2-1.6
1701.si
COhlhIUNICATIONS TO THE EDITOR
TARLE I1 RE1 P S I ' I O N r h f E S O F O R G A N I C h I A T E R 1 A I ~ S ( I N h I I Y l ? ' I . E ?
= t l MINUTE) Compound
Methylnopiiiul I Methylnopinol I1 Rornyl acetate n-Fenchyl acetate Terpinyl acetate Borneol a-Fenchol
1520
1600
24 28
19 22 20 15 3 I1 30 20
23 IS
.. 40
..
Infrared analyses were obtained using a Perkin-Elmer model 21 recording spectrophotometer employing sodium chloride optics. Methylnopino1s.-Each isomer was recrystallized from absolute ether m d its purity was established by partitioning .I sample dissolved in cyclohexane. Acetylation of Methylnopinol I.-Two grams of the alcohol (lissolved in 5 cc. of acetic anhydride was heated at the steambdth for 10 hours. The reaction mixture was decomposed with cold, saturated sodium bicarbonate solution and extracted with ether. A sample of the crude oil was partitioned by 1-v .p .c. to determine the product distribution. The product was distilled to remove most of the hydrocarbons and some of the terpinyl acetate identified by its infrared spectrum. Tile acetate fraction of the center distillation cut was then removed by repetitive partitioning of 50pl. portions. The material collected was twice repartitioned, yielding a colorless oil of TPD 1.4550 shown to be a-fenchyl acetate by comparison of its infrared spectrum with t h a t of a n authentic sample. The acetate (0.100 g.) was allowed to stand overnight in niet1i:tnolic potassium hydroxide. The
methyl alcohol was boiled off, and the residue was taken u p in ether. The oil remaining after evaporation of t h r ether \vas partitioned, yielding a partially solid tnatericil shown to be a-fcnchol by its infrared spectrum. Acetylation of Methylnopinol 11.-Three grntns of metliylnopinol dissolved in 5 cc. of acetic anhydride w;is heated for five hours at the steam-bath. The product was treated :is described above for isomer I. Multiple partitioning of the minor acetate fraction provided a partially solid material indicated to be bornyl acetate by its infrared spectrum. To 0.10 g. of acetate dissolved in 2-3 cc. of absolute ether was :idded a small lump of lithium aluminum hydride. After several hours water was added to decompose the excess h y dride, and the ether layer was removed and evaporated. The residue was dissolved in cyclohexane and partitioned, yielding a single crystalline solid melting a t 200-203" anti shown to be borneol by its infrared spectrum. Acetylation of the Magnesium Salt of Methylnopinol II.--4 solution of 1.0 g. of the methylnopinol in 10 cc. of ether was added dropwise to a solution of n-propylrnagncsiuin bromide prepared by adding 1.6 g. of n-propyl broniidc in 10 cc. of ether to 0.35 g. of magnesum ribbon. After 311 of the alcohol had been added the mixture was refluxetl gently for one hour. Acetic anhydride (2.0 g. in 10 cc. o f ether) was added slowly with cooling and the reaction mixture was allowed t o stand for two days at room temperature. The product was removed by steam distillation of the reaction mixture and treated as described for the other acetate preparations. The partitioned acetate was shown to be bornpl acetate by its infrared spectrum and by its conversion t o borneol by lithium aluminum hydride.
Acknowledgment.-The methylnopinol snniples were provided by Professor Saul Winsteiti, to who111 we are deeply grateful. SI'ANFORD,
CAI,IP.
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COhfMUNICATIONS T O T H E EDITOR FORMATION CONSTANTS OF METAL COMPLEXES CONTAINING OPTICALLY ACTIVE LIGANDS'
Sir: I t has been observed by other workers2 that metals (M) when combining with optically active ligands ( l - X ) and ( d - X ) form complexes of the type M(L-X)nand h l ( d - X ) , rather than the mixed complex M(L-X)n(d-X)m. To demonstrate whether this favoring of nonmixed complexes occurs, at equilibrium, in solution the author has measured the formation constants of both types of complex. Two potentiometric titrations were made3: (1) the titration of a 2 : l mixture of I-asparagine and copper (11) with potassium hydroxide and ( 2 ) the titration of a 2 : l mixture of racemic-asparagine and copper(I1) ion. In the first case the constant __
-
..
. .
