rates of lo4, 7 X IO4 and lo6 rads./h. A similar irradiation was carried out with 2 Mev. Van de Graaff electrons a t a current of 1 microampere (a dose rate in the irradiation zone of 7 X lo8 rads./ h.). After irradiation the samples were examined gas chromatographical!y with attention focussed on the products in the Clo to C12 region (cf. Table I).
the formation of C7Hs+ ion from 1-phenylbutane, now has been found to show a high degree of specificity. 1-Phenylpropane, to a slight extent, and higher 1-phenylalkanes, to a great extent, give rise not only to the expected C7H7+ ion of mass 91, but also to C7Hs+ of mass 92.* This ion must contain a hydrogen atom from the side chain in addition to TABLE I the elements of the benzyl group. We suspected EFFECTOF DOSE RATEON THE RADIOLYSIS OF CYCLOPEN- that the hydrogen comes from the gamma carbon, TANE-CYCLOHEXANE MIXTURES' because this migration would lead directly to the Dose Relative yieldsc formation of a stable 1-olefin as the neutral product Source rateb CioHiee C u H d CnHzzQ Rd of the dissociation. Co60 y-rays 0 . 0 1 1.65 1.75 0 . 6 0 1.71 T o determine the origin of the migrating hydroCow y-rays 0.07 1.51 1.83 0.66 1.54 gen atom, we made use of two independent apCobs y-rays 1.0 1.39 1 . 9 5 0.76 1.30 proaches. The first consisted of labeling the 3 mev. electrons 700 0.70 2.04 1 . 2 6 0.75 molecule with deuterium in known positions, and hlixtures 0.46 mole fraction in cyclohexane. hlegarads examining the fragment ions for deuterium retenper hour in irradiation zone. Normalized to a t,)tal ~ second was blocking with methyl R, the ratiu of twice the Cloconiponent t i ~ n . The relative yield of 4. -+ the CI1 coinponent to the Cll component -+ twice the CI? groups the positions from which the migrating ~ l J I I l p l l l l ~ l l t e~~~~ . Respectively, cyclupentyl cyclr~peiitatie, hydrogen atom was thought to come. r y I [ ~ p e ~ i t c> y l cliillexane aiid c y c l ~ ~ h e xcycli~liexane. yl Table I shows partial mass spectra of unlabeled I t is seen that a very pronounced increase in the 1-phenylbutane and 1-phenylbutane-3-d and -44. relative yield of cyclopentylcyclopentane and a The 3-d species gives rise to C7Hs+ ions that are corresponding decrease in cyclohexylcyclohexane 03.2/190 or 48.6y0 labeled, close to the 50c70 accompanies the decrease in intensity from the fast expected on the assumption t h a t the migrating atom electron to the y-ray experiments. \Ye have comes solely from the gamma carbon and that no taken as a quantitative measure of this change the isotope effect is involved. The discrepancy, though ratio (R)of the total Cg component to the Ca small, is shown to be real by the 4-d spectrum, in which 4.5/196 or 2.3% of the C7Hs+ions are labeled. component represented in the Cla to C ~ region. Z Thus, about 9E17~of the migrating hydrogen atoms Irradiation of a similar (z.e., 50/50) cyclopentanecyclohexane mixture containing 2 mM. iodine with originates on the gamma carbon. y-rays (at 70,000 rads./h.) indicated t h a t the ratio TABLEI of cyclopentyl to cyclohexyl radicals initially P A R T I A L M A S S SPECTRA O F DEUTERATED 1-PHESYLBUTANES produced was 0.70 in good agreement with the ratio Corrected for naturally occurring CI3 I? observed in the fast electron experiments. It is -3-d -44 nr/e Colaheled concluded therefore that a t the high intensities 100.0 100.0 135 represented by the Van de Graaff irradiations ( l o x 0.2 0.6 134 100.0 rads./h. and above) secondary reactions are not 95.3 4.5 93 product determining. The observed products 119.4 200 93 196 therefore represent reactions of radicals initially 420 432 91 438 produced by the radiation. At lower intensities Table I1 shows partial mass spectra of 1-phenylsecondary reactions occur here and may be expected to be of general importance in the radiolysis of pure butane, 3-methyl-1-phenylbutane and 3,3-dimethyl1-phenylbutane. The first two show large yields liquid hydrocarbons. J
