Oxygenate additive

Classical chemiluminescence from lucigenin (20) is obtained from its reaction with hydrogen peroxide in water at a pH of about 10 Qc is reported to be about 0.5% based on lucigenin, but 1.6% based on the product A/-methylacridone which is formed in low yield (46). Lucigenin dioxetane (17) has been prepared by singlet oxygen addition to an electron-rich olefin (16) at low temperature (47). Thermal decomposition of (17) gives of 1.6% (47). 

Methyl -Butyl Ether. MTBE is used as an oxygen additive foi gasoline. Production of MTBE in tiie United States has increased due to the... 

An especially interesting case of oxygen addition to quinonoid systems involves acidic treatment with acetic anhydride, which produces both addition and esterification (eq. 3). This Thiele-Winter acetoxylation has been used extensively for synthesis, stmcture proof, isolation, and purification (54). The kinetics and mechanism of acetoxylation have been described (55). Although the acetyhum ion is an electrophile, extensive studies of electronic effects show a definite relationship to nucleophilic addition chemistry (56). 

Butadiene is also known to form mbbery polymers caused by polymerization initiators like free radicals or oxygen. Addition of antioxidants like TBC and the use of lower storage temperatures can substantially reduce fouling caused by these polymers. Butadiene and other olefins, such as isoprene, styrene, and chloroprene, also form so-called popcorn polymers (250). These popcorn polymers are hard, opaque, and porous. They have been reported to... 

When the fuel gas is not pure hydrogen and air is used instead of pure oxygen, additional adjustment to the calciJated cell potential becomes necessary. Since the reactants in the two gas streams practically become depleted between the inlet and exit of the fuel cell, the cell potential is decreased by a term representing the log mean fugac-ities, and the operating cell efficiency becomes ... 

The Methanol Institute is the trade association representing the methanol industiy in the United States. One of its goals is to protect and expand markets for methanol. The single largest market for methanol is in the production of methyl tertiaiy butly ether (MTBE), the oxygenate additive used in cleaner-burning reformulated gasoline (RFG). 

The O-acylation of phenols with carboxylic acid anhydrides can be conveniently catalyzed in either of two ways. One method involves converting the acid anhydride to a more powerful acylating agent by protonation of one of its carbonyl oxygens. Addition of a few drops of sulfuric acid is usually sufficient. 

In the late 1990s, MTBE came under serious attack on grounds of both efficacy and safety. A report by the National Research Council (1999) stated that the addition of oxygen additives in gasoline, including MTBE and ethanol, are far less important in controlling pollution than emission control equipment and technical improvement to vehicle engines and exhaust systems. 

Another interesting oxidative formation of chlorins from porphyrins is the singlet-oxygen addition to protoporphyrin19 (see Section 1.1.2.2.). 

Nonperpendicular attack of the nucleophile explains Felkin s hypothesis for the predominance of interactions involving R1 and R2 over interactions involving the carbonyl oxygen. Additionally, as R1 increases in bulk, the nucleophile is pushed towards the stereogenic center and can better feel" the difference between the substituents, resulting in an increase in stereoselectivity. 

The removal of oxygen, addition of hydrogen, or gain of electrons. Refractory ... 

The extent to which this occurs depends on a number of issues (Finlayson-Pitts and Pitts 1997), including the reactivity of the hydrocarbon that is itself a function of many factors. It has been proposed that the possibility of ozone formation is best described by a reactivity index of incremental hydrocarbon reactivity (Carter and Atkinson 1987, 1989) that combines the rate of formation of O3 with that of the reduction in the concentration of NO. The method has been applied, for example, to oxygenate additives to automobile fuel (Japar et al. 1991), while both anthropogenic compounds and naturally occurring hydrocarbons may be reactive. 

The YSZ reactor could be operated catal3rtically or electrocatalytically, depending on the mode of oxygen addition. Oxygen could be supplied either electrochemically by means of the solid electrolyte wall of the reactor (electrocatal3 ic operation) or in the gas phase (catalsdic operation) (Fig. 1). 

In this work we present results obtained with the YSZ reactor operated in the hatch mode with electrochemical oxygen addition, and with the quartz plug flow reactor operated in the continuous-flow steady-state mode. In the case of continuous flow operation, the molecular sieve trap comprised two packed bed units in parallel in a swing-bed arrangement (Fig. 1), that is, one unit was maintained at low temperature (<70°C) to continuously trap the reactor products while the other was heated for -30 min to 300°C to release the products in a slow stream of He. 

The molecular sieve adsorbent traps ethylene quantitatively, thus practically freezing step 4. Ethane trapping is only partial, thus the desired step 3 is not decelerated significantly. Steps 1,3 and 4 are predominantly catalytic or electrocatalytic, depending on the mode of oxygen addition. 

Steady state measurements of NO decomposition in the absence of CO under potentiostatic conditions gave the expected result, namely rapid self-poisoning of the system by chemisorbed oxygen addition of CO resulted immediately in a finite reaction rate which varied reversibly and reproducibly with changes in catalyst potential (Vwr) and reactant partial pressures. Figure 1 shows steady state (potentiostatic) rate data for CO2, N2 and N2O production as a function of Vwr at 621 K for a constant inlet pressures (P no, P co) of NO and CO of 0.75 k Pa. Also shown is the Vwr dependence of N2 selectivity where the latter quantity is defined as... 

As it has been mention in preceding section, the vast effect of the mechanism of adsorption-caused change in electrophysical characteristics of adsorbent is provided by availability of defects [32]. However, various admixtures play similarly important role on effects of properties of oxides including the sensitivity of their electrophysical properties to adsorption [4, 5]. Small amounts of admixtures (of the order of 0.5 -1 mol.-%) can both increase the sensitivity of oxide for instance to oxygen (addition of Y2O3 to calcium oxide over pressure interval lO -10 Torr [189]) and decrease it (addition of Ga203 to ZnO [190]), or can result in insensitivity of electric conductivity on the pressure of the gas in question (as it is the case with respect to O2 while adding 0.5 -1 mol.-% of lithium to NiO [190]). 

The presence of oxygen in the reaction mixture drastically changes the course of the reaction.(a3> Under these conditions acetone, carbon monoxide, carbon dioxide, and tetramethylethylene oxide are produced. Presumably tetramethylcyclopropanone is still produced as an initial product and the products observed result from oxygen addition to this species ... 

El-Agamey, A. and McGarvey, D.J. 2005. First direct observation of reversible oxygen addition to a carotenoid-derived carbon-centered neutral radical. Org. Lett. 18 3957-3960. 

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