Oxidants in glacial acetic acid

The conversion was quantitative (>95%). The methanolic solution was cooled and neutralized with a small excess of sodium carbonate. Acetals were extracted from methanol with light petroleum. For structural studies, acetals were oxidized to the corresponding acids by the action of chromic oxide in glacial acetic acid. The esters produced by the esterification with methanolic HC1 were chromatographed and compared with standards. Schogt et al. [66] used silver oxide for the oxidation and diazomethane for the esterification. 

In an early study on the ozonation of lignin, Freudenberg et al (1935) found that both lignin and methylated lignin were more quickly oxidized in glacial acetic acid than in water Nakano and his coworkers (Matsumoto et al 1984a,b, 1986, Habu et al 1990) used acetic acid/water/methanol (16 3 1, v/v/v) as the reaction medium This mixture was also used by Sarkanen and his coworkers (Tsutsumi et al 1990 and unpubl work)... 

Oxidation of quinazolin-4(3/f)-one to quinazoline-2,4(l/f,3f )-dione with chromium(VI) oxide or potassium permanganate yields only traces of the product and is therefore preparative-ly not important. However, oxidation of quinazolin-4(3/f)-onc 1-oxide with chromiurn(VI) oxide in glacial acetic acid affords l-hydroxyquinazoline-2,4(l//,3//)-dione which is tautomeric with quinazoline-2,4-diol 1-oxide (50%). ... 

The most important oxidants in glacial acetic acid as solvent are lead tetraacetate, which oxidizes mercaptans RSH to disulfide RSSR cerium(rv), a strong oxidant, though its reactions tend to be slow iodobenzene dichlorideand bromine, which may be obtained conveniently by coulometric generation. 

Tin dibenzyl diacetate is deposited from the solutioxx obtained by dissolving tin dibenzyl oxide in glacial acetic acid. It forms long, colourless needles, M.pt. 136° to 137° C., readily soluble in acetone, chloroform, alcohol, or benzene. 

Catalytic hydrogenation of thebaine-quinone over platinum oxide in glacial acetic acid proceeds with the rapid absorption of one mole of hydrogen and the somewhat slower absorption of a second mole to give tetrahydro-thebaine-quinone [xvm]. If the reduction is stopped after the first mole of hydrogen has been absorbed, a product that is probably mainly [xix] is obtained it is believed to be mainly [xrx] as mainly non-phenolic matter is obtained after one minute s boiling with concentrated acid, under which conditions [xvi] is isomerized to [xvh] [3]. Attempted demethylation of [xvni] with hydriodic acid affords only tars [3]. 

KJ added to a soln. of 2-methy -], 4-riaphthoquinone 2,3-oxide in glacial acetic acid, and refluxed 45 min. — 2-methyl-l,4-naphtho-... 

Chromic oxide in glacial acetic acid converts tetraarylethylenes into their epoxides 54,55 and various steroids are oxidized at positions 5,6 to epoxides by potassium permanganate in glacial acetic acid.56... 

Fluoro-l-decanol is converted by chromium(vi) oxide in glacial acetic acid into the corresponding fluoro carboxylic acid in 93% yield.478... 

Formation of the Oxazolidine and Thiazolidine Ring in C20 Diterpenoid Systems.—A convenient method for the construction of oxazolidine and thiazolidine rings from the imine-containing diterpenoids has been reported. " Treatment of the imine, e.g. lindheimerine (63), with ethylene oxide in glacial acetic acid or with excess neat ethylene sulphide gave the corresponding oxazolidine [e.g. ovatine (64)] and thiazolidine [e.g. (65)], respectively, in yields of 90—98%. 

Selective reduction. Ethyl a - carbethoxy - - (2,4,5 - trimethoxybenzoyl) butyrate added to prehydrogenated palladium oxide in glacial acetic acid containing HGIO4, and hydrogenated 2 hrs. until the calculated amount of has been absorbed ethyl a-carbethoxy- -(2,4,5-trimethoxybenzyl) butyrate. Y 94%. F. e. and limitations s. E. Hardegger et al., Helv. 47, 1996 (1964). 

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