RADIATIOS RESEARCH LABORATORIES ROBERTH. SCHULER TABLE I1 MELLOSINSTITUTE, PITTSBURGH, PA.,AND MASSSPECTRA OF METHYLATED ~-PHENYLBUTANES DEPARTMEST OF CHEMISTRP G. A , MCCCISI PARTIAL BROOKHAVES NATIOYAL LABORATORY Corrected for naturally occurring C i 3 U P T O N , L O N G I S L A S D , XSW Y O R K m/c Unsubstituted 3-Methyl3.3-DimethylRECEIVED M A R C H 16, 1959 Parent 22.8 24.0 28.4 0.3 30.0 106 0.3 13.3 23.6 105 8.2 HYDROGEN MIGRATION IN GASEOUS ORGANIC 132.4 5.0 92 44.8 CATIONS 100.0 100.0 91 100.0 Sir:
Many ionic dissociations induced by electron impact involve migration of a hydrogen atom from one part of a molecule to another. In compounds containing oxygen, a favorably oriented hydrogen usually is pictured as migrating to the oxygen atom, which is considered trivalent by virtue of localization of the charge in a non-bonding orbital.' In hydrocarbon ions, on the other hand, hydrogenmigration processes are generally thought to be rather non-specific. However, one such process, ( 1 ) See f o r exilmplr, F. \V, lfrT.atTerty, A x u i . Ckcm , 31, 82 (1959).
-
of C7Hs+. Moreover, the mass-92 intensities shown define only lower limits for these yields; a pronounced metastable peak 90.0 (92+) (91+) 1 in both spectra indicates that the C7H7+ ion intensities a t mass 91 are due, a t least in part, to further dissociation of C7Hs+ions, I n sharp contrast, the spectrum of the 3,3-dimethyl compound shows but little C7Hst and no more than a suggestion of ;L metastable peak a t 90.0. The process leading to
+
(2) S. Meyerson. A p p l . Spectroscopy, 9 , I 2 0 (19:;). ( 3 ) S . hieyerson and P. N . Rylaodcr, J . P h y i i ' h e m , 62, 2 (1958)
AUg. 5 , 1959
C O h I h I T J N I C h T I O N S TO TIIE
EDITOR
'$117
C7&+ has been replaced by a process giving a large yield of CgHlo+of mass 106. Evidently production of the C7H8+ ion in high yield requires a t least one hydrogen atom on the gamma carbon.
group is participating in the first example described, and two in the second, are influenced both by reaction stoichiometry and by the electronic properties of the acetylenic substituents. It appears that the tetrahydrofuran molecules coordinated RESEARCH A N D DEVELOPMENT DEPARTMENT STANDARD OIL COMPANY (ISDIANA) J. D. MCCOLLUM directly with each triarylchromium, as in the WHITISG,INDIANA SEYMOUR MEYERSON example of triphenylchromium tri-tetrahydrofuranRECEIVED JUSE 11, 1959 ate, are displaced stepwise by the acetylenes, the extent of displacement being dependent on the amount of the acetylene available. According to T-COMPLEXES O F T H E TRANSITION METALS. XI. ADDITION REACTIONS OF TRIARYLCHROMIUM this concept, only one replacement leads to the styrenes and stilbenes, two to the polynuclear COMPOUNDS' Sir : aromatic hydrocarbons when an aryl ortho-position The preparation of triphenylchromium (111),its is open for ring closure,' and three replacements rearrangement of 9-bonded bis-arene chromium give the benzene derivatives. A second factor complexes and its ability to promote cyclic con- favoring addition instead of cyclic condensation densation of disubstituted acetylenes to benzene is the effect of electron-withdrawing groups, such as derivatives, polynuclear aromatic hydrocarbons carbomethoxy, in delocalization of the acetylenic and bis-arene ir-complexes have been described in n-electrons. No cyclic condensation products, recent papers.' The synthetic capabilities of this i.e., benzene or polynuclear aromatic derivatives, and other organochromium (111) compounds have were isolated from the reaction of dimethyl acetylnow been extended by the discovery that these ene-dicarboxylate and triphenylchromium in the organometallic reagents can participate in addition present case. reactions with acetylenes to give substituted RESEARCH & ENGINEERING DIVISION MONSANTO CHEMICAL COMPANY W. METLESICS styrenes and stilbenes. 