THE C H E M I C A L W O R L D THIS WEEK
Laboratories use
H e r m a n M a r k , Polytechnic Institute of " r o o k l y n ; Peter Debye, Cornell Universit>: a n d S. M . G o r d o n , E n d o Products, Inc., discuss Debye's paper o n light-scattering
C&EN REPORTS: Metropolitan-Long Island Subsection, Meeting-in-Miniature
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Promising Vinyl Plasticizers Derived from Itaconic Acid
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C o n t r o v e r s i a l subject of m e c h a n i s m discussed; D e b y e talks chemistry of light-scattering
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B R O O K L Y N . - T h e - accent was on youth at t h e M e t r o p o l i t a n - L o n g Island Subsection meeting~in-miniature here on March 16, By and large, the authors of t h e 66 papers presented were graduate students or young chemists who carried out research u n d e r direction of the older hands. T h e meeting was regarded by the committee as an opportunity for t h e laboratory chemist to provide his contribution to t h e literature and to scientific advancement through the medium of reporting results of cooperative research. As such, the program successfully covered a w i d e range of interest which included organic and polymer chemistry, ph) sical a n d inorganic, biochemistry, and analytical c h e m istry. Considerable interest was evoked in a presentation by P. E. Bruins and C J. Knuth of Chas. Pfizer & C o . on vinyl plasticizers derived from itaconic acid. T h e acid is made by the fermentation of sugar or molasses, using a different " b u g " that that used for the production of citric acid. The experimenters showed that esters of itaconic acid with high molecular weight alcohols w e r e stable, whereas those prepared from low molecular weight alcohols tended to polymerize—a tendency which was cited as a drawback for a vinyl plasticizer. Acceptable, efficient plasticizers were obtained with a 12-carbon side-chain. N-substituted
predicting reaction on a p p l i c a t i o n s to
diamides gave nonvolatile, waxy solids which were relatively inefficient as plasticizers. T h e two best materials were itaconic .V-octylamide N-butylester and tetrahydrofurhiryl itaconate. Another promising material was a polymeric plasticizer formed by heating dibutyl itaconate with air or a peroxide which produced colorless compounds, less officii at fluxing, superior to dioctyl phthala..- in heat and light stability hut similar in physical properties. A series of papers on nitrogen base compounds treated properties and reactions of some pyrazines, pyridines, pyrimidines, and quinolines. A. Maggiola of the Wellcome Research Laboratories discussed some reactions of thiocyanogen with various nitrogen heterocycles a n d concluded that thiocyanation will occur only when electron-rich groups are available on heterorings. His research also demonstrated a new method of condensing thiazole nitrogen heterocyclic rings. F u r t h e r studies ot condensed pyrimidine systems by Maggiola brought out the fact that two compounds are active against the typhoid bacillus. These compounds are 2-methylmercapto adenine and 2-amino, 5-methylmercapto,7-aminothiazol,4,5-D-pyrimidine. There w a s a lively discussion on the subject of the prediction of reaction mechanism by means of electron chemistry. Although some h a v e expressed the
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LIQUIDS or GASES view that this approach has been over done, Maggioia defended this system of prediction. He said that the researcher has a 50-50 chance of predicting reaction mechanism, a n d by eliminating possibili ties by prediction, laboratory work can be more efficiently performed. However, a case in point concerned t h e thiocyanation of the beta position in 4-hydroxyquinoline which would be predicted to occur, and does. Likewise, one would think that electron donation would also occur with 4-aminoquinoline, but in this case thio cyanation does not take place. Needless to say, no conclusions were reached on this controversial subject. A new mechanism of ethanol formation in heterolactic fermentation was postulated by I. C. Gunsalus and Martin Gibbs of the University of Illinois. Fermentation of glucose by the fermentative coccus, Leuconostoc meseteroides, yields lactate, ethanol, and carbon dioxide in equimolar ratio. Subsequent experimentation indi cated that formation of lactate was ac complished via the usual Meyerhof-Embden scheme, while an independent mechanism produced the ethanol and car bon dioxide. Isotope experiments using tagged carbon atoms permitted the analysis of the reaction pathway and the conclu sion that a new, but as yet undisclosed, mechanism for ethanol formation exists. Light-Scattering Applications to chemistry of the scatter ing of light provided the main address of the session and was delivered by Peter Debye of Cornell University. He explained the theory of light scattering by referring to the passage of light from a vacuum into some medium. In addition to refrac tion, the light from a b e a m loses intensity by scattering. In a gas such as air, this effect is so small that only one half the intensity of the primary beam is lost after passing a distance of roughly 300 kilom eters; with benzene as the medium, the distance covered is about 30 meters at which point half the intensity is lost. This type of molecular scattering is propor tional to the reciprocal of the fourth power of the w a v e length. Debye said that the theory h a d been grounded on the assumption that in a solution, solute particles act as disturbance centers. In t h e case of high polymers, this assumption might have to b e changed if molecular weight becomes high enough. For polystyrene of molecular weight of 1 million, a calculation of an average dist ance between ends from the model of a freely coiling chain yields a value of 300 angstroms. A measurement of the dis symmetry of scattering is an absolute measurement of the size in terms of t h e wave length of t h e light. For polystyrene, the average distance was determined to b e 1100 angstroms, m u c h larger than t h e theoretical calculation, and shows that the chain is appreciably stiffened by hindering of the free rotation around bonds. V O L U M E
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