106 SEGALLER THE RELATIVE ACTIVITIES OFX1V.- The Relative Activities of Certuin Organiclodo- compounds with Sodima Phenoxide inAlcoholic Solustion. P a ~ t 111. The Temperature-coe$icients.By DAVID SEGALLER.THE influence of temperature on the rate of reaction betweenaliphatic alkyl iodides and sodium phenoside in alcoholic solutionhas been studied, particularly with the object of determining therelative activities of these compounds when the effect of tempera-ture can be excluded.The following substances were dealt with : methyl, ethyl, propyl,isopropyl, butyl, isobutyl, sec.-butyl, tert.-butyl, amyl, isoamyl,sec.-amyl, hexyl, sec.-hexyl, heptyl, sec.-heptyl, octyl, sec.-octyl, andhexadecyl iodides, and their velocity-coefficients were measured atfour different temperatures (with two exceptions, which were onlymeasured a t three temperatures) over a range of approximately 50°.The temperature-coefficients are very large, most of the iodidesmentioned above being more than twenty times as reactive at 58Oas they are a t 3 1 O .Ths value K(,+,o, / Kt is practically constant throughout the series,and lies between 3-01 and 3.09.I n his principle of mobile equilibrium (,i!?t.rrdes, p.222), van'tHoff deduces the equation :* (1)9 dlogK - - - QdT 2Tz * ' a ' * CERTAIN ORGANIC IODO-COMPOUNDS, ETC. 10'7where q is the heat evolved in the formation of the system.on integration, leads tot the approximation :This,( a 1A9 m I'logK = 2 + c o n s t . = -+h . . . .421where A and b are both constants.It €ollows from equation (2)280 290 300 31 3 32010i x Reciprocal of absolute tcmpwatzwe.A = tert.-Butyl iodide.B = Methyl iodidc.C = Ethyl iodide. E = is0 PropgE iodide.D = Propgl iodida. F = sec. - OctyE iodide.G = Amy1 iodide. H = isoButyl iodide.that if log K is plotted against l / T , the reciprocal of the absolutet'emperature, the graph obtained should be a straight line.The velocity-coefficients obtained were plotted against 1/ T inthe diagram, and it is seen that the graphs are straight linesin all cases. The fourth point connecting the reciprocal of th108 SEGALLER : THE RELATIVE ACTIVITIES OFhighest temperature and the velocity-coefficient obtained lies some-what off the line in every case, the value of R, for each substancebeing lower than that obtained from the curve.This cannot be dueto experimental error, as the only possible variation from themethod adopted in determining the velocity-coefficients a t the otherthree temperatures lies in the fact that the reaction was notstopped as promptly in the case of the sealed tubes as in thosecases where stoppered tubes were employed. The error involvedhere, however, would be that. the time 6 would be somewhat largerthan that given in the tables, and consequently 2K4 would besmaller, instead of greater, than the value found. The only otherpossible source of error, namely, pressure in the tubes, could onlybe minute. It has been shown by a number of observers (Rontgen,A nn. Phys. Chem., 1892, [iii], 45, 98 ; Rothmund, Zeitsch.physikal.Chem., 1896, 20, 168) that the influence of pressure on the velocityof reaction between liquids is very slight. The reason for thelower values of K4 is probably to be found in the fact that themagnitude of p is dependent on the temperature, so that equation(2) holds only over a limited range.Very little work has been done up to the present in connexionwith the relative reactivities of any homologous series a t differenttemperatures. The work that has been published does not tendto show any regular increase or decrease in reactivity with anincreaae of *CH, in the molecule in an homologous series; forexample, Price in his research on ester saponification (Ofvers.E . Vet. Akad. Stockholm, 1899, 56, 932) gives values which showthat there is practically no difference in the magnitude of thevelocity-coefficients of methyl, ethyl, propyl, and isobutyl acetates.Crocker, on the other hand (T., 1907, 91, 611), by comparing thereactivities of the aliphatic amides, shows that there is a gradualtransition in the relative activities of the first eight homolopeswith increasing molecular weight.EXPERIMENTAL.It has been shown by the author (T., 1913, 103, 1162) that, inthe action of alkyl iodides on sodium phenoxide, the initial concen-tration of the reacting substances has a large influence on themagnitude of the