Peroxides lauroyl peroxide

Emulsions may be polymerized by use of a water-soluble catalyst (initiator), such as potassium persulfate, or a monomer-soluble catalyst, such as benzoyl peroxide, lauroyl peroxide or azobisisobutyronitrilc. Suspension and solution polymerizations employ the monomer soluble catalysts only. In addition to the above-mentioned initiators, diisopropyl pcroxydi-carbonatc may also be employed, where lower-temperature polymerization may be desired, e.g., to reduce branching and minimize degradation. 

Other peroxides—2,6-dichlorobenzoyl peroxide lauroyl peroxide, tert-butyl hydroperoxide, and methyl ethyl ketone peroxide—are also highly effective for the free radical reaction at low temperatures. On the other hand, azobisisobutyronitrile (AIBN) is ineffective. Hence, the mechanism cannot be simple, free radical formation which then initiates polymerization. 

The usual initiators are monomer-soluble ones sueh as dibenzoyl peroxide, lauroyl peroxide, and di-o-toluyl peroxide. Hydrogen peroxide and a few other water-soluble initiators usually associated with emulsion polymerizations have also been used. The molecular weight of the polymer may be controlled by variations in the concentration of the initiator. This effect is illustrated in Procedure 4-1. It is interesting to note that this procedure which goes back to FIAT Final Report 1102, i.e., a report compiled toward the end of World War II [4], was still used in 1974 according to Bravar et al. [117]. We have adapted these procedures to a laboratory scale. 

The most commonly used initiators in this system are AIBN, benzoyl peroxide, lauroyl peroxide (LPO), and diisopropyl peroxydicarbonate (IPP). The last two are probably of most interest industrially. In aromatic solvents, LPO has a half-life of 10 hr at 62°C while that of IPP is 10 hr at only 35[92]. Therefore one may expect that at the same temperature, polymerizations initiated with IPP proceed significantly more rapidly than LPO-initiated ones this, indeed, has been found. 

Some fabrication processes, such as continuous panel processes, are mn at elevated temperatures to improve productivity. Dual-catalyst systems are commonly used to initiate a controlled rapid gel and then a fast cure to complete the cross-linking reaction. Cumene hydroperoxide initiated at 50°C with benzyl trimethyl ammonium hydroxide and copper naphthenate in combination with tert-huty octoate are preferred for panel products. Other heat-initiated catalysts, such as lauroyl peroxide and tert-huty perbenzoate, are optional systems. Eor higher temperature mol ding processes such as pultmsion or matched metal die mol ding at temperatures of 150°C, dual-catalyst systems are usually employed based on /-butyl perbenzoate and 2,5-dimethyl-2,5-di-2-ethyIhexanoylperoxy-hexane (Table 6). 

In another method, phosgene is gradually passed into 1,2-propylene glycol (9). The chloroformate is washed, dried, and distilled at 266 Pa (2 mm Hg) and added slowly to a mixture of aHyl alcohol and pyridine below 15°C. The purified monomer 1,2-propylene glycol bis(aHyl carbonate) (C H O ) heated with lauroyl peroxide at 70°C gives a hard clear, polymer. 

Figure 2.20. Rates of catalysed and uncatalysed polymerisation of styrene at different temperatures. Catalysts used (all at 0.0133 moleA). A, bis-(2,4-dichlorobenzoyl) peroxide B, lauroyl peroxide C, benzoyl peroxide D, bis-(/)-chlorobenzoyl) peroxide E, none. (After Boundy and Boyer )...

DILAUROYL PEROXIDE, technical pure see LAUROYL PEROXIDE... 

Park and Skene [65] found that the effectiveness of the initiator end groups for causing dehydrochlorination was in the ratio lauroyl peroxide-isopropyl peroxidi-carbonate-benzoyl peroxide-azoisobutyronitrile = 9.7 5.8 4.4 1.6. These values were obtained at 220°C, and the degradation rates were taken as the mean value for 0-20% dehydrochlorination. 

Xanthates serve as a reliable source of electrophilic radicals, and this was exploited by Zard and coworkers for a short synthesis of ( )-matrine (3-304), a naturally occurring alkaloid which has been claimed to have anti-ulcerogenic and anticancer properties [116]. Heating a mixture of xanthate 3-299 and the radical acceptor 3-300 (3 equiv.) in benzene in the presence of lauroyl peroxide as initiator, gave 3-301 in 30% yield and a 3 1 mixture of the tetracylic products 3-302 and 3-303 in 18% yield (Scheme 3.76) [117]. The three compounds could be converted into the... 

