ANALYTICAL EDITION
52
all ferrous and vanadyl ions were oxidized could not be detected. LITERATURE CITED (1) Hamner, Met. & Chem. Eng., 17, 206 (1917). (2) Kolthoff and Sandell, IND. ENQ.CHEM.,Anal. Ed., 2, 140 (1930). (3) Kolthoff and Tomicek, Rec. trav. chim., 43, 447 (1924). (4) Lang and Kurtz, Z . anal. Chem., 86, 288 (1931). (5) Lundell, Hoffman, and Bright, "Chemical Analysis of Iron and Steel," p. 294, Wiley, 1931. (6) Ibid.,p. 298. (7) Waldcn, Hammett, and Edmonds, paper presented before the
Vol. 6, No. 1
Division of Physical and Inorganic Chemistry a t Washington Meeting of the American Chemical Society, March 26 t o 31, 1933; Edmonds, Dissertation, Columbia University, 1933. (8) Walden, Hammett, and Chapman, J. Am. Chem. Soc., 55, 2649 (1933). (9) Willard and Gibson, IND.ENG.CHEM.,Anal. Ed., 3, 88 (1931). (10) Willard and Young, IND.ENQ. CHEM.,20, 769 (1928). (11) Ibid., 20, 972 (1928). (12) Ibid., Anal. Ed., 5, 158 (1933). (13) Zintl and Zaimis, Z. angew. Chem., 41, 543 (1928).
RECEIVED July 24, 1933. Presented before the Division of Physical and Inorganic Chemistry st the 86th Meeting of the American Chemical Society, Chicago, Ill., September 10 to 16, 1933.
Iodine Value of Rubber and Gutta-percha Hydrocarbons As Determined by Iodine Chloride A. R. KEMPAND G. S. MUELLER,Bell Telephone Laboratories, 463 West St., New York, N. Y
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g l a c i a l a c e t i c acid has been ALOGEN a b s o r p t i o n The reactivity qf various halogens towards widely used and accepted. methods e m p l o y i n g rubber and gutta-percha hydrocarbons has been In a previous investigation solutions of b r o m i n e , studied quantitatively. The behavior of both (b), various halogen absorption iodine bromide, or iodine chlohydrocarbons toward halogens is very similar. methods for determining the unride are widely used for determinThe order of reactivity of the halogens is chlorine, saturation of rubber and guttaing the unsaturation of organic percha were studied and it was compounds. In the use of these bromine, iodine chloride, iodine bromide, and found that the W i j s r e a g e n t methods the choice of halogen iodine, The results show that gutta-percha (iodine chloride in glacial acetic reagent, the amount employed, possesses a greater initial reactivity towards acid) was the most satisfactory and the time and temperature iodine than does rubber. for this purpose. It was shown for the reaction are all important Data and detailed procedure are presented that under suitable conditions f a c t o r s which must be given iodine chloride adds quantitawhich offer further rejinements to the iodine careful consideration in order tively to the double bonds in that the best results may be obchloride method for the determination of the rubber h y d r o c a r b o n in close tained. Certain structural difunsaturation of rubber and gutta-percha hydroagreement with t h e o r y 4 e., one ferences in unsaturated organic carbons. molecule of iodine chloride adds compounds may have a decided Methods f o r the preparation of pure rubber and to each C& grouping. This is influence on the reactivity of equivalent to a theoretical iodine gutta-percha hydrocarbons are included and the these substances toward halovalue of 372.8 and values found gens, For example, the presence corresponding iodine values found by the use of by the iodine chloride method of negative groups on one or both modiJied iodine chloride procedure are shown to for p u r e r u b b e r hydrocarbon of the unsaturated carbon atoms be in close agreement with the theoretical. agree to within less than 0.5 per protects against halogen addiIt is recommended, in the case of gutta-percha cent of this figure. tion; thus m a l e i c or f u m a r i c The method previously dehydrocarbon, that a greater excess of iodine acids do not add iodine chloride scribed (6) involves s w e l l i n g (7). Styrene adds iodine chlochloride be used and that the reaction be carried 0.10-gram samples of rubber, ride quantitatively, but in the on at room temperature for a longer period of etc., in 75 cc. of carbon bisulfide, caseof c i n n a m i c acid only a time than that required for rubber. adding 25 cc. of 0.2 N i o d i n e slight reaction t a k e s place (4). chloride in g l a c i a l acetic acid. No addition of iodine chloride occurs with dichloroethylene andivery little with vinyl bromide allowing the solution to stand 2 hours a
