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THE INDUSTRIAL CHYMIST
CRYSTALLIZATION E . J . L u b e r o j , Ph.D. Since editors don’t get into the laboratory very much, and since your correspondent is rapidly becorning an editor, I thought I’d record, before they’re forgotten, some lab gimmicks I found particularly helpful. I don’t claim to have invented any of them; they were just part of the culture at Columbia when I was there. They may even be common knowledge, but I don’t recall having seen them in the literature. All have to do with lab scale crystallization, an operation whose aesthetics make it enjoyable, when done right, to nearly every chymist. I guess for this reason, plus the fact that I handled a lot of solids in my doctoral work, I set up everything described below in my first industrial l a b . . . a n d then watched it collect dust until I got my first solid five years later. First a point of personal philosophy: As soon as I had invested much time in a reaction, I split the batch into a leading, small pilot probe, which I followed with the main batch. Sometimes I divided the
As most know, the December zssue of I and EC Monthly a d 1 mark the end of thzs venerable magazzne and The Chymzst as you’ve known hzm. (The Quarterlzes wall continue!) In that last zssue there will be a questzonnazre that wzll solzcit your opznions to guide our new magazzne, Chem. Tech. Please look for the questzonnazre, complete at, and mad zt zn. For your trouble, you wall be sent a collectzon of Chymzst reprznts (while they last). Of course, we would always like your opznzons and, zf they’re approprzate, we wzll print them zn the letters column of Chem. Tech. Keep those cards and letters coming! 4
main batch in half, and if I decided to work u p the whole thing, then I processed the halves sequentially. Most often, however, I picked the initial batch size so that I could hold 50y0retain samples after each stage. SVhy? You’ll know the first time you put up two weeks worth of work to reflux in a flask with a star crack in it, or when the crystallizing solvent proves reactive, impure, or bumpy. The handiest gadget for handling the pilot probe-or the whole batch if it is less than a gram-is depicted in Figure 1. I t comprises five parts:
(1) A 1 5 in1 centrifuge conegraduated for quantitative work. (2) An 8 m m culture tube without lap. Again, for quantitative work get a tare weight on it and scratch the tare znto the side wzth a carbide scriber. Every piece of glassware I owned ended up marked thus. Such tares are quite constant. (3) A filter paper circle, cut with scissors, a sharp cork borer, or a hammer driven die made for the purpose. (4) The basis of the assembly is a hollow glass teardrop, whose broad face is a section of a sphere. I t takes a good glass blower to make these without any circumferential or radial ridges, but it can be done. (5) A holder made from stiff piano wire about 1 m m thick. I n operation, the solid is placed in the tube (2) and weighed. Solvent is added and dissolution effected by heating and stirring with a glass rod drawn to a fiber and twirled between thumb and finger. Cool to crystallize, place the moistened filter paper on top, then the teardrop, the wire holder, and finally the centrifuge cone. T u r n it over, put it in the centrifuge and spin it. Balance against a water-filled cone, or a similar assembly.
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
Dr. Luberoff is the newb appointed Editor of Chemical Technolog), the Society’s interdisciplinary magazine for the industrial practitioner. ( I t will begin publication in January 7977.) Prior to this appointment, D r . Luberof was M a n ager of Process Research for the Lummus Go., and was previously associated with American Cyanamid Co. and the Stauffer Chemical Go. H i s publications, which appear in the scient@ and patent literature both here and abroad, are characterized for the diversity of fields they cover from pesticide residue analysis through homogeneous catalysts to f u l l process j o w sheets. Dr. Luberoff received his Ph.D. from Columbia in 7953.
Done properly, the solids stay in the culture tube (quantitativcly) for drying, weighing, recrystallizing to constant mp, etc. The solvent in the cone can be measured, recovered, etc. Done in a hurry, hot filtration is even possible, although I’ve never had much luck with powdered charcoal filtration. For hot macrofiltration I use a solids funnel with a short, wide
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k Figure 7 .
stem, and fluted filter paper. Put a little solvent into the receiving flask, put the funnel with filter paper right on toF, and set it u p to boil. Let it boil until reflux forms just below the top of the funnel. (Wrap in a towel if necessary.) Then-with the filter still on the hot plate-run in the boiling solution to be filtered. (Ever run a boiling solution into a vacuum filter?) This works well for powdered charcoal filtration, but a cuter gadget is a “tea bag” made out of lens tissue and charcoal pellets. Drying with solid desiccants can be done similarly. They’re slow though, so stir occasionally and be patient. Finally you’ve got a crop of crystals (I prefer S-L-0-W cooling). Figure 2 depicts a handy system for any vacuum work-filtration, column chromatography, even drying. It’s made by having the bottom cut off a heavy wall filter flask-I used a 3 1. one-and then grinding it, with coarse carborundum, into a square of 1/4-in. plate glass. (The bigger the better to prevent the hose-or your lab partner-from tipping the assembly over.) T h e flask is sealed to the plate with grease, like a desiccator lid. And, like a desiccator, it should be taped or shielded. (I never knew one to implode.) This gadget enables you to collect, without transfer, into a flask, a beaker, or even a test tube. (All with scribed-on tare weights.) Cork rings or inverted glassware are useful to adjust height. If you overflow, pour out through the neck. If you want to concentrate or dry, use a heat lamp.
FUEL CELL SYSTEMS-II ADVANCES IN CHEMISTRY SERIES NO. 90 Thirty-one papers from the fifth of the biennial Fuel Cell Symposia sponsored by the Division of Fuel Chemistry, chaired by Bernard S. Baker. Topics Include: fuel cell power systems electrode structure use of hydrocarbons electrode catalysis and mechanisms high temperature fuel cells fuel cell systems Fuel cells are still doing their job well in the space program. Total energy, stationary fuel cell power plants seem worth a commercial push, and some hybrid devices look promising.
456 pages with index
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Other books in the ADVANCES IN CHEMISTRY SERIES in fuel chemistry include:
No. 80 Chemical Reactions in Electrical Discharges. 514 pages with index Cloth bound
(1969)
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No. 78 Literature of Chemical Technology. 732 pages with index Cloth bound
(1968)
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No. 69 Fuel Gasification. 276 pages with index
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(1967)
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No. 64 Regenerative EMF Cells. 309 pages with index Cloth bound
(1967)
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No. 55 Coal Science. 743 pages with index
Cloth bound
(1966)
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No. 54 Advanced Propellant Chemistry. 290 pages with index Cloth bound
( 1966)
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No. 47 Fuel Cell Systems. 360 pages with index
(1965)
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No. 20 Literature of the Combustion of Petroleum. 295 pages with index Paper bound
( 1958)
$8.00
No. 5 Progress in Petroleum Technology. 392 pages Pa per bound
(1951)
$8.00
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f Figure 2.
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