VOl. 7s
COMMUNICATIONS TO THE EDITOR
5698
tempt to come to a better theoretical understanding of these reactions. We have used an approach similar to that introduced by Eyring, Hirschfelder, and T a y l ~ rassuming ,~ the reaction cross section to be determined by the distance a t which the centrifugal force tending to separate the ion and the molecule is exactly counterbalanced by the polarization force between the ion and the molecule. The rotational energy arises from the translational energy of the ion and the molecule, and the rotation is treated classically. We obtain
of the components of the reaction. in the usual way gives
Evaluating $
where ma and ma are the masses of the faster and slower components respectively. The rate constant expression developed by Eyring, Hirschfelder, and TaylorSis (3)
This differs from Equation 2 by only a factor of two. Rate constants and cross sections for thermal reactions calculated from Equations 2 and 3 are given in Table 111.
where o = reaction cross section e = electronic charge 01 = polarizability of molecule V = ionization chamber field strength do = distance from electron beam to ion exit slit
TABLE
111 d
Cross sections a t 10 v./cm. calculated from Equation l are tabulated in Table I, and the values for reaction 2 as a function of field strength are shown in Table 11. The agreement is quite satisfactory. While there are some detailed differences betweei the theoretical and experimental values, we believe that the theoretical treatment is essentially valid and t h a t the dominant factor in determining the cross sections for ion-molecule reactions is the Dolarization interaction.
+ + + + + +
Reaction
+ +
CH,' CH4 + CHs' CH3 CH8+ CHa .-L C2H5+ H! C2H4 -+ [CaHs+l CzHd+ C&+ C2H4 [C4Hs+] CzH+ C2H4 + C4H3+ HP CzH4 + C,Hz+ HP Cz' -+
k thermal X 1010 calcd. cm.a/molecule sei, From la;#, From Eq. 2 Eq. 3 cm.
x
+ +
58 58 73 73 73 73
6.2 6.3 5.9 6.1 6.1 6.2
11.2 11.4 12.8 13.0 13.1 13.3
HUMBLEOIL AND REFININGCOMPANY F. H. FIELD RESEARCH DIVISION J. L. FRANKLIN TEXAS F. W. LAMPE BAYTOWN, RECEIVED SEPTEMBER 14, 1956
TABLEI B x 10'0 cm.a/ molecule sec.
5.8 5.6 2.3" 2.1 1.3 3.4 3.9 0 .4 4.3 9.2 3.3
a X 10'8, cm.2 at V = 10 v./ cm. Experimental retical
39
34
39
34
30
43
41 81 29
43 43 43
ALICYCLIC AMINE FROM REARRANGEMENT OF
2,4,6-TRIMETHYLBENZYLTRIMETHYLAMMONIUM
ION AND ITS RECONVERSION TO AROMATIC SYSTEM'
Sir: It has been shown previously2 that, whereas the benzyltrimethylammonium ion (I) undergoes the ortho substitution rearrangement to form tertiary amine I1 on treatment with sodium amide followed by acid, the 2,4,6-trimethylbenzyltrimethylammonium ion (111), in which the ortho positions are blocked, is converted t o isodurene (IV) under similar conditions. CHz;"tT(CH3)3 I
Field strength (volts/cm.)
2 6 8 10 20 40 60 100
kz X 10'0
ui(obs.) x 10'0
rz(ca1cd.) x 10'8
3.0 4.9 5.3 5.6 5.6 4.6 3.4 2.2
31 38 39 39 30 18 11 5
46 39 36 34 28 22 18 15
The rate constants or cross sections for thermal speed ions, which are of particular interest, may be obtained from Equation 1 for v = 0 and the equation k = of where is the average relative velocity
0 I11
IV
A further study has now revealed that the latter reaction undergoes the first phase of the ortho substitution rearrangement to form alicyclic amine (V)
(3) H. Eyring, J. 0. Hirschfelder and H. S. Taylor, J . Chcm. Phys., 4, 479 (1936). See also Glasstone, Laidler and Eyring, "The Theory (1) Supported in part by the National Science Foundation. of Rate Processes,'' McGraw-Hill Book Co., Inc., New York, N. Y., (2) S. W. Kantor and C. R. Hauser, Tnis JOURNAL, 73, 4122 (1951). 1941, pp. 220 ff.
COMMUNICATIONS TO THE EDITOR
Nov. 5, 1956
which, on treatment with acid, produces isodurene (IV). This intermediate amine (V) was isolated in 70% yield by steam distillation of the reaction product in slightly alkaline medium, followed by distillation in vacuo a t relatively low temperatures. The amine (V) boiled a t 50-51' a t 0.4 mm. A n d 3 Calcd. for C13H21N: C, 81.62; H, 11.07; N, 7.31. Found: C, 81.81; H, 10.93; N, 7.15. I t g a v e a n ultraviolet absorption spectrum characteristic of . ~ 313 mp. such an alicyclic compound. C a l ~ dXmax Found: 313 mpqlog E = 3.8.
