Antiknock agents

Whitcomb, R.M. (1975), Non-lead antiknock agents for motor fuels . Chemical Technology Review No. 49, Noyes Data Corporation, Park Ridge, NJ. 

Antiknock agent Antiknock index Antileishmanial agent Antileukemic activity Antdon... 

Structural, Al alloy Oxidation catalyst Fluxes, enamel frit Glass, ceramics Detergents Fire retardants Rubber catalyst Photographic Antiknock agents Medicinals Fertilizers... 

Cyanohydrins are used primarily as intermediates in the production of other chemicals. Manufacture of methyl methacrylate, used to make acrylic mol ding resins and clear sheet, eg, Plexiglas acrylic sheet, from acetone cyanohydrin is the most economically important cyanohydrin process (see Methacrylic polymers). Cyanohydrins are also used as solvents in appHcations including fiber-spinning and metals refining. Cyanohydrins and derivatives reportedly act as antiknock agents in fuel oil and motor fuels and serve as electrolytes in electrolytic capacitors. 

Kettering and Midgley were the first to identify it as a prime antiknock agent, though the compound had been known since 1852. They estimated that only a veiy small amount of TEL—a few parts per thousand— would result in a 25 percent increase in horsepower as well as fuel efficiency. 

Gasoline is a mixture of different compounds. A typical blend contains nearly 200 different hydrocarbons and additives such as antioxidants and antiknock agents. Thirteen of the chemicals commonly found in gasoline (nine hydrocarbons and four additives) are regulated as hazardous substances under CERCLA. Table 18.1 lists the chemicals along with the values of toxicity, water solubility, vapor pressure, and biodegradability.19... 

Tetraethyllead was used in the past as an antiknock agent in gasoline, but it has been phased out in most countries. Alkyllead compounds have a detergent-like activity on liposomes and black lipid membranes [232], Tributyllead destroys planar lipid membranes at lower concentrations than tripropyllead, which is again more effective than triethyl- and trimethyllead [232]. Inorganic lead compounds like lead acetate and lead nitrate were effective only at twice as high concentrations [232]. 

Uses. Primarily used in the production of styrene also used as an industrial solvent, as a constituent of asphalt and naptha, and as an antiknock agent in aviation and motor fuels... 

Uses. Manufacture of vinyl chloride antiknock agent fumigant, insecticide degreaser compounds rubber cements... 

Uses. As strong reducing agent in manufacture of high-frequency coils used in radios and televisions as antiknock agent in motor fuels... 

It is a common phenomenon to find that apparently innocuous species that do not participate in catalytic reactions can strongly poison or inhibit catalytic reactions. As examples, sulfur compounds are severe poisons for most catalysts, and the lead formerly added to gasoline as an antiknock agent completely kills the catalyst by covering its surface sites. 

Another limitation on the use of catalytic oxidation is the susceptibility of the catalysts to various deactivators or poisons, although according to the vendor the phase out of the use of volatile lead alkyls as antiknock agents in U.S. gasoline, catalyst poisoning is today rarely encountered. 

Alkyl lead compounds are extremely effective gasoline antiknock agents. By decomposing to form lead oxide compounds during the gasoline combustion process, lead alkyls interrupt the rapid chain scission reactions which lead to combustion knock. Also, lead alkyls help to prevent exhaust valve seat wear and may minimize octane requirement increase. However, unless utilized in conjunction with lead scavengers such as 1,2-dichloromethane, lead deposits can accumulate within the gasoline combustion chamber. 

W.L. Richardson et al, Ibid, 1023-33 (Organolead antiknock agents - their performance and mode of action) 5) A.D. Walsh, Ibid, 1046-55 (The knock rating of fuels) 6) S. Curry,... 

Of the organometallic compounds, there are many which exhibit antiknock value however, lack of one or more of the essential qualities of solubility, volatility, stability, and low cost has so far ruled out all but two—the lead alkyls and iron carbonyl. The latter is probably the cheapest known source of antiknock increase. It was marketed for a time in Germany and to a limited extent in this country, until it became generally recognized that the great increase in engine wear which its abrasive combustion products produce makes its use impractical. Only limited success has attended the tremendous amount of effort to reduce this wear, and there appear to be no prospects of the commercial use of iron carbonyl as an antiknock agent. 

In aviation gasoline, the value of tetraethyllead is still greater, as it would be practically impossible to manufacture aviation gasoline of the desired quality in quantity great enough to meet the demand, were it not for the use of an antiknock agent. 

Accomplishments to date in the utilization of antiknock agents have been largely made by cut and try methods, rather than by the application of theory. It is logical to expect that continuing basic research will provide a better understanding of knock and antiknock action, and of the tetraethyllead-fuel relationship, and this should lead to de-... 

Ethyl chloride was used in the manufacture of the antiknock agent tetraethyllead, which is, however, phased out. 

Antiknocks. Antiknock agents are used to improve the natural knock resistance of gasolines used in Otto-cycle gasoline engines, knock being the power-robbing, po-... 

Antiknock agents Ignition accelerators 1586b Affecting Combustion—Chamber Surfaces ... 

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