Di-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. 

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. 

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... 

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. 

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 ... 

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. ... 

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 ... 

MILLER S FUMIGRAIN (107-13-1) Forms explosive mixture with air (flash point 32°F/0°C oc). May polmerize spontaneously unless inhibited (usually with methylhydro-quinone). It may also polymerize on contact with oxygen, heat, strong light, peroxides, or concentrated or heated alkalis. Elevated temperatures, light, alkalis, silver nitrate, and peroxides (e.g., dibenzoyl peroxide, di-tert-butylperoxide) can cause explosive polymerization. 

Polymerization of substituted acetylenes has been carried out by a wide range of catalysts and condi-tions. Polymerization conditions include a homogeneous and heterogeneous Ziegler—Natta catalyst, transition metal complexes (Pd. Pt. Ru. W. Mo. Ni. etc.), free radical initiators such as 2.2 -azobis(isobu-tyronitrile) (AIBN). benzoyl peroxide (BPO). and di-tert-butylperoxide (DTBP). thermal polymerization, y-irradiation. cationic initiation with BF3. and anionic initiation by butyllithium. triethylamine. and sodium amide. 

With suitable safety precautions, purified vinyl fluoride is frozen in an ampoule by immersion in liquid air. The monomer is degassed several times to remove dissolved air. In the meantime, in a thick-walled glass ampoule (wall thickness, 4 mm, i.d. 12 mm, capacity approximately 12 ml) containing di-tert-butylperoxide (concentration 0.6 X 10 moles per liter of liquid monomer) and dimethyl sulfoxide (50% by volume of the total liquid monomer composition) is attached to a high-vacuum system so that a measured quantity of vinyl fluoride can be transferred to the ampoule bearing the solvent and photoinitiator. The solvent is thoroughly degassed and the monomer is transferred to the... 

Benzonitril polymerisiert nach einem anderen Mechanismus (78, 79) (Schema XIII). Aus dem Di-tert.-butylperoxid Widen sich bei den hohen Reaktionstemperaturen von 200° C CHj-Radikale (CH3)3CO —... 

Radikalische Polymerisation. Malonsauredinitril, Maleinsauiedinitril, Fumarsauredinitril, substituiertes und unsubstituiertes Bemsteinsaure-dinitril warden mit wganischen Peroxiden wie Di-tert.-butylperoxid, Cumolhydroperoxid und lerL-Butylhydroperoxid umgesetzt (77,78,103 bis 105). 

The spectrum near 600 cm of the V2 band of the CH3 radical generated by a glow discharge in di-tert-butylperoxide (Yamada et. al. 1981) provides a second example of this selectivity. With Zeeman modulation all the observed lines arise from CH3, but with source frequency modulation many additional lines from diamagnetic species are detected in the same spectral region. 

The propagating radical of dialkyl itaconate in the homogeneous polymerization was foimd by Sato et al. to be stable enough to be observed by ESR even above 60 °C. Fig. 62 a displays the 5-line spectra obtained when dimethyl 2,2 -azobis-isobutyrate, benzoylperoxide, and di-tert-butylperoxide were used as initiators. On the other hand, the polymerization of DBI initiated with azonitriles such as 2,2 -azobisisobutyronitrile, 2,2 -azobis(2,4-dimethylvaleronitrile), and cyclohexanecarbo-... 

Determine the reaction order and the rate constant for the catalytic decomposition of di-tert-butylperoxide ... 

Kagan and coworkers have shown [62] that iodides of samarium(II) and ytterbium(II) react with di-tert-butylperoxide at room temperature in THF to form the complexes of Ln(OBu-t)l2 composition ... 

The materials under study were an ISPLEN polypropylene homopolymer, PPO, and two ethylene-propylene block copwlymers, EPBCO and EPBCO-2, with an ethylene content of -8 wt%, supplied by REPSOL Quimica They were manufactured using a Spheripol process with a fourth generation Ziegjer-Natta catalyst. The peroxide used was di-tert-butylperoxide (DTBP). 

FIG. 11 Dependence of melt flow index (MFf) and of PP degradation on peroxide amount. Degradation at 190°C, 5 min, 2,5-dimethylhexane-2,5-di-tert-butylperoxide as initiator. (Adapted from Ref. 191.)... 

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