7, OHIO H. ZEISS A solution of the blue trimesitylchromium (111)in DAYTON JUNE 25, 1950 RECEIVED tetrahydrofuran, prepared by the addition of three mole equivalents of mesitylmagnesium bromide to one of chromic trichloride a t -20°,2 undergoes REACTION OF ALKOXIDE WITH CXz T O PRODUCE exothermic reaction with 2-butyne after a short CARBONIUM ION INTERMEDIATES' induction period to yield the liquid addition prod- Sir : uct, 2-mesityl-2-butene, I [Anal. Calcd. for CISWe wish to report a novel method for producing H18: C, 89.59; H , 10.41. Found: C, 89.70; highly reactive carbonium ion intermediates in H , 10.301, as well as the normal condensation basic media. It is generally accepted t h a t reproduct, hexamethylbenzene. Chemical evidence actions of haloform with alkoxide ions produces and infrared, ultraviolet and Raman spectroscopic dihalocarbene. Hine, Pollitzer and Wagner3 have measurements support this structural assignment. reported the conversions of alcohols to olefins by This substituted styrene is oxidized by osmium the halogen-base system. tetroxide to 2-mesitylbutan-2,3-diol, m.p. 110-1 12" While attempting the preparations of di-alkoxy[Anal. Calcd. for C13H2002:C, 74.96; H , 9.68; carbenes we noted olefins and carbon monoxide mol. wt., 208. Found: C, 75.62; H, 9 . i 1 ; mol. were often the major product^.^ wt., 2091, which in turn is cleaved by lead tetraReactions of alkoxides with bromoform in alacetate to acetaldehyde and 2,4,F-trimethylaceto- chohol solutions produce carbon monoxide and phenone. COOCHI
H8COOC
HjCs
Mes
I
I1
A second example of this reaction type involves the addition of two aryl groups from the organometallic reagent to an acetylenic bond. Dimethyl acetylenedicarboxylate and triphenylchromium in tetrahydrofuran a t room temperature interact exothermically to produce cis-dimethyl diphenylmaleate, 11, m.p. 110-112" (lit. 110-111"). The cis-configuration of this substituted stilbene was confirmed by its hydrolysis and subsequent acidification to diphenylmaleic anhydride which melted undepressed with an authentic sample, m.p. 1581600.3 These addition reactions of triarylchromium compounds with acetylenes in which one aryl (1) W. Herwig and H. Zeiss, THISJOURNAL, 79, 6561 (1957); 80, 2913 (1958); 81, In press (1959); W. Herwig, W. Rfetlesics and H. Zeiss, i b i d . . in press. (2) M . Tsutsui and H. Zeiss, unpublished results. (3) 1,. Chalanay and E. Knoevenagel, Be*.. 26,385 (1893).
n-CaH,OH n-CdH90H
s-CdHsOH i-CrHsOH I-C~HQOH t-C6HiiOH neo-CsHI1OH
Propylene, cyclopropane 1-Butene, cis-2-butene, Irans-2-butene, methylcyclopropane I-Butene, cis-2-butene, trans-2-butene Isobutylene, 1-butene, cis-2-butene, trans2-butene, methylcyclopropane Isobutylene 2-Methyl-l-butene, 2-methyl-2-butene 2-Methyl-I-butene, 2-methyl-2-butene
The yield of carbon monoxide increases as the structure of the alcohol is varied in the order prim., sec., and tert., (49-94%), and low concentrations of alkoxide ions favors this reaction. The ratios of olefins to carbon monoxide fall in the range 0.6-0.8. Bromoform is somewhat more (1) This work was supported by the Office of Ordnance Research, Contract No. DA-36-061-ODR-607, and was presented at the Seventh Reactions Mechanisms Conference, Chicago, Sept., 1958. (2) J. Hine, THISJOURNAL, 72, 2438 (1950). (3) J. Hine, E. L. Pollitzer and H . Wagner, i b i d . , 71, 5607 (1983). (4) Minor products observed are CHxClt (CHClr reactions), methyl ethyl ketone (s-CdHeOH), ethers and orthoformates. Methylene iodide has been repoited by Parham, ReiR and Swarzentruber, ibid., 78, 1437 (1956). and CHzCI? and ketone by lline and co-workers (private communication).
