In alkaline hydrogen peroxide

1 Bleaching of wool in alkaline hydrogen peroxide solution 

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Sakamoto [243] determined picomolar levels of cobalt in seawater by flow injection analysis with chemiluminescence detection. In this method flow injection analysis was used to automate the determination of cobalt in seawater by the cobalt-enhanced chemiluminescence oxidation of gallic acid in alkaline hydrogen peroxide. A preconcentration/separation step in the flow injection analysis manifold with an in-line column of immobilised 8-hydroxyquinoline was included to separate the cobalt from alkaline-earth ions. One sample analysis takes 8 min, including the 4-min sample load period. The detection limit is approximately 8 pM. The average standard deviation of replicate analyses at sea of 80 samples was 5%. The method was tested and inter calibrated on samples collected off the California coast. 

J. W. Weaver, L. R. Schroeder, and N. S. Thompson, Formation of organic peroxides from methyl / -1 )-gl ucopyranosidc in alkaline hydrogen peroxide solutions, Carbohydr. Res., 48 (1976) C5-C7. 

Some hydrolyses will first be described, then the preparatively important reductions, and finally some addition reactions. 5-Cyano-4-formamido-2-methyltriazole, refluxed with trifluoroacetic acid, gave 4-formamido-2-methyltriazole-5-carboxamide (1 hr, 85%). The same nitrile, set aside in 2 Af sodium hydroxide was hydrolyzed to 4-amino-2-methyltriazole-5-carbo-xamide (25°C, 15 hr, 95%) [73JCS(P1)2659], 5-Cyano-4-dimethylaminomethylenamino-1 -methyltriazole, in alkaline hydrogen peroxide solution, yielded the amide (25°C, 12 hr, 87%)... 

Some ring-expanding reactions leading to annelated pyrimidines will now be considered. The transformation of isatin-3-oxime (120) to 4-amino-quinazoline was described in Section VI,A,4. Isatin-2-oxime, when heated in dilute sodium hydroxide, rearranged to quinazoline-2,4-dione.383 Isatin-3-imine in alkaline hydrogen peroxide was converted to the same substance in excellent yield.384... 

Mesyloxy)epoxychalcones, obtained after epoxidation in alkaline hydrogen peroxide of the corresponding chalcones, led to a series of flavonols when irradiated with microwaves in the presence of montmorillonite KSF... 

Hydroboration of a terminal allalkaline hydrogen peroxide also gives an enol that, in this case, is in equilibrium with the more stable aldehyde. Thus, hydroboration-oxidation of a terminal allgme gives an aldehyde. 

The light-brown oil with molecular formula of C22H32O0 and a specific optical rotation of -172 at the Nap-line in iso-octane, displays nearly identical spectrometric and chemical properties as humulone. In the H NMR spectrum the methine proton of the acyl side chain is shifted between 5 1 and 5 2, while an additional methylene function absorbs in this region also. Since the spectrometric changes did not allow unequivocal identification, chemical proofs have been worked out. In addition to the synthesis (see 2.4) prehumulone has been degraded in alkaline hydrogen peroxide (48). In the reaction mixture 4-methylpentanoic acid has been isolated corresponding to oxidative fission of the acyl side chain (49). It follows that prehumulone is (-)(6R)-4,6-bis(3-methylbut-2-enyl)-3,5,6-trihydroxy-2-(4-methylpentanoyl)cyclohexa-2,4-dienone (10, Fig. 12). 

Weak to moderate chemiluminescence has been reported from a large number of other Hquid-phase oxidation reactions (1,128,136). The Hst includes reactions of carbenes with oxygen (137), phenanthrene quinone with oxygen in alkaline ethanol (138), coumarin derivatives with hydrogen peroxide in acetic acid (139), nitriles with alkaline hydrogen peroxide (140), and reactions that produce electron-accepting radicals such as HO in the presence of carbonate ions (141). In the latter, exemplified by the reaction of h on(II) with H2O2 and KHCO, the carbonate radical anion is probably a key intermediate and may account for many observations of weak chemiluminescence in oxidation reactions. 

The hydroboration step, being very sensitive to steric effects, yields only secondary alkylboranes from trisubstituted double bonds, whereas the less hindered alkylborane is formed predominantly from disubstituted steroidal double bonds. The diborane attack occurs usually towards the a-side and hence results in overall a-hydration of double bonds after alkaline hydrogen peroxide oxidation. ... 