5699
THE RATE AND MECHANISM OF SOME REACTIONS OF METHYLENE
Sir:
We have studied the flash photochemical decomposition of ketene' by simultaneously illuminating two quartz cells. Both contained the same amount of ketene (1 to 10 mm.). One contained 100 mm. of an inert gas, the other 100 mm. of ethylene, acting as a getter for methylene.203 Using a Vycor filter t o absorb radiation below 2200 A., a virtually constant carbon monoxide yield ratio of 1.8 was obtained from the two cells when 0.04 t o 20% ketene CHaCHaN(CH3h was decomposed per flash. With weak, steady illumination the ratio was 1.9. Thus, in the cell containing inert gas, methylene reacts with ketene2-4 rather than recombining, whether its rate I of formation is slow or fast. I I CHs CHa The recombination rate of simple alkyl radical^^-^ is close to collision frequency. The recombination v VI of methylene cannot be much slower. Hence we On heating a t 150" for one hour, alicyclic amine estimate that its reaction probability with ketene is (V) underwent rearrangement, involving the 1,3- a t least times the collision probability. Since shift of the dimethylaminomethyl group, to form the rates of its reactions with olefins,zwith the C-H tertiary amine (VI) (83%) the structure of which bond,8 with h y d r ~ g e n ,and ~ , ~with ~ carbon monoxwas established by an independent synthesis starting ides are all comparable with that with ketene, methwith 2-bromomesitylene. The product (VI) boiled ylene appears to be extraordinarily reactive. a t 73-74' a t 0.4 mm. A n d 3 Calcd. for C I ~ H Z I N : Methylene must react with ketene by forming C, 81.62; H, 11.07; N, 7.31. Found: C,'81.56; cyclopropanone in one elementary act. I t s transiH, 10 96; N, 7.18. tory formation has been demonstrated by Roberts, Also, alicyclic amine (V) reacted with butyllith- et al.," in liquids. It is not observed in the gas ium in ether t o form an organolithium compound phase because its formation is accompanied by a t (VII) which slowly eliminated the carbanion of tri- least 78 kcal. energy release, 13 kcal. or more in methylamine t o give 2-n-amylmesitylene (VIII) excess of the minimum activation energy for the de(67%), b.p. 103-103.5" a t 3 mm. A n d 3 Calcd. composition of cyclopropane,12and a t low gas presfor C14H22: C, 88.35; H, 11.65. Found: C, 88.60; sures i t decomposes before being quenched by colliH, 11.44. The structure of this hydrocarbon was sions. Decomposition must occur through breakestablished by an independent synthesis from 2- ing of a carbon-arbon bond, all three being apbromomesitylene. The intermediate organolith- proximately equivalent because of the excess energy ium compound (VII), on hydrolysis, yielded appar- available. Thus the radicals .CHpCHz-CO. and ently a mixture of two isomeric alicyclic amines, CHz-CO-CHz. are formed in the ratio 2: 1. The b.p. 85-86' at 0.3 mm. AnaL3 Calcd. for (217- former rapidly decompose into ethylene and carHz1N: C, 81.85; H, 12.53; N, 5.62. Found: C, bon monoxide. The latter are long-lived and are . ~ 267-272 responsible for the observations in flow systems13 81.85; H, 12.35; N, 5.62. C a l ~ d Amax mp. Found 269 mp. and for most of the "by-products" observed in ketene photolysi~.~-4 Striking confirmation of this r CHz-CdHs mechanism is derived from the observa tion4 that HIC\,!QH~ in the presence of oxygen only one-third of the methylene from ketene leads t o oxidation products;
v
(1) K. Knox, R . G. W. Norrish and G.Porter, J . Chem. Sac.. 1477 (1952). (2) G. B. Kistiakowsky and N. W. Rosenberg, THIS JOURNAL, 71, 321 (1950). VI1 VI11 (3) G.B. Kistiakowsky and W. L. Marshall, ibid., 74, 88 (1952). (4) A. N . Strachan and W. A. Noyes, Jr., i b i d . , 76, 3258 (1954). A further study is being made of the reactions of (5) R . Gomer and G. B . Kistiakowsky, J . Chem. P h y r . , 19, 85 amine V and of related alicyclic amines with (1951). electrophilic and nucleophilic reagents and with (6) K. J. Ivin and E. W. R. Steacie, Proc. R o y . Soc., AZO8, 25 heat alone. The rather remarkable nature of (1951). (7) S. G. Whiteway and C. R . Masson, J . Chcm. Phys., 35, 233 amine V is indicated by the present results. (1950). (3) Galbraith Laboratories, Knoxville, Tennessee. (8) W. von E. Doering, R . G . Buttery, R . G. Laughlin and N. (4) See R. B. Woodward, THISJOURNAL,64, 72 (1942). A disChaudhuri, THIS JOURNAL, 78, 3224 (1956). placement value of 30 mr is used for the conjugated exo-methvlene (9) J. Chanmugam and M. Burton, ;bid., 78, 509 (1956). group. (10) H.Gesser and E. W. R . Steacie, Can. J . Chem., 34, 113 (1956). ( 5 ) Monsanto Chemical Company Fellow, 1955-1956. (11) D . A. Semenow, E. F. Cox and J. D . Roberts, THISJOURNAL, 78, 3221 (1956). DEPARTMENT OF CHEMISTRY DUKEUNIVERSITY C. R. HAUSER (12) H.0.Pritchard, R. G.Sowden and A. F. Trotman-Dickenson, DURHAM, NORTHCAROLINA D. N. VANEENAM5 Proc. Roy. Soc., 8317, 563 (1953). (13) T. G. Pearson, R. H. Purcell and G. S. Saigh, J . Ckcm. Sor., RECEIVED SEPTEMBER 10, 1956 409 (1938).
