With Dibenzoyl Peroxide

Alkoxycarbonylmethyl alkyl tellurium react with dibenzoyl peroxide in chloroform to produce alkoxycarbonylmethyl alkyl tellurium dibenzoates ° . 

Irgolic Organo Tellurium Compounds with 2 Te —C Bonds or 1 Te = C Bond 

Butyl /-Menthoxycarbonylmethyl Tellurium Dibenzoate 3,8 g (10 mmol) of butyl menthoxycarbonylmethyl tellurium are dissolved in 25 ml of chloroform and a solution of 2.4 g (10 mmol) of benzoyl peroxide in 25 m/ of chloroform is added. The mixture is heated under reflux for 1 h, the chloroform is allowed to evaporate at 20°, and the residue is stored for 4 days to allow the product to crystallize. The product is filtered off, washed with water, and dried in vacuum yield 5.4 g (86%) m.p. 133°. 

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The oxidation of norhomadiene by i-butyl perbenzoate and Cu(I) leads to 1-t-butoxynorbomadiene. Similarly, oxidation with dibenzoyl peroxide and CuBr leads to 7-benzyloxynorbomadiene. In both cases, when a 2-monodeuterated sample of norbomadiene is used, the deuterium is found distributed at all seven carbons in the product. Provide a mechanism which could account for this result. In what w s does this mechanism differ from the general mechanism discussed on pp. 724-725 ... 

A distinction between these four possibilities can be made on the basis of the kinetic isotope effect. There is no isotope effect in the arylation of deuterated or tritiated benzenoid compounds with dibenzoyl peroxide, thereby ruling out mechanisms in which a C5— bond is broken in the rate-determining step of the substitution. Paths (ii) and (iii,b) are therefore eliminated. In path (i) the first reaction, Eq. (6), is almost certain to be rate-determining, for the union of tw o radicals, Eq. (7), is a process of very low activation energy, while the abstraction in which a C—H bond is broken would require activation. More significant evidence against this path is that dimers, Arz, should result from it, yet they are never isolated. For instance, no 4,4 -dinitrobiphenyl is formed during the phenylation of... 

The quantitative phenylation of pyridine has been studied by two groups of workers. Dannley and Gregg showed that 2-, 3-, and 4-phenylpyridine are formed in relative amounts 58 28 14 in the phenylation of pyridine with dibenzoyl peroxide, as estimated by infrared spectrophotometry. Hey and his co-workers obtained the ratios shown in Table I for the phenylation of pyridine using four different sources of phenyl radicals. ... 

The phenylation of quinoline with dibenzoyl peroxide was studied by Pausacker, who obtained all seven monophenylated quinolines in relative amounts shown in (4).- He also examined the phenylation of pyridine-iV-oxide with diazoaminobenzene and obtained the results shown in (5). ... 

The phenylation of quinoline with dibenzoyl peroxide has been reported to give a mixture of 4- and 5-phenylquinoline which can be separated by the fractional recrystallization of their picrates, In a later investigation, the other five phenylquinolines have also been identified among the products, the relative reactivities of the nuclear positions being 8- > 4- > 3-, 5- > 2-, 6-, 7-... 

Cross-linking with peroxides has been known since 1915 when Ostromyslenski [46] disclosed that NR could be transformed into a cross-linked state with dibenzoyl peroxide. However, little interest in peroxide cross-linking evolved until the development of fully saturated ethylene-propylene copolymers in the early 1970s. 

FIGURE 6.6 Hypothetical radical mechanism for the formation of 5a-a-tocopheryl henzoate (11) hy reaction of a-tocopherol (1) with dibenzoyl peroxide. 

Basically, three reactions were evoked to support the occurrence of 5a-C-centered radicals 10 in tocopherol chemistry. The first one is the formation of 5a-substituted derivatives (8) in the reaction of a-tocopherol (1) with radicals and radical initiators. The most prominent example here is the reaction of 1 with dibenzoyl peroxide leading to 5a-a-tocopheryl benzoate (11) in fair yields,12 so that a typical radical recombination mechanism was postulated (Fig. 6.6). Similarly, low yields of 5a-alkoxy-a-tocopherols were obtained by oxidation of a-tocopherol with tert-butyl hydroperoxide or other peroxides in inert solvents containing various alcohols,23 24 although the involvement of 5 a-C-centered radicals in the formation mechanism was not evoked for explanation in these cases. 

The formation of 5a-a-tocopheryl benzoate (11) upon reaction of a-tocopherol (1) with dibenzoyl peroxide, which has usually been taken as solid proof of the involvement of 5a-C-centered radicals in tocopherol chemistry (see Fig. 6.6), was shown to proceed according to a nonradical, heterolytic mechanism involving o-QM 3 (Fig. 6.9). 

