NOTES
April, 1937 them to differ sharply with respect to their solubility in acids. The semicarbazoneswhich we have considered may be divided into two groups, those that are soluble and those that are insoluble in dilute hydrochloric acid. The former include the semicarbazones of pyrethrone, formula I, R = C& R’ = H ; dihydropyrethrone (jasmone), R = CsHs, R’ = H; tetrahydropyrethrone (dihydrojasmone), R = C6H11, R’ = H ; and tetrahydropyrethrolone, R = C6H11, R’ = OH. The acid-insoluble semicarbazones include those of pyrethrolone, formula I, R = c6H.1, R’ = OH; -pyrethrin I, R = .
761
Photoreaction of Chlorine Monoxide and Hydrogen BY T. IREDALE AND T. G. EDWARDS
According to Finkelnburg, Schumacher and Stiegerl chlorine monoxide dissociates, in the continuous absorption region of the visible spectrum, into C1 and CIO. We have found that addition of hydrogen accelerates the decomposition, at any rate, up to the stage where the secondary reaction Hz Clz = 2HC1 becomes prominent. As without the Hz, Cl2 and 0 2 are the main products, but there are now also small amounts of HCl and HsO. Finally all the Cl2 H H H C6H7,R’ = Ooc-c-c-C=C-(CHJ~; pyrethrin goes to HCl. \ / Since the reaction C1 H2 = HC1 H has a collision efficiency of and C1 Cl20 = Cl2 C10’ a collision efficiency of H atoms are not so important as the C10 and two geometric forms of hexahydropyrethrone radical in continuing the chain, that is, where the semicarbazone of melting points 160 and 194O, ClzO and Hz pressures are comparable. The chain must, therefore, be continued by the rerespectively, represented by formula 11. activity of C10 and H2, a state of affairs not much understood in the literature of this subject. We may have either C10 H2 = HClO H or C10 HZ= HC1 OH. The latter reaction seems the more probable. Further details will be forthcoming when we have studied the reaction more closely. I1 Contrary to the experience of others,2 we did not find that Cl20 was explosively unstable in the There seems to be no chemical feature distinpresence of strong light. A 500 candle power guishing the members of each group. The solulamp brought within 2.5 cm. of a spherical glass bility of some of the semicarbazones has been bulb (7.6 cm. in diameter) containing Cl20 at a utilized in their separation from other material. pressure of half an atmosphere, did not cause an All of an acid-soluble semicarbazone present in an explosion, nor did it do so when hydrogen was impure reaction mixture may be obtained pracpresent at the same pressure. tically pure by extraction with dilute hydrochloric (1) Finkelnburg, Schumacher and Stieger, 2. physik. Chsm., BlS, acid, removal of the by-products with a water- 127 (1931). (2) Wallace and Goodeve, Trans. Faraday Soc., 17, 653 (1931). immiscible solvent, and precipitation of the semiOF PHYSICAL CHEMISTRY carbazone with alkali. For example, a reaction LABORATORY OF SYDNEY UNIVERSITY product consisting of tetrahydro- and hexahydro- SYDNEY,AUSTRALIA RECEIVED SEPTEMBER 9, 1936 pyrethrone semicarbazones was separated into the two components by dissolving the one in dilute The Heat of Mixing of Diisobutylene and Isoacid and filtering from the other. octane To what extent the property of solubility in hydrochloric acid is shared by the semicarbazones BY WM.D. KENNEDY AND GEORGE S. PARKS of other ketones is a matter of interest, but one In connection with the recent study by Crawwhich we have not investigated. ford and Parks’ of the liquid-phase hydrogenation CONTRIBUTION FROM THE of &isobutylene (i. e., a material containing about BUREAUOF ENTOMOLOGY AND PLANTQUARANTINE 4 parts of 2,4,4trimethylpentene-l and 1 part U. S. DEPARTMENT OF AGRICULTURE
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(1) B. L. Crawford and 0.5.Parka, THISJOURNAL, 68,373 (1938).
