Ceric ammonium sulfate oxidant

Ceric ammonium sulfate, 5 674 Ceric fluoride, 5 674 Ceric hydroxide, 5 676 Ceric oxide, 5 670, 675 Ceric rare earths (RE), 74 631 Ceric sulfate, 5 674 Ceric sulfate method, for tellurium determination, 24 415 Cerium (Ce), 5 670-692 74 630, 63 It, 634t. See also Cerium compounds analysis, 5 679-680 color, 7 335... 

Oxidation of arenes This oxidant is somewhat superior to CrOs for oxidation of arenes to quinones but less efficient than ceric ammonium sulfate (8,80-81). An example is the oxidation of naphthalene to 1,4-naphthoquinone in 75% yield. 

Other chemical oxidants that have been examined include ceric ammonium sulfate,74 potassium dichromate,75 and hydrogen peroxide,76 although it is reported that optimal conductivities are obtained when (NH4)2S208 is used as oxidant. It has been suggested that the polymerization process is less dependent on the oxidation potential of the particular oxidant (see Table 4.1) than on the degradation processes associated with each. 

Cerium(IV) presents an interesting case. The useful oxidant ceric ammonium nitrate (CAN) can be extracted from an aqueous solution as a complex salt [NBu4]2[Ce(N03)6] into hexane. Ceric ammonium sulfate, however, being a true double salt, cannot be transferred by a QX catalyst [14], In an actual catalytic oxidation procedure, naphthalene is converted into naphthoquinone in a water/hexane... 

Cerium(IV) has been used extensively, and the two most common reagents are ceric ammonium sulfate [Ce(S04)2 2(NH4)2S04 2 H2O] and ceric ammonium nitrate [Ce(NH4)2(N03)6].l 3 Modified cerium reagents such as Ce(OH)302Hl 4 d [(N03)3Ce]3H2l06l - have been used by Firouzabadi et al. or the oxidation of primary alcohols, especially benzylic and allylic alcohols. 

The radical can also be formed by an oxidizing agent, such as ceric ammonium sulfate.In phenothiazines generally, the semiquinone radical undergoes disproportionation. The products of oxidation are the sulfoxide or the 3(or 7)-hydroxy-derivatives. However, formation of the latter is severely inhibited in 10-substituted phenothiazines. The second-order decay rate constant of the semiquinone radical of fluphenazine was found to be 1100 (1/mole/min), as measured by electron spin resonance.The sulfoxide content of several commercial batches of fluphenazine was determined to be around 0.1% by... 

OXIDATION, REAGENTS 1,1 -(Azodi-carbonyl)dipiperidine. Benzeneseleninic acid. Benzeneseleninic anhydride. Barium manganate. Bis 3-salicylidene-aminopropyl] aminecobalt(II). Bisltri-n-butyltin) oxide. /-Butyl hydroperoxide. /-Butyl hydroperoxide-Selenium dioxide. Caro s acid. Ceric ammonium sulfate. Chromic acid-3,5-Dimethyl-pyrazole. Chromic acid-Silica gel. 1,4-Diazabicyclo[2.2.2] octane-Bromine. 

A soln. of 1,3-bishomocubanone in acetonitrile added to a stirred aq. slurry of ceric ammonium sulfate, and warmed 1 hr. at 60° product. Y 78%. - The products obtained by this method may differ from the ones obtained by conventional peracid oxidation. F. e, s. G. Mehta, P. N. Pandey, and T.-L. Ho, J. Org. Chem. 41, 953 (1976). 

Quinones (Table 6.10, item 4) are formed only with difficulty from benzene (CfiH ) itself. However, as shown in Equations 6.77 and 6.78, on oxidation in solution with, for example, ammonium cerium(IV) sulfate [ceric ammonium sulfate, Ce(NHi)4(S04)4], naphthalene (CioHg) and anthracene (C14H10) yield p-quinones and phenanthrene (C14H10), an isomer of the latter (Equation 6.79), yields an o-quinone much more readily. It has been argued that maintaining aromaticity in portions of each of these polynuclear systems aids in making the oxidation reaction much more facile. Similar oxidation patterns are common in naturally occurring quinones. 

Phenols (e.g., phenol itself [CeHs-OH or Ar-OH], Table 6.10, item 2) and their esters (e.g., the trifluoroacetate ester of phenol [C6H5-O2CCF3 or Ar02CCH3], Table 6.10, item 3) have been oxidized with air and oxygen (O2), in neutral and alkaUne solutions, with and without ionic and/or radical catalysts and/or irradiation and in a variety of solvents. Enzymes (this chapter and Chapter 12) from a wide variety of sources have also been used. Frequently, oxidation of aromatic systems to phenols cannot be stopped before quinones and products of ring fragmentation occur and numerous, sometimes ill-defined, products result. Thus, as shown in Equation 6.80, oxidation of the polynuclear hydrocarbon chrysene with anunonium cerium(IV) sulfate [ceric ammonium sulfate, Ce(NH,)4(S04)4] is reported to produce 6H-benzo[d]naphtho[l,2-/>]pyran-6-one (8% yield) and a quinone (23% yield). The remainder of the product(s) (69%) was unidentified. 

