5902
Fig. 2.-A,
JAMES
R. MCNESBY AND ALVINS. GORDON
Vol. 79
X-ray interference diagram of almost pure FeC (contaminated by FeaOJ; B, X-ray,interfererice dingram of a-Fe; (1) most intense line a t d = 2.05 kX. units; (2) most intense line a t d = 2.004 kX. units.
Fig. 3.--A, X-ray interference diagram of almost pure FeC (contaminated by FerO,); B. X-ray interference diagram of catalyst sample containing P e G FeaO,, Fe and FeC. where PenC:Fes04:Feis approximately 25:25:1 and the relative amount of FeC has not been established: (1) a-Fe; (2) FeC; (3) Fea04; (4) Fed2 (Hiigg). The cluster of lines due to 1 , 2 and 4 which are grouped around the most intense line of FeC (d = 2.004 kx.units) is clearly shown.
I n all three figures FeaOt is present as a contaminant in the X-ray diagrams of FeC. Further work, studying the catalytic behavior,
the physical and chemical properties and the mode of formation of this carbide is being continued. SASOLSU~C. UNION OF SOUTH AFRICA
u. s. NAVALOKDNANCE TESTSTATION] Reactions of CD, Radicals with the Butenes
[CONTRIBUTION FROM
THE MlCHELsoN LAB.,
BY JAMES R. MCNESBY AND ALVINS. GORDON RECEIVED MAY22,1957
~
~
~~~~~~~~~
~~~~~~~~~~
I~~~~~~~ ~
~
of CHI and CHaDare produced. "Thishas been interpreted as evidence for addition of CDI a t abarticnlar posrtion in the double bond in a butene, followed by the loss of a CHs radical. Using this interpretation, rate constants for addition of CDa to these positions are obtained relative t o the rate constant for abstraction of D from acetone-dc by the CDa radical. For butene-1. addition of CDs t o the non-terminal carhon atom end of the double bond results in the formation of propylene-&. This can be used as a measure of the rate of addition of methyl radicals to the nom-terminal carbon atom of the double bond.
The addition of methyl radicals to olefins in the gas phase has bcrn the subject of only 3 feu. investi~atioris. Rust and his eo-workers' examined the products of the rcnction of nictl~ylradicals with vnrious olefins in a flow system a t 2%" and found evidence for nnn-trrminal 3s well ns terminal nddition. kial and D;tnby? indicate that the :Ihstmetion of H from acetddehyde hv CH, is about three times :IS fast 3s nddition ui CH, to the various butenes a t 300". Thcrc is no dctnilcd :icrount in tlie litcraturc of
the mechanism of the reaction of methyl radicals with butene-I.3 The present work is a report on the reactions of methyl radicals with the four butenes in the temperature range 350-500'.
( 1 ) 1: 1: Rttrf. Ji 1 1 S u h M nnd \V k. V d u d h ~ n 1'111s , JOURWAI.. 70. D'I 1191d! 0 1 I' A Kndl and C J n a n b y , I C'hrm SI , ?222 11111)
(1954). ( 5 ) C. M. Drew. J. R . McNenbv. S. R . Smith and A. S. Gordon, Anal. Cham.. 18, 078 (1050).
Experimental Techniques of photolysis,' mass spectronietry,' and gas chromatography@have been described elsewhere. The 50cc. cylindriod reaction vessel with plane windows was fabri(3) In the reaction of CDCHL!H=CH, and light methyl radicals, propylene-da has been observed in the products (private commmnication. Paul Kebarle and W. A. Bryce). (4) I. R. MeNerby and A. S. Gordon. Tars J o n n s ~ 76, ~ . 4106
REACTIONS OF CD3 KADICALS WITH THE BUTENES
Nov. 20, 1957
cated from quartz. The reaction niixture was between 30 and 100 mm. of a 1: 1 acetone-butene blend. The butenes were Phillips Research Grade compounds. The areas under each peak in a gas chromatogram were measured and compared with the areas obtained using a synthetic blend of the compounds in question. I t was found that the area under a peak was approximately proportional to the amount of the compound. Using this information, the product analyses reported in Table I11 were obtained. The light source was a Hanovia medium pressure mercury arc. Reactions were permitted to proceed less than 10% toward completion. Under our own reaction conditions, this corresponds to five minutes irradiation with full intensity of the mercury arc. 12 f t . 1.5% squalane on carbon black (Pelletex) column was used for the chromatographic analyses.
Results and Discussion The a priori formulation of the mechanism of the reaction of CD3 radicals with butene-1 should predict all of the products of the reaction. To simplify the presentation of the possible reactions, the butene molecule is labeled as CHz=CH-CHz-CHs (1) (2) (3) (4)
The abstraction of H from position 3 should be favored since a resonance stabilized radical results. Abstraction of H from position 1 would result in a CH=CHCH,CH, radical which could pyrolyze to acetylene and an ethyl radical. No acetylene is observed in the products of reaction a t temperatures up to 500'. Attack on position 2 would result in the CHz=C-CH,CH3 radical which should pyrolyze to allene and a methyl radical. No allene is noted in the products. Position 4 is an unlikely point of attack, since it is a primary H and is more resistant to attack than position 1. The methyl radical attack on position 3 results CD3
+ CHz=CHCHzCHa
--+ CD3H
+ CHz=CHCHCHZ
(1)
in the CH2=CHCHCH3 radical. This radical can undergo the reactions CHz=CHCHCH3 ++ CHpCH=CHCH3 CHz=CHCHCH3 HR --+ CHz=CHCHzCH3 R CH?CH=CHCH3 HR --+ CHaCH=CHCH3 R CHz=CHCHCH3 Ads --+ CHz=CH--CHDCH3 CDzCOCD3 CHzCH=CHCH3 Ads --+ CHzDCH=CHCH3 CDzCOCD3
+ + + +
CHz=CHCHCH3 CHzCH=CHCHa
Similar relations hold for the other butenes and the CD3H CDI ratios are given in Table I for each of the four butenes studied. The table also shows that large amounts of CHI and CH3D are formed, increasing with temperature. These light rnethanes result from the addition of CD3 to the double bond of the butenes followed by elimination of CH3 from the pentyl radical. The reaction sequence is shown for the case of butene-1.
+ CHz=CHCH?CHj +CDJCH~CHCIILCHJ(9) CD,92
