126th NATIONAL
ACS MEETING
DIVISION OF ANALYTICAL CHEAAsSTRY
Aluminum via Infrared Spectroscopy • " H y d r o x y l " O H stretching a n d d e f o r m a t i o n vibrations g i v e n e w data on b a u x i t e a n d d i a s p o r e clays • X - r a y photometry a n d increasing k n o w l e d g e of a b s o r p t i o n coefficients e n h a n c e use in analysis TNFRARED
SPECTROSCOPY
has
been
"*- used satisfactorily for the first t i m e for the characterization of all alumina hydrate forms, according to Leo D . Frederickson, Jr., Aluminum Research Labs. T h e technique cuts to five to 10 minutes the time required for complete identification, which includes grinding to required particle size. Frederickson predicts that this method will prove to b e a valuable adjunct to x-ray identification in t h e study of other systems of a similar nature. Frederickson pointed out to Analytical Division that while bauxite ores are the principal source of material useful for reduction to metallic aluminum, deposits throughout the world differ in type of h y d r a t e they contain. For example, U. S. and South American ores contain a trihydrate phase, while European bauxites are predominantly a monohydrate form. In the past, various phases h a v e b e e n identified, both in their p u r e state and in ores, by characteristic x-ray diffraction patterns. Use of infrared spectroscopy involves "hydroxyl" O H stretching and deformation vibrations. A number of interesting observations have been m a d e in survey spectra of bauxite ores and diaspore clays. T h e broad nature of the O H vibration pattern in t h e oalumina trihydrate is suggestive of hydrogen bonding in the crystal. The O H stretching vibration in diaspore occurs at a lower frequency than those of other hydrates. T h e structure in this form—closely-packed hexagonal, each oxygen atom equivalent to every other and joined together through a h y d r o gen atom—agrees with the observed low frequency and broad, weak nature of the O H stretching band, indicative of a strong hydrogen bond. Vacuum Fusion. Research at General Electric shows that tungsten carbide can b e completely burned in 3.5 minutes without a flux. E. L. Simons says t h a t in t h e n e w technique t h e combustion temperature of 1400° C. is rapidly obtained by subjecting sample, contained in a small porcelain crucible, to radiation from a surround3832
ing platinum case. This case is heated to about 1600° C. by high frequency field of a modified Lindberg induction furnace. Resulting carbon dioxide may b e measured by any convenient means. Investigations Simons m a d e jointly with E. W. Balis and J. E. Fagel show the average of eight determinations of carbon in a previously analyzed tungsten carbide sample containing 6.12% carbon is 6.10% with standard deviation of 0.07%. In other vacuum fusion work at G E , J. E. Fagel finds that in determining oxygen by iron bath technique, the iron b a t h solidifies at normal operating temperatures because graphite precipitates. It is not because of the previously held view that an iron-carbon alloy forms, which melts above operating temperature. The earlier misconception has been a major source of error in the iron bath technique of vacuum fusion analysis and is believed to explain the common difference in results between labs employing this technique. Fagel says that the realization of the
reported phenomenon, w h i c h concerns only the iron-carbon system, should lead to significant improvement in vacuum fusion work in iron bath technique. Heretofore, attention has been focused on limiting concentrations of other metals in the bath b u t not to the fundamental limitation imposed b y precipitation of graphite in the bath alone. Tin Studies. Quercetin has been used for satisfactory quantitative colorimetric determination of microgram amounts of tin (IV) in range from 0 to 150 y. Leo Schubert, American University, and Charles E. W h i t e , University of Maryland, h a v e found it the most suitable reagent after investigating about 150 compounds as possible reagents. Sensitivity of reaction is better than 0.01 y of tin ( I V ) per ml. Work indicates a 1 to 1 mole ratio for the tin (IV)-quercetin complex. Use of technique has been employed in a hydrolytic method to separate microgram quantities of tin from brasses and bronzes a n d give excellent results with analysis of standard samples, says Schubert. Spectrophotometric determination of esters and anhydrides by the hydroxamic acid reaction, accurate t o ±:2%, was reported b y R. F . G o d d u giving results of his investigations w i t h N . F . LeBlanc and C . M. Wright, all of Hercules Powder. Esters or anhydrides are allowed to react with hydrosylamine in alkaline solutions. Hydroxamic acid forms with ferric ion a highly colored chelate complex, which is measured spectrophotometrically. Accuracy is less when
Louis Meites, Yale University, described current integrator which can be used for controlled potential coulometric analysis accurate to 0.1% before Analytical Division
CHEMICAL
AND
ENGINEERING
NEWS
CARBOHYDRATE CHEMISTRY both esters or anhydrides are p r e s e n t in mixture. Intensity of color is affected by presence of high concentrations of carbonyls, transition elements, and ions which complex ferric ion. G o d d u said t h a t optimum c o n c e n t r a tion range of technique is 1 0 - 3 t o 10- 2 M. N o n a q u e o u s Titrations. Conductometric titration of sulfuric a n d h y d r o chloric acids a n d their mixtures in a n hydrous acetic acid with alkali acetates show a differentiation in the neutralization end points of the two h y d r o g e n s of sulfuric acid. Takeru Higuchi and Carl R. R e h m also find in work at University of W i s consin t h a t mixtures of sulfuric a n d hydrochloric acid show t h r e e b r e a k s w h e n titrated with lithium a c e t a t e . These occur w h e n the first h y d r o g e n of sulfuric acid is neutralized, w h e n the hydrochloric acid is neutralized, and finally w h e n the second sulfuric hydrogen is neutralized. T h e t h r e e breaks serve as means to estimate q u a n titatively sulfuric and hydrochloric acid in t h e mixture. Bismuth can b e accurately titrated in the presence of other ions i n c l u d i n g large amounts of lead b y use of e t h y l enediaminetetraacetic acid, a c c o r d i n g to James S. Fritz, Iowa State College. In this reaction, disodium ethylenediaminetetraacetate forms a stable soluble complex. Excess thiourea is added, forming a weak complex w i t h bismuth, avoiding any precipitation before or during the procedure. T h e endpoint of titration is m a r k e d by disappearance of last yellow color from complex. This m e t h o d has advantage of avoiding numerous interferences w h i c h d e velop in titrimetric determination of bismuth b y commonly used tests. Tracer S t u d i e s . Of possible application in atomic research is the carrierfree yttrium-90 prepared b y M. L . Salutsky and H . W . Kirby of M o n santo. C o m p o u n d is separated from its parent b y precipitation of strontium 90 with strontium nitrate carrier i n 8 0 % nitric acid. Yttrium-90 has proved its value as a suitable yttrium tracer for fractionation and coprecipitation studies as it has a convenient half life, has no r a d i o active d a u g h t e r , and is a pure b e t a emitter. However, Salutsky said t h a t there has been lack of agreement in reported values for half-life v a l u e . Beta counting at Monsanto shows halflife to b e 64.0 hours.
