Butadiene and styrene have been copolymerized by the use of sodium sand as a catalyst. The copolymers containing 75 parts of butadiene and 25 parts of styrene and made at 30° and 50° are soluble in benzene and have intrinsic viscosities ranging from 2.5 to 7.5. The copolymers has a very nearly constant composition throughout the course of the polymerization. The amount of butadiene which has entered the chain by 1,2 addition is greater than in the case of the emulsion copolymer.

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Some reactions of the tabulated compounds are mentioned below. The reactions are rapid and quantitative, and serve to characterize the compounds as derivatives of RSe+.In ethyl acetate-ethanol solutions o-nitrobenzeneselenenyl thiocyanate, di-O-alkyl monothiophosphates and thiosulfonates react with aqueous sodium thiosulfate as follows RSeX + 8,0," = RSeSiO,-+ X" This is analogous to the behavior of the corresponding sulfenyl compounds.4 o-Nitrobcnzeneselenenyl sulfinates, in ethyl acetate-ethanol or ethanol solutions, react with aqueous potassium cyanide to give o-nitrophenyl selenocyanate RSeS02R' + CN-= RSeCN + R'SOr o-Nitrobenzeneselenenyl thiosulfate reacts with sodium cyclopentamethylenedithiocarbamate thus RSeSiOr + C5HioNCS2-= RSeS(S)CNC6H10 + & The product has previously been prepared1 from the bromide.

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compose amylose, and the value obtained for iodine absorption may be only a practical maximum and fortuitous. Packing considerations alone would allow about one iodine molecule for five glucose residues, since one molecule would require about 6.8 A. along the helix. Furthermore, it is hard to understand why reflections of the type (00hi) are absent if the iodine molecules are spaced 7.91 A. apart along the helix. It seems possible that their arrangement is at random in a set of six equivalent positions per turn in the helix, giving rise to an effective sixthing of the spacing along the c axis. Unfortunately, the temperature factor for the complex is so high that the reflection (006) could not possibly be observed at room temperature. This leaves the space group in doubt. Summary 1.The amylose -iodine complex has a hexag-onal unit cell, 0 -12.97, Co = 7.91, dm = 11.23 A.2. The unit cell confirms a helical structure for the starch-iodine complex; 12.97 A. is the diameter of the helix, 7.91 Á. is the length of a turn in the helix. These dimensions are in good agreement with the dimensions of a space-filling model of a helix with six glucose residues per turn.