334
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 18, No. 4
Antiknock Materials‘ A n Experimental and Theoretical Study By Wm. Hale Charch, Edward Mack, Jr., and Cecil E. Boord CHEMICAL LABORATORY, THE OHIO STATEUNIVERSITY, COLUMBUS, OHIO
Part I-Action
of Certain Compounds on Detonat ion
Results
Partial results are given in Tables I and 11. It has been shown that the antiknock property is exhibited by four elements not included in previous lists.2 Nickel as the 0 STCDY the relative effectiveness of antiknock carbonyl was found to have an antiknock coefficient of 30; compounds, a one-cylinder, 3/4-kilowatt, Delco light bismuth in its trialkyl and triaryl derivatives possesses a motor was employed. The set-up, including the coefficient of 18.2 to 20.2;.cadmium in its alkyl compounds bouncing pin apparatus, was similar to that described by and titanium as the tetrachloride were also found to function, Midgley and Boyd,5 and their method of comparison was in but in a less marked degree. New data are also presented general followed. relative to some additional compounds of metals alThe antiknock effectiver e a d y k n o w n to possess ness of any compound is exThe control by chemical means of detonation, as antiknock properties. pressed below by an “antioccurring in internal combustion engines, has been It h a d been supposed knock coefficient.” I t is studied by Midgley and B0yd,~J84 who have pointed out that the state of valence of the inverse ratio of the numthat certain compounds and elements possess the abilthe antiknock element was ber of mols of a given comity either to suppress or to induce this type of detoe s s e n t i a l in determining pound required t o give the nation. w h i c h of i t s compounds same degree of suppression Part I of this paper presents the results of an investis h o u l d f u n c t i o n . Thus, of detonation as does one gation to extend our knowledge as to what class of tetravalent lead in its alkyls mol of lead tetraethyl in a compounds may function as antiknock materials. was known to function as constant volume of the same Part I1 questions the relationship between the supan antiknock, while in its basic fuel mixture. Lead pression of detonation as occurring with acetylene in an divalent form, as in lead tetraethyl, the most effecopen tube and as occurring in motors with motor fuels. acetate, it was known not tive of known antiknock Part 111 points out the relationship between detoto function. That such a compounds, is given an nation and the electrical conductivity of the burning generalization, b a s e d on antiknock coefficient of 100 gases. valence alone, is not valid and all other values are rePart IV suggests a chemical theory for the action of b e c a m e apparent in this ferred to it. antiknock materials, based upon experimental data w o r k w h e n certain comFor example, 0.0033 mol thus far bearing on the phenomenon. pounds of tetravalent lead, of lead tetraethyl and 0.0051 as lead tetrastearate, lead mol of lead tri-p-xylyl per d i p h e n y 1 di-acetate, etc., liter of fuel were equivalent in their effect in suppressing the knock; hence the antiknock were found to be without effect, while certain compounds of divalent lead, as lead thioacetate, were shown to give coefficient of lead t,ri-p-xylyl is effective suppression. Considerable negative evidence was naturally collected. It is reproduced in part here in Table I1 to give a general This means that the latter compound is molecularly but idea as to what type of compound was investigated, but 64.7 per cent as effective as lead tetraethyl, t.he standard. chiefly to serve as an experimental basis from which certain This method of comparison serves as a convenient and theoretical conclusions are drawn in Part IV. natural means whereby a number of widely varying results Part 11-Suppression of Detonation in a n Open may be compared. Tube Of the more important solvents employed to carry a Ilidgley and Boyd3 have described the effect of a small compound into solution with kerosene or gasoline for a motor test, there may be mentioned absolute alcohol, amyl amount of diethyl selenide upon the detonation of acetylene alcohol, absolute ether, benzene, xylene, anhydrous pyridine, mixtures in an open tube. The detonation of acetylene glacial acet,ic acid, and various combinations of these. I n in the absence of diethyl selenide takes place with a loud, several instances 3 to 5 per cent emulsions of aqueous solu- sharp report. However, the presence of this compound tions were tested. I n all cases the compositions of the fuel, in the explosive gases causes a marked suppression of this containing the compound under examination, were the detonation, observed by the absence of the sharp characteristic “crack” accompanying detonation. same throughout the comparison. If these phenomena are analogous to detonation and its 1 Received February 8, 1926. Abstract of a dissertation presented suppression in the motor, the detonation tube should serve by MI. Charch to the Graduate School of The Ohio State University, as a convenient instrument whereby the action of antiknock September, 1923, in partial fulfilment of the requirements for the Ph.D. degree. materials could be studied apart from internal combustion * THISJOURNAL, 14, 849 (1922). engines. The present work attempts to discover what a I b i d . , 15, 421 (1923). relationships may exist between the action of certain com4 I b i d . , 16, 893 (1924). pounds on the two types of detonation. I J . SOC.Aulomotive Eng., 10, 7 (1922). Experimental
T
INDUSTRIAL A N D ENGINEERING CHE-WISTRY
April, 1926 T a b l e I-Antiknock
Compounds ANTIKNOCK METHODOF FORMULA COEFFICIEXT PREPARATION Pb(CzHd4 100 General Motors Research C( Pb(C8Hs)c 59 B e r . . 37. 112.
COMPOUND Lead tetraethyl Lead Lead Lead Lead Lead
tetraphenyl diethyl dic diphenyl dimethyl diphenyl diethvl diphenyl d
Pb(CaHsi*iC Pb(C& Pb(CcHi)zBrz
Lead diphenyl diiodide Lead tri-0-xylyl
Pb(CeHj)zIz P b ( CsH 9) 3
(appEpdr.) } B e r . , 20, 3332 (1887) (approx.) J 80 B e r . , 20, 721 (1887) 6 4 . 7 Ber., S2B, 2165
Pb(C2HsOCSS)z
7.1 8.4
Lead thioacetate
Pb(CH3COS)z
Bismuth triphenyl Bismuth trimethyl Bismuth triethyl Stannic chloride Stannic iodide
Bi(CsHa)a Bi(CH3)3 Bi(CzHd3 SnCla SnIa
Tin diethyl diiodide
Sn(CzHs)zIz
,'
