Imrganic Chemistry
972 CORRESPONDENCE
mechahism was consid&ed to accotrnt for the mechanism accounts for alkylborane isemeibaalkylisomerization. tioa more satisfactorily th&B the previously sugThe bridge hydrogen tautomerism mechanism gested dissociation-association mechanism. explains several observations with respect to Hydrogen tau torne‘rism and intramolecular realkylborane isomerization which are not satisarrangement have been observed to take place in factorily explained by the dissociation-association many electrob-deficient borm containing commechanism. pounds. Examples are: A1(8H&,2 BQ&-,’ BSH , : O ( C Z H ~ )B6H10,394 ~,~ B z H ~ - , ~BJ~ H ~ : N ( C H S ) ~ , ~(1) The bridge hydrogen tautomerism mechand 3310H14:cineo1e5~6; the Bl1n.rtl.t. spectra of 1310- anism requires that RzBH be present. UnusWlly rapid isomerization has been reported“ in cases HI$-’ and (CH3)2NBzHs.s where the olefin is too bulky to allow the forrnaWe suggest that the bridge hydrogen tauto’tion of the trialkylborane. merism mechanism in B3H8- and (CH&NBZHE,is relevant to alkylborane isomerization. (2) The addition of a small amount of diborane should increase (Zr;a rapid alkyl-hydrogen exThe hydrogens in B3HS- may be considered to change12) the concentration of R2BH present in migrate about the molecule ion in the following the system. Subsequent rapid alkyl-hydrogen manner exchange would allow all alkyl groups to exist K .HH. .H“part time” in R2BH molecules and dkylborane isomerization consequently should bq speeded up. Such atl effect for diboratle has been reporkd.lg (3) Alkylborane isomerhation proceeds a t I H H 160’ (ca. 1 hr-)in diglyme, whereas 215’ ( W W H .----.a hr.) is necessary’* in the absence of diglyme. I Diborane and diglyme react reversibly to form The B” n.m.r. spectra o€ p-dimethylamhodidiglyme:BH2+ and B s H ~ - . ~ ~ ’ ~ borane at several temperatures are compatible It is probable that the diglyme-dibrane equilwith the bridge hydrogen tautomerism mechanism ibrium is such that the last traces of diborane are about the bomn-boron-nitrogen skeleton d t h u g h not easily removed, therefore a small amount of other processes also have been suggestdS diborane is retained which catalyzed the isonlefiOne might speculate that an electron-deficient zation reaction as in (2) above. (and isoelectronic) system of boron, carbon, and It is probable that alkylalurnkane isomerizahydrogen atoms also could tautornerize. For tionl6vl7 and certain rearrangements and hydrogen exampk, di-Bbutylborane could rearrange via a migration in carbonium ions also take place vk a tautomeric process. bridge hydrogen tautomerism mechanism.
This intermediate structure was suggested previously to account for the cis addition of BH3 groups to the double bond in the hydroboration of olefin^.^ However, the dissociation-association (2) R. A Ogg and J. n. Ray, Discussions Faraday Soc., 19, 239 (1955). (3) W. N. Lipscomb, Advan. Inwg. Chcm., 1, 139 (1959). (4) R. E.Williams, J. Inorg. Nucl. Chcm., 20, 198 (1961). (5) R. E. Williams, 140th National Meeting of the American Chemical Society, Chicago, Illinois, September, 1960. (6) R. 3. F. PalchbTt, J. H.Namaf~,ah6 R. E. Wikiams, Y. Am. C h m . Soc., 88, 3380 (1961). (7) This conclusion also was made independentIy by Dr. R. L. Williams, Admiralty Materials Laboratory, Dorset. England. (8) W. D. Phrtlps, € C. I. M i l k , and E. L. Mu&r€ies, J . Am. Chew SOG.,81, 4496 (1959).
(9) H.C Brown and G . Zweifel, ibid., 81, 247 (1959). (10) H.C. Brown and B. C. Suba Rao, iMd., S I , 6434 (1959). (11) H.C. Brown and G. Zweifel, ibid., $2, 4708 (1960). (12) H.I. Schlesinger and A. A. Walker, ibid., 67, 621 (1935). (13) G. Zweifel, Tetrahedron, Z, 117 (1961). (14) G. F. Hennion, P. A. McCusker, E. C. Ashby, and A. J. Rutkowsky, J . A m . Chem. Sod., 79, 5190 (1957). C. I. Brown and P. E. Tierney, i b i d . , 80, 1552 (1958). (15) € (16)R.Ziegler, Brennstof-Chcm.,SQ, 321 (1954). (17) K. Ziegler, “Metal-Organic Syntheses,” in “Perspec~vesin Organic Cbemistry,” A. Todd, ed., rntersdence Publ., New York, N. Y.,1956.
