Aug. 5 , 1062
SILVER
NITRATE-BUTADIENE COhlPLEX
2893
ORGANIC AND BIOLOGICAL CHEMISTRY [CONTRIBUTION FROM
THE
M. W. KELLOCGCo., JERSEY CITY3, N. J.]
I. Silver Nitrate Butadiene
Silver Salt-Olefin Complexes.
BY J. W. KRAUSAND E. W. STERN RECEIVED MARCH27, 1962 Under suitable conditions of pressure and temperature, a solid results from the interaction of butadiene with 8 Af AgNOa solution. A study of the decomposition pressure of the dry solid indicated the presence of two complexes: AgNOs/C+ and (2AgNO3)/C,H6. The stoichiometry of the solid and the solubility of butadiene in AgNOB solution are discussed in the light of this information. The heats of reaction for the two species, as calculated from equilibrium data, are 10.8 and 13.0 kcal./mole, respectively.
was recorded, a light yellow crystalline phase precipitated and the pressure decreased t o 474 mm. This decrease in pressure corresponded to a calculated increase in butadiene solubility from 0.50 to 0.52 mole of butadiene/mole of Ag. In another experiment, the attempt was made to exceed this ratio by the application of greater butadiene pressure. Due to the limitations of the apparatus, however, i t was not possible to exceed 900 mm. Because of extremely slow equilibration (stirring was hampered by the crystalline phase) C hemica1s.-The materials used in this study were reagent it was not possible to reach values significantly grade silver nitrate (Baker & Adamson Products, Allied Chemical Corp.) and C.P. grade 1,3-butadiene (The Mathe- greater by this method. A discussion of these data is deferred until the remainder of the experison Co.). Procedure.-Solubility studies and equilibrium pressure mental results are described. measurements were conducted in a conventional manometric Dissociation Studies.-Equilibrium pressure apparatus comprising a vacuum manifold, gas transfer lines 2,11 were obtained in the data, presented in Fig. and calibrated vessels. The anhydrous complex salt was prepared by passing course of two experiments made with separate butadiene gas through aqueous 8 M AgNOs a t 16" and samples of the crystalline complex. In the first, atmospheric pressure. The resulting precipitate was iso- presence of a second complex species was inferred lated on a fritted glass funnel by pressure filtration with butadiene gas and dried by passing butadiene gas over the from discontinuities in the data above 10' (see crystals for 30 to 60 minutes with occasional stirring. The dotted line, Fig. 2). Since these data were too few light yellow product was stored a t -35" in a container in number and lacked sufficient precision, a second sealed from light to prevent photochemical darkening. sample of the crystalline material was allowed t o Equilibrium pressure data were obtained from portions of reach equilibrium a t l 5 O , pumped rapidly to zero this material in a conventional manometric apparatus. Preparatory to making equilibrium pressure measure- pressure, and allowed to establish a new set of ments, the sample was pumped a t -32" for 30 minutes. equilibria (plot B, Fig. 2). The thermostat bath was then adjusted to the desired Stoichiometry.-At the conclusion of the first temperature and periodic pressure readings were made until series of pressure measurements, the mixture of an equilibrium pressure was achieved. complexes was totally decomposed by heating, and Results and Discussion a total of 0.100 mole of butadiene (analytically Solubility Study.-The solubility of butadiene pure by mass spectrum) collected.'2 The residue in aqueous 8 M AgNOD a t 15" is shown in Fig. 1. contained 62.5% Ag (equivalent to 0.0153 mole of Under these conditions, the solubility of butadiene Ag) as compared to a theoretical 63.5% Ag in increased markedly with pressure to 0.5 mole of AgNOa. Thus, the mole ratio of butadiene to butadiene/mole of Ag. At this point, the pres- silver was 0.65 for the dried mixture. A mole sure of butadiene above the solution was 662 ratio of butadiene to silver greater than 0.5 and mm. and the solution possessed a yellow color less than 1.0 is consistent with the reasonable incharacteristic of silver complexes of conjugated ference that the material under study is a mixture dienes.I0 Shortly after the equilibrium pressure of two complex silver salts, AgN03/C4H~(s) and (1) G. Salomon in "Catinnic Polymerization and Related Com(28gNO3)/GHs(s). plexes," P. H. Plesch, Ed., Academic Press, Inc., New York, N. Y., The mole ratio of butadiene to silver for a mix1953. p. 02. ture consisting of one part (2AgN03)/C4H6(s) and (2) W.0.Jones, J . Chem. Soc., 312. 1808 (1954). one part AgNOa/C4He(s) is 0.67. The amount of (3) A. C . Cope, D. C. McLean and N. A. Nelson, J . A m . Chem. Soc., butadiene released by the decomposing species in 77, 1828 (1955). (4) S. G. Traynham and J. Olechowski, ibid., 81,571 (1050). the initial experiment up to the point where dis( 5 ) E.W. Abel, M. A. Bennet and G. Wilkinson, J . Chem. Soc.. 3178 sociation of a second species was inferred, was (1059). 0.00247 mole. This represents 25% of the total (0) A. C. Cope and F. A. Hochstein, J . A m . Chem. SOC.,'73,2515
Introduction While the preparation of a number of crystalline silver nitrate olefin complexes has been reported in the no material of this sort has been prepared directly from hydrocarbons having less than five carbons. A solid silver nitrate/butadiene complex has now been prepared. The object of this paper is to describe its formation and properties. Experimental
(1950).
(7) A. C. Cope and IT. C. Campbell, ibid., 74, 17!) (ln52). (8)A. C. Cope a n d M. R. Kintner, ibid., '72,030 (1950). (9) A. C. Cope and W. R. Moore. i b i d . , '77,4939 (1955). (10) G.Salomon, Disc. Faraday Soc., 353 (1947-1948).
(11) Reversibility of complex forrnation under anhydrous conditions deiti9). ( 4 ) C \Tailing, "Free Radicals in S(,lutinn," J. Wiley a n d Sl,ns. Iric., S e w York, S . Ti., ICLi7.
but it scciiis tlixt orily sc.;tiit attention has been focused on an explicit comparison of the reactivity of a neutral free radical with its charged isoelectronic analogs. This neglect stems in large measure from the absence of comparative information on (3) A . F. 'l'rr,tm;Ln-Dickcnsoii."Frcc Radicals," .ZIctl~iicn dntl Cc), I.td , L o n d o n , 19.i9, p . 90. (6) I .\I Tedcler. ( J i i ? i . l , R'i'v , 14, :3:j6 ( I M O ) .