To conclusively disprove the involvement of the chromanol methide radical, the reaction of a-tocopherol with dibenzoyl peroxide was conducted in the presence of a large excess of ethyl vinyl ether used as a solvent component. If 5a-a-tocopheryl benzoate (11) was formed homolytically according to Fig. 6.6, the presence of ethyl vinyl ether should have no large influence on the product distribution. However, if (11) was formed heterolytically according to Fig. 6.9, the intermediate o-QM 3 would be readily trapped by ethyl vinyl ether in a hetero-Diels-Alder process with inverse electron demand,27 thus drastically reducing the amount of 11 formed. Exactly the latter outcome was observed experimentally. In fact, using a 10-fold excess of ethyl vinyl ether relative to a-tocopherol and azobis(isobutyronitrile) (AIBN) as radical... 

Polymerisation of the ester with dibenzoyl peroxide in ethyl acetate accelerated out of control and led to discharge of a large volume of vapour which ignited and exploded. 

From this perspective one realizes that most previous literature data were greatly impacted by the Knackmuss reinvestigation, the results of which are summarized in a review [73AG(E) 139]. The only correct structure of an azaquinone previously reported appears to be that of compound 4c, which could not undergo dimerization due to its substitution pattern. A more recent report claims that oxidation of 2-pyridone with dibenzoyl peroxide in chloroform gave 50% of 3-benzyloxy-2-pyridone 13 and 40% of azaquinone 1 (Scheme 3) [85IJC(B)972]. 

Unsymmetrical secondary aliphatic amines have been prepared by reaction of alkyl halides with benzylidene amines and subsequent hydrolysis 814 by reaction of alkyl halides with alkyl amines 5 by reduction of amine-aldehyde adducts 8-8 and by dealkylation of tertiary amines with dibenzoyl peroxide. ... 

It must be emphasized that, in contrast to the initiation of polymerization with peroxo compounds or azo compounds, not every redox system is suitable for initiating polymerization of every unsaturated monomer. Before attempting to polymerize a new compound with a redox system it is, therefore, advisable first to test its radical polymerizability with dibenzoyl peroxide. 

Pyrroles, furans and thiophenes react preferentially with free radicals at the 2-position. Thus, reaction of pyrrole with benzyl radicals gives 2-benzylpyrrole. With triphenylmethyl radicals, pyrrole behaves like butadiene giving the adduct (163). /V-Methylpyrrole undergoes free radical benzoyloxyla-tion with dibenzoyl peroxide to give the 2-benzoyloxypyrrole (164) and 2,5-dibenzoyloxypyrrole (165). Furan, however, is converted in good yield to a mixture of cis and trans addition products analogous in structure to (163). 

Compound 2 was then transformed into the conjugated enone 161. Lithium dimethylcopper 1,4-addition on enone 161 and reaction of the resulting enolate with dibenzoyl peroxide gave compound 162 in good yield. Reaction of 162 with methylmagnesium iodide at low temperatures furnished compound 163 again in good yield. Thus by this sequence, an excellent control of... 

Dealkylation of tertiary amines with dibenzoyl peroxide, 44, 74 Decarboxylation, intermolecular, of isocyanates to carbodiimides, 43,32 Decker synthesis of amines, 44, 7t, 75 Dehalogenation of l,l,2-trichloro-2,3,3-trifluorocydobutane, 42,45 Dehydration, of formamides with phosphorus oxychloride to isocy-anides, 41, 13, 101 of 4- 2-hydroxyethyl)piperidine to quinuclidine, 44, 90 Dehydrohalogenation of 2-chloroallyl-amines to propargylamines, 44,55 Delepine reaction, to prepare 2-bromo-allylamine, 43, 6 Deoxyanisoin, 40,16 Deoxybenzoin, 40, IT Deoxypiperoin, 40, IT Deaylamine, 41, 8T... 

Enolate hydroxy lotion. a-Hydroxylation of the ketone 1 is best effected by reaction of the enolate with dibenzoyl peroxide. In this case Vedejs oxidation fails, and m-chlo-... 

RJVH RjNOH,1 This reaction has generally been conducted by reaction of the amine with dibenzoyl peroxide followed by saponification of the intermediate O-benzoyl-hydroxy lamine. Yields can be markedly improved by addition of Na2HP04 to trap the benzoic acid formed and by debenzoylation with KOCH3/CH3OH (equation I). 

Secondary phosphines, R2PH, can be chlorinated under controlled conditions to give the corresponding chlorophosphines. These compounds can be further oxidized in a number of ways (Scheme 30). The reaction of chlorodiphenylphosphine with dibenzoyl peroxide gives diphenylphosphinic acid... 

Cyclic peroxides may serve as a source of singlet oxygen. Wasserman et reacted 9,10-diphenylanthracene peroxide (238, conveniently prepared as in Nilsson and Kearns ) with 138 to give 140 rubrene peroxide proved to be considerably less efficient. Decomposition of anthracene peroxide alone takes another course. When 13 is treated with phthaloyl peroxide (239), 140 is isolated in 59% yield the reaction is accompanied by a weak chemiluminescence. A bright yellow chemiluminescence has been observed when a solution of 240 in 1,2,4-trichlorobenzene is treated with dibenzoyl peroxide at about 210°C. The generation of visible light from 138 under conditions where peroxides may present has been described. 

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