SPACE-GENERAL CORPORATION ROBERT E. WILLIAMS EL MONTE,CALIFORNIA RECEIVED FEBRUARY 23, 1962
The Reaction of Dioxygen Difluoride with Tetmfluoroethylene Sir: Bbrygen difluoride, OzFz, discovaed by Ruff and Menzel,’ melts at - 163.5’ to a red liquid; it
Vd. 1, ,NO.4, Noote~nb~, 1962 decomposes rapidly to 0 2and FZklose to its norihal boiling point of -57'. Littie is published concerning the chemistry of this compound and we wisb to report here its reaction with tetrafluoroethytene. Dioxygen difluoride was prepared in an electrical discharge by a method described by Kinhenbaum and GrosSe.2 The method +&Is 02372 when the proportions of oxygen and fluoiine are 1 :1. The discharge tube, which also was used as the reactdr, was maintained a t -196' during the preparation and was warmed and cooled slightly several times with pumping to remove aky dissolved oxygen. The reactions were conducted by allowing tetrafluordethylene to condense hito the reattor containing the solid 02F2 a t - 196', maintained with a liquid nitrogen-filled dewar. Upon contact, flashes here observed eveh at this temperature and these continued with gradual lowering of the liquid nitrogen level. The products from the reaction were COR and CF4 with lesser amounk of c2F6, SiF4, and C?F300CF~.All products were isolated by conventional vacuum line fractional condensation and chromatographic techniques and were identified by their reported infrared and mass spectra. In an additional experiment, several liquid cc. of diluent argon (vapor pressure a t -196' = 200 mm.) were condensed into the reactor containing the 02F2. The C2F4 was allowed to diffuse to the cold zone. A single small flash was observed. In addition to the above products, CF30F, OF2, and C4F10 also were produced. Finally, the C2F4was highly diiuted with helium before being passed through the reactor at -196' and 2-4 mm. No flashes were noticed during addition, but on warming a few were again observed. Most of the condensable material was volatile a t -160' and the products included the above (with the exception of OF2) along with do,,
C2F60CFd,and
0
Fq'
' y 2 .
No CtF4 or 02F2was
FtC-CF2
recovered from any of these experiments. These resuits were generally reproducible if similar conditions were employed. Most of the steps necessary td give the products isokiked (undevlined) can be explained by 'known feaetions Ceq. & 4,and 5 ) . 3Zquations 1 and B day offer zin explanation for the prikary reactim. (1) b. Ruff and W. Men&, Z. ahom. ullgsnt. mht'm.,111, 204 (1933). (2) A. D. Eirsheubaum and A. V. Cltoske, J . A m . Cheh. Soc., bl, 1277 (1959).
-
CXF
+ COF2 -
(1)
or
0
F
F
+ (flF2')n-1-4
COFZ
C S O F ;F C2F4 +CzFsOCFa
(2)
(3)
*s4
A
2CFsOF
+Y)F4 -+ COz -+ 1Fz-1
CFoOF $. COFs 4CF@XFs
ab
(4)
(5)
The great reactivity of CF&F at ignition t h peratwe BO doubt explains its idation in low yieid. It is suggested that this reaction under the proper conditions probably would give a higher yield of CF80F. Grateful acknowledgment is made to Mr. L. Adlum for interpretation of the infrared data.
(s)
(3) m e n tlie authors in ref. 3b attem~tedtKs reattion, additian dPd hot dccnr; in*ead Teflon-like polymers or CF4 and C d were produced. However, the authors in ref. 4 did effect addition 6f CF&P to ethyrene to give C ~ O C I H C and ~ T the conditions ased ih the curretit Work may erbkain the results. (b) R. S. Porter and G. H. Cady, J. Am. Chcm. SOC.,79, 5625, 5628 (1957). (4) J. A. C. Allisqn and G. H. Cady, ibid., 81, 1089 (1959). (5) Offiee bf th'e Screkary of DQedSe, Advahced Research pro$ ects Agency, Washington 25, D. C. REA:hcTION MOTORS Dfns10~
RICHARD T.HOLZMANN' S. COHEN THIOKOL C m m w CORPORATION MURRAY DENVILLE, NEWJERSEY
R~BIVED SEPTEMBER 5, 1961
Commenk Concerning the Effect on the DiliormePentaborane Exchan&eReaction of the Reported Deuterium Isotope ERect in 'the Decomposition of Diboranel Sir: In a recent paper2 calculation of the ratio of equilibrium constants for dissociation of B2Da and B2H6 was reported to lead to the conclusion that under identical conditions the BD, concentration will be about twice as large as the RHs concentration. This is significant in view of the h & Wt d+bire-pentaW&fie isotopic ekcliange reactions which Professor Koski and the author (1) l%B wdkk w6s shppor'ftd ?n pdrt by the Office of Wakal
Research ($ R. E. EfnTont Qnd R. Scbaeffer, J . Inarg. Nucl. Chhn., 18, 103 (1961).
