IDEAS Chemical Heavyweight acid. We bring phosphotungstic acid out of its corner to display its chemical prowess. First thing you notice, it's built like a bull, weighing in at almost 3000 a.m.u. Formula H3[P(W 3 Oio)4]'5H 2 0. The phosphotungstate ion is built out of WC>6 octahedra. Three such octahedra share oxygen atoms at the corners to form a triangular group. Four groups share corners to create a cage. The P atom sits inside this cage, trapped in a tetrahedral hole and handcuffed to four nearby O's. This structure still looks elegant at a mol. wt. of 2879. Of this, 2208 is tungsten.
With this massive body it's easy to overlook the three active H's that give it the acid punch. PTA is a strong acid. It dissolves very easily in water where it provides powerful oxidizing action. It also dissolves in organic solvents such as acetone and diethyl ether. At the AEC they use it to precipitate radioactive cesium. But if you're a dye chemist, you can use the precipitating action of PTA and its sodium salts to make brightcolored organic dyes and pigments that defy light, heat and moisture. You can use them as catalysts to hammer petroleum and other organic molecules into new shapes. They're good for isomerization, polymerization, aromatization, ring-closure, ketone and nitrile syntheses and a lot of other clever catalytic tricks described in the literature. You might try using PTA and its salts as oxidants in photographic processes, let's say as fixing agents. In furs, the sodium salt is used as a "carroting" agent, and in textiles both acid and salt are used as antistatic agents. You'll find PTA in the Merck Index as a respected reagent for alkaloids, albumin, peptones, aminoacids, blood, carbohydrates, etc. We could go on and on. We sell phosphotungstic acid and its sodium salt derivatives. The acid is noted for its low alkali content, and we recommend it wherever sodium and chloride ions can't be tolerated. What we recommend right now is that you send for more details on this fighting acid. Through rain and snow and sleet—faster. There's an extra lift to your airmail letters and more of a kick in your first-class mail thanks to new phosphores4
C&EN
SYLVANIA GENERAL TELEPHONE & ELECTRONICS
cent inks used to print postage stamps. The phosphors come from us. (We ship them to the government by the ton.) The purpose is simple: to boost the efficiency of a canceling machine and speed up the mail. A ray of ultraviolet light in the machine makes airmail stamps glow orangered and regular stamps glow green. The machine can then separate the two at a furious rate and cancel the stamps at the same time. Our part in this speedup, however, is not as simple as you might think. We ran through thousands of phosphors before we developed the perfect twins. Sure, we have phosphor powders that luminesce brightly, and it's no trouble to grind powders very fine. But just try to make a phosphor that's both bright and superfine. Turns out the two are incompatible. There's also the matter of making the phosphors non-toxic for people who might lick their stamps on the wrong side. Our solution for the red phosphor is a manganeseactivated calcium silicate with an average particle size of 2 microns. The green phosphor is zinc silicate. They join other of our phosphors that have made technological history in jobs such as detecting counterfeit money, illuminating safety devices, coating fluorescent tubes, tracing air currents, making plastics glow and—not least of all —brightening your TV picture. Your phosphor problem may not be as far-reaching as the U.S. Mail's, but we are inclined to treat it with the same importance it has to you. Ask us. Sylvania in chemicals? People are so used to seeing our name on television sets, lamps, electron tubes and a lot of esoteric devices that depend on making electrons and photons behave in intricate ways, that they fail to see us as chemists (which we are). With all the tungsten and molybdenum we use in light bulbs alone, it's no wonder we got into the chemistry of these elements. Especially since the starting point for the pure metals is in high-grade compounds like tungstic acid and molybdenum oxide. Fluorescent and cathode-ray tubes in all their forms, including the one we spend so much time staring at, were the stimulus for our getting into the phosphor business. We've been in these chemical areas for 28 years, and though we don't find anybody chalking "Yankee Go Home" on our doorstep, we still occasionally meet somebody who raises an eyebrow at the name Sylvania on a chemical package. Let's get better acquainted. We'll gladly send you a non-electronic description of what we've got. It's plenty. Sylvania Metals & Chemicals, Chemical and Metallurgical Division, Towanda, Pa. 18848
