Lead tetraoxide

SYNS C.I. 77578 C.I. PIGMENT RED 105 DILEAD(II) LEAD(IV) OXIDE GOLD SATINOBRE LEAD ORTHOPLUMBATE LEAD TETRAOXIDE MINERAL ORANGE MINERAL RED MINIUM MINIUM NON-SETTING RL-95 ORANGE LEAD PARIS RED PLUMBOPLUMBIC OXIDE RED LEAD RED LEAD OXIDE SANDIX SATURN RED TRILEAD TETROXIDE... 

LEAD TETRAOXIDE (1314-41-6) An oxidizer. Decomposes above 932°F/500°C, emitting oxygen. Reacts, possibly violently, with reducing agents, powdered metals aluminum, titanium, zirconium, zinc, etc., alcohols, dichloromethylsilane, hydrazine, hydrogen bisulfide, ethers, glycols, peroxyformic acid, phosphorus, selenium oxychloride, sulfur trioxide. Incompatible with ammonium nittate, diboron tetrafluoride, hydrazinium nitrate, hydrogen sulfide, nitroalkanes, rubidium acetylide, selenium oxychloride. Forms heat-sensitive explosive material with anilinium perchlorate. Increases the thermal and/or explosive sensitivity of 2,4,6-trinitrotoluene, hydrazinium perchlorate, silver azide. Incompatible with sodium, sulfur trioxide. 

Examples P2O5, diphosphorus pentaoxide or phosphorus)V) oxide Hgj, mercury(I) ion or dimercury(2-l-) ion K2[Fe(CN)g], potassium hexacyanoferrate(II) or potassium hexacyanofer-rate(4—) PbJPb 04, dilead(II) lead(IV) oxide or trilead tetraoxide. 

Overall, the reaction leads to addition of two hydroxyl groups to the double bond and is refened to as hydroxylation. Both oxygens of the diol come from osmium tetraoxide via the cyclic osmate ester. The reaction of OSO4 with the alkene is a syn addition, and the conversion of the cyclic osmate to the diol involves cleavage of the bonds between oxygen and osmium. Thus, both hydroxyl groups of the diol become attached to the sfflne face of the double bond syn hydroxylation of the alkene is observed. 

Unlike palladium(II), osmium tetraoxide and ruthenium tetraoxide catalyze the dihydroxylation of one or both double bonds of an allene. The osmium tetraoxide-catalyzed dihydroxylation of unsymmetrically substituted allenes 45 can lead to two different a-ketols, 46 and 47, depending on which of the double bonds is oxidized. David et al. studied this reaction using NMO as a stoichiometric oxidant and found good product selectivity in a few cases, but the yields were only moderate (Scheme 17.15) [16]. They showed that the most substituted double bond was oxidized preferably when the bulkiness of the allene substituents did not interfere. 

See Carbon dioxide, above Ammonium nitrate Metals Barium peroxide Metals Dinitrogen tetraoxide Metals Hydrogen peroxide Metals Lead(IV)oxide Metals Nitric acid Metals Oxygen (Liquid) Metals Potassium chlorate Metals Potassium perchlorate Powdered metals Sodium iodate Metals Sodium nitrate Magnesium See Halogens etc., above See Metal oxides, above See Metal oxosalts, above See Sulfur, etc., below... 

Chromyl perchlorate, 4049 Cobalt(II) nitrate, 4209 Di-terf-butyl chromate, 3061 Dichlorine oxide, 4089 Dilead(II)lead(IV) oxide, 4855 Dinitrogen oxide, 4739 Dinitrogen pentaoxide, 4743 Dinitrogen tetraoxide, 4720 Dinitrogen trioxide, 4741... 

Thiazoline-azetidinone 36 is a versatile intermediate for the synthesis of varieties of beta-lactam antibiotics 24>. The most straightforward route to 36 must be the removal of the feta-lactam A-substituents of thiazoline-azetidinone 35, which is readily obtained from penicillins by Copper s method 4>. This has usually been done by the two-step operation, involving ozonolysis and subsequent methanolysis 25). Direct transformation of 35 to 36 also has been achieved by oxidation with potassium permanganate or osminum tetraoxide, but yields are unsatisfactory (—37%)25). An efficient method for the removal of A-substituents of 35 is the electrochemical acetoxylation procedure which may lead to the compound 36 along with 37 (Scheme 2-12)3). For example, the... 

Consideration of the absorption spectra of these two gases leads to the conclusion that the primary photochemical decomposition in nitrogen peroxide, which consists of nitrogen peroxide and nitrogen tetraoxide, is due to the tetraoxide constituent. 

The first work of this kind was carried out as long ago as 1936 (Criegee). It was shown that osmium tetraoxide could lead to the d.v-dihydroxylation of olefins. The electrochemical method of making such compounds is simple and more cost effective than competing chemical methods. 

The same features are observed in the osmylation of arene donors. Thus, osmium tetra-oxide spontaneously forms complexes with arenes, and the systematic spectral shift in the CT bands parallels the decrease in the arene IP [59]. The same osmylated adducts are obtained thermally on leaving mixtures to stand in the dark or upon irradiation of the CT bands at low temperature. Time-resolved spectroscopy establishes that irradiation of the CT band of the anthracene/osmium tetraoxide complex leads directly to the radical-ion pair ANT+, 0s04, which then collapses to the osmium adduct (with a rate constant fc 109 s 1) in competition with back ET [59]. 

The /7-toluenesulfonylimidoosmium reagent, which may be generated from Chloramine-T and osmium tetraoxide, leads to cis-addition of OH and HNTs to the least-hindered face of double bonds. With the hex-2-enopyranoside 97, the addition occurs to the top face of the double bond to give the regioisomers 109 and 110 (O Scheme 54) [92]. 

Exposure to nitrogen tetraoxide in the missile industry can lead to symptoms identical to those from nitrogen dioxide. Medical assistance should be sought immediately after any inhalation exposure, however small. If eyes or skin are exposed these should be well rinsed with water. 

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