Related Butyl Hydroperoxide

In a related reaction, primary aromatic amines have been oxidized to azo compounds by a variety of oxidizing agents, among them Mn02, lead tetraacetate, O2 and a base, barium permanganate, and sodium perborate in acetic acid, tert Butyl hydroperoxide has been used to oxidize certain primary amines to azoxy compounds. 

Various transition metals have been used in redox processes. For example, tandem sequences of cyclization have been initiated from malonate enolates by electron-transfer-induced oxidation with ferricenium ion Cp2pe+ (51) followed by cyclization and either radical or cationic termination (Scheme 41). ° Titanium, in the form of Cp2TiPh, has been used to initiate reductive radical cyclizations to give y- and 5-cyano esters in a 5- or 6-exo manner, respectively (Scheme 42). The Ti(III) reagent coordinates both to the C=0 and CN groups and cyclization proceeds irreversibly without formation of iminyl radical intermediates.The oxidation of benzylic and allylic alcohols in a two-phase system in the presence of r-butyl hydroperoxide, a copper catalyst, and a phase-transfer catalyst has been examined. The reactions were shown to proceed via a heterolytic mechanism however, the oxidations of related active methylene compounds (without the alcohol functionality) were determined to be free-radical processes. 

The measured rate constants show some inconsistencies in relation to other work. The most noticeable is the low ratio of kceric/kphotoiysis at 30°C. for f erf-butyl hydroperoxide and cumene hydroperoxide compared with estimates, —5 to 10 for k /k2, obtained from studies of the induced decomposition of these hydroperoxides (22, 46, 48). The photolytic rate constant for cumene hydroperoxide is considerably larger than the termination constant for the oxidation of cumene containing cumene hydroperoxide as determined by the rotating sector (25, 26, 27, 28). It is not clear whether these differences represent some unappreciated features... 

The existence of a facile epoxidation of II at a more rapid rate than that of TME is of interest in relation to a possible intermolecular pathway for formation of an epoxy alcohol from an allylic hydroperoxide during olefin oxidation. When a solution of II (0.01 mole) in TME (0.09 mole) was treated with tert-butyl hydroperoxide (0.01 mole) in the presence of... 

Finally, a,[3-unsaturated carbonyl compounds are converted to [3-keto systems when treated with 20% Na2PdCl4 catalyst in 50% acetic acid as solvent and r-butyl hydroperoxide or hydrogen peroxide as reoxidant (equation 3).9 It is not clear if the mechanism of this process is related to the other palladium(II)-catalyzed addition of oxygen nucleophiles to alkenes. 

The synthesis of mixed peroxides formed from /-butyl hydroperoxide and carbon-centred radicals has been studied. The reactions were strongly effected by solvents as well as catalytic amounts of Cun/Fem. The kinetic data suggest that the conditions for the Ingold-Fischer persistent radical effect are fulfilled in these cases.191 The use of Cu /Cu" redox couples in mediating living radical polymerization continues to be of interest. The kinetics of atom-transfer radical polymerization (ATRP) of styrene with CuBr and bipyridine have been investigated. The polymer reactions were found to be first order with respect to monomer, initiator and CuBr concentration, with the optimum CuBr Bipy ratio found to be 2 1.192 In related work using CuBr-A-pentyl-2-... 

The retarding effect of alcohols on the rate of epoxidation manifests itself in the observed autoretardation by the alcohol coproduct.428,434 446,447 The extent of autoretardation is related to the ratio of the equilibrium constants for the formation of catalyst-hydroperoxide and catalyst-alcohol complexes. This ratio will vary with the metal. In metal-catalyzed epoxidations with fe/T-butyl hydroperoxide, autoretardation by tert-butyl alcohol increased in the order W < Mo < Ti < V the rates of Mo- and W-catalyzed epoxidations were only slightly affected. Severe autoretardation by the alcohol coproduct was also observed in vanadium-catalyzed epoxidations.428 434 446 447 The formation of strong catalyst-alcohol complexes explains the better catalytic properties of vanadium compared to molybdenum for the epoxidation of allylic alcohols.429 430 452 On the other hand, molybdenum-catalyzed epoxidations of simple olefins proceed approximately 102 times faster than those catalyzed by vanadium.434 447 Thus, the facile vanadium-catalyzed epoxidation of allyl alcohol with tert-butyl hydroperoxide may involve transfer of an oxygen from coordinated hydroperoxide to the double bond of allyl alcohol which is coordinated to the same metal atom,430 namely,... 

The related sulfone (73) is formed in an analogous reaction (74JHC1085). In contrast to 72, this compound shows the expected higher reactivity at phosphorus than nitrogen. It is alkylated on phosphorus by methyl iodide and converted into the P-oxide by t-butyl hydroperoxide. This compound was also prepared as a potential flame retardant. The crystal has C—P—C angles of 95.8, 96.4, and 98.0°, very little changed from phosphatriazaadamantane (76JHC757). 

It is possible to oxidize an alcohol in the presence of sulfur- or selenium-containing groups (equation 16) using r-butyl hydroperoxide and a diselenide as the oxidizing system (this also oxidizes secondary alcohols, see later).Selenium chemistry can also be used to oxidize benzylic and related primary alcohols to the aldehydes without oxidizing pyridyl (18 equation 17) or thiophenyl (19 equation 18) groups. ... 

