Tert-Butylperoxide

The polymerization of vinyl monomers on the surface of silica can be induced also by free radical initiators such as azo-bis-isobutyronitrile (AIBN), di-tert-butylperoxide, benzoyl peroxide etc. The selection of initiator type and method of its introduction in polymerizable systems are determined by the nature of monomers and tasks of investigations. Usually, the following procedures are used ... 

In a typical experiment, the sample is a solution (e.g., in benzene) of both the ferf-butoxyl radical precursor (di-tert-butylperoxide) and the substrate (phenol). The phenol concentration is defined by the time constraint referred to before. The net reaction must be complete much faster than the intrinsic response of the microphone. Because reaction 13.23 is, in practical terms, instantaneous, that requirement will fall only on reaction 13.24. The time scale of this reaction can be quantified by its lifetime rr, which is related to its pseudo-first-order rate constant k [PhOH] and can be set by choosing an adequate concentration of phenol, according to equation 13.25 ... 

One of the methods used in PV to produce the free radicals is similar to the one illustrated in chapter 13, that is, when a substance like di-tert-butylperoxide is irradiated with energy of a suitable wavelength, the 0-0 bond is cleaved and two tert-butoxyl radicals are generated. These radicals can then abstract a hydrogen atom from another molecule RH, yielding the radical R. 

In the phosphoryl fullerenyl radical the unpaired electron is - similar to the alkylfullerenyl radical - delocalized over two six-membered rings adjacent to the C-P bond [10]. The rotation barrier for the radical C5oP(0)(0 Pr)2 was determined to be 4.8 kcal mol Another phosphorus-containing radical fullerenyl adduct, determined via ESR spectroscopy, is PFjjO BujCgQ. It can be obtained by photolytic reaction of Cgo with HPF4 and tert-butylperoxide in tert-butylbenzene [43]. 

Table 6 Non-adiabaticity calculations for the homogeneous electron transfer to di-tert-butylperoxide, di-cumylperoxide and f-butyl bromide (t-BuBr).

Data on such densely sterically hindered compounds that would hinder the attack by the electron have not been reported. There are two cases in which such an effect can be expected to operate. Whereas dial-kylperoxides are generally reducible at positive potentials, di-tert-butylperoxide has been reported as irreducible (139). Similarly for cyclic diketones (140), the unreducibility of 3,3,8,8-tetramethyl-l,2-cyclo-octanedione can arise from a similar effect, but the steric hindrance of coplanarity of the diketo grouping cannot be excluded in this case. A more detailed examination of these and similar systems would be necessary to reach a decision as to whether this type of steric effect can change the polarographic behaviour or not. 

Lithium ferf-butylperoxide has been used effectively as an epoxidising agent with electron deficient alkenes (Scheme 40) [91, 92]. However, application of this methodology to systems containing fluorine has only recently been explored, and it is now established that this can be a very successful procedure with fluoroalkenes. Indeed, the Lithium tert-butylperoxide system worked in some cases where the calcium hypochlorite reaction was ineffective [93,94]. 

Dialkylperoxides are used as high temperature catalysts for suspension and bulk polymerization as well as hardeners for unsaturated polyester resins and for cross-linking polymers because of their good thermal stability. While the liquid di-tert-butylperoxide is relatively volatile at application temperatures, dicumylperoxide is much less volatile and has the disadvantage of forming decomposition products with intense odors (acetophenone)(Chapter 13). 

Als Radikalstarter sind auch Dibenzoyl- odcr Di-tert.-butylperoxid gebrauchlich. Bei der Reaktion von 0,5 Mol Phosphorigsaure-diethylester bei 140° mit je 0,1 Mol... 

Analog erhalt man mit Natrium-tert.-butylperoxid die Diperphosphonsaure-di-tert.-butylester-imide988,989. 

Serum and bile thiocyanates are raised. See also HYDROCYANIC ACID. Unstable and easily oxidized. Explosive polymerization may occur on storage with silver nitrate. Potentially explosive reactions with benzyltrimethylammonium hydroxide + pyrrole, tetrahydrocarbazole + benzyltrimethylammonium hydroxide. Violent reactions with strong acids (e.g., nitric or sulfuric), strong bases, azoisobutyronitrile, dibenzoyl peroxide, di-tert-butylperoxide, or bromine. 

SYNS PEROXIDE, (PHENYLENEBIS(1-METHYL-ETHYUDENE))BIS(1,1-DIMETHYLETHYL)- PEROXIDE, (PHENYLENEDIISOPROPYUDENE)BIS(tert-BTJTYL)- D (PHENYLENEDnSOPROPYLIDENE)BIS(tert-BUTYLPEROXIDE) VUL-CUP VUL-CUP 40KE VUL-CUP R... 

