Chemicals benzoyl peroxide

Randazzo et al. [1047] electropolymerized 2-vinylthiophene in a nonaqueous electroyte solution at a platinum electrode. Ttvo oxidation products were found a semiconducting dark coating of the electrode and a nonconducting dark precipitate in the anode compartment. The latter product could also be obtained by chemical, benzoyl peroxide-inititated free radical polymerization in a spectroscopically very similar form with a higher molecular... 

The aqueous phase into which the monomer mix is dispersed is also prepared in a separate tank before transferring to the copolymerization ketde. It contains a catalyst, such as benzoyl peroxide [94-36-0], to initiate and sustain the polymerization reaction, and chemicals that aid in stabilizing the emulsion after the desired degree of dispersion is achieved. Careful adherence to predeterrnined reaction time and temperature profiles for each copolymer formulation is necessary to assure good physical durabiHty of the final ion-exchange product. 

Chemical Designations - Synonym Benzoyl Peroxide Benzoyl Superoxide BP BPO Lucidol-70, Oxylite Chemical Formula C HjCO-O-O COC Hj. 

Few CIDNP studies on free radical reactions with olefins and related unsaturated molecules have been reported, and relatively little chemically useful information seems to have been derived, despite the potential relevance in polymerizing systems. Thus CIDNP has been reported in the decomposition of benzoyl peroxide in the presence of styrene and... 

Figure 22.2 Chemical structure of monomer soluble initiators for polyvinyl chloride a) dilauryl peroxide, b) benzoyl peroxide and c) azobisisobutyronitrile...

Reactivity. Chemicals that react violently with air or water are considered hazardous examples are sodium metal, potassium metal, and phosphorus. Reactive materials also include strong oxidizers such as perchloric acid, and chemicals capable of detonation when subjected to an initiating source, such as solid, dry < 10% H2O picric acid, benzoyl peroxide, or sodium borohydride. Solutions of certain cyanide or sulfides that could generate toxic gases are also classified as reactive. The potential for finding such chemicals in a refinery is... 

Fig. 3-10 Inhibition of the benzoyl peroxide-initiated polymerization of vinyl acetate by duroquinone at 45°C. The three lines are for different concentrations of duroquinone. After Bartlett and Kwart [1950] (by permission of American Chemical Society, Washington, DC).

AIBN or benzoyl peroxide and the nitroxide radical. Nitroxide radicals are sufficiently stable (due to steric hindrance) that they can be stored at ambient temperatures without change and some are available for purchase from chemical vendors. 

Fig. 6 CIDNP spectrum from benzoyl peroxide (reproduced from reference 237 with the permission of the American Chemical Society).

Because of its chemical inertness, no direct way of curing poly(thiocarbonyl fluoride) has been found. However, creep has been reduced and strength at elevated temperatures improved by milling into the polymer a free-radical generator, such as dicumyl peroxide or azobisisobutyronitrile, and a free-radical acceptor, such as N,N -m-phenylenebismaleimide or triacryloylhexahydro-s-triazine, and curing with heat and pressure (65). A better method is to mill in divinylbenzene and a small amount of benzoyl peroxide and cure with heat and pressure (66). The divinylbenzene forms a crosslinked matrix that mechanically traps poly(thio-carbonyl fluoride) molecules. Since the elastomer is in effect filled with poly(di-vinyl benzene), the final composition is less resilient than untreated poly(thio-carbonyl fluoride). 

Materials. GMC and PCLS were synthesized by free radical solution polymerization initiated by benzoyl peroxide as described previously (5,6). Nearly mono and polydisperse polystyrenes were obtained from Pressure Chemical Co. and the National Bureau of Standards respectively. Molecular weight and polydispersity were determined by gel permeation chromatography (GPC) using a Water Model 244 GPC, equipped with a set (102-106 A) of —Styragel columns using THF as the elution solvent. The molecular parameters of the above three polymers are listed in Table I. The copolymer, poly(GMA-co-3-CLS), contained 53.5 mole % 3-CLS and 46.5 mole % GMA, as determined by chlorine elemental analysis. The structure of the copolymer is shown in Figure 1. 

Production of benzoyl peroxide in the United States in 1982 was 2300 tonnes. Information available in 1995 indicated that it was produced in 16 countries (Chemical Information Services, 1995). 