For the oxidation of alkenes, osmium tetroxide is used either stoichiometrically, when the alkene is precious or only small scale operation is required, or catalytically with a range of secondary oxidants which include metal chlorates, hydrogen peroxide, f-butyl hydroperoxide and N-methylmorpholine A -oxide. The osmium tetroxide//V-methylmorpholine A -oxide combination is probably the most general and effective procedure which is currently available for the syn hydroxylation of alkenes, although tetrasubstituted alkenes may be resistant to oxidation. For hindered alkenes, use of the related oxidant trimethylamine A -oxide in the presence of pyridine appears advantageous. When r-butyl hydroperoxide is used as a cooxidant, problems of overoxidation are avoided which occasionally occur with the catalytic procedures using metal chlorates or hydrogen peroxide. Further, in the presence of tetraethylam-monium hydroxide hydroxylation of tetrasubstituted alkenes is possible, but the alkaline conditions clearly limit the application. 

Further support for the attainment of a critical concentration of hydroperoxide prior to the passage of a cool flame at temperatures corresponding to the Lq and L, lobes has been obtained by Taylor [131], and more recently by Pollard and co-workers [68,132], who determined the maximum concentrations of tert-butyl hydroperoxide found during the cool-flame oxidation of isobutane. Again, the concentration of hydroperoxide increased prior to the cool flame and it was almost entirely consumed during its passage (Fig. 12). Also, in common with other hydrocarbon + oxygen systems, (e.g. refs. 55, 65, 78,133) the induction period to the first cool flame (r,) was related to the initial reactant pressure (po) by the expression... 

If ferf-butyl hydroperoxide is the major branching agent below 320 °C, [TBH]max should be related to the critical concentration required for cool-flame propagation even though it may not be an exact measure of [TBHlcrit.. This indeed appears to be so, since values of [TBH]max observed at temperatures too low for cool-flame propagation are always lower than that predicted by eqn. (3.5) whilst they are in excellent... 

Relatedly, despite the synthesis and structural characterization of numerous arsine and stibine oxides, bomb calorimetry measurements have only been reported on triphenylarsine oxide . While corresponding measurements have been made on triphenylarsine, it is clearly premature to make general observations as to E—O bond enthalpies in the absence of additional data. In principle, reaction calorimetry should prove useful. Indeed, we note a solution phase (benzene) enthalpy of reaction study of triphenylarsine and -butyl hydroperoxide according to the reaction... 

The formation of 3-methyl-2-buten-l-ol, 4, and of 3-methyl-2-butenal, 5, in some experiments can be related to the isomerization of la and subsequent oxidation of product 4, thus formed, to 5. We observed that the vanadium oxo-alkoxide, [OV(OC3H7)3], is a good precursor for the catalytic epoxidation of substrates la, lb and Ic with systems involving tert-butyl hydroperoxide and tertiary allylic alcohols. These systems proved to be more active than those involving [VO(acac)2] usually associated with anhydrous r-BuOOH in benzene or toluene (Figure 1 and Table 2). 

Several solvents have been tested in the epoxidation of a- isophorone with t-butyl hydroperoxide (TBHP). The best performance of the aerogel was observed in low polarity solvents such as ethylbenzene or cumene (Table 1). In these solvents 99 % selectivity related to the olefin converted was obtained at 50 % peroxide conversion, independent of the temperature. Rasing temperature resulted in increasing initial rate and decreasing selectivity related to the peroxide. The low peroxide efficiency is explained by the homol5d ic peroxide decomposition. Protic polar solvents were detrimental to the reaction due to their strong coordination to the active sites. There was no epoxide formation in water. 

Many peroxides affect pol mierization, but those used are available in quantity and the choice is based both on economics and performance. It has been shown that the activity of the organic peroxides in any polymerization is related to their decomposition rates at various temperatures. If elevated cure temperatures, 200- 250°F (93-121°C), are used, benzoyl peroxide is preferred. The amount required is about 1.0 per cent. It is preferred because a long catalyzed tank life results at room temperature. If lower temperatures in the 120 180 F (49-82°C) range are employed, hydroperoxides are more effective. Methyl ethyl ketone peroxide and cumene and ter- tiary butyl hydroperoxide all find application. Lauroyl peroxide, cyclohexanone peroxide, and <-butyl perbenzoate are used in limited amounts. Mixtures of two peroxides are often used, one to initiate the reaction and a second to promote the polymerization once it is started. 

While Proeedure 8-1 purports to illustrate the use of a high-temperature initiator to bring about polymerization at the relatively modest temperature of 65°C, a more reeent patent details the use of a high-temperature initiator at a high temperature (200°C). At that temperature the half life of the initiator tert-butyl hydroperoxide is approximately 60 min in an aromatic solvent. The polymerization is carried out for 780 min (13 hr). It is noted that the process is quite rapid during the first 20 min. Thereafter the process is said to be quite slow. Since the initial initiator concentration is deliberately kept quite low, it is possible that the reduction of the polymerization rate is related to the destruction of a substantial portion of the hydroperoxide relatively early in the process [101]. Procedure 8-3 is given here only for purposes of illustration since the procedure is patented. 

N-Oxidation takes place readily with compounds containing the per-oxy link (-0-0-). Hydrogen peroxide, alkyl peroxides (especially t-butyl hydroperoxide), and peroxy acids (notably m-chloroperbenzoic acid, ArC(O)OOH) are used most frequently. The common oxidizing agents of organic chemistry, such as dichromates and permanganates, have no effect on pyridine. In fact, a pyridine-chromic oxide mixture is used for the oxidation of alcohols to carbonyl compounds. Pyridine N-oxide and related compounds retain aromatic character but have some valuable properties, which will be discussed in section 6.3.1.12. 

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