Tert-Butyl hydroperoxide , olefin

The Sharpless-Katsuki asymmetric epoxidation reaction (most commonly referred by the discovering scientists as the AE reaction) is an efficient and highly selective method for the preparation of a wide variety of chiral epoxy alcohols. The AE reaction is comprised of four key components the substrate allylic alcohol, the titanium isopropoxide precatalyst, the chiral ligand diethyl tartrate, and the terminal oxidant tert-butyl hydroperoxide. The reaction protocol is straightforward and does not require any special handling techniques. The only requirement is that the reacting olefin contains an allylic alcohol. 

Olefin epoxidation is an important industrial domain. The general approach of SOMC in this large area was to understand better the elementary steps of this reaction catalyzed by silica-supported titanium complexes, to identify precisely reaction intermediates and to explain catalyst deachvahon and titanium lixiviation that take place in the industrial Shell SMPO (styrene monomer propylene oxide) process [73]. (=SiO) Ti(OCap)4 (OCap=OR, OSiRs, OR R = hydrocarbyl) supported on MCM-41 have been evaluated as catalysts for 1-octene epoxidation by tert-butyl hydroperoxide (TBHP). Initial activity, selechvity and chemical evolution have been followed. In all cases the major product is 1,2-epoxyoctane, the diol corresponding to hydrolysis never being detected. 

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. 

Kinetics. The kinetics of the epoxidation of olefins with tert-butyl hydroperoxide in the presence of molybdenum hexacarbonyl have been studied. The reaction rate is first order in tert-butyl hydroperoxide, in olefin, and in molybdenum hexacarbonyl. Olefins substituted near the double bond by electron-releasing alkyl groups react more rapidly than the corresponding unsubstituted olefins. The kinetic data indicate that the epoxidation reaction proceeds according to the rate law,... 

The decomposition rate of tert-butyl hydroperoxide is much slower than the epoxidation rate. When tert-butyl hydroperoxide and molybdenum hexacarbonyl are refluxed in a mixture of toluene and benzene at 87°C. for 1 hr., only 6.2% of the hydroperoxide decomposes. Under the same conditions with 2-octene present in large excess, 80% of the hydroperoxide is converted, and a quantitative yield of the epoxide results. Thus, the decomposition of tert-butyl hydroperoxide is insignificant when the olefin is present. 

The order with respect to olefin was determined by experiments with 2-octene and tert-butyl hydroperoxide in benzene. The mole ratio of reactants was 1.5 to 1 and 2 to 1. The first-order plot of log Ctert-buooh... 

The fact that the epoxide yield decreases at higher temperatures, longer reaction time, higher catalyst concentration, and lower olefin concentration may be caused by two possible side reactions—decomposition of the hydroperoxide and addition of the alcohol to the epoxide. Initial kinetic studies of the decomposition of tert-butyl hydroperoxide in the presence of molybdenum hexacarbonyl showed second-order dependence on hydroperoxide and first-order dependence on catalyst concentration. These results indicate that the decomposition of hydroperoxide is caused by the reaction between the hydroperoxide-metal complex and another molecule of hydroperoxide. With higher temperature, higher... 

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... 

After generating the active catalytic species, 0.1 mole tert-butyl alcohol was added to 0.1 mole of the olefin containing 4 X 10"4 mole of catalyst, and the mixture was stirred under nitrogen. Thus, TME, II, and a 90/10 mixture (vol %) of TME and II were each allowed to react with tert-butyl hydroperoxide at 50°C. Similarly, cyclohexene, VIII, and a 90/10 mixture of cyclohexene and VII were each allowed to react with tert-butyl hydroperoxide at 70°C. Product work-up and analysis are identical to previous runs (GLPC and iodometric titration). Results are listed in Table VIII. 

