peroxide, chromium(VI) oxide, nitrogen dioxide, chromyl(VI) chloride, sulflnyl chloride, magnesium perchlorate, peroxodisul-fates, phosphorus pentoxide, acetaldehyde, ethylene oxide, acrolein, gold(III) chloride... 

Actinide ions of the 111, IV, and VI oxidation states can be adsorbed by cation-exchange resins and, in general, can be desorbed by elution with chloride, nitrate, citrate, lactate, a-hydroxyisobutyrate, ethylenediaminetetraacetate, and other anions (11,12). 

The synthesis of the smaller fragment methyl esters 144-147 was completed as depicted in Scheme 20. Chelation-controlled allylation of aldehydes 135-138 prepared by chromium(VI) oxidation of alcohols 122,123,133, and 134 with allyltrimethylsilane (139) in the presence of titanium(IV) chloride proceeded... 

B. General Oxidation Procedure for Alcohols. A sufficient quantity of a 5% solution of dipyridine chromium (VI) oxide (Note 1) in anhydrous dichloromethane (Note 7) is prepared to provide a sixfold molar ratio of complex to alcohol. This excess is usually required for complete oxidation to the aldehyde. The freshly prepared, pure complex dissolves completely in dichloromethane at 25° at 5% concentration to give a deep red solution, but solutions usually contain small amounts of brown, insoluble material when prepared from crude complex (Note 8). The alcohol, either pure or as a solution in anhydrous methylene chloride, is added to the red solution in one portion with stirring at room temperature or lower. The oxidation of unhindered primary (and secondary) alcohols proceeds to completion within 5 minutes to 15 minutes at 25° with deposition of brownish-black, polymeric, reduced chromium-pyridine products (Note 9). When deposition of reduced chromium compounds is complete (monitoring the reaction by gas chromatography or thin-layer chromatography analysis is helpful), the supernatant liquid is decanted from the (usually tarry) precipitate and the precipitate is rinsed thoroughly with dichloromethane (Note 10). 

I )ipyridine chromium(VI) oxide is available from East-imni (Irganic Chemicals. To be an effective reagent, it must be ttnliydi oiis. It should form a red solution on dissolution in mdiydroiis methylene chloride. 

Piroxicam Piroxicam, 1,1 -dioxid-4-hydroxy-2-methyl-iV-2-pyradyl-2//-1,2-benzothiazine-3-carboxamide (3.2.78), is synthesized from saccharin (3.2.70). Two methods for saccharin synthesis are described. It usually comes from toluene, which is sulfonated by chlorosulfonic acid, forming isomeric 4- and 2-toluenesulfonyl chlorides. The isomeric products are separated by freezing (chilling). The liquid part, 2-toluenesulfonyl chloride (3.2.68) is separated from the crystallized 4-toluenesulfochloride and reacted with ammonia, giving 2-toluenesul-fonylamide (3.2.69). Oxidation of the product with sodium permanganate or chromium (VI) oxide in sulfuric acid gives saccharin—o-sulfobenzoic acid imide (3.2.70) [123-126]. 

Peroxyacids oxidize the imine group in (236) and related compounds to the nitrone. The 1,4-benzodiazepine (178) and its 4,5-dihydro analogue can be oxidized to the 2-oxo derivatives with chromium(VI) oxide. The benzodiazepinone (236) can be hydroxylated at the 3-position via a two-step process firstly reaction with LTA gives the 3-acetoxy derivative and this can then be hydrolyzed in high yield using sodium methoxide in methanol/methylene chloride. The 3-acetoxy derivative may also be prepared via bromina-tion with NBS and reaction with sodium acetate in situ (79JHC1449). 

All of the usual chromium-based oxidation reagents that have been used for the oxidation of cyclobutanols to cyclobutanones, for example, chromium(VI) oxide (Jones reagent),302 pyri-dinium chlorochromate,304 pyridinium dichromate,307 and chromium(YI) oxide/pyridine (Collins),303 are reported to do so without any serious problems. Alternatively, tetrapropylam-monium perruthenate in the presence of A-methylmorpholine A -oxide. oxalyl chloride in the presence of triethylamine in dimethyl sulfoxide (Swern),158,309,310 or phenyl dichlorophos-phate in the presence of triethylamine and dimethyl sulfoxide in dichloromethane (Pfitzner-Moffatt),308 can be used. The Pfitzner-Moffatt oxidation procedure is found to be more convenient than the Swern oxidation procedure, especially with respect to the strict temperature control that is necessary to achieve good yields in the latter, e.g. oxidation of 1 to give 2.308... 

---