In a study based on the Los Angeles County, United States, Cancer Surveillance Program, white male chemists with malignant melanoma and with other cancers (used as controls) were interviewed (Wright et al., 1983). Four of the seven chemists with malignant melanoma gave a history of exposure to benzoyl peroxide (among many other chemicals) and none of the nine controls. 

Epstein, S.S., Arnold, E., Andrea, J., Bass, W. Bishop, Y. (1972) Detection of chemical mutagens by the dominant lethal assay in the mouse. Toxicol, appl. Pharmacol., 23, 288-325 Hazlewood, C. Davies, M.J. (1996) Benzoyl peroxide-induced damage to DNA and its compo-... 

The last of the direct methods for graft initiation in liquid phase presented in this review involves chemical additives. Either free radical or ionic initiators can be chosen. Benzoyl peroxide is reported for grafting styrene on Nylon fibers in methanol media (71,105-107), as well as vinyl acetate (106). Azoisobutyro-nitrile has been employed in systems where the graft monomer is styrene (71,106) or vinyl acetate (106). Redox systems involving hydrogen peroxide and monomers like styrene (106,108,109). vinyl acetate (106), acrylic acid (108,109), methyl... 

On the other hand, chemicals might be chosen as agents for generation of active centers in the polymeric backbone and grafting of monomer in the vapor phase. Ammonium persulfate and styrene (189), acrylic acid (190), butyl acrylate (191), potassium persulfate and n-butyl maleate or 2-ethyl hexyl acrylate (55,134) and ammonium ceric nitrate and methacrylic add (192) are examples of this method. Benzoyl peroxide deposited on polycaprolactam fibers initiates the grafting of styrene in vapor phase (193). 

Figure 9.1 Spectrum recorded during the decomposition of a solution of propionyl benzoyl peroxide and iodine in o-dichlorobenzene at 100°C. The numbers in parentheses below the formulas indicate the relative spectrum amplitudes for the underlined protons. Spectrum groups referred to in the text are indicated at the top of the figure. Reprinted with permission from H. R. Ward, Accts. Chem. Res., 5, 18 (1972). Copyright by the American Chemical Society.

The 2-heptene was the pure grade material purchased from Phillips Petroleum Company, Bartlesville, Oklahoma. This olefin is comparable to material prepared by a Boord synthesis. The N-bromosuccinimide was obtained from Arapahoe Chemicals, Inc., Boulder, Colorado. The benzoyl peroxide was used as received from Distillation Products, Rochester, New York. The carbon tetrachloride was reagent grade, from J. T. Baker Chemical Company, Phillipsburg, New Jersey. 

Vinyl monomers, such as styrene, methyl methacrylate, vinyl acetate, vinyl chloride or acrylonitrile are preferably polymerized by chain polymerization techniques initiated by free radicals. Suitable free radicals can be handily achieved from unstable chemicals like peroxides (benzoyl peroxide, dicumil peroxide) or di-azo reagents (e.g. 2,2 -azo-bis-isobutyronitrile, AIBN) which are dissolved in monomer and usually thermally decompose at temperature range of 40-120 °C. Alternatively, suitable radicals for polymerization can also be activated without addition of external initiators, by just applying ultraviolet light (wave length 200-350 nm) or ultrasound (15,33,34) onto monomer. 

A further extension of the principle of polymerization through ethylenic unsaturation allows copolymers to be made with the chemically similar organic substances. For example, methylallyldichloro-silane may be hydrolyzed to the corresponding diol and mixed with monomeric methyl methacrylate, and the mixture polymerized to a homogeneous solid by heating with benzoyl peroxide as a catalyst. 

The use of chemical sensitizers such as benzoyl peroxide, cumene hydroperoxide, or azo-bis-isobutyronitrile, which decompose thermally to give free radicals in a convenient temperature range (i.e., 60 C to 150 C), makes it possible to study polymerizations over an extended temperature range. The form of the rate law with chemical initiations would be given by setting III = 2k (ln)< >i in Eq. (XVI.10.4). Here (In) is the initiator concentration, k I its specific rate constant of decomposition which can usually be measured independently, and is the efficiency with which its radicals initiate chains. The measure of t is subject to the difficulties already indicated in connection with the photolysis systems. ... 

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