Sodium dichromate groups

Removal of the ketal protecting groups, followed by oxidation with sodium dichromate ia acetic acid gave... 

A hydroxyl group in the neighborhood of fluoroalkyl is oxidized by sodium dichromate to yield a ketone [481 (equation 44)... 

Trinitrobenzene is present in crude TNT manufactured by mixed acid nitration and results from methyl group oxidation followed by decarboxylation." In fact, a convenient method for the synthesis of 1,3,5-trinitrobenzene involves oxidation of 2,4,6-trinitrotoluene with a solution of sodium dichromate in sulfuric acid, followed by decarboxylation of the resulting 2,4,6-trinitrobenzoic acid in boiling water." 1,3,5-Trinitrobenzene is prepared from 2,4,6-trinitro-m-xylene by a similar route." 2,4,6-Trinitroanisole can be prepared from the... 

The oxidation of 4-aminophenols containing two or three pentafluoroethoxy groups to the corresponding 1.4-benzoquinones is accomplished with sodium dichromate and sulfuric acid.230 The reaction is carried out in such a manner that the second portion of the oxidizing agent is added after allowing the mixture to stand overnight, for example, the formation of 3.230... 

An indirect vanadometric method of assay for camphor was developed. The method involves the formation of 2, -dinitrophenylhydrazone of camphor. The nitro groups in the hydrazone are then reduced to amines by treatment with vanadium sulfate (VSOl ) and the excess of the reagent is back titrated with sodium dichromate (NapCrpO-y). The entire procedure is carried out in a modified separatory funnel into which standard vanadate, 6tJ and zinc amalgam... 

The hepatic effects observed in animals after inhalation exposure to chromium or its compounds were minimal and not considered to be adverse. Rats exposed to as much as 0.4 mg chromium(VI)/m3 as sodium dichromate for 90 days did not have increased serum levels of alanine aminotransferase or alkaline phosphatase, cholesterol, creatinine, urea, or bilirubin (Glaser et al. 1990). Triglycerides and phospholipids were increased only in the 0.2 mg chromium(VI)/m3 group exposed for 90 days (Glaser et al. 1985). Chronic exposure of rats to 0.1 mg chromium(VI)/m3 as sodium dichromate, to 0.1 mg total chromium/m3 as a 3 2 mixture of chromium(VI) trioxide and chromium(III) oxide, or to 15.5 mg chromium(IV)/m3 as chromium dioxide did not cause adverse hepatic effects as assessed by histological examination and liver function tests (Glaser et al. 1986,1988 Lee et al. 1989). 

Benzoin can be oxidized to the a-diketone, benzii, very efficiently by nitric acid or by copper(II) sulfate in pyridine. On oxidation with sodium dichromate in acetic acid the yield is lower because some material is converted into benzaldehyde by cleavage of the bond between two oxidized carbon atoms and activated by both phenyl groups (a). Similarly, hydrobenzoin on oxidation with dichromate or permanganate yields chiefly benzaldehyde and only a trace of benzii (b). 

Sodium dichromate hydroxylates tertiary carbons [620] and oxidizes methylene groups to carbonyls [622, 623, 625, 626, 631] methyl and methylene groups, especially as side chains in aromatic compounds, to carboxylic groups [624, 632, 633, 634, 635] and benzene rings to quinones [630, 636, 637] or carboxylic acids [638]. The reagent is often used for the conversion of primary alcohols into aldehydes [629, 630, 639] or, less frequently, into carboxylic acids or their esters [640] of secondary alcohols into ketones [621, 629, 630, 641, 642, 643, 644] of phenylhydroxylamine into nitroso-benzene [645] and of alkylboranes into carbonyl compounds [646]. 

The degradation of benzene rings to carboxyls is facilitated by the presence of electron-donating groups. m-Trifluoromethylaniline is converted into trifluoroacetic acid in 90-95% yield on heating with sodium dichromate and dilute sulfuric acid for 30-40 min at 70-170 °C [638]. 

Methylene groups adjacent to aromatic rings are oxidized to keto groups by oxygen with chromium sesquioxide as a catalyst [1128] or by mercuric bromide [11], ceric ammonium nitrate [380, 417, 422], selenium dioxide [509], sodium dichromate [622, 625], pyridinium chlorochromate [607], manganese dioxide [814], potassium permanganate [866, 877], and alkyl nitrites [452]. 

Fluorene is oxidized to fluorenone in 65-70% yield by refluxing for 3 h with sodium dichromate in acetic acid [622], and 2-methylfluorene is converted into 2-methylfluorenone via its oxime on treatment with amyl nitrite (pentyl nitrite) [452]. The methylene group between two aromatic rings is oxidized in preference to the methyl group because nitrites react only with highly activated methylene groups (equation 177). 

In acenaphthene, both methylene groups are oxidized by sodium dichromate to give acenaphthenequinone (equation 180) [625]. 

The oxidation of a methyl ketone to a carboxylic acid with one less carbon by oxidants other than hypohalites is exemplified by the oxidation of 2-acetylfluorene with sodium dichromate. In addition to the methyl keto group, the methylene group is also oxidized (equation 432) [626]. 

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