Tert-butyl hydrogen peroxide

In the first of these techniques the lanthanoid complex (33) (5-8 mol%) is used as the organometallic activator in cumene hydroperoxide or tert-butyl hydrogen peroxide-mediated oxidation of chalcone (epoxide yield 99 % 99 % ee) or the ketone (34) (Scheme 20)[1001. 

The acid-catalysed oxidation of a protected S-methyl cysteine, which gives poor diastereoselectivity when oxidized in conventional solvents, shows density-dependent diastereoselectivity as shown in scheme 6.1 [8], Here, tert-butyl hydrogen peroxide (TBHP) is used as the oxidant and the reaction is catalysed by an Amberlyst resin (a solid acid). By tuning the pressure at which this reaction was carried out, almost 100% selectivity to one diastereomer could be achieved (Figure 6.4). 

Dirhodium caprolactamate [Rh2(cap)4] is reported to be an effective catalyst with tert-butyl hydrogen peroxide for benzylic oxidation of chromans, for example, 490, 492, and 495 under mild conditions to give lactones 491, 493, and 496, along with peroxide 494 (Scheme 89). This method has been applied to a synthesis of Palmarumycin CP2 <20050L5167>. 

Fe20(0Ac)2Cl2(bipy)2 successfully hydroxylates C6, C3, and C2 alkanes when tert-butyl hydrogen peroxide (TBHP) is used as the oxygen donor ([5] [TBHP]-.[substrate] = 1 150 1100) the observed reactivity is C6 > C3 > C2 (Table IV). This work represents the first report of the oxidation of a small molecular weight alkane (ethane) by a characterized iron model compound. Reactions of this complex with Zn dust and acetic acid under 1 atm of dioxygen with cyclohexane gave rise to only cyclohexanone (turnover number 2.5). The parent tetrameric compound, 6, was reported to be a more efficient catalyst. 

Prior to the discovery of the aryl-Heck reaction (Chapter 72), the direct Pd-promoted oxidative cyclization of diaryl amines to carbazoles was well known. In 1975 Akennark reported this reaction (Scheme 1, eqnation 1) [1], In addition, A -phenylanthranUic acid gave carbazole-l-carboxylic acid (60%). Miller and Moock used Pd(OAc)j to cyclize 6-anilino-5,8-dimethylisoquinoIine to eUipticine in low yield [2]. The second advance in this chemistry was reported independently by Bittner [3] and Furukawa [4], who described the Pd-mediated (stoichiometric) oxidative conversion of 2-anilino-l,4-benzoquinones and 2-anilino-l,4-naphthoquinones to the corresponding carbazole-l,4-diones and benzo[ ]carbazole-l,6-diones (equations 2, 3). Furukawa s studies included syntheses of several carbazolequinone alkaloids. In 1995 Akermark and colleagues developed catalytic versions (i.e., using tert-butyl hydrogen peroxide [TBHP] or oxygen) of this cyclization (equation 3) [5,6], which elevated the importance of this palladium oxidative cyclization, mainly because of the expense of Pd(OAc)2. Somewhat earlier, Knbiker used cupric acetate as a reoxidant in a synthesis of carbazole-l,4-quinones [7]. 

Sour gasoline (ASTM fuel C + tert. butyl hydrogen peroxide) 60 °C/3 d A... 

The combination of potassium iodide and tert-butyl hydrogen peroxide (TBHP) is an alternative approach to the halogenation of highly activated arenes (Scheme 7.68) [119],... 

Acetyl cyclohexanesulfonyl peroxide, 3033 Bis(3-carboxypropionyl) peroxide, 2990 Bis(2,4-dichlorobenzoyl) peroxide, 3623 Bis(2-hydroperoxy-2-butyl) peroxide, 3078 Bis(l-hydroperoxycyclohexyl) peroxide, 3553 O-O-tert-Butyl hydrogen monoperoxymaleate, 3015... 

Hg [212], is prepared from tert-butyl hydrogen sulfate and 27% hydrogen peroxide [212] and is commercially available as a 70 or 90% solution containing water and tert-butyl alcohol. Anhydrous rert-butyl hydroperoxide is obtained from the 70% aqueous solution by azeotropic distillation with toluene [213]. Anhydrous, as well as highly concentrated, tert-bvXy hydroperoxide must be handled with utmost care, because it may decompose violently in the presence of strong acids and some transition metals, especially manganese, iron, and cobalt [213, 214],... 

The reagent Is expensive and poisonous, consequently the hydroxylation procedure is employed only for the conversion of rare or expensive alkenes (e.g., in the steroid field) into the glycols. Another method for hydroxylation utilises catalytic amounts of osmium tetroxide rather than the stoichiometric quantity the reagent is hydrogen peroxide in tert.-butyl alcohol This reagent converts, for example, cyc/ohexene into cis 1 2- t/ohexanedlol. 

The method is basically an application of the Wacker oxidation except that the catalyst used is palladium acetate ( Pd(AcO)2 or Pd(02CCH3)2). the solvent is acetic acid or tert-butyl alcohol and the oxygen source is the previously suggested hydrogen peroxide (H202)[17]. 