velocity-coefficients. It was theref ore necessaryto perform all the reactions at the various temperatures with thesame initial concentration in order that the results should becomparable, and this made the times for half reaction vary fromten minutes t o seven days.The concentrations of both the phen-oxide and iodide used throughout this work was N/10, and themethod adopted for the three lower temperaturcss is the same aCERTAIN ORGANIC IODO-COMPOUNDS, ETC. LO9that already described (T., 1913, 103, 1154, 1422), the additionalprecaution being adopted of blackening the outsides of all vesselsused. I n the case of the highest temperature employed (80*1*) i twas necessary to work in sealed tubes. These tubes were made tohold just over 20 c.c., and were drawn out to a narrow end justwide enough to admit a special pipette with a very narrow stem.The reaction mixtures were transferred to the tubes by means of apipette, the narrow ends drawa out to a point and sealed off.Duringthe sealiug, the tubes rested in an asbestos cloth bag. As each tubewas removed from the thermostat i t was rapidly cooled by immer-sion in a large volume of mercury on which ice was floating. Thistreatment cooled the reaction mixture to the room temperature ina very short time. The capillary was then broken off, the contentsof the tube were thoroughly washed out into a beaker containingthe N/20-acid, and the titration was completed as described.The method of calculating the velocity-coefficients was the sameas before, and the following table gives the results of the measure-ments, showing the mean values of K at the four temperatures:30.1°, 42'5O, 58'5O, and 80'1O.Substance.Methyl iodide ............n-Butyl , , ............n-Amy1 ,, ............n-Heptyl ,, ............12-Octyl , , ..........w-Hexadecyl iodide ...isoButyl ,, ...isoAmyl ,, ...isoPropyl ,, ...sec.-Rutyl ,, ...~ e c .- A l ~ y l ,, ...sec.-Hexyl ,, ...sac.-Heptyl ,, ...sec.-Octyl ,, ...tert.-Butyl ,, ...Ethyl ,, ............R - Prop yl , , ...........n-Hiexyl , , ............4. K2. K3. KPTemperature, Temperature, Temperature, Temperature,30.1". 42.5". 58.5". 80'1".0.01550-003420-091280*001270.0005450 -001210'001160*001090-OOlOf0*0005120.0007270 001230.001320'001 200*001130 -00 1100.001070.0295OaO6070.01350 005200.004h50 *002100 *OO 4 ti 40*004 5 10-004340.004290 -00 1930 002850'004650,005130'004700.004330 004200 004110.1210.3260.07 100.02830 02670.01170.02550.0'2480-02410.02310.01030.01560.02590.02770.02600.02400.02300'0226Temperature 0"-0.5100 2090.1 970.0850.1920.1900.1870.1840'07000.07600 '1 930-2050.1970.1780.1700.1680.000381The relationship between the velocity-coefficients and the tem-perature is expressed much more accurately by an equation thanby a graph.The data obtained above are well represented by theequation K/K,= (Z'/To)B, proposed by Harcourt and Esson (Phil.Trans., 1867, 157, 117; 1913, A , 212, 187), but are betterexpressed by Arrhenius' equation (Zeitsch. physikal. Chem., 1887,4, 226):.. . . . p,where A is a constant110 SEGALLER : THE RELS'I'IVE ACTIVITIES OFIn the following table the values of K , are compared with thosllecalculated by means of equation (3) :K2 K2Snbstance. Kl4 A:. A. calculated. found.Methyl iodide ......... 0.0155 0.326 4850 0.0591 0.0607Ethyl ,, ......... 0.00342 0.0710 4825 0.0130 0.0135Propyl ,, ........ . 0.00128 0.0283 4922 0*00500 0*00519isoPropyl iodide ... ... 0*00123 0'0259 43-16 0'00465 0'00466But-yl ,, ... ... O*OOl2T 0.0267 484% 0'00494 0,00485isoButyl ,, ...... 0*000512 0'0103 4778 0*00192 0*00190sec.-Butyl ,, ...... 0'00132 O.OU277 4844 0'01,1502 0,00513tert.-Butyl ,, ...... 1~00~000381 .K10*121 5100 K20'0301 0,0295Amy1 ,) ... ... 0-000545 0.0117 4887 0.00210 0.002102isoAniyl ,, ......0*000727 0 0156 4880 0.00279 0 00285Hexyl ,, ... ... 0'00181 0'0255 4852 0.00461 0'004641Heptgl ,, ...... 0.00116 0.0218 4 8 i 4 0'00445 0 00451sec.-Heptyl ,, ...... 0'00110 0 0230 4845 0.00318 0.00420JOctyl ,, ...... 0.00109 0.0232 4933 0.00435 0.00434-jHexadecyl ,, ...... 