placed next to the flask as a source of illumination. The reaction proceeded rapidly at room temperature. After the addition was complete, the reaction mixture was washed with sodium bisulfite followed by water, dried and rectified to give principally the tetrabromo addition product along with some of the dibromo compound.Bromination of 2,7-Dimethyl-3,3,4,4,5,5,6,6-octafluoro-1 ,'l-octadiene.-This olefin was brominated in a similar manner with the exception that the reaction temperature was maintained a t the reflux temperature of the mixture. Only the tetrabromo addition product was isolated.Bromination of 5,5,6,6,7,7,7-Heptafluoro-3-heptene.-A solution of 150 g. of the olefin in 100 ml. of carbon tetrachloride was cooled to 12" and a solution of 120 g. of bromine in 100 ml. of carbon tetrachloride was added dropwise. The reaction was illuminated by a 150-watt light bulb placed next to the flask. After one-half the bromine was added, the temperature rose to 22" and hydrogen bromide was liberated. The temperature was lowered to 10' and the remaining bromine added. After standing for 12 hours a t room temperature, the reaction mixture was refluxed for two hours causing further liberation of hydrogen bromide. The solution was then washed with sodium bicarbonate followed by water, dried and rectified. Both the dibromo addition product and an olefin resulting from its dehydrobromination were obtained.Bromination of 2-Methyl-4,4,5,5,6,6,6-heptafluoro-2-hexene.-A solution of 160 g. of the olefin in 150 ml. of chloroform was placed in the flask and a mixture of 125 g. of bromine in 100 ml. of chloroform was added dropwise. No cooling was employed and the reaction temperature rose rapidly to reflux with the liberation of hydrogen bromide. After the addition was complete, the mixture was refluxed for 48 hours. The solution was then washed with sodium bicarbonate followed by water, dried and rectified. The dibromo addition product was obtained as well as two bromine substituted derivatives of the starting material.Acknowledgment.-The authors wish to express their appreciation to the Petroleum Branch, Materials Laboratory, Wright Air Development Center, Dayton, Ohio, for supporting this work. LAFAYETTE, IND.The latter material was not identified. ~~The present investigation shows that the earlier assignment of a "head-to-head'' arrangement of the monomer units it1These polymers have beeii polyalkyl a-haloacrylates was based on a misinterpretation of the reactions of these polymers. proved to have predominantly the "head-to-tail" structure.
The impact of the lithium initiator system has begun in the rubber synthesis field; it will surely expand into the production of plastics of controlled and desirable structure. Polymers can be designed in both fields with precise structure control for desired processing characteristics and properties. This will become more useful as the concept of domains and heterogeneity is more fully understood and utilized. The system will also lend itself to planned termination by functional groups where the products will have unusual reactivities. Solution polymerization systems should play an increasing role in the production of synthetic rubber. Of course, the emulsion system must be considered in applications where latex itself is desired and in those cases where monomers with functional groups would react with the organometallic initiator. Otherwise, we believe that solution systems will produce rubber with especially desirable properties more cheaply without as much harm to the ecology.
The observations of Peters and Walker (1) and Mohler and Hartnagel (2) that the rate of hydrolysis of ß-chloroethyl sulfide (I) in water was first order, independent of the pH and a number of added anions and cations, led the latter authors to point out that this behavior resembled that of an SNi process proceeding by a solvolytic mechanism in which the rate controlling step was an ionization of the carbon-chlorine bond.
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