.ORGANIC
CHEMISTRY
DIVISION OF ORGANIC CHEMISTRY
paper of proteins, saccharides.
Packaging on the Molecular Level
• First Chemical Reduction.of Nonterminal Unsaturation Sodium in liquid ammonia has in the past proved to be satisfactory for chemical reductions of terminal un saturation, but to the present chemists have not had a means of chemically re ducing unsaturation centers within molecules. Such a tool is now avail able, however, as Robert A. Benkeser, Purdue, extends his work first reported at the 126th meeting in New York last September on reduction of aromatics t o mono-olefins b y lithium in low molec ular weight amines. Specifically, Benkeser finds a 19^> yield of decane w h e n 5-decyne is re duced at 17° C. b y lithium in ethylamine. H e also finds cyclohexene t o b e reduced to cyclohexane, 1-ethylcyclohexene to ethylcyclohexane. There appears little doubt but t h a t the reduction is chemical and is not due to lithium's reacting with t h e amine to yield hydrogen, which then performs the reduction. If t h e latter were the reaction, mechanism, lithium would presumably react with the sol vent in no definite ratio. However, 1.9 atoms of lithium are used per molecule reduced, indicating that lith ium is performing true chemical reduc tion. Coal Structure Analysis. Mean while, Irving Wender, Bureau of Mines, has put a related reduction— lithium in ethylenediamine—to use in hydrogenating and splitting coal and coal precursors—wood, lignin, and p e a t . Usual ways to obtain characterizable fragments from complicated coal mole cules are so drastic and chemical changes are so deep seated that these luigments bear little or no relation t o structures of starting materials. W i n der's method, operating under mild conditions, gives products whose struc tures are closely related to the original ones. Coal contains aromatic and hydroaromatic structures, phenolic hydroxyl groups, and ether linkages. Model compounds containing these functions have been selected for preliminary work. In general, Wender finds polynuclear aromatics to be reduced to mix tures of polynuclear olefins having various degrees of unsaturation, plus completely reduced products. Phenol reduces to a mixture of cyclohexanol and cyclohexanone, and di-n-hexyl ether gives a small amount of hexenes plus 89c hexanol. Neither of these lat ter two reductions have been affected by metals in liquid ammonia. Very recent work shows that a terminal
• Lithium in l o w molecular w e i g h t amines gives first chiemîcal reduction of nonterminal unsaturation • Thioctic acid synthesis achieved on large scale; p r o d u c t f o u n d useful for treating chronic liver diseases A new "packaging" method for un•** stabLe materials is at the test tube development stage at Hormel Institute. Scientists there propose protecting vitamins, essential fatty acids, and other easily deteriorated biological and pharmaceutical products with "molecular" cases by including them within crystal lattices o f adducts such as urea, thiourea, de=oxycholic acid, cyclodextrins, and starch. Present t work stems from 1940 when German workers discovered that urea forms addition products with straightchained hydrocarbons, a reaction which h a s since become important in hy&rocar^bon separations. Working with this general technique, Hermann Schlenk and coworkers h a d found by 1950 thait autoxidizable fatty acids are stabilized! when crystallized in combination with urea. Each fatty acid molecule is isolated within the urea's crystal lattice, and the lattice serves as a barrier- to oxygen's penetrating and causing tihe acid to deteriorate. Since only straight-chained compounds 3-eact with urea, Schlenk has extended his work to other host materials w^hich can include larger, branchecl-chain molecules. As a further reason for change, Schlenk observes thaat urea is not a normal diet constituent and that it may cause undesirables physiological effects, although urea corrmplexes of fatty acids have been used successfully in recent nutrition studies. So far, Schlenk has tested inclusion stabilization of linoleic acid, linolenic acid, methyl linolenate, cinnamaldehyde, a n d vitamin A palmitate with such hosts as a- and β-dextrin, deoxycholic a_cid, and starch. Of these, preservation of vitamin A is one of the more urgent practical problems, and Schlenk gets "indefinite" stabilization of this essential material when included in starcih. However, while essential fatty aci'ds in inclusion complexes are nutritionally available, this has yet to be proved for included vitamin A or its derivatives. Reactions are reasonably straight forward, although care must be taken to work under oxygen-free conditions. VOLUME
