Benzene combustibility

Notably, NH3 is indispensable for the catalytic phenol synthesis. In the absence of NH3, neither benzene combustion nor phenol formation occurred on the Re-CVD/HZSM-5 catalyst (Table 10.6). Other amine compounds such as pyridine and isopropylamine did not promote the catalytic reaction at aU, which indicates that the role of NH3 in the catalysis is not due to its basic function. Fe/ZSM-5 has been reported to be active and selective for phenol synthesis from benzene using N2O as an oxidant [90, 91], but N2O did not act as an active oxidant on the Re-CVD/ HZSM-5 catalyst Furthermore, no positive effects were observed by the addition of both N2O and H2O. Notably, the NH3-pretreated Re-CVD/HZSM-5 catalyst selectively converted benzene into phenol with O2 in the absence of NH3, as discussed below. 

The tendency of the benzene combustion mechanism to substantially overestimate the formation of phenoxy radical suggested either flaws in the kinetic data involving C6H5O or incompleteness of the combustion mechanism. Subsequent work verified the kinetics and energetics used in modeling C6H5O decomposition. In separate studies, Liu et al. and Olivella et al. used ab initio and DFT models, along... 

Consequently, the benzene oxidation mechanism was further developed by considering additional decomposition and oxidation steps. Sethuraman et al. proposed that phenyl radical decomposition can occur by either of two key pathways (3-scission of phenyl radical or by breakdown of the phenylperoxy radical formed by the oxidation of phenyl radical (Fig. 9). Using PM3 calculations,which were ultimately verified by DFT studies,Carpenter predicted that another species, 2-oxepinoxy radical (3 in Fig. 9b), is an important intermediate due to its relative stability, formed via a spirodioxiranyl intermediate (2 in Fig. 9b) from phenylperoxy radical. Pathway A in Fig. 9b is the thermodynamically preferred pathway at temperatures increasing up to 432 K, while pathway B has an entropic benefit at higher temperatures. While pathway B essentially matched the traditional view of benzene combustion, pathway A introduced a new route for phenylperoxy radical, which could resolve discrepancies observed using previous models. 

This supposition was validated by experimental studies that demonstrated the prevalence of different ROS at different temperatures. Using CRDS, Yu and Lin studied the reaction of phenyl radical and oxygen, noting that phenylperoxy radical was the only adduct formed at temperatures ranging up to 473 Venkat et al. completed flow reactor studies of benzene combustion at 1200K and identified phenoxy radical as a key intermediate. 

Phenylperoxy radical, originally assumed to be a factor in low-temperature combustion only, has actually been shown to play a substantial role in dictating the overall combustion trends of benzene. Just as the isomerizations and eliminations of the alkylperoxy radicals significantly affected their overall combustion pathways, rearrangements and other intramolecular pathways available to phenylperoxy radical similarly impact the overall progress of benzene combustion. This knowledge can be extrapolated to more complex aromatic species. 

The C4 dinitriles were more stable than the dinitriles. Although their selectivity decreased with increasing benzene conversion, they were still present at high benzene conversion. CO formed mainly by decomposition of the nitriles, but a primary contribution (benzene combustion) cannot be excluded. The authors also mention a slight increase of the selectivity to Q dinitriles on increasing the reaction temperature (giving 5% more when raising from 440 to 500 °C). 

Properties Colorless, thick liquid. Hygroscopic. D 1.206 (20/4C), bp 158C (165 mm), 130C (3 mm). Soluble in water, alcohol slightly soluble in ether insoluble in benzene. Combustible. 

Properties White, crystalline solid. Mp 85C, d 1.26, flash p 325F (162.7C). Resembles ethyl acetoace-tate in chemical reactivity. Slightly soluble in water soluble in dilute sodium hydroxide, alcohol, ether, acids, chloroform, and hot benzene. Combustible. 

Properties Needles, plates, rhombic crystals (from glacial acetic acid). Mp 185C. Slightly soluble in water soluble in hot alcohol, ether, and benzene. Combustible. 

Properties Yellowish granules. Mp 20C. Soluble in water, hot alcohols, and benzene. Combustible. 

Properties White, waxlike solid. Mp 66.5C bp 369C (220C at 3 mm Hg) refr index 1.455. Soluble in hot benzene. Combustible. 

Properties White, orthorhombic crystals. Mp 58C, bp 238C, refr index 1.450 (25C). Soluble in water, aqueous acids, alcohol, and acetone insoluble in ether and benzene. Combustible. 

Properties Colorless crystals or liquid. Active base. Mp 28.0, bp 269C, d 1.092 (30/20C), flash p 306F (152C) (OC). Very soluble in water and alcohol insoluble in ether, benzene. Combustible. 

Properties Liquid. Bp 125-127C (5 mm Hg), flash p 295F (146C). Soluble in acetone, alcohol, ether, chloroform, and benzene. Combustible. 

Properties Colorless liquid amine odor. Bp 134.6C, fp -59.0C, d 0.8879 (20/20C), bulk density 7.4 lb/gal (20C), refr index 1.4300 (20C), flash p 105F (40.5C) (OC). Miscible with water, acetone, ether, and benzene. Combustible. 

Properties Yellowish-white solid odorless. Mp 56-58C bp 325C. Insoluble in water soluble in alcohol, acetone, ethyl acetate, and benzene. Combustible. 

Properties Colorless, odorless crystals fruit acid taste. Stable in air, d 1.635, sublimes at 290C, mp 287C (sealed tube), soluble in water 0.63g/100 g (25C), soluble in alcohol 5.76 g/lOOg (30C). Insoluble in chloroform and benzene. Combustible. 

Properties Colorless, fragrant liquid odor of anise. D 1.117-1.120, ref index 1.576, bp 253C. Soluble in alcohol, ether, and benzene. Combustible. Derivation Treatment of safrole with alcoholic potash. 

Properties Light-pinkish powder or coarse, pink granules. Soluble in water insoluble in alcohol and benzene. Combustible. 

Properties Yellow liquid. D 1.1629 (20C), fp -9.3C, bp 220.4C, refr index 1.544 (25C), flash p 223F(106C). Insoluble in water miscible with alcohol and benzene. Combustible. 

Properties Liquid. D 1.28 (25C), refr index 1.5300 (25C). Insoluble in water, alcohol, and hexane soluble in acetone and benzene. Combustible. 

Properties White, crystalline powder. Solidification p99-101C,d 1.20 (105C), flash p315F (157C) (OC). Slightly soluble in petroleum ether and ethyl ether soluble in benzene. Combustible. 

Properties Colorless leaflets. Mp 115C. Stable in solution. Soluble in water, alcohol, ether, benzene. Combustible. 

Properties (96% pure) White solid. D 0.928 (55/ 15C), mp 46-55C, bp 215-235C, flash p 235F (112.7C). Slightly soluble in water soluble in alcohol, acetone, ether, and benzene. Combustible. Use Polyester resins, plasticizers, lubricants, surface coatings and printing inks, insect repellent. 

Properties White solid. Mp 135C, bp (dissociates) 180C (3 mm Hg). Very soluble in water somewhat soluble in alcohol and acetone insoluble in chloroform and benzene. Combustible. 

Saha B, Shindo S, Irle S, Morokuma K (2009) Quantum chemical molecular dynamics simulations of dynamic fuUerene self-assembly in benzene combustion. ACS Nano 3 2241-2257... 

Ag/Si02 and Cu/SiOa cogelled xerogel catalysts for benzene combustion and 2-butanol dehydrogenation... 

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