L I T E R A T U RE
New Mathematical Code Devised for Molecules Matrix concept provides method of converting chemical compounds and systems into computer-oriented names 145TH
ACS
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Chemical Literature
A chemist wants to know the best way to synthesize a chemical compound. He sketches the compound on a card, indicates the data desired, and hands the card to a clerk. The clerk converts the query into a format suitable for use by a computer and sends it to an international computer center. The center, which has direct ties to all technical libraries and research labs, processes the query and sends the chemist the information he wants. As every chemist knows, no such computer center exists. The usual practice is a two- to three-week search through the literature. But Dr. Leonard Spialter, a physical organic chemist at Wright-Patterson Air Force Base in Ohio, has devised a new nomenclature which he believes might be one step toward a computer center for chemical literature. Dr. Spialter calls his computeroriented chemical nomenclature the ACM—the atom connectivity matrix. The ACM has a characteristic polynomial, the ACMCP, which is the mathematical "name" for the molecule and the form in which the molecule is identified by the computer. Currently, the concept is limited to information associated with a pictograph, such as that of a molecular compound or system. However, Dr. Spialter says that as long as current theories of molecular structure exist (molecules are composed of atoms bonded together), corresponding pictographs can be drawn. He believes the system provides a simple, universal method for converting chemical compounds and systems into computer-oriented names. What's Needed. High-speed computers with large memory capacity now make it possible to store and retrieve chemical data. The problem, Dr. Spialter believes, is the absence of 86
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a versatile, language-independent, computer-oriented nomenclature for chemical compounds, molecular systems, and reactions. What is needed is a suitable type of "address" or "location" under which chemical information can be stored and searched. The "address" must be unique and not subject to special corrections as new types of molecules are discovered. The problem is well known, and attempts to overcome it have been going on for more than 10 years. The mathematical topological mapping system devised by Delbert L. Ballard and Francis Neeland is a recent example of a proposed solution (C&EN, April 15, page 129). Others have worked on systems for coding chemical structural features using arbitrary symbolism, among other methods. Dr. Spialter feels that most of the systems devised to date place the burden of learning complex rules and manipulations on
the chemist or a trained associate. He claims his proposal transfers these operations to a computer and a clerk. The ACM concept is that of a matrix, the atom connectivity matrix. In general, the concept treats the chemical molecule or molecular system as a collection of points (atoms) with interconnectivities (bonds) between respective pairs of such points. The ACM amounts to mapping a molecular pictograph into a matrix form. For the pictograph of the hypothetical molecule:
the ACM is: A 2 1 1 0 0
2 B 0 1 1 0
1 1 0 0 1 1 C 1 0 1 D 1 0 1 E 0 0 1
0 0 0 0 1 F
COMPUTER IDENTIFIES MOLECULE BY ITS POLYNOMIAL Pictograph of the Hypothetical Molecule A—B=C Yields Six ACM's
A10 1 B2 02C
AOl 0C2 12B
B12 1A 0 20C
B21 2CO 10A
C02 OA1 21B
C20 2B1 OlA
The six ACM's all look different. The important identifying mark is their characteristic polynomial (ACMCP). The ACMCP for all six compounds is ABC—4A—C. It is the mathematical name for the molecule, and the form in which it is identified by the computer. It is obtained by evaluating the matrix as a determinant.
