Separate amines easily, efficiently with
Report
have wide liquid ranges and have been used extensively with the facility described here. A mixture of 65% isopentane and 35% 2-methylpentane (by weight) freezes a t 105 °K and boils at 308 °K, thus being considerably safer t h a n propane. However, the relatively high freezing point leaves a gap of about 15° to the pressurized liquid nitrogen t e m p e r a t u r e . T h e Fréons are neither flammable, explosive, toxic, nor overly viscous a t low temperatures. Their liquid range is somewhat smaller than t h a t of propane, but it can be extended by using solutions. A mixture of 14% Freon-12 (CC1 2 F 2 ), 72% Freon-13 (CC1F 3 ), and 14% Freon-22 (CHC1F 2 ) has a freezing point of about 86 °K and a normal boiling point of about 197 °K, and it is therefore especially suitable for the requirements of this facility. A major disadvantage is the high price which necessitates a recovery system. T h e vapor pressure of the mixture is about 26 atm. at 25°. To fill the reactor system, the Freon mixture is liquefied by passing it through a coil immersed in liquid nitrogen. T o return the Freon back to storage, the refrigerant system is pressurized—e. g., with dry nitrogen. Before receiving the refrigerant solution, the 30-1. stainless steel storage container, which is insulated with pliable plastic foam sheeting, must be prccooled by passing liquid nitrogen through a coil which is soft soldered to its outer surface. Without this precooling, vaporization of the Freon would cause a pressure buildup in the t a n k and prevent refrigerant backflow.
New Chromosorb* 103
Chromosorb 103 is a polyaromatic porous resin developed by Johns-Manville as a solid-type support for the separation of amines and basic compounds. Until now, amine separation has been both laborious and difficult. With new highly selective Chromosorb 103, it's fast and easy. For more specific information, write for our bulletin FF-181. Johns-Manville, Box 290-C, Trenton, New Jersey.
Johns-Manville
*Chro,Tiosorb is a J o h n s - M a n v i l l e registered t r a d e m a r k f o r its b r a n d of p r o d u c t s deve o p e d for use as s u p p o r t m a t e r i a l or a d s o r b e n t s for gas c h r o m o t o g r a p h y . Circle No. 38 on Readers' Service Card
32 A .
ANALYTICAL CHEMISTRY
The useful ranges of these several convenient cryogens are evident from Figure 4 as are the technical difficulties, should an experiment require a temperature range exceeding t h a t of a single refrigerant. An alternative design imposes less restrictions from this perspective (β). Mass Spectrometer Inlet. The valve between the reactor and the inlet tube has very demanding pre requisites. It must be chemically inert, and it must reliably close off 1 atm from 10-° tort· at 77 °K. After m a n y design tests, a N u p r o bellows-type valve (Model B4BKSÏ with a brass body and a stainless Circle No. 126 on Readers' Service Card
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