All reactions of benzotriazole derivatives of the type Bt-CR RbS discussed above are based on electrophilic or nucleophilic substitutions at the ot-carbon, but radical reactions are also possible. Thus, the first report on unsubstituted carbon-centered (benzotriazol-l-yl)methyl radical 841 involves derivatives of (benzotriazol-l-yl)methyl mercaptan. 3 -(Benzotriazol-l-yl)methyl-0-ethyl xanthate 840 is readily prepared in a reaction of l-(chloromethyl)-benzotriazole with commercially available potassium 0-ethyl xanthate. Upon treatment with radical initiators (lauroyl peroxide), the C-S bond is cleaved to generate radical 841 that can be trapped by alkenes to generate new radicals 842. By taking the xanthate moiety from the starting material, radicals 842 are converted to final products 843 with regeneration of radicals 841 allowing repetition of the process (Scheme 134). Maleinimides are also satisfactorily used as radical traps in these reactions <2001H(54)301>. 

Spiro tricyclic pyrrolizinone 171 was obtained with 65% yield (and almost poor stereoselectivity) by intramolecular radical cyclization of the xanthate 170 upon exposure of the latter to 2equiv of lauroyl peroxide, in a refluxing 3 1 mixture of methanol and 1,2-dichloromethane. The radical generated from the xanthate moiety cyclizes with the... 

Szwarc (99) found a great affinity for methyl radicals in carbon black. Donnet and co-workers [58, 100, 101) determined the concentration of free radicals on carbon black surfaces by the fixation of the radicals of isobutyronitrile, 3,5-dichlorobenzoyl peroxide, and lauroyl peroxide. The number of radicals bound by the surface coincided satisfactorily with the number of unpaired electrons determined by e.s.r. 

In the suspension polymerization process, the autoclave reactor is filled with water. PVA, polyvinyl alcohol is the dispersing agent that helps stabilize the suspension. Lauroyl peroxide is the free radical catalyst that starts it all off. The reaction temperature is around 130°F, and the process takes 10—12 hours per batch, with 95% conversion. 

Benzoyl peroxide has clear IR and Raman stretching frequencies at vO—O 846 and 847 cm , respectively, whereas for lauroyl peroxide the IR band at 886 cm is very weak and only the Raman band at 876 cm can be useful for structural assignments . ... 

THF tetrahydrofuran, NaNap sodium naphthalenide, Na2St disodium stilbene dianion, BP benzoyl peroxide, DME 1,2-dimethoxyethane, TMBD tetramethylbenzidine dication diperchlorate, WBP Wurster s blue perchlorate, LP lauroyl peroxide, FLSPEC fluorescence spectrum obtained, FPSPEC fluorescence and phosphorescence spectrum obtained, FXSPEC fluorescence and eximer spectra obtained, DPAC12 9,10-dichlorO 9,10-dihydro-9,10-diphenylanthracene. 

Compound Name Lauroyl Peroxide 1,1 -Dimethylhydrazine Endrin... 

Divinyl DMDT DMF DMS DMSO DNT DOA 1-Dodecanethiol Dodecanol Dodecanol Dodecanol Peroxide Dodecene 1-Dodecene Dodecene (Non-Linear) Dodecene (Non-Linear) Dodecyl Alcohol Dodecylbenzene Butadiene, Inhibited Methoxychlor Dimethylfbrmamide Dimethyl Sulfide Dimethyl Sulfoxide 2,4-Dinitrotoluene Dioctyl Adipate Lauryl Mercaptan Linear Alcohols (12-15 Carbons) Dodecanol Lauroyl Peroxide Dodecene 1-Dodecene Propylene Tetramer Dodecene Dodecanol Dodecylbenzene... 

Latex, Liquid Synthetic Laughing Gas Lauroyl Peroxide Lauryl Alcohol Lauryl Ammonium Sulfate Lauryl Benzene Lauryl Magnesium Sulfate Lauryl Mercaptan... 

Lithium Aluminum Hydride Latex, Liquid Synthetic Nitrous Oxide Lauroyl Peroxide Dodecanol... 

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