Dual Schlenk/Vacuum Line
Several components for this line were generously donated by Dr. Lewis J. Fetters while at Exxon Corporate Research. The system is useful for a range of reagent manipulations under inert atmosphere, and is the staging ground for the majority of our anionic polymerizations of styrene, isoprene, butadiene, and related monomers. The line consists of two Schlenk lines (vacuum/nitrogen), with the vacuum halves connected together through an Ace valve; the vacuum line is driven by an Edwards 12 pump at the right end of the line, which routinely achieves a base pressure of 40 mtorr with liquid nitrogen trapping. The central isolation valve allows the system to be used either as one large line (when open), or (when shut) to use the right half as a normal vacuum line (with a low base pressure) and the left half for other operations such as the collection of liquid butadiene monomer. The nitrogen gas in the Schlenk line can be exchanged for CO2 to permit selective acid-functionalization of chain ends; a Firestone valve prevents entry of atmospheric gases into the line when backfilling large vessels.
This dual Schlenck line provides three ports each of vacuum and nitrogen. Its main use is in providing oxygen free conditions for free radical polymerizations. It also allows vacuum distillation for the purification of reagents. Vacuum is provided by an Edwards RV12 pump, an Edwards diffusion pump, and a liquid nitrogen trap, providing base vacuum of 45 mtorr. House nitrogen is used after purification through a copper catalyst, and a Firestone valve prevents the entry of atmospheric gases.