• Polychromatic X-Ray Studies Although x-ray absorption has b e e n used increasingly for nondestructive testing, it has not been applied t o u s ual type of chemical analyses as widely VOLUME
3 2,
NO.
39
•
as it could be. Information regarding x-ray absorption coefficients for materials in solution is not generally available as the coefficients cannot b e calc u l a t e d accurately. Maurice C. Lambert, Hanford Atomic Product Operation, is investigating absorption of polychromatic xrays b y aqueous solutions of 3 5 comp o u n d s and ions of 2 5 elements widely distributed in t h e periodic chart. K e uses voltages ranging from 25 to 75 p e a k kilovolts. G E scientists are studying absorption as function of several v a r i a b l e s atomic number, concentration, and voltage on x-ray t u b e , which is a measu r e of wave length of x-radiation. Lamb e r t says that for elements between 1 a n d 4 1 a n d over 66, coefficients increase in same order as their atomic n u m b e r s . But for elements 42 to 6 5 , whose K-absorption edges are in range of "effective" w a v e lengths of polychromatic x-rays employed, behavior is anomalous. Lambert has also developed further
applications of the method. A routine precision of 0 . 1 % is possible in some applications of x-ray photometry to rapid analysis of solutions containing both single and mixed solutes. He states t h a t techniques can be used for determination of heavy metals, halogens, hydrocarbons, a n d ash content of coal and tetraethyllead in gasoline. Lithium can b e simply and rapidly separated from other alkali metal ions with dipivaloylmethane, ( C H 3 ) 3 C C O — C H 2 - C O - C ( C H 3 ) , or D P M , according to G. A. Guter and G. S. Hammond, Iowa State College. Earlier use of organic chelating agents have not permitted separation of lithium from other metals except b y tedious procedures which involve stepwise removal of other ions. Separation is possible with D P M as result of formation of a Hthium chelate which is soluble in organic solvents. It is possible to extract lithium efficiently from alkaline aqueous solutions with solutions of 0.1N D P M in diethyl ether.
D I V I S I O N OF CARBOHYDRATE CHEMISTRY
Plotting the Carboxylotion Cycle • C a r b o n d i o x i d e enters photosynthetic cycle by c a r b o x y l a t i o n of five-carbon sugar, not t w o - c a r b o n acceptor • C a r b o h y d r a t e s m a y b e c o m e basic m a t e r i a l f o r synthetic detergents a n d other i n d u s t r i a l products • Research on chemistry of n o n s u g a r constituents of c o m m e r c i a l sugar liquors v i t a l t o s u g a r refiners TN
PHOTOSYNTHESIS
of
sugars
and
-*• carbohydrates t h e r e are very few intermediates b e t w e e n carbon dioxide a n d sugar. Of ideas current o n this subject thirty years ago, this is about t h e only fact still remaining, Melvin Calvin, University of California told t h e Division of Carbohydrate Chemistry. Briefly, tracer methodology, which h a s contributed so much to advancing knowledge of photosynthesis, consists of exposing photosynthesizing plants to carbon dioxide labelled with radioactive carbon-14, and after a short time analyzing products formed b y paper strip chromatography a n d radioautography. Several years ago tracer studies led to t h e conclusion t h a t carbon is incorp o r a t e d into carbohydrate molecules b y a carboxylation reaction leading to t h e three-carbon c o m p o u n d , phosphoglyceric acid w h i c h is then converted b y a series of reactions to six-carbon fructose and glucose phosphates. A
SEPTEMBER
2 7.
1954
long search for t h e two-carbon compound supposed to b e the acceptor of carbon dioxide, however, was fruitless. Finally, it was discovered t h a t the seven-carbon carbohydrate, sedoheptulose monophosphate, and the fivecarbon ribulose diphosphate appeared, labelled with radioactive carbon, a short time after exposure. T h e early appearance of five- and seven-carbon sugars led to an idea that perhaps there is no two-carbon compound acting as an acceptor b u t that the two carbons might b e in some way connected with the fact that the difference in n u m b e r of carbon atoms per molecule in sedoheptulose and ribulose is two, a n d also t h a t there is a like difference in n u m b e r between ribulose a n d several three-carbon compounds assigned to the photosynthetic cycle. I n d e e d , this seems to b e the case. N o w t h e cycle Calvin proposes for carbon reduction involves carboxylation of ribulose to two molecules of three3833
