Ruthenium tetroxide 5 states

Osmium tetroxide used in combination with sodium periodate can also effect alkene cleavage.191 Successful oxidative cleavage of double bonds using ruthenium tetroxide and sodium periodate has also been reported.192 In these procedures the osmium or ruthenium can be used in substoichiometric amounts because the periodate reoxidizes the metal to the tetroxide state. Entries 1 to 4 in Scheme 12.18 are examples of these procedures. Entries 5 and 6 show reactions carried out in the course of multistep syntheses. The reaction in Entry 5 followed a 5-exo radical cyclization and served to excise an extraneous carbon. The reaction in Entry 6 followed introduction of the allyl group by enolate alkylation. The aldehyde group in the product was used to introduce an amino group by reductive alkylation (see Section 5.3.1.2). 

Osmium tetroxide used in combination with sodium periodate can also effect alkene cleavage.135 Successful oxidative cleavage of double bonds using ruthenium tetroxide and sodium periodate has also been reported.136 In these procedures, the osmium or ruthenium can be used in substoichiometric amounts because the periodate reoxidizes the metal to the tetroxide state. Entries 1 4 in Scheme 12.17 are examples of these procedures. 

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... 

Ruthenium tetroxide is permanent when kept in sealed tubes in the dry state and protected from light. Exposed to light it assumes a brown colour, but the brown product is soluble in alkali, yielding a ruthenate. Presumably the coloration is due to partial reduction. Owing to its ready reduction by organic substances whereby a black precipitate of finely divided ruthenium is obtained, potassium per-ruthenate has been found useful for histological microscopy. ... 

In the solution, americium and curium, most of the FPs are in a single relatively nonextractable valence state. Iodine and ruthenium are important exceptions. Iodine may appear as nonextractable iodide or iodate or as elemental iodine, which would be extracted by the solvent and react with it. Ruthenium may appear in any valence state between 0 (insoluble metal) and 8 (volatile ruthenium tetroxide), and, at valence 4, it may form a number of nitrosyl ruthenium (Ru(IV)NO) complexes of varying extractabil-ity. An important objective of dissolution and the preconditioning of the feed solution prior to extraction is to convert these FP elements into states that will not contaminate uranium, plutonium, or solvent in subsequent solvent extraction (Benedict, Pigford, and Levi, 1981). 

As stated in the previous sections, the chief drawbacks in reactions using osmium tetroxide are its volatility, toxicity, and high cost. The less expensive and hazardous isoelectronic ruthenium tetroxide has long been appreciated for its powerful oxidation chemistry, especially oxidative cleavage of alkenes to aldehydes, ketones, and carboxylic acids [57]. Sharpless and Akashi showed for the first time that RUO4 can... 

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