NOMENCLATURE
WORDS ABOUT WORDS AUSTIN M. PATTERSON*
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Naming Starch Fractions
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Thomas John Schoch ( 1 2 6 Brainard Ave., L a Grange, 111.) feels that the term "aroylose" for the linear starch fraction and "amylopectin" for the branched fraction, which have been endorsed by the International Union of Pure and Applied Chemistry [/. Polymer Set., 8, 269 (1952)], are completely inappropriate. The linear fraction is not a sugar ( h e n c e -ose is not good), the branched fraction is not a pectin, and both terms have been used in opposed senses. Also, "amyl-" and "amylo-** are more likely to suggest the amyl group than starch. Dr. Schoch says: "Until the development of selective precip itation methods for the linear fraction with butyl or amyl alcohol, no authentic starch fractions had ever been isolated. In all instances the products were degraded, highly contaminated, or else merely rep resented a minor subfraction. It seems preferable to forget our early errors and not burden the present starch fractions with names which have been so misused in the past. "We could perhaps devise new terms for the starch fractions which would be scientifically correct. A suitable termi nology might be maltosan and isomaltosan, as polymers of maltose. But I doubt whether there would be any general ac ceptance of such designations. I have a suggestion which may perhaps resolve this confusion. After all, any trivial name is merely a convenient label to assist identi fication of t h e substance. W h y not simply "linear starch fraction" and "branched starch fraction"? These serve the purpose precisely, require no mental gymnastics, and are chemically correct (thanks to the classical studies of the late Κ. Η. Meyer). They are capable of all sorts of variations to avoid monotony, e.g., the branched component, linear corn starch substance. They are readily applicable to derivatives of the fractions, e.g., short-chain linear material, acetylated branched fraction. During the past several years I have de liberately tried out this practice in a num ber of talks and in several publications ( see particularly Gortner, Outlines of Bio chemistry/ 3rd éd., pp. 627—45). N o one has y e t questioned my meaning or asked me to identify the linear fraction with amylose, amylo-amylose or α-amylose. The system is ridiculously simple—but it seems to work." Dr. Schoch will be glad to receive comments.
Conn. Advantages claimed for it are tbat compounds of the same empirical formula are grouped at the same place in a subject index, many prefixes are eliminated, and functional groups of a single species at tached to the same skeleton are treated alike. Carbon atoms are numbered con tinuously, those in the longest straight chain first, then those in the side chains. Branched alkanes take the same name as the corresponding normal alkanes, but with numbers, to indicate their structures. For example, all hydrocarbons of the formula C&H12 are called "pentane"; for the normal compound this name is tinmodified; 2-methyibutane(isopentane) is called [2 5 ] pentane, while 2,2-dimeth.ylpropane(neopentane) is [2*·δ] pentane. The "2" denotes the position of attachment of the side chain and the superscripts the numbers of the carbon atoms in the side chains. 1
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Similarly, 2,4-dimethylpentane is [2%47]heptane and 3-ethyl-2-methylpentane is [2 e ,3 7 ]octane; 3-ethylpentane is [3 e ]heptane. CH3 CH;
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