Starch chemistry - Journal of Chemical Education (ACS Publications)

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Starch Chemistry

Liquid Oxygen Explosives (1)


TARCH is now being acetylated to give three types of products: (1) those soluble in water, (2) those soluble in both water and organic solvents, and (3) those that are soluble only in certain types of organic solvents. Sweetose is obtained from corn starch by a combined acidenzyme hydrolysis. I t is sweeter and less viscous than ordinary corn sirup, is permanently clear, and does not crystallize on standing. I t is normally marketed, slightly flavored, as Staley's Waffle Syrup. Acid hydrolysis of starch. in the presence of molybdenum salts, gives a sirup with a high dextrose content and a desirable degree of fluidity. It is known as liquid sugar, and will find use in the confectionery trades. Fro-Dex, Dri-Dex, and Malto-Dextrine are among the newer crystalline sugars. They are produced by the vacuum pan drying of appropriate corn simps. Levulinic acid, which is 4-ketopentanoic acid, is being produced from waste sugars and starch by a special acid hydrolysis. This makes another addition to the long list of carbohydrate products that are now commercially available. The depolymerizatian of starch may be effected by (1) the wet process, or (2) the dry process. I n the former, the nature of the end product is determined primarily by the hydrogen-ion concentration and the time of heating. whereas in the latter there are four variables: the moisture content of the starch, the concentration of the hydrogen chloride, the temperature of the reaction. and the time of heating. The use of these processes, together with different types of starch as starting materials, give rise to a large number of products with distinctly differentphysical properties. According to G. E. Hilbert, Chief of the Starch and Dextrose Division at the Northern Regional Laboratory, about 80,000,000 pounds of starch were used last year in place of sodium silicate in the manufacture of corrugated cardboard by torrefying the starch in situ. Increasing amounts of starch are being used in the sizing of painted walls. This enables the walls to be cleaned and resized when needed by washing with a starch solution. The production of a starch engine, which will operate on pulverized starch, seems a little distant but no more so than did the airplane a few years ago. When ethylene chlorohydrin is used as a dedormitizing agent for potato tubers and gladiolus corms, it is converted, according to recent studies by Denny and Miller of Boyce Thompson Institute, to the gentiobioside. The gentiobiose, incidentally, is also foreign to these plants or exists in very small concentrations. This seems to be the first experimental evidence that glycoside formation is a part of a protective detoxication process. Dormitization of potato tubers and gladiolus corms may be effected, according to Denny and Guthrie of Boyce Thompson Institute, by treatment with a solution of potassium naphthaleneacetate or the vapors of methyl naphthaleneacetate. These dormitized tubers and corms may be dedormitized successfully by treatment with ethylene chlorohydrin. This suggests that dormitization may play an important role in the storage of various perishable farm products. Fractional sedimentation of starch, over a period of about six weeks, gives two distinct fractious, one of which (the more soluble) seems to be of the long chain variety whereas the other (the less soluble) has a tree-like structure. The use of the dropping mercury cathode, the formation and subsequent decomposition and analysis of thioacetals, and fractionation of alkylated derivatives are the newer methods that are being applied to a study of the progressive degradation of the starch molecule. --ED. F. DEGERING



IQUID oxygen explosives as formerly made from a carbonaceous absorbent and relatively pure liquid oxygen presented serious hazards owing to their high inflammability. These mixtures are high explosives of good strength, which are useful far certain operations in the open, such as the strip mining of coal or open-cut metal mining. Because of their potential capacity for producing large quantities of carbon monoxide, their use underground or in confined places cannot be recommended. Because of the spontaneous evaporation of liquid oxygen under ordinary atmospheric conditions, these explosives have a short life; this gives rise both to unique safety features and to limitations in their application. A recent cooperative investigation a t the Bureau of Mines (2) has developed procedures for treating a granular carbonaceous absorbent and a canvas wrapper used commercially in liquid oxygen explosives to render these markedly fire-resistant. Phosphoric acid proved the most effective material of those examined for application to the granular carbonaceous absorbent; and aqueous solutions of mono- and di-ammonium phosphates, ammonium chlorides, and phosphoric acid gave very good results in applications to the canvas wrapper for cartridges. These fireretardant treatments render the explosive immune to practical sources of ignition without serious detriment to its useful physical and explosive characteristics, and substantially eliminate the possibility that accidental ignition may develop into dangerous detonation. A. R. T. DENUES (3)


ROM the General Electric Research Laboratory comes the announcement of an electron accelerator, operating on an induction principle. I t is a glass doughnut of less than a foot in diameter, looks somewhat like a miniature cyclotron, hut is capable of handling electrons instead of positive ions. The accelerator's magnet. composed of thousands of small pieces of iron. can be used on alternating current. Instead of encircling the magnetic core by following a coil of wire, as they do in a power t a n s former, electrons in the induction accelerator arc free to circulate about the magnetic core in the doughnut-shaped vacuum tube. Hence they make many revolutions, in 200,000 of which they travel 60 miles and gain 2,300,000 volts energy. When directed against a target the electrons from the present laboratory model produce radiation equivalent to that of 10 millicuries of radium.


ROFESSOR N. Henry Black, author of popular chemistry and physics textbooks, has retired from active teaching a t Harvard University. On November 22. 1940, a group of his friends and colleagues gathered a t the Harvard Faculty Club in Cambridge, Massachusetts, to honor him. Responses were made in behalf of several large groups of teachers. In conclusion Dr. Black related a few anecdotes from his experiences, including the story of a formal dinner with Sir J. J. Thomson.


ERGITOL T, a reagent to decrease surface tension, is found to be useful for assisting the separation of the precipitate when the centrifuge is employed. I t is also a valuable aid in stabilizing colloids such as silver chloride for nephelometric measurements. 1 Contribution from the Central Experiment Station. U. S. Bureau of Mines, Pittsburgh, Pennsylvania. Published by permission of the Director. Bureau of Mines. U. S. Department of the Interior. Not subject to copyright. A detailed account of this cooperative work may be found in Bureau of Mines Bulletin 429. 3 Assistant chemical engineer, Explosives Division. Central Experiment Station. Pittsburgh, Pennsylvania.