Benzoyl peroxide esters

Esters of unsaturated acids are of experimental interest because of their ability to be converted into insoluble products. Cellulose crotonate, upon heating in the presence of air, or upon exposure to ultraviolet light, becomes completely insoluble. This action may be accelerated by the addition of small quantities of benzoyl peroxide. Esters of more active unsaturated acids, such as cellulose acetate linoleate, become insoluble upon exposure to air at ordinary temperatures. ... 

Derivative Formation. Hydrogen peroxide is an important reagent in the manufacture of organic peroxides, including tert-huty hydroperoxide, benzoyl peroxide, peroxyacetic acid, esters such as tert-huty peroxyacetate, and ketone derivatives such as methyl ethyl ketone peroxide. These are used as polymerization catalysts, cross-linking agents, and oxidants (see Peroxides and peroxide compounds). 

Tables 7 and 8 give properties of some diaHyl esters. DimethaHyl phthalate [5085-00-7] has been copolymerized with vinyl acetate and benzoyl peroxide, and reactivity ratios have been reported (75).

In studies of the polymerization kinetics of triaUyl citrate [6299-73-6] the cyclization constant was found to be intermediate between that of diaUyl succinate and DAP (86). Copolymerization reactivity ratios with vinyl monomers have been reported (87). At 60°C with benzoyl peroxide as initiator, triaUyl citrate retards polymerization of styrene, acrylonitrile, vinyl choloride, and vinyl acetate. Properties of polyfunctional aUyl esters are given in Table 7 some of these esters have sharp odors and cause skin irritation. 

The only other study of the polymerization of a furanic vinyl ester concerns allyl 2-furylacrylate120, but the conditions used were so violent (bulk at 200 °C with benzoyl peroxide) that no conclusions meaningful in the present context can be drawn. 

Prepn is by dropwise addn of a cold aq sodium peroxide (1.0 molar) so In to 1.0 mole of vigorously stirred ethyl chloroformate while maintain, ing the temp at 6— 10°. The mixt is stirred for an addnl half hr after all the sodium peroxide has been added. The oily prod is then sepd, washed with distd w and dried using anhyd Naj S04. An 81 % yield is obtd. The frozen ester is sens to the shock from a No 6 elect detong cap, producing a more brisant deton than an equal amt (0.25 lb) of benzoyl peroxide Ref F. Strain et al, JACS 72,1254-63 (1950) CA 46,1984(1950)... 

Oleic acid, linolic acid, ricinolic acid, and 2-bromostearic acid methyl ester as well are reacting with diethyl phosphite in the presence of benzoyl peroxide to the corresponding phosphono fatty acid esters [156-158]. 

Since the benzene emission in the thermal decomposition of benzoyl peroxide results from radical transfer by the phenyl component of a benzoyloxy-phenyl radical pair, phenyl benzoate produced by radical combination within the same pair should appear in absorption. A weak transient absorption has been tentatively ascribed to the ester (Lehnig and Fischer, 1970) but the complexity of the spectrum and short relaxation time (Fischer, personal communication) makes unambiguous assignment difficult. Using 4-chlorobenzoyl peroxide in hexachloro-acetone as solvent, however, the simpler spectrum of 4-chlorophenyl 4-chlorobenzoate is clearly seen as enhanced absorption, together with... 

N -Fmoc serine benzyl ester 2, which could be prepared as shown or purchased commercially, was smoothly converted to the crystalHne O-methylthiomethyl (MTM) ether 3 in high yield via a Pummerer-Hke reaction using benzoyl peroxide and dimethyl sulfide in acetonitrile [39]. This common intermediate was used to synthesize both 5 and 8 [40]. Both Ogilvie [41] and Tsantrizos [42] had reported that I2 was an effective activator with similar MTM ether substrates. The H promoted nucleosidation reaction between O-MTM ether 3 and bis-silylated thymine 4 produced the nucleoamino acid 5 in 60% isolated yield (100% based on recovered 3). Hydrogenolytic deprotection of the benzyl ester with H2, Pd/C in MeOH gave the thymine-containing nucleoamino acid 6 in quantitative yield. 

Dilution or simple mixing with a stable compound is sufficient to stabilise an unstable substance. In the case of a simple mixture with a neutral substance, this stabilisation process is called desensitisation . Thus hardeners such as benzoyl peroxide are nomially in the form of suspensions in heavy esters or oils. This peroxide is mixed with 30% of water by weight. Dynamite is nitroglycerine stabilised with the help of a neutral material. In all these cases, heat that is produced by the potential beginning of decomposition is absorbed by the inert substance. 

Benzoyl peroxide had been introduced into vinyl acetate with the idea of polymerising it ethyl acetate was used as a solvent. The polymerisation went out of control and vapourised the ester. Ester formed a vapour cloud , which detonated. 