(1) This investigation was supported in part by a research grant R G 5532 from t h e Division of General Medical Sciences, Public Health Service. (2) Fred Basolo, "The Chemistry of the Coordination Compounds," Edited by John C. Bailar, Jr., Keinhold Publishing Corp., New York, N. Y.,1956, p. 313. (3) T h e conditions were a t a constant iouic strength of 0.1 (maintnincd by RCl) and a t 2 5 ' .
Asp- = negative ion of asparagine
could be calculated by conventional methods. 111 the second case the same calculations would give the constant K, =
I t is to be expected that [cu(l-'\sp)Ll
=
Icu(d-.zsP~21
=
[Cu(d-.%irI) +I
=
[d-ilsp-]
and [Cu(l-.lsp) 1'
13)
and [l-Asp-]
thus K -
[Cu(2-.4SP)21
- Z[Cu(l-Asp)+] [I-Asp-]
+
1 [CU(Z-AS~)(~-ASP)] (4) 4 [CuA+][B-] where A - = 1-Asp- if B- = d-Aspand A - = d-Asp- if B = I-Asp-
The second term of (4) represents the formation constant of the mixed complex from the mixed
Jan. 5, 1959
237
COMMUNICATIONS TO THE EDITOR
species CuAf and B-. I t can be formed by a com- dimethylcyclohexene was converted into 1,2-dibination of Cu(Z-Asp)+ and d-Asp- or from CU methylcyclohexanol, b.p. 94' a t 40 mm., nBn 1.4639, m.p. 24-25'.' (d-Asp) + and I-Asp-. Statistical arguments give In each case the reaction products were examined [ CU(I-Asp)(d - A ~ p ) ] = 1 [ CU,I-Asp)(d-Asp)] Ka = (5) by gas chromatography (glycerol column for 22 [ CU(l-Asp) 1' [&ASP-1 [ CUA+] [B-1 riiethylcyclohexanol, Carbowax column for others). ( 0 , (4) and (5) give In each of the four cases, the crude reaction product Kz = 2K1 1 + 5Ka 1 or Ks = 2 Kz - & I ) (6) was shown to contain a t least 97-98y0 of the isomer We have found K1 and K Z to be 2.82 X lo6 and indicated, with a maximum of 2-3% of the other 1.74 X lo6, respectively. Equation (6) thus isomer present. Not only does this hydration occur cis, but it gives a value of 7 X 1oj for Kt, which is the formation constant of the mixed complex. The non- takes place predominantly from the less hindered mixed complex is thus favored as compared to the side of a double bond. Thus, norbornene is converted to exo-norborneol, m.p. 125-126', 3,5-dimixed one. Equation (6) further indicates that if the mixed nitrobenzoate, m.p. 104-105'.* a-Pinene yields an alcohol, m.p. 35-38'. On complex did not form a t all the value of Kz would basis of proposed rules, this should be isopinocambe one-half of K1. Also, if no preferential formation of non-mixed complexes existed Kz would equal phenol.9 Examination is continuing. The following procedure is typical. Excess diK1. And, finally, in the case that the mixed com- borane (from 3.8 g. of sodium borohydride in diplexes were favored K.2 would be greater than K1. The experimental details of this and the results glyme and boron trifluoride etheratelo was passed of further experiments will be reported in a later into 16.4 g., 0.2 mole, of 1-methylcyclopentene, b.p. 74-75' a t 744 mm., n% 1.4313, in 60 ml. of publication. tetrahydrofuran a t 0' over a period of two hours. DEPARTMENT OF CHEMISTRY WILLIAM E. BENNETT After 1 hour a t room temperature, several small STATEUNIVERSITY OF IOWA pieces of ice were added to hydrolyze the excess IOWACITY,IOWA RECEIVED NOVEMBER 1, 1958 diborane. The reaction mixture was immersed in an ice-bath, 45 ml. of 3 M sodium hydroxide was added,. and then 25 ml. of 3Oy0hydrogen peroxide, A STEREOSPECIFIC CIS HYDRATION OF THE DOUBLE BOND IN CYCLIC DERIVATIVES over a period of 1 hour. After 1 hour a t room temperature, the upper layer was separated, the aqueSir: The hydroboration of olefins, followed by oxida- ous phase was extracted