Oxides sesquioxide

Among rare earth oxides, sesquioxides show high activity for base-catalyzed reactions. The activities are comparable to those of alkaline earth oxides. The rare earth oxides which are stable at higher oxidation states of metal cations such as Ce02, Tb40 , and PreOn show weakly basic properties. 

Chromic Oxid—Sesquioxid, or green oxid of chromium—CtjOj -t-152.8—obtained, amorphous, by calcining a mixture of potas- sium dichromate and starch, or, crystallized, by heating neutral iwtassium chromate to redness in Cl. 

Ferric Oxid—Sesquioxid or peroxid of iron—Colcothar—Jeweller s rouge—Venetian red—FejOa—159.8—occurs in nature (see above and is formed when ferrous sulfate is strongly heated, as in the manufacture of pyrosulfuric acid. It is a reddish, Amorphous solid, is a weak base, and is decomposed at a white heat into O and Pes04. 

This chapter reviews and compares the thermochemical properties of f-element ions in aqueous solution, in oxides (sesquioxides, dioxides, and complex oxides), in selected... 

Lead sesquioxide is used as an oxidation catalyst for carbon monoxide ia exhaust gases (44,45) (see Exhaust control), as a catalyst for the preparation of lactams (46) (see Antibiotics, P-lactams), ia the manufacture of high purity diamonds (47) (see Carbon, diamond-natural), ia fireproofing compositions for poly(ethylene terephthalate) plastics (48), ia radiation detectors for x-rays and nuclear particles (49), and ia vulcanization accelerators for neoprene mbber (50). 

Manganese(III) Oxides. The sesquioxide, Mn202, exists in dimorphic forms. The a-Mri202 exists in nature as the mineral bixbyite. 

The oxide monobutyltin oxide [51590-67-1J, is a sesquioxide, C H SnO from which it is difficult to remove the last traces of water. It is an infusible, insoluble, amorphous white powder that forms when butyltin trichloride is hydrolyzed with base. The partially dehydrated material, butylstaimoic acid [2273-43-0] is slightly acidic and forms alkaH metal salts. These salts, ie, alkaH metal alkylstaimonates, form when excess alkaH is used to hydrolyze the organotin trichloride ... 

Va.na.dlum(III) Oxide. Vanadium(III) oxide (vanadium sesquioxide, V2O2) is a black soHd, having the comndum (AI2O2) stmcture. It can be prepared by reduction of the pentoxide by hydrogen or carbon. Air oxidation proceeds slowly at ambient temperatures, but oxidation by chlorine at elevated temperatures to give VOCl and V20 is rapid. 

Antimony Trioxide. Antimony(III) oxide (antimony sesquioxide) [1309-64-4] Sb203, is dimorphic, existing in an orthorhombic modification valentinite [1317-98-2] is colorless (sp gr 5.67) and exists in a cubic form and senarmontite [12412-52-17, Sb O, is also colorless (sp gr 5.2). The cubic modification is stable at temperatures below 570°C and consists of discrete Sb O molecules. The molecule is similar to that of P40 and As O and consists of a bowed tetrahedron having antimony atoms at each corner united by oxygen atoms lying in front of the edges. This solid crystallizes in a diamond lattice with an Sb O molecule at each carbon position. 

Arsenic trioxide [1327-53-3] (arsenic(III) oxide, arsenic sesquioxide, arsenous oxide, white arsenic, arsenic), AS2O2, is the most important arsenic compound of commerce. The octahedral or cubic modification, arsenoHte [1303-24-8], 298 1313.9 kJ/mol (—314 kcal/mol) 214 J/(mol-K)... 

Cerium Oxide. The most stable oxide of cerium is cerium dioxide [1306-38-3] Ce02, also called ceria or ceric oxide. When cerium salts are calcined in air or if oxygen is present, this tetravalent Ce(IV) oxide is formed, cerium sesquioxide [1345-13-7] can be prepared in strongly reducing... 

Chromium Oxide Green. Chromium oxide green is principally chromic sesquioxide [1308-38-9], (Cl Pigment Green 17, Cl No. 

Chemical Designations - Synonyms Arsenous Acid Arsenous Acid Anhydride Arsenous Oxide Arsenic Sesquioxide White Arsenic Chemical Formula AsjOj. 

Ln203 are all well eharaeterized. With three exeeptions they are the final produets of eombustion of the metals or ignition of the hydroxides, earbonate, nitrate, ete. The exeeptions are Ce, Pr and Tb, the most oxidized produets of whieh are the dioxides, from whieh the sesquioxides ean be obtained by eontrolled reduetion with H2. Ln203 adopt three strueture types eonventionally elassified as )... 

Melles and Backer " found, from a study of the oxidation of substituted thiophenes with perbenzoic or peracetic acid, that sulfones could be obtained from polysubstituted methyl- and phenyl-thiophenes and that the presence of electron-attracting groups, such as nitro, hindered the oxidation. Oxidation of thiophene - led to a product which was formed through a Diels-Alder reaction between the intermediate thiophene sulfoxide (211) and thiophene sulfone (212) and for which two alternative structures, (213) or (214), were suggested. Similar sesquioxides were also obtained from 2- and 3-methylthiophene and 3-phenylthiophene. The structures were not proved. Bailey and Cummins synthesized thiophene-1,1-dioxide... 

