Ammonium hexanitratocerate

Colorimetric methods have been successfully used for determining trace amounts of ethanol. Ammonium hexanitratocerate(IV) has been used as a reagent (262) and for continuous automatic analysis. Alcohols form colored complexes with 8-hydroxyquinoline and vanadic compounds. The absorbance of these complexes, measured at 390 p.m has been used to provide an analytical procedure (263). 

The use of cerium(IV) salts as catalytic oxidation mediator is restricted by their insolubility in non-aqueous media. Cerium(IV) ammonium nitrate (CAN) may be used in organic solvents upon the addition of quaternary ammonium salts, but cerium(IV) sulphate is not transferred under analogous conditions. Bis(tetra-/t-butyl-ammonium) hexanitratocerate(IV) is obtained in a solid form by metathesis of CAN... 

Synonyms ammonium ceric nitrate ammonium hexanitratocerate (IV)... 

Another mild oxidant for aromatic iodination is ammonium hexanitratocerate(IV) (CAN)358. This reagent is useful in the synthesis of 5-iodouracil derivatives (equation 47)359. 

Cerium(IV) is used as an oxidant both in analysis and in preparative chemistry. Dissolved in acetic acid it oxidizes aldehydes and ketones at the or-carbon atom a solution of ammonium hexanitratocerate(IV) will oxidize toluene to benzaldehyde. Aqueous CeIV oxidizes concentrated Cl- to Cl2, but the rate depends strongly on the pH and the presence of a catalyst.40... 

We also observed similar phenomena in the reaction of silyl enol ethers with cation radicals derived from allylic sulfides. For example, oxidation of allyl phenyl sulfide (3) with ammonium hexanitratocerate (CAN) in the presence of silyl enol ether 4 gave a-phenylthio-Y,5-un-saturated ketone 5. In this reaction, silyl enol ether 4 reacts with cation radical of allyl phenyl sulfide CR3 to give sulfonium intermediate C3, and successive deprotonation and [2,3]-Wittig rearrangement affords a-phenylthio-Y,6-unsaturated ketone 5 (Scheme 2). Direct carbon-carbon bond formation is so difficult that nucleophiles attack the heteroatom of the cation radicals. 

Ceric Ammonium Nitrate (Cerium Ammonium Nitrate, Ammonium Hexanitratocerate). Ce(N03)4.2NH4N03, mw 548.3, small prismatic yeUow crysts, sol in w ale. Prepd by electrolytic oxidation of cerous nitrate in nitric acid soln, and subsequently mixing solns of cerium nitrate and AN, foUowed by crystn. It is a strong oxidizing agent and a dangerous fire risk in contact with organic materials... 

Sodium oxalate has been used as a primary standard substance for Ce(IV) in sulfuric acid. In the absence of a catalyst a temperature of 70 to 75°C is necessary. Smith and Getz found that in 1 to 2 M perchloric acid solution, sodium oxalate can be titrated at room temperature with Ce(IV) perchlorate or nitrate but not with sulfate. Rao, Rao, and Rao carried out the titration at room temperature in the presence of barium chloride to remove sulfate, which retards the reaction between oxalate and Ce(IV) and between oxalate and oxidized ferroin. Alternatively, some Fe(III) was added, and the trace of Fe(II) produced photochemically then reacted with the indicator. Rao, Rao, and Murty carried out the titration in 0.5 M HNOj with ammonium hexanitratocerate(IV) instead of the sulfate. With a small amount of KI and KIO3, a satisfactory end point was obtained at room temperature with ferroin as indicator. 

Because ammonium hexanitratocerate(IV) in dilute nitric acid oxidizes Cr(III) quantitatively at room temperature in 10 to 15 min, it has found practical application in the determination of chromium. ... 

The preparation of Ce(IV) compounds free of foreign metals is facilitated by the fact that, when ammonium nitrate is added to a concentrated nitric add solution of Ce(IV), the compound (NH4)2Ce(N03)g is precipitated in relatively pure form. Because the Ce(rV) exists as the complex ion Ce(N03)g", the ammonium salt is properly caUed ammonium hexanitratocerate(TV). In water and in dilute nitric acid, extensive dissodation occurs. Ammonium hexanitratocerate(IV) was suggested as a primary standard, and drying it to constant weight at 100°C was recommended. Later it was recognized that slow decomposition occurs at this temperature, and Smith and Fly recommended a procedure that involved drying a product of primary-standard grade at 85°C for 1 to 6 h. The accurate results of Smith and Fly have been confirmed. ... 