0 0010i 0-0236 4918 0 00417 0'60429J .The "constant " A varies very little throughout the series, andif the interpretation of Arrhenius is adopted, then A representsapproximately half the heat required to convert the inactive forminto the active. It follows also that the heat of transformationfrom the inactive to the active form is independent of the tempera-ture. This is apparently the case for the range of temperatureconsidered in this investigation (excluding the highest tempera-ture).Comparing the series separately, for example, normal primary,iso-primary, secondary, and tertiary, it will be wen that the velocity-coefficients become gradually less with increasing molecular weights,and in no case was there any inversion of the order of reactivitiesfrom one temperature to another.If the velocity-coefficients ar0 examined in relation to one anothera t the various temperatures, some remarkable points are noticed.I n the following table the velocity-coefficients are given relativelyto methyl iodide, the velocity-coefficient of which is taken equal to1000.Kl, E2, li, are the "relative" velocity-coefficients a t the tem-peratures 31'0°, 42'5O, and 68'5O.s~c.-A111yl ), ......0*00120 0'0260 4893 0.00463 0'00470JSCC.-HCXYI ,, ..... 0.00113 0'0240 4SGti 0 00433 O 00433 :sec.-Octyl ,, ...... 0'00107 0 0226 4848 0'00409 0'00411Subst awe.Methyl iodidc ...... ... ... ...Et liyl . . . . . . . . . . . . . .Propyl ), ... ,...........Butyl , , . . . . . . . . . . . . . .see.-Butyl iodide .. , . . . .. . . . .tert. - I5ntyl , , . . .... . , , . ..Amj1 ,, ... . . . , . . .. .,,7koPropyl , ,is0 t< uty 1. . . . . . . . . . . . . . ., , . . . . . . . . . , . . . .Kl*1000 -0221 -182-7579.6982-2233-0785.1335-211904 0K2.1000~0222'185-6376 5681-3731 3 084-4834-671987'0K3.1000*0217.686.5859.418 I .9631-5184.8236.00CERTAIN ORGANIC IODO-COMPOUNDS, ETC.Substance.isoArnyl iodidesec. -Aniyl ,,Hex$ 2 ,Heptyl 9 2OCtYl > 7 sec.-Octyl ,)SCC.- Hexyl , ,set.-Heptyl ,)Hexadecyl ),............ .......... ...................................................................... ............Kl*46.9577-5277.5072.8874.8070.7471'4769'2669-33K!P46.967 7 -457 6 4 97 1.4274.3069-1670-4269.0070 76111K3*47'9779.5478.0173.6076.0170.4774.3269'1172.38The numbers in the above table show that approximately therelative velocity-coefficients of the alkyl iodides are independent ofthe temperature. I f a mean is taken of the velocity-coefficientsrelatively to methyl iodide a t t.he temperatures considered, wetherefore obtain a series of numbers which express the relativereacOivities of the alkyl iodides independent of the temperature.The following table gives the order of the reactivities so obtained :tert.-Butyl iodide ......1945'0Methyl , , ...... 1000 '0Propyl ,, ...... 84.95), 81.85 ButylisoPropyl , , 78 *53sec.-Amy1 ) ) ...... 78-17Ethyl ) ) ...... 2 2 0 2 .~ c . - B ~ t y l ,, ...... 84.81 ' ...... i ......Hexyl ,, ...... 77 3 3Heptyl iodide .........sec. - Hexyl , , .........Octyl ,, .........Hexadecyl , , .......sec. -Heptyl ), .........see. -0rtyl , , ........isoAniyl ), .........isoButyl , , ......... Amy1 ,) .........74-7072-6372.0770.8270.1269.1242 2935'2931.96Gepneral Conclusions.(1) The temperature-coefficients of the alkyl iodides with sodiumphenoxide in alcoholic solution are large, the ratios of the velocity-coefficients for two temperatures differing by 10 degrees are fairlyconstant for the series, and lie between 3-01 and 3.09.(2) The coefficients found for the three lower temperatures arein good agreement with those found by means of the equation ofArrhenius. Jn the case of the highest temperature the valuesfound are in all cases somewhat lower than those required by theformula, since the equation holds only for a limited range.(3) The results show that the relative activities of the alkyliodides towards sodium phenoxide are almost independent of thetemperature.( 4 ) The relative activities of the alkyl iodides may therefore beexpessed by the relative numbers representing their velocity-coefficients, ,(5) The reactivities so obtained are in the following descendingorder of magnitude : tcrt.-butyl, methyl, ethyl, propyl, sec.-butyl,butyl,'isopropyl, sec.-amyl, hexyl, heptyl, sec.-hexyl, octyl, hexadecyl,sec.-heptyl, set.-octyl, ieoamyl, amyl, isobutyl112 SEGBLLER : THE RELATIVE ACTIVITIES OFThe author wishes to express his thanks to the Research FundCommittee of the Cheniicnl Society for a grant which has helped todefray the expenses of this investigation, and to Dr.J. C . Crockerfor his kindness in supervising this work.CH EM ICA L DEP A It TM E K T,8. If’. POLYTIICHNIC,CHELSEA, S. W.THE RUTLISH SCIIOOL,MERTOK, S. W