Ruthenium-ozyd, n. (any) ruthenium oxide, esp. the sesquioxide, ruthenium(III) oxide, -oxydul, n. ruthenium monoxide, ruthenium-(II) oxide, -saure, /. ruthenic acid, -ver-bindung, /. ruthenium compound. 

Bismuth sesquioxide, BijOj, exhibits a high oxide ion conductivity at high temperature without doping of aliovalent cations. The oxide transforms from the monoclinic... 

Vanadium forms numerous oxides, the most important of which are vanadium monoxide, vanadium sesquioxide, vanadium dioxide and vanadium pentoxide. In the earlier examples (e.g., oxides of chromium and of niobium) the enthalpy values for the aluminothermic reduction of each of the oxides was given for the purpose of illustration. Normally, the consideration can be restricted to only those oxides which are readily obtained and which can be handled freely without any special or cumbersome precautions. In the case of vanadium for example, it is sufficient to consider the reduction of the sesquioxide (V203) and the pentoxide (V2Os). The pertinent reactions are ... 

A mixture of anhydrous hydrogen fluoride and 60% argon is passed over yttrium sesquioxide (Y203) at 700 °C for 16 h. The oxide is contained in a platinum boat, and the inconel furnace tube is also lined with platinum. 

Ammonium hydrogen fluoride (NH4HF2) is useful for converting pure oxides or hydroxides to the corresponding fluorides. The reaction occurs through the formation of a double fluoride. For example, with vanadium sesquioxide the following reactions occur ... 

Gasgnier M (2000) Ultrasound effects on metallic (Fe and Cr) iron sesquioxide (a-, y-Fe203) calcite copper, lead and manganese oxides as powders. Ultrason Sonochem 7 25-39... 

Oxidation of thiophene and its derivatives was studied using hydrogen peroxide (H2O2), t-butyl-hydroperoxide and Ti-Beta redox molecular sieve as selective oxidation catalysts. A new reaction pathway was discovered and investigated using C-13 NMR, GC, GC-MS, HPLC, ion chromatography, and XANES. The thiophene oxidized to thiophene-sesquioxide [3a,4,7,7a-tetrahydro-4,7-epithiobenzo[b]-thiophene 1,1.8-trioxide] and the sesquioxide oxidized mostly to sulfate. 2-Methyl-thiophene and 2,5 dimethylthiophene also oxidized to sulfate and sulfone products. The Benzothiophene oxidation product was sulfone. This proposed new reaction pathway is different from prior literature, which reported the formation of thiophene 1,1-dioxide (sulfone ) as a stable oxidation product... 

Oxidation of these model sulfur compounds was studied without solvent to investigate the chemical structure of the products using S K-edge XANES. A solvent free tri-phase (organic/ H202aq./catalyst) was used under the described conditions. Figure 1 shows the XANES spectra from the organic and aqueous phases as well as reference materials. The thiophene oxidized to thiophene-sesquioxide [3a,4,7,7a-tetrahydro-4,7-epithiobenzo[b]-thiophene 1,1.8-trioxide ] first.. The sesquioxide solid precipitated from the solvent free reaction mixture and was identified by NMR, IR and C,H,S elemental analytical. The sesquioxide oxidized to sulfate. 2-MT and 2,5 DMT also oxidized to... 

The relative stabilities of the dioxides, sesquioxides and monoxides for first period transition metals are given in Figure 7.11(c). The stability of the higher oxidation state oxides decreases across the period. As we will discuss later, higher oxidation states can be stabilized in a ternary oxide if the second metal is a basic oxide like an alkaline earth metal. The lines in Figure 7.11(c) can in such cases be used to estimate enthalpies of formation for unstable oxidation states in order to determine the enthalpy stabilization in the acid-base reactions see below. Finally, it should be noted that the relative stability of the oxides in the higher oxidation states increases from the 3d via 4d to the 5d elements, as illustrated for the Cr, Mo and W oxides in Figure 7.11(d). 

Cerium oxide, 74 649, 650 air/fuel conditions and, 70 50 for oxidizing iron in glass, 7 343 energy gap at room temperature, 5 596t Cerium(III) oxysulfide, 5 677 Cerium(III) phosphate, 5 677 Cerium sesquioxide, 5 675 Cerium(III) sulfide, 5 676 Cerium tetrachloride, 5 674 Cerium-zirconium oxides, 74 649 Cerius2 software, 7 629 7 385, 399, 422 76 754... 

Moore, M. D. and Kaplan, S. (1992) Identification of intrinsic high-level resistance to rare-earth oxides and oxyanions in members of the class Proteobacteria Characterization of tellurite, selenite, and rhodium sesquioxide reduction in Rhodobacter sphaeroides. J. Bacteriol. 174,1505-14. 

Figure 8.23A shows a simplified Eh-pH diagram for the Mn-O-H system. Within the stability field of water, manganese occurs in three valence states (2+, 3 +, and 4+). Figure 8.23A shows the condensed phases relative to the three valence states as the hydroxide pyrochroite Mn(OH)2 (2+), multiple oxide haus-mannite Mu304 (2+, 3 + ), sesquioxide Mu203 (3 + ), and oxide pyrolusite Mn02 (4+). 

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