Tetraoxides formation

To prevent oxidation of nitrous oxide to nitrogen tetraoxide, excess ascorbic acid must be used. Douglas et al (1978) has reviewed the numerous literature reports on ascorbic acid inhibition of nitrosamine formation in amine-nitrite systems. 

Presence of dinitrogen tetraoxide appears to be essential to catalyse smooth formation of nitrosylsulfuric acid from sulfur dioxide and nitric acid. In its absence, reaction may be delayed and then proceed explosively. 

Osmium(VIII) tetraoxide (0s04) is an effective reagent for the cis hydroxylation of olefins under stoichiometric conditions as well as in a variety of catalytic variants.213 Under both catalytic and stoichiometric conditions, the critical step is the formation of an osmium(VI) cycloadduct, the formation of which is dramatically accelerated in the presence of amine bases such as pyridine,214 i.e.,... 

Donor-acceptor complexes. A colorless hexane (or dichloromethane) solution of osmium tetraoxide upon exposure to benzene turns yellow instantaneously owing to the formation of a donor/acceptor complex,218 i.e.. 

Scheme 10 shows the course taken by these reactions. No trace was found of the 5,5-dioxide, the 5,5,10-trioxide, or the 5,5,10,10-tetraoxide. This reaffirms that sulfide oxidation precedes sulfone formation (42). 

This mechanistic question is one of the examples of the success of density functional theory methods in organometallic chemistry. Earlier work on the reaction mechanism could not discriminate between the two alternatives. Analysis of the different orbitals based on extended Hiickel calculations came to the result that the [3+2] pathway is more likely, but could not exclude the possibility of a [2+2] pathway [13]. Similar conclusions where obtained from the results of Hartree-Fock calculations in combination with QCISD(T) single point calculations [21], Attempts to use Ru04 as a model for osmium tetraoxide indicated that the formation of an oxetane is less favorable compared to the [3+2] pathway, but still possible [22, 23],... 

This reaction plays an important role in the oxidation of hydrocarbons, as illustrated in Scheme 1,2 5-267 self-reaction of the intermediate peroxyl radicals to form transient tetraoxide intermediates 44 was shown by the direct observation of these intermediates at low temperatures, and isotope scrambling when 2 and 02 was used in auto-oxidation with formation of Tetraoxides with secondary hydrogens (45) can undergo... 

Osmium tetraoxide-promoted reactions are stevically controlled that is, in all instances, the predominant formation of products having tram-oriented substituents at C-2 and C-3, and C-2 and CA, is ob-served, and, consequently, 277 and 279 preponderate over 278 and 280. However, for 2-0-acetyl-l,6-anhydro-3,4-dideoxy-/3-DL- n/t/iro-hex-3-enopyranose (281), reaction with osmium tetraoxide leads175 to 2-0-acetyl-l,6-anhydro-/3-DL-alloside (282 88%) and -galactoside (283 8%). Obviously, the 1,6-anhydro bridge creates greater steric... 

An alternate entry to the narciclasine class of alkaloids has provided access to compounds related to isonarciclasine (263) (Scheme 24). In the event, the aryla-tion of p-benzoquinone with diazonium salts derived from the aryl amines 250 and 251 yielded the aryl-substituted benzoquinones 252 and 253, respectively (146). The selective hydroxylation of 252 and 253 with osmium tetraoxide provided the corresponding m-diols 254 and 255. Catalytic hydrogenation of 254 and 255 using Pd/C or Raney Ni and subsequent lactonization gave the triols 256 and 257 together with small amounts of the C-2 a-epimers 258 and 259. Aminolysis of 256 and 257 afforded the corresponding racemic tetrahydrophen-anthridones 260 and 261, whereas similar treatment of the a-epimers 258 and 259 led to the formation of ( )-isolycoricidine (262) and ( )-isonarciclasine (263), respectively. 

Oxidation of organic compounds by ruthenium tetraoxide has been reviewed. The oxidation of various types of organic compounds such as alkanes, alkenes, allenes, aromatic rings, alcohols, amines, and sulfides has been discussed The cyclic oxoruthe-nium(VI) diesters that are formed in the initial step of the oxidation of alkenes are considered to be intermediates in the formation of 1,2-diols.70 The development of new and selective oxidative transformations under ruthenium tetroxide catalysis during the past 10 years has been reviewed. The state of research in this field is summarized and a systematic overview of the reactivity and the reaction mode of ruthenium tetroxide is given.71... 

Viridifloric /3-lactone, 143, has been identified as one of the pheromone components of a complex mixture of volatiles released by the pheromone glands of the male Idea leuconoe butterfly during courtship <1996BMC341>. A racemic mixture of both diastereoisomers was synthesized in four steps from the dilithio salt of 3-methylbutyric acid 144 alkylation with ethanal, dehydration of the secondary alcohol with phosphorus pentoxide, dihydroxylation of the C-C double bond with osmium tetraoxide, and finally formation of the /3-lactone by cyclization with sulfonyl chloride. By comparison with the sample isolated from I. leuconoe, the absolute configuration was established to be (2V,3V)-2-hydroxy-2-(l-methylethyl)-3-butanolide 143. 

The lithiation of the seven-membered sultone 217 with lithium iV,./V-diisopropylamide at -78 °C led to the rapid formation of the 1,3-dithietane 1,1,3,3-tetraoxide 218 in 55% yield, via the intermediate 219 (Scheme 26) <2003SL667>. 

Lithiation of sultone 238 with LDA in THF at — 78 °C gave the rapid formation of the 1,3-dithietane tetraoxide 239 in 55% isolated yield in the apparent form of a 60 40 mixture of trans/cis-diastereomers bearing double bonds with the (Z)-configuration <2006T9017>. The authors explained the formation of the 1,3-dithietane 239 by the transformation of the a-lithiated sultone into the corresponding sulfene, which dimerized to give dithietane 239 (Scheme 28). 

The thermal reaction of thianthrene tetraoxide (233) with selenium (39JCS151) or tellurium (58Ac(R)738) yields dibenzoselenophene and dibenzotellurophene respectively. The corresponding thermal reaction of 2,5-diaryldithiin 1,1,4,4-tetraoxides (234) with selenium gives acceptable yields of 2,5-diarylselenophenes and in one case a small amount of the 2,4-isomer (76JHC57). It has been established fairly convincingly that the reaction proceeds via formation of the arylacetylene and its subsequent reaction with selenium. 

Sugimoto H, Sawyer DT, Kanofsky JR. Transient formation of hydrogen tetraoxide [HOOOOH] from the dimerization of perhydroxyl (HOO) Concerted homolytic dissociation to singlet oxygen (102) and hydrogen peroxide. J Am Chem Soc 1988 110 8707-8. 

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