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Care must also be exercised to be sure all unreacted material is removed from the complex; otherwise, this uncomplexed material will be lost, as it is not stabilized. Once the compounds are included, such care in handling is no longer necessary. Chromatography of Fats. Paper chromatography has proved to be the analyst's salvation in many a field, but so far it has not been of much help in fat analysis. This is probably due to difficulty in developing the chromatograms, as functional groups in fats are diluted by long aliphatic chains to which they are attached, making such compounds hard to detect unless an extremely sensitive indicator reagent is available. Helmut K. Mangold and Beverly G. Lamp, Hormel Institute, in a n out growth of work by Schlenk o n inclu sion compound formation, find that long chain alcohols and fatty acids also react on paper with complex formers such as cyclodextrins and thiourea. After spraying paper chromatograms of such products with α-cyclodextrin, the complexed dextrin can be distin guished from free dextrin with iodine. Thus, areas with complexed dextrin ap pear as white spots against the general purple background formed by the reac tion between dextrin and iodine. Since the method depends only on complex formation and does not re quire a functional group for inclusion, Mangold believes the method may also be applied to paper chromatography of hydrocarbons or other inert molecules as well, provided these react with the complex former. Di- and triglycerides do not respond readily to this treatment, however, and Mangold has worked out a method for splitting these enzymatically with pancreatin to free acids and glycerol on the paper after development. These fragments can then be complexed with α-cyclodextrin and location of com plexed spots determined with iodine. It is conceivable that fragments of the enzymatic split can be chromatographed in the second dimension, and the method could thus be applied to chromatography and electrophoresis on
APRIL
II,
1955
nucleotides,
and
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127th NATIONAL
ACS
MEETING acetylene linkage is reduced to a saturated hydrocarbon, with no trace of olefinic product. W e n d e r is now extending the system to wood, ligniiL, peat, and various coals. In addition, experiments are underway using other mettais (sodium, potassium, calcium, barium, and aluminum, for in stance) and ofcher amines (piperazine, morpholine, diaminocyclohexanes). T o date, t h e system of lithium in ethylenediamine appeaars to be one of the most effective alkaL metal-amine combina tions k n o w n for carrying out reductions and cleavage reactions of organic com pounds, W e n d e r says.
Walter M. Eller, left, Fritzsche Brothers, Inc., congratulates Hans Schinz, Federal Institute of Technology, Zurich, Switzerland, as he receives the Fritzsche Award
Hans Schinz Fritzsche A w a r d winner of the Fritzsche THISGoldyear's Medal and $1000 devoted practically all of his scientific work to studies of the chemical compo nents of essential oils, perfume aromatics, and their synthesis. Early in his career Schinz, a native of Swit zerland, had the good fortune to be come associated with L. Ruzicka, and was an assistant to the noted or ganic chemist at t h e Federal Insti tute of Technology at Zurich. Three of Schinz' outstanding re searches in the essential oil field h a v e obtained recognition both here and abroad: Determination of the con stitution of irone, a n d its subsequent synthesis; cyclization studies in the field of terpenes, sesquiterpenes, and diterpenes, and determination of the constitution of Lavandulol and its successful synthesis. At the N e w York office of Firmenich, Inc., the Swiss firm which has supported the medalist's labors through a fellowship, Schinz said his investigations h a d shown Lavan dulol to be a mono-terpene alcohol of lavender oil. This led to investi gation of irregular isoprene chains as well as of cyclization of the monoand sesquiterpene series where new types of cyclic compounds were
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brought to light. In addition to Ruzicka, he also conducted m u c h of this work with the collaboration of C. F. Seidel. While his researches involving irone, Lavandulol, and terpene cycli zation were fundamental, Schinz had m a d e in addition w h a t could b e termed very extensive analyses of violet flower and violet leaf oil. This work also proved fruitful as i t led to the synthesis of Nonadienol, a constituent of these oils. The association between the medalist and Ruzicka has b e e n very close. W h e n the latter m o v e d o n to the University of Utrecht t o oc cupy t h e chair of chemistry a t that famous citadel of learning, Schinz became his assistant. Later, lie r e turned to the F e d e r a l Institute of Technology in Zurich, and since then became research fellow of Chuit, Naef, Inc. and its successor, Firmenich. The medalist has c o n d u c t e d some of his investigations w i t h his stu dents, notably researches on
