Tert-Butyl hydroperoxide aromatics

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. 

Materials. Poly (olefin sulfone)s were prepared by copolymerization of liquid mixtures of sulfur dioxide and the appropriate olefin using tert.-butyl hydroperoxide as initiator in the temperature range from —80 to 0°C. The poly (amino acid)s were obtained from Sigma Chemical Co. and used without further purification. The poly (olefin) s were provided by Mr. O. Delatycki and Dr. T. N. Bowmer and were prepared under controlled conditions. The aromatic polysulfones were prepared and purified by Mr. J. Hedrick. The purity of all polymers was checked by H and 13C NMR. 

The use of amides as source of carbamoyl and a-aminoalkyl radicals has also been widely employed since the 1970s [11]. Fenton-type systems utilizing tert-butyl hydroperoxide or hydrogen peroxide in the presence of Fe(II) salts and the S2Os2 / Ag+ system have been applied in the functionalization of aromatic bases with amides (Equation 14.7). 

Another approach to designing shape-selective heterogeneous oxidation catalysts was to use redox metal oxides as the pillaring agents in the preparation of pillared clays. These redox pillared clays have been used for a number of selective oxidations. Chromium pillared montmorillonite (Cr-PILC) is an effective catalyst for the selective oxidation of alcohols with tert-butyl hydroperoxide. 7 Primary aliphatic and aromatic alcohols are oxidized to the aldehydes in very good yields. Secondary alcohols are selectively oxidized in the presence of a primary hydroxy group of a diol to give keto alcohols in excellent yields (Eqn. 21.12). 2... 

Soluble chromium compounds are known to catalyze the allylic oxidation of olefins [22,23] and benzylic oxidations of alkyl aromatics [22,24] using tert-butyl-hydroperoxide as the primary oxidant. Chromium-substituted aluminophosphates, e. g. CrAPO-5, were shown to catalyze the allylic oxidation of a variety of terpene substrates with TBHP to give the corresponding enones [25,26]. For example, a-pinene afforded verbenone with 77% selectivity (Eq. 6) and 13% of the corresponding alcohol. 

Substituted aromatic molecules can be oxidized under mild conditions using Ti or V substituted molecular sieves. The nature and the selectivities of the products formed strongly depend on the oxidant used in the catalytic reaction. H2O2 favours the hydroxylation of the aromatic ring whereas tert-butyl hydroperoxide is very selective in the side-chain oxidation. For V-substituted ole ar sieves, we have proposed a mechanism which involves the redox system... 

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. 

Robert D.A., Geoffroy G.L. Compounds with heteronuclear bonds between transition metals. In Comprehensive Organometallic Chemistry, Wilkinson G., Stone F.G.A., Abel E.W. Eds., Perga-mon, Oxford, UK, 1982 Vol. 6, pp. 821-877 and references therein Rogovin, M., Neumann, R. Silicate xerogels containing cobalt as heterogeneous catalysts for the side-chain oxidation of alkyl aromatic compounds with tert-butyl hydroperoxide. J. Mol. Catal. A Chem. 1999 138 315-318... 

More recent reports in 2012 and 2013 focus on the use of more sustainable metals such as iron in these cases an oxidant is required. Two equivalents of tert-butyl hydroperoxide (TBHP) for example were used with 2.5 mol% FeCla. In times as short as 1 h, in acetonitrile at 85 °C, various aliphatic and aromatic aldehydes were able to be oxidatively amidated to the corresponding amides with a range of secondary and tertiary amines. Similar work has been done by De Luca and co-workers using TBHP as an oxidant in combination with either an FeCls or Cu(OAc)2 catalyst. However, in both cases, iV-chloroamines had to be formed in situ in order to generate the required amino radical coupling partner. 

Three peroxides with aromatic substituents have reported enthalpy of vaporization data, all from the same source". The enthalpies of vaporization of cumyl hydroperoxide and ferf-butyl cumyl peroxide are the same, which makes us skeptical of at least one of these values. The calculated b value for cumyl hydroperoxide is 31.5, consistent with the alkyl hydroperoxides. The calculated b value for tert-butyl cumyl peroxide is 15.4 and more than twice that for the mean of the dialkyl peroxides. The structurally related tert-butyl p-isopropylcumyl peroxide has a b value of 8.8 and so is consistent with the other disubstituted peroxides. 

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