W. M. Hoehn and J. Derland Johnston
G. D. Searle and Company
Chicago, Illinois
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Equipment for Use in Orgpnk Synthesis
Stainless steel cans have been adapted for certain operations in organic chemical synthesis to replace five-gallon Pyrex glass bottles. The bottles were used extensively in the past for filtrations and as reaction vessels, but at the risk of breakage and implosion. Five gallon stainless steel milk cans' were first tried for filtrate collection. The lid fitthe can well and two holes were bored in the lid. Stainless steel tubes were cut to proper lengths and fitted into the holes, one tube for connection to a Lapp filter and the other for connection to a vacuum line or a water aspirator. Each can had two sturdy handles which made it easy to lift.
After the initial work with the cans, it was found that the false bottom could be easily made into a steam chamber (Fig. 1). Two stainless steel tubes were welded into holes in the false bottom. The can was then used for recrystallization procedures. The next step was to modify the lid for reactions which might require a stirrer, a condenser, an addition tube, and a thermometer. One method was to use a ground-glass joint fabricated from standard 2-in. conical Pyrex pipe. A 6-in. nipple was cut in two, a bead was formed on the cut end of the pipe, and a $ 5 5 / 3 5 taper was ground into the cut end to accommodate a + 55/50 joint (Fig. 2 ) . A hole was cut into the lid and a Chole pipe flange2 'The can used for this purpose was obtained from The John Wood Co., St. Paul, Minn.; Catalogue No. 620.5. A Corning Style-2 cast iron flange ASME Chalt circle far 2-in. Pyrex pipe was used.
Figure 1. Tubing welded to holes in false bottom converts the can into o vesrel that con be heated with steam. Spring clornpr hold down the lid in which a hole has been cut and o 355135 ioint held in pioce with 0 pipe flange.
Figure 2.
Modification of the milk con iidr.
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was attached with stainless steel bolts to the lid at this opening over a 2-in. Teflon Ful-Flo gasket. The gasket was cemented with silicone rubber to the lid and the conical pipe. Silicone rubber3 was applied to the base of the holder, and the ground joint was secured in place with a rubber insert in the upper part of the flange. A space existed where the underside of the lip made contact with the lip of the can. A ring of rubber tubing was placed in this space and covered with silicone rubber (Fig. 2). The lid was held firmly in place with spring clamps welded or bolted to the shoulder of the can. Distillation at atmospheric pressure or under reduced pressure was carried out by applying steam to the bottom section. An arrangement for stirring was satisfactory, but additional equipment on this size joint was awkward and top-heavy.
Iarged to a 4-in. diameter, and a 2-in. length of stainless pipe (4in. diameter) was welded to the dispenser at this place. A 4in. Corning Drainline Coupling6 was installed to accept a special open-bottom three-neck bulb (Fig. 4). The bulb was made from a 1-liter roundbottom Pyrex flask with T 29/42 outer joints. A 4in. hole was blown into the flask, a piece of Pin. diameter heavy-wall glass tubing was fused to the bottom of the flask, and the bottom edge was beaded. A Teflon coating baked onto the inner surface of the can8 enables one to use the can for liquids which might attack the metal. I t has been ohserved, however, that a stainless steel milk can that was coated about two years ago has shown a tendency to collapse slightly under vacuum. Possibly the heat treatment during the coating procedure affected the metal structure. Experimentation with this type of vessel has been encourag-
I n addition to the milk can, a stainless-steel softdrink dispensing unit4 was modified. This can (Fig. 3) has two small valves located on the top surface. One of these valves is connected to a short piece of stainless steel tubing and the other to a piece of tubing that extends to the bottom of the container. These tubes make the container useful for filtration under reduced pressure. The bottom was modified for steam and water circulation. A circle of stainless steel was welded to the base, tubes for steam and water connections were added, and existing openings in the base were filled (Fig. 4). The opening on the top of the can was en-
ing, and other modifications will be made. Reactions have been carried out a t low temperatures (0" to -70°C) with excellent results due to the good heat transfer by the metal container. The breakage problem has been eliminated, the equipment has been much easier to handle, and time has been saved in the rapid removal of solvent. One disadvantage to the equipment is not being able to observe what is occurring inside the vessel. A sightrglass fitted to the side of a milk can did not prove as useful as had been anticipated. The authors gratefully acknowledge the suggestions received from Gatis Plume, William Aksamit, and Jack Drogt during the evaluation of the equipment described.
General Electric RTV-102 silicone rubber was used ss a sealing agent. 'Firestone Steel Products Co. lists this can as a 5-gal Stubby Premix Container No. 26979; Stainless Steel Type 304.
Corning Glass Co., Catalog No. 4009. 6The coating was done by the Ecko Products Co., Chicago.
Talanta Publishes G. Federick Smith Issue The July issue of Talanla honors Emeritus Professor Smith of the University of Illinois, on the occasion of his 75th birthday. The issue contains papers by his former students. The range of topics is wide, as have been Dr. Smith's interests. Professor Harvey Diehl (Iowa State University) has prepared a summary tribute to Dr. Smith's 45 year career in analytical chemistry,
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