C7H602 salicyl aldehyde 90-02-8 in benzene 3.088 1 11927,1 C7H1402 allyl-tert-butylperoxide 39972-78-6 gas 0.510 2... 

Three deuterated analogues of 5-diethoxyphosphonyl-5-methyl-l-pyrrolidine N-oxide (DEPMPO) (494), (495) and (496) were synthesised and used to trap tert-butylperoxide radical (Figure 94b). ... 

Liepins et al. reported the formation of black polymer from maleonitrile and fumaronitrile at 160 °C, in the presence of high temperature free radical initiators such as di-tert-butylperoxide. Based on IR and NMR, the following structure was suggested for the polymer ... 

The well-known Sharpless system for the enantioselective epoxidation of allyl alcohols has been investigated [23]. This system employs a tetra-alkoxy titanium precursor, a dialkyltartrate as an auxiliary, and an alkyl hydroperoxide as oxidant, to effect the enantioselective epoxidation. The key intermediate is thought to be a dimeric complex in which titanium is simultaneously coordinated to the chelating tartarate ligand, the substrate in the form of an oxygen bound / -allyl-oxide and an -tert-butylperoxide. 

Although the formation of 2-(trimethylsilyl)ethylphosphonates by addition of dialkyl phosphites to vinylsilanes in the presence of di-tert-butylperoxide or 2,2 -azobisisobutyronitrile (AIBN) generally needs severe conditions, milder methods have been reported that employ the 1,2-addition... 

Heating diethyl 2-propenylphosphonate with Et.SiH in the presence of di-tert-butylperoxide at 140°C affords diethyl 3-(triethylsilyl)propylphosphonate in low yield (21%). Under the same conditions, diethyl 4-(triethylsilyl)butylphosphonate is prepared in 63% yield from diethyl phosphite and 4-(triethylsilyl)-l-butene. Addition of (trimethylsilyl)methylmagnesium chloride to diethyl l,l-difluoro-2-oxo-2-(tert-butoxycarbonyl)etliylphosphonate in THF at low temperature results in the formation of y-silylated P-hydroxyphosphonate in 65% yield. ... 

Quantitative cuialyses were carried out by GC with a semi-capillary column, CP-Sil-5 CB (50 m X 0.53 mm) for cyclooctene or on a CB wax 52 CB (50 m x 0.53 mm) for cyclohexene and carveol. Qualitative identification of peaks was made by reference samples and GC/MS analyses. Also cyclohexenyl-tert-butylperoxide could be analyzed in this way. Quantitative cmalysis was performed by using molar responses with respect to the internal standcird. 

Copolymerization of Ethylene with 2-Methylene-l,3-dioxepane (I)— Typical copolymerizations were carried out as follows To a 10.125 X 1.5-inch steel pressure vessel (300-ml capacity) was added 50 ml of a solution of 1.1 g (1.0 mol- ) of di-tert-butylperoxide and 5.0 g (0.043 mol) of 2-methylene-l,3-dioxepane, bp 49-50 C (20 mm), in purified cyclohexane to give 50 ml of the reaction mixture. The sealed vessel was flushed twice with ethylene gas (99.9 pure) and finally filled with ethylene to an equilibrium pressure of 1000 psi. If one neglects the amount of ethylene that dissolves in the organic layer, the amount of ethylene gas with a volume of 250 ml at 1000 psi was calculated to be 21 g (0.75 mole). The copolymerization was allowed to proceed to low conversions (less than 2%) at 120 C for 30 minutes. After the reaction vessel was quickly cooled in Dry Ice, it was opened and methanol was added to it to facilitate the removal of the product as a white precipitate. After the solid was collected by filtration with suction and washed with methanol, the polymer was purified further by dissolution in hot chloroform and addition of the resulting solution into the nonsolvent methanol. The polymer was collected by filtration and dried in vacuo at 40 C for 24 hours to give a white powder. 

Auch radikal induzierte Substitutionen der a—H-Atome mit 1-Alkinen sind unter drasti-schen Bedingungen moglich. So reagiert z.B. 2-Methyl-propanal mit 1-Hexin in Gegen-wart von Di-tert.-butylperoxid unter Druck zum Gemisch der cis-trans-2,2-Dimethyl-3-alkenale30 ... 

Eine oxidative Dimerisierung von 3(5)-Amino-5(3)-anilino-4-ethoxycarbonyl-lH-pyrazol unter Knupfung einer N,N-Bindung ist mit Hilfe von Radikalen (Di-tert-butylperoxid/UV, Diben-zoylperoxid)561 oder durch anodische Oxidation moglich1613 ... 

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