It is a square array whose order (number of rows or columns) equals the number of atoms (constituent components) of the molecular system. The atoms of the molecule are placed in the diagonal positions and the connectivities between atoms are in the off-diagonal spots. According to Dr. Spialter, the system differs from other matrix, mapping, and accounting methods in that the atomic symbols are restricted to the principal diagonal. Polynomials. The heart of Dr. Spialter's system, however, is not the ACM itself, but the ACM's characteristic polynomial. The order of entering the atoms into the diagonal position of the diagram, or square array, isn't important. The hypothetical molecule A—B=C, for example, can yield six different ACM's depending on the order of placing the atoms in the diagonal. This makes the ACM unsuitable for primary identification and comparison purposes. The important identifying attribute is that all ACM's for a given molecule have identical characteristic polynomials or ACMCP's, Dr. Spialter stresses. For the molecule A—B=C, all six ACM's yield the polynomial: ABC— 4A—C. It is obtained by evaluating the matrix as a determinant, using common mathematical procedures. One big advantage of the system, according to Dr. Spialter, is that the ACM can be constructed without any special mathematical or chemical training. It is amenable to all laws and theorems of matrix and determinantal algebra and is suitable for input to a computer, since all elements are addressable and identifiable, he says. Furthermore, the ACMCP can be computed directly, making the concept adaptable to manual coding systems. "The ACMCP is independent of chemical name and language, atom numbering conventions, and size and orientation of the molecular pictograph. It is different for every different molecule, but characteristic for its own specific progenitor," he explains. Dr. Spialter has used the ACM concept to describe covalent compounds, ionic salts, free radicals, zerobonded components in molecules, such as clathrates, and transition states of reaction. The concept has also been extended to include stereoisomerism by the introduction of imaginary bond orders, systems in equilibrium, and both the reactants and products of reactions.
Book for ComputerOriented Specialist Multicomponent Distillation. CHARLES D. HOLLAND, xiii + 506 pages. Prentice-Hall, Inc., Englewood Cliffs, N.J. 1963. $15. Reviewed by Dr. James R. Fair. Dr. Fair is manager of the engineering department at Monsanto Chemical Co. This book should perhaps have been titled "Multicornponent Distillation Calculations" with the possible subtitle "Procedures for Use with High Speed Computers." It does not deal with the broad aspects of fractionator design and operation, but rather with the various relationships between equilibrium stages and separation specifications. These relationships are treated mathematically and are amplified by suggestions and recommendations which enable the reader to proceed with preparing programs for the computer. The author presumes that the reader has been introduced previously to distillation (in the unit operation sense) and to chemical engineering thermodynamics. The opening chapters of the book then introduce the reader to elementary concepts of iterative methods and techniques for getting them to converge to final solutions; to bubble- and dew-point calculations; and to multicomponent equilibrium flash calculations. After this opening material, the reader is conducted through multistage calculation techniques for a variety of conventional and complex separation situations. For these calculations, extensive use is made of the O-method of convergence in combination with the Thiele-Geddes stage-tostage procedure. Concluding chapters of the book contain background information on thermodynamics of solutions, and a summary of published correlations of vapor-liquid equilibria. The book format is excellent, and the author's style reads fairly easily in view of the large amount of mathematical notation necessarily used. The author leans heavily on his several years of direct experience with computer solutions of distillation problems, and his terminology indicates that he is familiar with industrial application of his work. He has been surprisingly successful in controlling what could be a very cumbersome nomenclature problem. He has wisely included numerous solved problems which amplify the text. Additional problems are included for outside solution.
The book could have been strengthened by additional figures and descriptive matter relating the mathematical material to the physical problems of distillation. Some practical "flavor" would not have lengthened the book unnecessarily. To reduce distillation to a purely mathematical exercise of computing equilibrium stages may be to misplace some of its important economic implications. But other than this mild argument with point of view, the reviewer could find little fault with the book. For those directly concerned with computer solutions to distillation problems, this book will be quite useful. As a textbook it will be useful only to those students making calculations as part of computer laboratory work. For the chemical engineer in design or manufacturing, the book will be of relatively minor value as a working tool since it does not consider such problems as ti'ay design, efficiency prediction, or column control. The practitioner may, however, find valuable reference material in the chapters dealing with vapor-liquid equilibria. In summary: a worthwhile book for the computer-oriented specialist.
Well Presented Chemical Reference Encyclopedia of Chemical Technology. Kirk-Othmer. 2nd ed., rev. Vol. 1, A-Aluminum.
ANTHONY
STAN-
DEN, editor, xix + 990 pages. Interscience Publishers, 440 Park Ave. South, New York 16, N.Y. 1963. Subscription, $35; each, $45. Reviewed by Dr. Julian F. Smith. Dr. Smith is professor of chemistry at Lenoir Rhyne College and partner in the firm, Singer, Smith & Co., technical information consultants. Edition 1 of the Kirk-Othmer Encyclopedia had what any actor would call rave reviews, which need not be quoted here. Supplemental volumes in 1957 and in 1960 did not suffice. In edition 2 the encyclopedia is being thoroughly overhauled, to appear in 18 volumes at about the same intervals as the original 15, so that publication dates will have about the same time lag from edition to edition. Volume 1 (A to Anthrimide) first had over 90 articles and over 90 contributors; Volume 1 (A to Aluminum) now has 46 articles by 65 contributors, some of whom wrote for both editions. Static technology is uncommon, but in SEPT.
