Butene sulfide polymerization

In the polymerization of propylene sulfide and 1,2-butylene sulfide mainly tetra-mers were observed. Cycles were formed mostly during the slow degradation process that followed rapid polymerizations. Degradation can also be induced by adding cationic initiators to polymer prepared by other mechanisms, e.g. by anionic processes. Thus, poly(trans-2,3-butene sulfide) is rapidly degraded to equimolar amounts of 3,5,6,7-tetramethyl-l,2,5-trithiacycloheptane and trans-butene 47). Poly(cis-2,3-butene sulfide) forms, however, a mixture of tetramer, trithiacycloheptane derivative and cis-butene 47 . If one is forced to use cationic processes for the synthesis of poly-sulfides, the reaction conditions should be controlled to avoid macrocyclization. If cyclic products are desired, the kinetics of their formation should be studied to determine optimum yields. 

In the cationic polymerization of heterocycles, a similar phenomenon was observed by Goethals in the polymerization of propylene sulfide and trans 2,3-dimethyl-thiirane. The latter monomer polymerizes rapidly and quantitatively to a linear polymer which is then relatively slowly converted into 3,4,6,7-tetramethyl-l, 2,5-tri-thiepane (J67a). In this particular process, the macroring formation is a practically irreversible reaction and differs in this sense from the equilibrium processes discussed so far. The irreversibility is due to the formation of one molecule of cis-butene per one molecule of a cyclic trithiepane ... 

For both oxide and sulfide molybdenum catalysts, the ratio between butane and butenes is much higher than 1. As temperature rises, this ratio decreases for the oxide forms and increases for the sulfide forms. Polymerization begins at T > 300"C on both catalyst forms. For all bimetallic catalysts, excepting Mo-Ni oxide catalysts, the ratio butane butenes is higher than 1 at 300 C. The amount of resin materials holds with time only for Mo catalysts. For bimetallic catalysts, the conversion of THF into resin materials increases with time by 10-15%. For all catalysts, excepting Mo-Ni sulfide catalysts, the yield of resin con lexes increases with increasing temperature. 

BUTENE OXIDE (106-88-7) Forms explosive mixture with air (flash point -7°F/-22°C). Unless inhibited, violent polymerization can be caused by elevated temperatures, sunlight, acids, aluminum chlorides, bases, iron, tin, potassium, sodium, sodium hydroxide, or certain salts. Reacts violently with oxidizers, alcohols. Reacts with hydroxides, metal chlorides, oxides. Flow or agitation of substance may generate electrostatic charges due to low conductivity. Storage tanks and other equipment should be absolutely dry and free from air, ammonia, acetylene, hydrogen sulfide, rust, and other contaminants. 

---