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Vol. 81
ston-Salem, N. C., for a generous initial sample of solanesol. Our simplified procedure for the isolation of solanesol from tobacco will be described later.
none with a substituent in the 5-position composed of 9-isoprenoid units Kofler and co-workersl0 have proposed structure I I b which has a 10isoprenoid unit side chain for a plant quinone beCONTRIBUTION F R O M THE ROBERT E. ERICKSOS lieved to be identical with "Q-254." The strucCLIFFORD H. SHCNK ture having the 9-isoprenoid unit side chain has MERCK,SHARP& DOHME RESEARCH LABORATORIES SELSON R TRENNER been confirmed by synthesis. 2,3-DimethylhydroOF MERCK& Co , INC. DI~ISIOS BYROXH. ARISON quinone was condensed with solanesol in the presS , J. KARLFOLKERS RAHWAY, ence of boron trifluoride etherate, and the resulting RECEIVED JULY 31, 1959 hydroquinone was oxidized yielding 2,3-dimethyl5-solanesylbenzoquinone (IIa), m.p. 43.5-45', COENZYME 0. Q. X. SYNTHESIS OF COENZYME pismuno 253 mp (E:c%239) and 261 mp (E:: 222) Q ,, 2,3-DIM-ET'HYL-S-S0LANESYLBENZOQUINONE 2,3-DIMETHYL-S-SOLANESYLBENZOQUINONE (Anal. Found: C, 84.87; H , 10.63). This comQ.254 , AND A VITAMIN K ANALOG pound is identical with "Q-234" with respect to Sit,: m.p., Rf, ultraviolet, infrared and nuclear magnetic X polyisoprenoid alcohol, solanesol, was isolated resonance data. Vitamin Kz recently has been shown to have the from tobacco and evidence was presented indicating that it was composed of 10 isoprenoid units.' We formula IIIa." We have now synthesized the corobtained a sample of solanesol through the generos- responding naphthoquinone in which the side chain ity of Dr. R. L. Rowland and Dr. M. Senkus2 to contains nine isoprenoid units (IIIb). 2-Llethylcondense with 2,3-dimethoxy-5-methylhydroqui-naphthohydroquinone was condensed with solanesol none, because the reaction could be expected t o give in the presence of boron trifluoride etherate. Oxisynthetic coenzyme Q1(, (Ia).3 4,5$ The resulting dation of the product yielded 2-methyl-3-solanesylar'c 2,:3-dimethoxy-5-methyl-6 -solanesylbenzoquinone, naphthoquinone (IIIb), m.p. 60-61', X ~ ~ ~ ~ t233, tn p. 42-43 .!io, 271 mp (E:% 175). (lInal. 248, 260, 269 and 322 m p (E: 2 218, 232, 212, 210 Found: C, 81.06; H, 10.47) was different from co- and 38 resp.) (-4nal. Found: C, 83.01; H , 10.39). enzyme Qla,but proved to be indistinguishable from R . Trenner, B. H . d r i s o n , R . E . Erickson, C. H . Shunk, I) I C . (9) il'. coenzyme Q g (III)~with respect to m.p., R f ,ultravio- Wolf and K. Folkers, THISJ O U R N A L , 81, 202G (1939). (10) hI. Kofler, 4 . Langemann, R . Ruegg, I,. H. Chopard-dit-Jean, let, and infrared data. The structure of solanesol and 0. Isler, Helv. Chim. A c t a , 42, 1283 (1959). was reinvestigated' and it was found to be com- R . iRavroud l l ) 0 . Isler, R . Ruegg, L . H. Chopard-dit-Jean, A \Vinterstein and posed of nine isoprenoid units rather than ten. 0. \Viss, i b i d . , 41, 786 (1958). 0
CONTRIBUTIOX FROM T H E CLIFFORD H. SHUSK MERCK,SHARP & DOHME ROBERT E . ERICKSON RESEARCH LABORATORIES EMILYL. Woxc KARLFOLKERS DIVISIONO F MERCK & C O . , ISC. SEW JERSEY RAHWAY, RECEIVED JULY 31, 1959 ACTIVATION OF BRIDGING GROUPS IN ELECTRON TRANSFER. 11. THE POSITION OF BOND-BREAKING IN ESTER HYDROLYSIS'
Sir: It has been shown that when certain half-esters function as bridging groups for electron transfer, ester hydrolysis accompanies electron transfer. The point of bond scission in these hydrolyses is a matter of interest, and forms the subject of this cornmunication. The reaction of C r + +with 0
IIIb, n = 9
X quinone (Q-254) has been isolatedbfrom alfalfa and has been shown to be 2,3-dimethylbenzoqui(1) R. I>. Rawland, P. H . Latimer and J. A . Giles, THISJ o u R N . s L , 7 8 , 4680 ( l 9 . X ) .