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a few instances direct quotations from the first edition are still valid. A departure from former practice is attention to foreign technology; the new Volume 1 has two British contributors and one French. Other foreign reports will appear in later volumes. A commendable new feature is a "nomenclature" section in articles (e.g., Absorption) involving much mathematical discussion; it lists the symbols, abbreviations, units, etc., introduced with the mathematics. Some articles are quite academic in tone, and not all of them are from the few authors having academic affiliations. Nearly all the contributors are from industrial laboratories, but they take an interest in theory too. Tables, charts, and drawings are used liberally. Photographs are few in number but excellently presented. Inevitably, style is variable but there is evidence of skilled editing. Misprints were not sought, nor were any noticed. "Anhydrization" (page 577) is probably a purist's protest against the Latin-Greek hybrid "dehydration" (which would express the meaning a little better). Webster insists on "anhydridization." As a slight inconsistency, the article "Alkoxides, Metal" prints alkyl radical designations as abbreviations (Me, Et, Pr) or as formulas without apparent system. This gives propyl three handles: Pr, - C 3 H 7 , and - C H 2 C H 2 C H 3 . The feature of the new Volume 1 which earns the rave notices of 1963 is the sustained care in selection and presentation of articles. Modern treatment describes current technology, with bibliographies carrying references into 1962. Some articles represent concepts not even clearly recognized in 1947, e.g., the two leadoff A's, Abherents and Ablation. No one reviewer can pass on the technical excellence of all the articles over such a wide range. The professional standing of the contributors and the care devoted to this volume by editors and publishers offer potent circumstantial evidence to justify a thumbs-up verdict.
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"The Naming and Indexing of Chemical Compounds from Chemical Abstracts" is the title of a publication which introduces the Volume 56 (January-June 1962) Subject Index of Chemical Abstracts. The 98-page paperbound book (CA size) represents a
comprehensive discussion of chemical nomenclature as applied to inorganic as well as organic compounds for systematic indexing, with a classified bibliography, an index and the following appendixes: (I) miscellaneous chemical prefixes, (II) inorganic groups and radicals, (III) anions, (IV) organic groups and radicals, and (V) organic suffices. Copies may be ordered for $5.00 apiece from Chemical Abstracts Service, Ohio State University, Columbus 10, Ohio.
BRIEFS The 1964 Official Publication of the Association of American Feed Control Officials will be available Nov. 1. It contains all the changes adopted at the recent meeting of AFCO in Salt Lake City and provides a record of all definitions and other facts necessary for registration and labeling of feedstuffs. Copies may be ordered for $5.00 apiece from Marvin H. Snyder, Treasurer, AAFCO, West Virginia Department of Agriculture, Capitol Bldg., Room E-109, Charleston 5, W.Va.
National Catalog of Patents is being published by Rowman & Littlefield. The first four volumes are now available. The complete work will place the complete patent literature of the U.S. Patent Office, from 1790 to the present, at the fingertips of the world's industrial, scientific, and engineering communities. The project has the cooperation of the U.S. Patent Office, Washington, D.C. The first four volumes list all patents filed with the U.S. Patent Office in 1961 in the electrical and chemical fields. Patents are shown in the form of one major claim and one drawing. Write to the publishers, who also publish the Library of Congress catalogs, 84 Fifth Ave., New York, N.Y. 10011, for further information.
The Determination of Forms of Moisture in Coal, by Peter O. Krumin, has been published as No. 195 of Ohio State University's Engineering Experiment Station Bulletins. The bulletin embodies basic results of simultaneous determination of forms of moisture in coal. The bulletin is available for $4.00 from Engineering Experiment Station, Ohio State University, 156 West 19th Ave., Columbus 10, Ohio.