Halogens are frequently used as oxidation agents and, under two-phase conditions, they can either be employed as ammonium complex halide salts [3], or in the molecular state with or without an added quaternary ammonium catalyst [4]. Stoichiometric amounts of tetra-n-butylammonium tribromide under pH controlled conditions oxidize primary alcohols and low-molecular-weight alkyl ethers to esters, a,cyclic ethers produce lactones [3], and secondary alcohols yield ketones. Benzoins are oxidized to the corresponding benzils (80-90%) by the tribromide salts in acetonitrile in the presence of benzoyl peroxide [5]. 

Benzoyl peroxide (8) Peroxide, dibenzoyl- (9), (94-36-0) Hexanoic Acid, 4-oxo-, ethyl ester (8,9) (3249-33-0)... 

Faraone, Parasacco, and Cogrossi (87) have introduced maleic and crotonic ester groups and methacryloyl ethylamine ether groups into partially acetylated celluloses. These cellulose derivatives containing substituents with polymerizable double bonds grafted with styrene when brought in contact in presence of benzoyl peroxide. 

The most widely investigated optically active poly-acrylic-esters are the polymers of bomyl and menthyl acrylate and methacrylate in this case the monomers have been polymerized by radical polymerization using benzoyl-peroxide (135), A. I. B. N. (134, 135), y-rays (131, 135), U. V. rays (4) in the presence of benzoin (134), and by anionic polymerization using LiC4H9 (4, 135) or C6H5MgBr (134, 135) as catalyst. 

Deoxygenation of esters. Esters can be reduced to hydrocarbons by (QH5)3SiH in the presence of a radical generator, di-f-butyl peroxide, at 140°. Highest yields are obtained with acetates yields based on the alcohol decrease in the order secondary > primary > tertiary. Other silanes are much less effective than triphenylsilane, which is required in excess for high yields. Radical initiators such as AIBN or benzoyl peroxide are not useful.1... 

The stability of org peroxides (such as acetyl benzoyl peroxide) is greatly increased by prepg a soln of the peroxide in at least 25% by wt of the esters of phthalic acid (such as di-Me or de-Et phthalate)] 14)H-A. Aaronson, "Desensitization of High Explosives by Waxes, Semi-Plastic RDX Compositions , PATR 1761 (1950) (A number of commercially... 

Cold curing unsaturated resin was obtained in the following way. A mixture of BPA, BPA monocyanate and BPA dicyanate was cyclotrimerized and reacted with BMI. The obtained prepolymer with phenolic hydroxyls (cf. Scheme 9) was then treated with epichlorohydrin and alkali. The phenolic hydroxyls were thus transformed into glycidyl ether groups. Then the addition of methacrylic acid to the epoxy groups was carried out. The obtained vinyl ester (epoxyacrylate) type resin was dissolved in styrene and cured with the usual benzoyl peroxide/dimethylaniline system [131],... 

In Fig. 13 are shown typical spectra for 15% solutions of two methyl methacrylate polymers in chloroform. The polymers were prepared with (a) benzoyl peroxide in toluene at 100° and (b) n-butyllithium at — 62°. The large peak at the left is that of the chloroform solvent. The ester methyl group appears at 6.40r in both spectra, and is not affected by the chain conformation. There are three cc-methyl peaks, at 8.78t, 8.95 t, and 9.09r, whose relative heights vary greatly with the method of polymer preparation. Polymers prepared with n-butyllithium show a very prominent peak at 8.78r, the others being much smaller. Polymers prepared with benzoyl peroxide initiator show the same three peaks, but now the peak at 9.09r is the most prominent. 

To check whether vinyl esters of strongly branched acids behave differently, mixtures of vinyl acetate and VV 911 in molar ratios of 1/3, 1/1, and 3/1 were polymerized in bulk to a conversion of about 10%, using benzoyl peroxide as initiator at 50°C. The reaction mixtures were then diluted with benzene, and the polymers were precipitated with methanol. After five further dissolutions in benzene and precipitation with methanol the polymers were freeze dried from their solutions in benzene and analyzed for carbon content. The results given in Figure 1 show that, at least for practical purposes, the assumption that r1 = r2 = 1 is valid, and at any time during the polymerization random copolymers are formed at any vinyl acetate-VV 911 ratio. 

In the absence of benzoyl peroxide, no discernible conversion of acrylic esters has been observed under the conditions used for AFR polymerization. At levels of 0.1-0.3 gram of peroxide and 0.5-5.0 ml. of dimethylaminoethyl methacrylate, conversion to graft polymers was observed at 70 °C. for 16 hours with an active polypropylene slurry, as shown in Table VIII. 

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