with ether, and the comtion of the product with hydrogen peroxide, pro- bined extracts were dried. Gas chromatographic vides a highly convenient procedure for the anti- examination of the organic phase showed the presIn ence of 9S% tians-1-methylcyclopentanol,with a Markownikoff hydration of double applying this reaction to cyclic olefins we have ob- small neighboring peak of 2% which may be the served that the reaction proceeds stereospecifically cis derivative. The product was isolated by fracto add the elements of water, hydrogen and hy- tionation in an efficient column. (7) G. Chiurdoglu, Bull. Soc. chim. Belg , 47, 241 (1938). reports droxyl, in a cis configuration to the double bond. cis-1,2-dimethylcyclobexaool,b.p. 82.8O at 25 mm., n*oHe 1.4649, In this way 1-methylcyclopentene has been con- m.p. 23 2'; trans-, b.p. 74' at 25 mm., nmHe 1.4614, m.p. 13.2". verted in a yield of 85% to trans-2-methylcyclo(8) K . Alder and H. F. Rickert, A n n . , 643, 1 (1939), report czopentanol, b.p. 152-153O at 745 mm., n% 1.4488, oorboroeol m p. 12&12Q0, 3.5-dinitrobeozoate, m p. 105O; endo-, m.p. of 3,5-dinitrobenzoate, 86-87°.3 Similarly, 1- m.p. 149-150°, 3,5-dinitrobeozoate, m.p. 123". (9) H. Schmidt, B e y . , 77, 544 (1944). methylcyclohexene has been converted in a yield of (10) H. C. Brown and P. A. Tieroey, THISJOURNAL, 80, 1552 90% to trans-2-methylcyc1ohexano1, b.p. 166.5' a t (1958). 745 mm., n 2 0 D 1.4614, m.p. of 3,5-dinitrobenzoate, RICHARD B . WETHERILL LABORATORY 113-115°.4~5 C. BROWN PURDUEUNIVERSITY HERBERT INDIANA GEORGE ZWEIFEL I n these cases the cis hydration results in the for- LAFAYETTE, RECEIVED DECEMBER 4, 1958 mation of the thermodynamically more stable isomer Consequently, the hydroboration of 1,2dimethylcyclopentene and 1,2-dimethylcyclohexene THE SYNTHESIS OF DIPHENYLCYCLOPROPENONE was examined. I n these cases, cis hydration would Sir : form the less stable isomers. 1,2-DimethylcycloTo date no stable compound is known containing pentene yielded cis-l,2-dimethylcyclopentanol,b.p. a carbonyl group in a three-membered ring. For 66-68' a t 21 mm., m.p. 23-24°.8 Similarly, 1,2- this reason cyclopropenones are of special interest, (1) H. C. Brown and B . C. Subba Rao, THISJOURNAL, 1 8 , 5694 for although the greater expected strain in the un(1956). saturated cyclic ketones would seem likely to (2) H. C. Brown and B. C. Subba Rao, J . Org. Chem., 2 2 , 1135 make them even less stable than the saturated (1957). (3) W. Huckel and H. D. Sauerland, B n . , 87, 1003 (1954), report compounds, cyclopropenones should be aromatic b p. 149-151.2° at 735 mm., nmo 1.4501, m.p. of 3,5-dinitrobeozoate, (being the analogs in the two-r-electron system of 88'. tropone in the six).l So, the preparation of a cyclo(4) M. G. Vavon, A. Perlio and M. A. Horeau, Bull. Sac. chim.
(
France, 61, 644 (1932). report b.p. 165" at 750 mm. (5) L. M. Jackman, A. K. Macbeth and I. A. Mills, J . Chcm. Soc., 1717 (1949). report n% 1.4616, m.p. of 3,5-dioitrobenzoate, 117'. (6) L. W. Trevoy and W. G. Brown, THIS JOURNAL, 71, 1675 (1949). report cir-1,2-dimethylcyclopentaool, b.p. 62O at 17 mm., m.p. 24-26'; trans-, b.p. 51' at 17 mm., m.p. 2425O.
(1) Our calculations, using the L.C.A.O. method with all the usual approximations, except that on is taken as oc 8 , show that cyclopropeoooe should have a vertical resonance energy of 1.48, and that this value is esseotially the same for diphenylcyclopropeoone if one corrects for the stilbene system. I t is thus possible that our observed stability will also be found for the simpler cyclopropenooe.
+