( 2 ) R. J. Reynolds Tobacco Co., Winston-Salem, North Carolina. t.3) R . L Lester, F. L . Crane a n d Y . Hatefi. THISJ O U R N A L , 8 0 , 4731 (1958). ( 4 ) D. E IV'olf. C H . Hoffman, N R . Trcnner, R . H. .4riwn, C . I1 $hunk, B. 0 Linn, J . F. McPhersoa and K . Folkers, ibid., 80, 4752 (1938). ( 3 ) C . H. S h u n k , B. 0 ],inn, E . I.. \\'ong. P. E. \Vlttreich, F 11 Robinson and K. Folkers, i b i d . , 80, 47:X (lY38). f 0 ) R . A. Morton, U . Gloor, 0. Schindler, G . X. \Vilson, L. H. Chopard-dit-Jean, F. W .Hemming, 0. Isler, \V. M . F. Leat, J. F. Pennock, R . Ruegg, U. Schwieter and 0 . Wiss, H i l u . C h i m . A d a , 41, 2358 (1958). ( 7 ) R . E. Erickson, C. H . Shunk, x, R . Trenner, B. H . Arison and K. Folkers, THISJ O U R X A L , 81, 1999 (1959). ( 8 ) F . L . Crane and R. L. Lester, Plan! P h y s i o l . , 33 (Suppl.), V I 1 ( I 958).
0
H
'OCHa
(the ligand is the methyl half ester of fumaric acid, containing oxygen of normal isotope composition) was carried out in aqueous solution 8.5-fold enriched in 0l8and containing 0.3 X HC104. The fumaric acid was removed as described earlier,2 and after purification was heated with Hg(CNh and HgClS3to convert oxygen to COS. The CO:! was found to be enriched in 0l8by only a factor of 1.048 above that of a sample derived from acid of normal isotopic composition. Thus it appears (1) Supported by t h e A . E . C . under Contract AT(11-1-)-378. (2) R. T . M. Fraser, D. K. Sehera and H. Tauhe, THISJ O U R X A L , 81, 290G (1959). ( 3 ) M . Anbar and S. G u t t m a n n , private communication.
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Sept. 20, 1959
that the bulk of the reaction occurs with methyloxygen bond scission, and the carboxyl carbonoxygen bond breaks only in 2-3y0 of the events. When V++ is used as the reducing agent, the procedure for separating the fumaric acid is much simpler than with Cr++; the organic acid can be extracted directly from the reaction mixture. Complete hydrolysis of the ester again accompanies electron transfer. The tracer experiment shows that the CHy-0 bond breaks in 95% of the events. With the same reducing agent, but with the methyl maleate half-ester as ligand, bond rupture occurs a t the CH3-0 position in 97-9S% of the hydrolysis events. When the phenyl fumarate half-ester is the ligand and V++ is the reducing agent, complete hydrolysis of the ester also accompanies electron transfer. In this system, the isotopic compositions of both the phenol and the fumaric acid were determined. The results of a series of experiments are summarized.
