Antiknock action

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-... 

Several theories exist on the mechanism for antiknock action, such as outlined in Refs 1 5. Demougin(Ref 6, p 139), H.Moureu C.Dufresse attribute the action of... 

Refs 1)G.L.Wendt F.V.Grimm, IEC 16, S90-3( 1924)(A suggested mechanism for antiknock action) 2)T A.Boyd, IEC 16, 893-5 (1924) (Relative effect of some nitrogen compds upon detonation in engines) 3)Wm.H.Charch et al, IEC 18, 334-40(1926) (Antiknock mate-... 

Early experiments of Berl and coworkers (15, 16), together with the findings of Withrow and Rassweiler (136), support the metallic theory of antiknock action. In Berl s work colloidal lead exhibited antiknock action, while colloidal lead oxide had no effect. Spectra of engine knocking combustion obtained by Withrow and Rassweiler showed the presence of metallic lead but not lead oxide or other lead oxides. The metallic theory is also supported by other investigators (96, 101, ) ... 

The nature and mechanism of the antiknock effect is still little understood. Considerable effort has been devoted to a study of the mechanism since the time tetraethyllead first became a commercial antiknock agent but direct proof of the mechanism is still lacking. Very possibly, both homogeneous and heterogeneous mechanisms maybe competing in antiknock systems. Reviews of the various theories that have been proposed to explain antiknock action have been made byBaruschandMacpherson 31>, Lewis and von Elbe 206), Ross and Rifkin 267>, Chamberlain, Hoare and Walsh 88>, and Beatty and Edgar 44>. 

K.C. Salooja, Studies Relating to the Mechanism of Antiknock Action of Tetraethyl Lead, Comb, and Flame 9 (1965) 211. 

Also, the higher alkyl derivatives of lead are not as efficient as the tetraethyl compound. Thus, the butyl triethyl lead derivatives are only about 85 per cent as effective in suppressing knock as is the tetraethyl compound.18 The dibutyl diphenyl lead compounds range from 33 to 45 per cent as good as lead tetraethyl. While the various quadrivalent derivatives of lead show varying degrees of antiknock action, the bivalent derivatives with a few exceptions show no action. 

The theory in common with a number of the others does not explain the antiknock action of the organic amines nor does it explain the action of knock inducers. It is not clear why trietliylchlorolead and diethyl-dichlorolead should be, respectively, 75 per cent and 50 per cent as effective as tetraethyl lead. 

OTHER COMMENTS used as an antiknock action enhancer of tetraethyl lead, especially at very high octane levels useful as a gasoline additive and solvent. 

The role of physical factors in the antiknock action of Pb(C2H5)4, such as temperature, time, pressure, diffusion, and surface action of particles in the fuel-air mixture, has been... 

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