Sodium chlorochromate

Sodium Chlorochromate, NaClCrOj. HaO, may be prepared from sodium chromate and chromyl chloride as reddish-yellow crystals, somewhat unstable, especially in solution. A chromoiodate, Na2Cr03. lOg.HgO, has also been described. ... 

This protecting group is stable to n-BuLi (THF, — 25°C), s-BuLi (Et20, -25 °C), LDA, saturated ammonium chloride solution, water, MeOH, sodium hydrogen carbonate solution (2m), pyridinium dichromate/ dichloromethane, and, surprisingly, KF.2H20/THF/H20. It is unstable to 0.1 M HC1, 1m KOH, 75% aqueous AcOH, NaBH4, and pyridinium chlorochromate/dichloromethane. 

OXIMES Hydrogen peroxide. Pyridinium chlorochromate-Hydrogen peroxide. Sodium dithionite. Vanadium(II) chloride. 

Oxidative ring fission of furans using the commercially available reagent pyridinium chlorochromate (PCC) has been studied as well (80T661). Experimental evidence supports the preliminary formation of intermediate (87) formed by 1,4-electrophilic attack of chlorochromate anion upon the furan ring. This intermediate then breaks down by heterolytic cleavage of the Cr—O bonds to afford initially the cis enedione which isomerizes to the trans product. Treatment of (88) with sodium hydroxide in methanol effects ring closure with formation of the 4-methoxycyclopentenone (89 Scheme 22). 

Oxidation of 8-hydroxymethyl-2-isopropyl-l 1 //-pyrido[2,l-b]quinazolin-11-one with pyridinium chlorochromate in methylene chloride gave the 8-carboxaldehyde, which was converted into its 8-aminomethyl derivatives by reacting with amines followed by reduction of the Schiff bases with sodium cyanoborohydride in acetic acid (87JOC2469). 

Chloramine-T-Sodium iodide, 70 Iodine-Trimethylsilyl chlorochromate, 327... 

NMO NMP Nu PPA PCC PDC phen Phth PPE PPTS Red-Al SEM Sia2BH TAS TBAF TBDMS TBDMS-C1 TBHP TCE TCNE TES Tf TFA TFAA THF THP TIPBS-C1 TIPS-C1 TMEDA TMS TMS-C1 TMS-CN Tol TosMIC TPP Tr Ts TTFA TTN N-methylmorpholine N-oxide jV-methyl-2-pyrrolidone nucleophile polyphosphoric acid pyridinium chlorochromate pyridinium dichromate 1,10-phenanthroline phthaloyl polyphosphate ester pyridinium p-toluenesulfonate sodium bis(methoxyethoxy)aluminum dihydride (3-trimethylsilylethoxy methyl disiamylborane tris(diethylamino)sulfonium tetra-n-butylammonium fluoride f-butyldimethylsilyl f-butyldimethylsilyl chloride f-butyl hydroperoxide 2,2,2-trichloroethanol tetracyanoethylene triethylsilyl triflyl (trifluoromethanesulfonyl) trifluoroacetic acid trifluoroacetic anhydride tetrahydrofuran tetrahydropyranyl 2,4,6-triisopropylbenzenesulfonyl chloride 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane tetramethylethylenediamine [ 1,2-bis(dimethylamino)ethane] trimethylsilyl trimethylsilyl chloride trimethylsilyl cyanide tolyl tosylmethyl isocyanide meso-tetraphenylporphyrin trityl (triphenylmethyl) tosyl (p-toluenesulfonyl) thallium trifluoroacetate thallium(III) nitrate... 

Potassium superoxide. Pyridinium chlorochromate. Pyridinium dichromate. Pyridinium fluorochromate. Silver(I) oxide. Silver(II) oxide. Sodium chlorite. Sodium hypochlorite. Sodium periodate. Sodium peroxide. Thallium(in) trifluoroacetate. Trifluoroperacetic acid. 

A. (4R)-(+)-Acetoxy-2-cyclopenten-l-one. A flame-dried, 2-L, three-necked, round-bcttomed flask, equipped with a Teflon-coated magnetic stirring bar, is purged with nitrogen and charged with 1.0 L of dry dichloromethane (Note 1), 1.5 g of anhydrous sodium acetate (Note 2), 70 g of 4 A molecular sieves (Note 3), and 23 g (162 mmol) of (1R,4S)-(+)-4-hydroxy-2-cyclopentenyl acetate (Note 4). Finely powdered pyridinium chlorochromate (50 g, 240 mmol) is added portionwise over a period of 5 min, and the mixture is stirred at room temperature for 3 hr (Note 5), then filtered through a pad of Florisil. The filtrate is concentrated on a rotary evaporator,... 

If necessary, bipyridinium chlorochromate may also be buffered with sodium acetate. In a system especially prone to epimerization (equation 10), bipyridinium chlorocliromate/sodium acetate gave 90% of the ketone (5) with little isomerization, whereas use of unbuffered PCC on a closely related substrate gave significant epimerization. ... 

H2O. On the other hand, cleavage occurs with 0.1 M hydrochloric add, 1M potassium hydroxide, 75% acetic acid, 0.1 M acetic acid, sodium borohydride in ethanol, or pyridinium chlorochromate.t ... 

In the present experiment pyridinium chlorochromate (PCC) is used to oxidize citronellol, a constituent of rose and geranium oil, to the corresponding aldehyde. If PDC in CH2CI2 were used, the reaction would stop at this point and citronellal could be isolated in 92% yield. Or if sodium acetate (a buffer) were added to the PCC reaction, the oxidation would also stop at the aldehyde stage, in 82% yield. It has been found that PCC deposited on alumina will effect the same oxidation in less time and even higher yield. ... 

In the following experiments cyclohexanol is oxidized to cyclohexanone using pyridinium chlorochromate in dichloromethane. The progress of the reaction can be followed by thin-layer chromatography. On a larger scale this reaction would be carried out using sodium dichromate in acetic acid because the reagents are less expensive, the reaction is faster, and much less solvent is required. 

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]. 

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