The following commercially available dialkyl peroxides are produced according to equations 24—27 di-Z fZ-butyl peroxide from hydrogen peroxide and sulfated tert-huty alcohol or isobutylene dicumyl peroxide from a-cumyl hydroperoxide and cumyl alcohol, cumyl chloride, and/or a-methylstyrene m- and -di(2-/ f2 -butylperoxyisopropyl)ben2ene [2781-00-2] from tert-huty hydroperoxide [75-91-2] and m- and -di(2-hydroxyisopropyl)ben2ene ... 

Reaction protocol 0.9 M 1-pentene, 0.18 M hydrogen peroxide (30%) and 0.2 M tert.-butyl methyl ether were dissolved in methanol [30], This mixture was passed over the catalyst at a rate of 30-120 pi h . Reaction was carried out at room temperature. The product mixture was collected in an ice bath. 

Preparing tert-butyl peroxide by the effect of 50% hydrogen peroxide in the presence of 78% sulphuric acid has led to numerous accidents. They were due to the high exothermicity of the reaction causing a temperature rise and leading to the explosive decomposition of the peroxide formed, if the temperature rise is badly monitored. 

The trityl radical (gold-coloured) is readily oxidized to peroxide (white) the comparable 2,4,6-tri-(tert-butyl)phenoxy radical (blue) in, e.g., cyclohexane was applied by Paris et al." to so-called free radical titration (either potentiometric or photometric) of oxygen or antioxidant (the latter by hydrogen abstraction). 

Determination of Additive Effects on the Decomposition of tert-Butyl Hydroperoxide and Hydrogen Peroxide. Solutions of tert-butyl hydroperoxide (1.0 mmol) and 30% aqueous hydrogen peroxide (1.32 mmol) in 5 mL of tert-butyl alcohol with the various additives (Tables 9 and 10) were held at 80°C for 24 hr. Peroxide analyses were obtained by sodium iodide/0.05N sodium thiosulfate titration. 

This gives tautomeric mixtures119 when the tert-butyl group is removed. The methyl ether has been used to obtain 3-hydroxy-2-carbonyl derivatives in the selenophene series.120 The unsubstituted 2-hydroxyselenophene system has been prepared by hydrogen peroxide oxidation of 2-selenophene-boronic acid.121 However, in the 5-methyl-substituted system deboronation became such an important side reaction that 5-methyl-2-hydroxyselenophene had to be prepared by acid-catalyzed dealkylation of 5-methyl-2-fert-butoxy-selenophene. Both 2-hydroxy- and 5-methyl-2-hydroxyselenophene exist mainly as 3-selenolene-2-ones (93) and for the 5-methyl derivative it was possible to isolate the / ,y-unsaturated form (92) and follow the tautomeric isomerization. The activation parameters thus obtained were compared with those for the corresponding furan and thiophene systems. 

Two types of addition to pyrimidine bases appear to exist. The first, the formation of pyrimidine photohydrates, has been the subject of a detailed review.251 Results suggest that two reactive species may be involved in the photohydration of 1,3-dimethyluracil.252 A recent example of this type of addition is to be found in 6-azacytosine (308) which forms a photohydration product (309) analogous to that found in cytosine.253 The second type of addition proceeds via radical intermediates and is illustrated by the addition of propan-2-ol to the trimethylcytosine 310 to give the alcohol 311 and the dihydro derivative 312.254 The same adduct is formed by a di-tert-butyl peroxide-initiated free radical reaction. Numerous other photoreactions involving the formation by hydrogen abstraction of hydroxyalkyl radicals and their subsequent addition to heterocycles have been reported. Systems studied include 3-aminopyrido[4,3-c]us-triazine,255 02,2 -anhydrouri-dine,256 and sym-triazolo[4,3-fe]pyridazine.257 The photoaddition of alcohols to purines is also a well-documented transformation. The stereospecific addition of methanol to the purine 313, for example, is an important step in the synthesis of coformycin.258 These reactions are frequently more... 

Diaryl diselenides and benzisoselenazole-3(27/)-ones are used as efficient catalysts in the process of imine oxidation with hydrogen peroxide and tert-butyl-hydroperoxide (25). 

Laser Flash Photolysis at 351 nm of tert-Butyl Peroxide/Benzene Solutions Containing MDI-PUE and Model Compounds. Photolysis of tert-butyl peroxide (TBP) results in a highly efficient production of tert-butoxy radicals. It has recently been shown (15) that tert-butoxy radicals generated by the laser flash photolysis of TBP can rapidly extract hydrogen atoms from appropriate substrates such as aniline and diphenylamine (Scheme III). 

For MDI based polyurethanes we have provided evidence for formation of a diphenylmethyl radical by direct excitation (248 nm) of the carbamate moiety as well as hydrogen abstraction by a tert-butoxy radical which is produced by excitation (351 nm) of tert-butyl peroxide. The diphenylmethyl radical readily reacts with oxygen. A proposed mechanism which accounts for the production (direct or indirect) and subsequent reaction with oxygen of the diphenylmethyl radical is shown in Scheme IV. The hydrogen peroxide product depicted in Scheme IV has been previously identified by FT-IR (7) we have simply provided a plausible mechanism for its formation. 

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