Alkyl hydroperoxides, including ethyl hydroperoxide, cuminyl hydroperoxide, and tert-butyl hydroperoxide, are not used by V-BrPO to catalyze bromination reactions [29], These alkyl hydroperoxides have the thermodynamic driving force to oxidize bromide however, they are kinetically slow. Several examples of vanadium(V) alkyl peroxide complexes have been well characterized [63], including [V(v)0(OOR)(oxo-2-oxidophenyl) salicylidenaminato] (R = i-Bu, CMe2Ph), which has been used in the selective oxidation of olefins to epoxides. The synthesis of these compounds seems to require elevated temperatures, and their oxidation under catalytic conditions has not been reported. We have found that alkyl hydroperoxides do not coordinate to vanadate in aqueous solution at neutral pH, conditions under which dihydrogen peroxide readily coordinates to vanadate and vanadium( V) complexes (de la Rosa and Butler, unpublished observations). Thus, the lack of bromoperoxidase reactivity with the alkyl hydroperoxides may arise from slow binding of the alkyl hydroperoxides to V-BrPO. 

Jia, C. Lu, W. Kitamura, T. Fujiwara, Y. Highly efficient Pd-catalyzed coupling of are-nes with olefins in the presence of tert-butyl hydroperoxide as oxidant. Org. Lett. 1999, 1, 2097-2100. 

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,... 

Elimination reactions leading to olefins are usually performed on the corresponding selenoxides 3 9,1 12) (Scheme 2 a). These are often unstable and decompose at room temperature to olefins and selenenic acid (further oxidized to the more stable seleninic acid by excess of oxidant). Hydrogen peroxide in water-THF, ozone and further treatment with an amine or tert-butyl hydroperoxide without or with alumina proved to be the method of choice for such a synthesis of olefins. The reaction is reminiscent of the one already described with aminoxides or sulfoxides 22) and occurs via a syn elimination of the seleninyl moiety and the hydrogen attached to the P-carbon atom. However it takes place under smoother conditions. 

A. Corma, P. Esteve, A. Martinez, S. Valencia, Oxidation of olefins with hydrogen peroxide and tert-butyl hydroperoxide on Ti-Beta catalyst, /. Catal. 152 (1995) 18. 

M. Fujiwara, H. Wessel, H. Park, H. W. Roesky, Formation of titanium tert-butylperoxo intermediate from cubic silicon-titanium complex with tert-butyl hydroperoxide and its reactivity for olefin epoxidation. Tetrahedron 58 (2002) 239. 

K. B. Sharpless, R. C. Michaelson, High stereo- and regioselectivities in the transition metal catalyzed epoxidations of olefinic alcohols by tert-butyl hydroperoxide, J. Am. Chem. Soc. 95 (1973) 6136. 

Di-tcrt-butyl peroxide (terf-butyl peroxide) [110-05-4] M 146.2, d 0.794, 0 1.389. Wash the peroxide with aqueous AgN03 to remove olefinic impurities, water and dry (MgS04). Free it from tert-butyl hydroperoxide by passage through an alumina column [Jackson et al. J Am Chem Soc 107 208 79S5], and if necessary two high vacuum distillations from room temperature to a liquid-air trap [Offenbach Tobolsky J Am Chem Soc 79 278 1957]. [Beilstein 1 IV 1619.] The necessary protection from EXPLOSION should be used. 

TS-1 catalyzes the smooth epoxidation of relatively unreactive olefins, e. g. propylene and even allyl chloride, with 60 % aqueous H2O2 at 40-50 °C in methanol [20]. A serious shortcoming of TS-1 is, however, its restriction to substrates with kinetic diameters < 5.5 A. For example, 1-hexene is readily epoxidized at 50 °C whereas cyclohexene is essentially unreactive. By the same token TS-1 does not catalyze epoxidations with the more bulky tert-butyl hydroperoxide (TBHP),... 

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. 

In fact, the small pore opening of the MFI and MEL structures (= 5.5 A) makes that hydrogen peroxide is the single stable peroxide capable of entering the zeolite channels and, therefore, permitting the reaction. Yet, tert-butyl hydroperoxide (TBHP) has proved to be an efficient oxidant in the homogeneous epoxidation of olefins catalyzed by titanium alkoxides [4]. 

To a cooled, glass pressure vessel are added 40 gm (0.62 mole) of liquid sulfur dioxide, 30 gm (0.27 mole) of octene, and 0.3 gm tert-butyl hydroperoxide. The vessel is sealed and the contents agitated and warmed to room temperature. After 50 hr, the container is vented and the polymer placed in a vacuum oven to strip off excess sulfur dioxide and unreacted olefin. The polymer yield is 45.6 gm (95%). 

---