The high degree of stereoselectivity associated with most syntheses and reactions of oxiranes accounts for the enormous utility of these systems in steroid syntheses. Individual selectivity at various positions in the steroid nucleus necessitates the discussion of a collection of uniquely specific reactions used in the synthesis of steroidal epoxides. The most convenient and generally applicable methods involve the peracid, the alkaline hydrogen peroxide and the halohydrin reactions. Several additional but more limited techniques are also available. 

Double bonds in a,/3-unsaturated keto steroids can be selectively oxidized with alkaline hydrogen peroxide to yield epoxy ketones. In contrast to the electrophilic addition mechanism of peracids, the mechanism of alkaline epoxidation involves nucleophilic attack of hydroperoxide ion on the con-... 

Thus, reaction of 3 -acetoxypregna-5,16-dien-20-one (48) with alkaline hydrogen peroxide produces the 16a,17a-epoxide in 95 % yield, and only a 2% yield of the 16, 17 -epoxide. ... 

Nonconjugated double bonds fail to react with alkaline hydrogen peroxide, e.g., see ref. 53, 54 and 56a. The 1,2-double bond of A " -3-ketones e.g., 61, reacts with alkaline peroxide to give the la,2a-epoxide in over 70% yield.""... 

Many functional groups are stable to alkaline hydrogen peroxide. Acetate esters are usually hydrolyzed under the reaction conditions although methods have been developed to prevent hydrolysis.For the preparation of the 4,5-oxiranes of desoxycorticosterone, hydrocortisone, and cortisone, the alkali-sensitive ketol side chains must be protected with a base-resistant group, e.g., the tetrahydropyranyl ether or the ethylene ketal derivative. Sodium carbonate has been used successfully as a base with unprotected ketol side chains, but it should be noted that some ketols are sensitive to sodium carbonate in the absence of hydrogen peroxide. The spiroketal side chain of the sapogenins is stable to the basic reaction conditions. 

The Dakin reaction proceeds by a mechanism analogous to that of the Baeyer-Villiger reaction. An aromatic aldehyde or ketone that is activated by a hydroxy group in the ortho or para position, e.g. salicylic aldehyde 12 (2-hydroxybenzaldehyde), reacts with hydroperoxides or alkaline hydrogen peroxide. Upon hydrolysis of the rearrangement product 13 a dihydroxybenzene, e.g. catechol 14, is obtained ... 

An important stage in the synthesis has been reached. The reaction processes described thus far have proceeded uneventfully and have culminated in the synthesis of compound 9. The stage is now set for an evaluation of the first of two hydroboration reactions. Treatment of 9 with diborane in THF, followed by standard alkaline hydrogen peroxide workup, furnishes an 8 1 stereoisomeric mixture of alcohols in favor of 28 (85 % total yield). On the basis of some important precedent,32 it is presumed that compound 9 preferen-... 

Epoxyeyclohexanone has been prepared in 30% yield4 by epoxi-dation of 2-cyclohexen-l-one with alkaline hydrogen peroxide, using a procedure described for isophorone oxide (4,4,6-trimethyl-7-oxabicyclo[4.1.0]heptan-2-one).5 A better yield (66%) was obtained using f r/-butyl hydroperoxide (1,1-dimethylethylhydroperoxide) and Triton B in benzene solution.6 The procedure described here is simple and rapid. 

The most widely used reaction of organoboranes is the oxidation to alcohols, and alkaline hydrogen peroxide is the reagent usually employed to effect the oxidation. The mechanism, which is outlined below, involves a series of B to O migrations of the alkyl groups. The R—O—B bonds are hydrolyzed in the alkaline aqueous solution, generating the alcohol. 

The reaction is usually performed at low temperatures, and sometimes water has been used as solvent. For example, cyclooctene is ozonized in the presence of an emulsifier (polyoxyethylated lauryl alcohol) with aqueous alkaline hydrogen peroxide to give a,co-alkanedi-carboxylic acid in one pot (Eq. 3.21).91... 

All gaseous sulfur products obtained as a result of incubation of sulfur-treated fruit were oxidized with alkaline hydrogen peroxide, precipitated as barium sulfate, and counted with a thin window Geiger counter. The peel and peel proteins were oxidized with magnesium nitrate, the sulfur was precipitated as barium sulfate according to standard methods, and counted as in the case of the gaseous products. Counting data, as reported, are fully corrected. 

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