THESE ARE THE TOOLS

The Chemist Seeks One of Three Goals

Harry W. von Loesecke.

If you ask the chemist to find a profitable use for any product that is wasted or overabundant, he will first study the substances of which it is made up and then try to reach one of three goals.

He may process the whole product to see if he can find in it an entirely new item that can be sold at a profit.

He may separate from the raw material a particular constituent that is valuable enough to yield a profit over the cost of material and operations.

Or he may make the material more acceptable to the chemical industry for present uses by learning how to prevent deterioration before utilization, how to purify the material, how to improve the product, or how to utilize the raw material more effectively.

ONE DAY, before the turn of the century, a chemist took some kernels of corn and started an industry that today uses more than 140 million bushels of corn annually. He employed many techniques, operations, and processes in order to separate particular substances, modify the things he had separated, and convert the materials into other chemical entities that have different chemical and physical properties. His methods and accomplishments with corn exemplify the methods and accomplishments of the chemists with other farm products.

One of the first products the chemist obtained from corn was starch. That was comparatively simple. He then set about finding means of making other products from starch and methods of changing the properties of starch so that it could be used for entirely different purposes. For instance, starch does not dissolve in water, but when it is heated under proper conditions, a chemical change takes place that reduces the number of atoms in the molecule, so that the new products thus obtained combine readily with water to form a variety of pastes, gums, and adhesives. The new products are called dextrins. More than 100 different kinds and blends of dextrins are mad4industrially from cornstarch.

Another product from cornstarch is sugar. The chemist knew that a starch could be changed to sugar if it were broken down by hydrolysis. When the breaking down is carried to completion, the final product is dextrose, the sugar that is in the blood stream of humans. Its common commercial name is corn sugar. It is about half as sweet as cane or beet sugar. If hydrolysis is not carried to completion, a sugar sirup (corn sirup) is the end product.

Even the corncobs themselves can be made into sugars by treating them with sulfuric acid under certain conditions. The sugars can be recovered as a sirup by neutralizing the excess acid with chalk, separating the calcium sulfate formed by the action of the chalk on the sulfuric acid, decolorizing the neutralized sugar solution with charcoal, and, after removing the charcoal, evaporating the sugar solution to a sirup.

The sugar or sirup made from cornstarch is at first dark, as is the sirup from corncobs. The color is removed by adsorption. Quite different from absorption, adsorption is based on the tendency of all solids to hold on their surfaces a layer of any gas or liquid with which they are in contact. A solution of corn sugar is allowed to come in contact with very porous charcoal, which adsorbs the dark substances in the sugar solution.

Corn sugar itself has many uses, but it also is the basic material for making substances of quite different properties. For instance, vitamin C, so essential in the human diet, and found in citrus and other fruits and in green and yellow leafy vegetables, has been prepared commercially in pure form from corn sugar by synthesis. Synthesis is a process in which a chemical compound is obtained by building up or adding elements or simple compounds by a series of reactions. The reactions in the synthesis of vitamin C from corn sugar involve, among others, fermentation, hydrogenation, oxidation, reduction.

WHEN MOLECULES of the same kind unite to form a new substance, which consists of large molecular units and from which the original compound may or may not be regenerated, the change thus effected is said to be caused by polymerization. The new compound is called a polymer. A polymer of corn sugar is dextran, which sometimes is used as a substitute for blood plasma. Condensation is applied to polymerization reactions in which a molecule of water or other substance is split off. Several condensation products of corn sugar have been prepared in the laboratory and may eventually be of use in our agricultural economy.

HYDROGENATION raises the melting point of the oil obtained from the corn germ by pressing. Thus corn oil, which is fluid at room temperature, becomes a plastic fat. Such a product is used as a shortening in cooking. Hydrogenation means the addition of hydrogen, and is probably the most valuable tool of the oil technologist. What happens is that the hydrogen molecule attaches itself to the double bonds that link the molecular chains of the fatty acids that constitute the oil. When that happens, the chemist says the fatty acids have become saturated, because the double bonds have taken on hydrogen and can no longer take on any other element. The final hardness of the oil being hydrogenated can be controlled by the amount of hydrogen permitted to be attached to the double bonds of the fatty acids in the oil.