The reactions of 2-benzal-1,3-indanediones and the cyano-containing benzalmalononitriles, ethyl benzalcyanoacetates. be~lzalcyanoacetamides, and benzalcyanoacetanilldes with 12-butanethiol at 25 "C in 20%kthanol-80% pH 7 buffer attain equlibrium at a rate too fast to measure by standard methods.The equilibrium constants have been calculated and these in turn related to Hammett o and Taft o* constants. The differences in the reactions of these and other gem difunctional systems which react virtually completely with 12-butanethiol under the same experimental conditions and at a measurable rate, are attributed to participation of the functional group cis to the phenyl group in the reverse reaction. It is shown that 12-butanethiol adds to cinnamalacetophenone by a 1,4-mechanism and the reactions of this nucleophile with similar compounds having extended conjugated systems are discussed.

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The concept of additive constants to predict the partition coefficient of a compound has been developed and applied to 244 compounds. Some of the limitations of such a concept are discussed.

oxide has a very low paramagneti~ml~ it is still necessary to postulate the presence of other copper(I1)-containing materials, such as IV and V, to explain the paramagnetic nature of the residues obtained. ExperimentalPreparation.-Three hundred and ninety-six mg. (2 X 10-3 mole) of tetraacetylethanezo was dissolved in 100 ml. of tetrahydrofuran. Exactly 10 ml. of 0.200 M aqueous cupric acetate was added, a t room temperature, dropwise from a buret over a period of one hour. The mixture was stirred with a magnetic stirrer. A green precipitate formed continuously during the addition, after the first few drops of cupric acetate solution had been added. The mixture was allowed to stand for an hour and then the solid was filtered off on a sintered glass crucible. The blue filtrate contained copper but the absence of tetraacetylethane in the filtrate was established by the lack of significant light absorption in the 240 to 300 mp region of the ultraviolet.21The polymer was washed with water, tetrahydrofuran and acetone, air-dried a t room temperature for several days, and finally dried for an hour in a vacuum oven at 100".Sealed Tube Experiments.-One hundred mg. of the sample was sealed, under vacuum, into a Pyrex tube and heated for 4 hr. in the same manner as described previously.3 In computing T , the actual concentrations of the leading and indicator solutions in each measurement were employed: these deviated slightly from the rounded value quoted in Table I, but r itself is insensitive to small changes in concentration. See ref. 3.

The y-ray induced, and photochemical, chain decompositions of stirred, concentrated aqueous solutions of hydrogen peroxide at 10 and 25°C and at natural pH and pH 1 have been investigated gasometrically. The curves of decomposition rate against peroxide concentration always have a maximum. The dose-rate and light intensity exponents in the empirical rate equation are close to 0.5 and the kinetic chain life-time (measured by the rotating sector method) is independent of the peroxide concentration but shorter at natural pH than at pH 1. The results are explicable on the basis that (i) at pH 1 the chain carriers are OH and H02 whereas at natural pH they are OH and 0 2 ; (ii) k(2H02 -+H202+02) = 2 x 106 M-1 sec-1; (iii) the form of H202 which reacts with HO2 or 0 5 in the propagation step is the dihydrate, and (iv) K H O ~ 1: 1.5 [H+] in concentrated peroxide solutions at 10°C.