The most widely used method for chemical initiation for graft copolymerization on polysaccharides has been with ceric salts such as CAN or ceric ammonium sulfate. Free radical sites are generated on a polymeric backbone by direct oxidation through ceric metal ions (e.g., Ce "). The ceric ion with low oxidation potential is the proper choice for the reaction. The proposed mechanism for such processes has been depicted by an intermediate formation of metal ion polymer complex (chelate type) [17, 21-24]. Such a complex formation is not restricted to all polymers. The plausible mechanism for ceric ion induced graft copolymerization by direct oxidation method is shown in Scheme 3.1. A series of four grades of Ag-g-PAM copolymers have been synthesized by the conventional method. 

One of the few disadvantages of CAN lies in the quantity of material sometimes required to oxidize alcohols in addition, such processes may not be as systematic or consistent as other methods. However, both ceric ammonium sulfate and CAN have been used as catalysts in the sodium bromate oxidation of secondary alcohols to ketones (Tomioka et al., 1982). 

This may relate to the oxidizing effect of sulfuric acid on the poly-hydric alcohol structure of lignin and its transformation into the quinonoid form. Oxidation of the polyhydric alcohol of lignin into quinone has been achieved on using ceric ammonium sulfate which inhibited graft polymerization reactions on using this initiator. ... 

Pramanick and Sankar [99] investigated the polymerization of methyl methacrylate polymerization initiated by only ceric ions and found that the mechanism of initiation depends strongly on the acidity of the medium and is independent of the nature of anion associated with the ceric ion. In a moderately acidic medium, the primary reaction is the formation of hydroxyl radical by ceric-ion oxidation of water. When ceric sulfate is used, the hydroxyl radicals initiate the polymerization and appear as end groups in the polymer molecule. If, on the other hand, ceric ammonium sulfate or a mixture of ceric sulfate and ammonium sulfate are used, some of the hydroxyl radicals react with the ammonium ion, producing ammonium radicals, and both radicals act as initiators, giving polymers with both hydroxyl and amino end groups. In the polymerization of acrylamide by ceric salt, the infrared (IR) spectra suggests the formation of monomer-ceric salt complexes in aqueous solution [98]. This coordination bond presumably consists of both... 

Although gravimetric methods have been used traditionally for the determination of large amounts of tellurium, more accurate and convenient volumetric methods are favored. The oxidation of teUurium(IV) by ceric sulfate in hot sulfuric acid solution in the presence of chromic ion as catalyst affords a convenient volumetric method for the determination of tellurium (32). Selenium(IV) does not interfere if the sulfuric acid is less than 2 N in concentration. Excess ceric sulfate is added, the excess being titrated with ferrous ammonium sulfate using o-phenanthroline ferrous—sulfate as indicator. The ceric sulfate method is best appHed in tellurium-rich materials such as refined tellurium or tellurium compounds. 

Bromide ndIodide. The spectrophotometric determination of trace bromide concentration is based on the bromide catalysis of iodine oxidation to iodate by permanganate in acidic solution. Iodide can also be measured spectrophotometricaHy by selective oxidation to iodine by potassium peroxymonosulfate (KHSO ). The iodine reacts with colorless leucocrystal violet to produce the highly colored leucocrystal violet dye. Greater than 200 mg/L of chloride interferes with the color development. Trace concentrations of iodide are determined by its abiUty to cataly2e ceric ion reduction by arsenous acid. The reduction reaction is stopped at a specific time by the addition of ferrous ammonium sulfate. The ferrous ion is oxidi2ed to ferric ion, which then reacts with thiocyanate to produce a deep red complex. 

An acidic solution of tellurium (IV) or tellurium (VI) is treated with sulfur dioxide and hydrazine hydrochloride. Tellurium precipitated from solution can be estimated by gravimetry. Selenium interferes with this test. A volumetric test involves converting tellurium to tellurous acid and oxidizing the acid with excess ceric sulfate in hot sulfuric acid in the presence of Cr3+ ion as catalyst. The excess ceric sulfate is measured by titration with a standard solution of ferrous ammonium sulfate. 

Ceric ammonium nitrate or ceric sulfate is used to oxidize saturated and unsaturated secondary alcohols to ketones. The ceric salts are used only in catalytic amounts with sodium bromate as a reoxidant (equation 241) [741]. 

Secondary alcohols are oxidized in preference to primary alcohols also by sodium bromate in the presence of catalytic amounts of ceric ammonium nitrate or ceric sulfate [741]. 

A general rule is that allylic alcohols are more readily oxidized than saturated secondary alcohols [975], and these, in turn, are more readily oxidized than saturated primary alcohols [681, 741, 1041, 1152], Ceric sulfate [741], ceric ammonium nitrate [741], chlorine [681], sodium hypochlorite [1152], and 2,3-dichloro-5,6-dicyano-p-benzoquinone [975] are successfully used for this purpose (equations 287-289). 

In this procedure [3, 12, 13] a known excess of standard ceric ammonium nitrate solution is added to an azide solution or slurry. The excess ceric ammonium nitrate is titrated with standard ferrous ammonium sulfate or sodium oxalate, using ferroin as indicator. The method is extremely simple and flee from hazard once the reagents have been mixed. A serious drawback is that dextrin and polyvinyl alcohol are oxidized by ceric ion. Blay [1] reports gelatin and carboxymethyl cellulose are not oxidized. The method is as follows. 

To eliminate the problem caused by oxidation of the phlegmatizing agents, it is common practice to distill hydrazoic acid from the azide solution or slurry using perchloric acid. The hydrazoic acid (boiling point 35.7°C)is distilled into a known volume of standard ceric ammonium nitrate. The excess ceric ammonium nitrate is titrated with either standard ferrous ammonium sulfate or sodium... 

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