Ammonium hexanitratocerate(IV) as a standard oxidant for reactions at room temperature has been developed for several substances. " Oxalate can be titrated with Ce(IV) in 0.5 M HNO3 with an iodide catalyst mandelic acid at a lower acid concentration, 0.1 MHNO3 Mn(II) with excess Ce(TV) in 0.5 to 2M HNO3 with silver nitrate catalyst hydrazine or isonicotinic acid in HCl-KBr solution and As(III) in HCl, HNO3, or H2SO4 solution with a trace of iodine as catalyst. 

Abbreviations Ac, acetyl AIBN, 2,2 -azobisisobutyronitrile All, allyl Alloc, allyloxycarbonyl Bn, benzyl BOM, benzyloxymethyl BPC, p-phenylbenzoyl Bu, butyl t-Bu, tert-butyl Bz, benzoyl CAN, ammonium hexanitratocerate (IV) Cbz, bezyloxycarbonyl CDl, carbonyldiimizazole ClAc, chloroacetyl Cp, cyclopentadienyl CSA, DL-lO-camphorsulfonic acid DABCO, l,4-diazabicyclo[2.2.2]octane DAST, diethylaminosulfur trifluoride dba, dibenzylideneacetone DBU, l,8-diazabicyclo[5.4.0]undec-7-ene DCC, iV,iV-dicyclohexylcarbodiimide DDQ, 2,3-dichloro-5,6-dicyano-l,4-benzoqui-none DEAD, diethyl azodicarboxylate DEIPS, diethylisopropylsilyl DIBAL, diisobutylaluminum hydride DMAP,... 

The most frequently used method to destroy unused or unwanted azides requires ammonium hexanitratocerate(IV), (NH4)2Ce(NO3)6 (common name. 

Reactions of ammonium hexanitratocerate(IV) with organic substrates other than benzyl alcohol have also been examined, and 1,4-hydroquinone was quantitatively transformed into 1,4-quinone. Anisole and naphthalene can be nitrated. For the cerium-mediated oxidation reactions in ionic liquids, high reaction temperature is beneficial because of the formation of smaller amounts of by-products. 

Ammonium hexanitratocerate(IV) (2.0 g, 3.64 mmoles) in acetone (20 mL) is treated with triphenylphosphine oxide, OPPh3 (2.05 g, 7.36 mmoles), in acetone (20 mL). The mixture is filtered to remove a white precipitate (NH4NO3), and the solvent is removed under reduced pressure. The orange crystals are washed with chloroform and recrystallized from acetonitrile. Anal. Calcd. forCe(N03)4-2 OPPh3 Ce, 14.84 NOr, 26.26 P, 6.56. Found Ce, 14.76 NOr, 26.20 P, 6.40. 

Ceriuin(iv) is used as an oxidant, not only in analysis, but also in organic chemistry where it is commonly used in acetic acid. The solid acetate, which is bright yellow, can be made by ozone oxidation of Ce111 acetate.45 The solutions oxidize aldehydes and ketones at the a-carbon atom, and benzal-dehyde, for example, gives benzoin while ammonium hexanitratocerate will oxidize toluenes to aldehydes. These oxidations appear to proceed by the initial formation of 1 1 complexes the complexes of alcohols are red.46... 

A number of transition metals can be determined conveniently if their cations undergo a definite change of oxidation state see Oxidation Number) on titration with a standard solution of potassium permanganate, potassium dichromate, cerium(IV) sulfate, or ammonium hexanitratocerate(IV). Several visual indicators have been proposed, including diphenylamine and its derivatives, xylene cyanole FF, and especially A-phenylanthranilic acid and tris(l,10-phenanthroline)iron(II) sulfate ( ferroin ). Solutions of have been used in the determination of iron, copper, titanium, vanadium, molybdenum, tungsten, mercury, gold, silver, and bismuth, and standard solutions of and Sn F U, and and Mo have also... 

When a cerium(IV) solution is prepared by dissolving ammonium hexanitratocerate(IV) in sulfuric acid, both sulfate and nitrate ions are present. In many cases, the nitrate ions do not interfere in the analysis. When the presence of nitrate ions is undesirable, the ammonium... 

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