;001
The absorption and fluorescence of tris-5-methyl1,lO-phenanthroline ruthenium chelate have been reported and utilized for a microdetermination of ruthenium5 although the electronic transition involved has not been discussed. The luminescence shown in Fig. 1 was obtained from a l(Ip4solution of tri~-2,2’-bipyridineruthenium(II) chloride a t 7 i ° K . The line-like character of the luminescence is re.miniscent of the f-f emission in the rare earth chelates. However, i t is a completely different phenomenon produced by an allowed transition whose mean lifetime is less than sec6 As shown by the absorption spectra in Fig. 1 there is no analogous allowed absorption band a t the wave length of the luminescence.
Acidity of the solution, If 1 0.50 0 . 2 5 0.05 Fraction of phenol enriched 0.071 ,094 ,105 .118 Fraction of fumaric acid enricheda 0 925 ,898 ,884 ,878 h s containing one oxygen derived from the solvent.
The isotope balance is good so that the fractions reported can be taken as indicating the fractions of bond rupture a t the two positions. I t is evident that the course of the reactions can be altered when an alcohol radical such as CEH6,which is reluctant to accept substitution is used. It is perhaps even more remarkable that a substantial fraction of the bond breaking occurs at the C8H5-O position. The results incidentally show that no exchange of the carboxyl oxygen with the solvent accompanies this type of hydrolysis reaction, in contrast to the behavior demonstrated for a number of other ester hydrolyses.4 (4) RI. L. Bender, THIS J O U R N A L , 7 9 , 1020 (1951); references t o other work cited by hl. L. Bender, R . D. Ginger a n d J. P. Unik, ibid., 80, 1044 (1958).
GEORGE HERBERT JONESLAB. UNIVERSITY OF CHICAGO R. T. M. FRASER H. TAUBE CHICAGO, ILLINOIS RECEIVED AVGWT5, 1959
E
20
I
I
I
25
30
35
I 1 40
45
WAVE NUMBER, cm:’ x IO3.
Fig.
l.-Tri~-2,2’-bipyridineruthenium( 11) chloride: absorption spectra; --------- luminescence spectra (plotted on an arbitrary intensity scale).
We have explained our data in this manner. The broad absorption band between 17,000 and 27,000 cm.-’ may be due to a charge transfer absorption (E > lo4). That is, the d electron from CHARGE TRANSFER LUMINESCENCE OF A RUTHENIUM(I1) CHELATE the ruthenium atom may be excited to an antibondSir: ing orbital of the bipyridine molecule (d --c pi*). We would like to report the first example of lumi- Thus we may have a very broad absorption band nescence resulting from a charge transfer transition due t o excitation t o various vibrationally excited in the transition metal chelate tris-2,2’-bipyridine- levels of the pi* electronic state and yet have a sinruthenium(I1). The luminescence of chelates has, gle emission from the lowest vibrational level of the in general, been studied as a function of electronic excited state to the ground d orbital. This may transitions within the ligand itself except for a few be represented pictorially as shown in Fig. 2. As predicted there should also be an absorption isolated cases as for the rare earth chelates with energy transfer and luminescence from f-f transi- band from the d orbital to the second antibonding pi tions1#2and for luminescence characteristic of cop- orbital. This band was found experimentally to per(I1) in mixtures of copper(I1) and aminoanthra- have emax. a t 41250 em.-‘ as shown in Fig. 1. The q ~ i n o n e sas , ~pointed out by Kasha and M ~ G l y n n . ~remaining band with emax. a t 35000 cm.-’ is of course the pi + pi* transition of bipyridine. Ex.
I
(1) S. I. Weissman, J . Chem. P h y s . , 10, 214 (1942). (2) G. A. Crosby and M. Kasha, Spectuochim. Acta, 10, 377 (1958). (3) A . V. Karyakin and Ya. 1. Kalenichenko, Doklady A k a d . N a u k S . S . S . R . , 66, 191 (1949). (4) h f . Kasha and S. P. McGlynn, A n n . R E V .Chem., 7 , 403 (1950).
(5) H. Veening, Ph.D. Thesis, Purdue University, 1958. Submitted t o Analyfical Chemistry. (6) T h e lifetime estimate was kindly provided by Dr. M. Kasha a t the Florida S t a t e University.
