Organic Chemistry, Third Edition (Fessenden...
4 downloads
250 Views
1MB Size
drive access are trapped by an unconditional return to the Main Menu, and the Applesoft error number (which can be looked up in the appropriate Apple manual) is printed and labelled as such. The only instance of the program "hanging" in our experience was an attempt t o enter the coordinates for the 41th atom in a 48-atom structure. Because this is essentially a graphics utility product, adaptation to a particular curriculum or institution would be relatively easy in terms of generating the shapes needed for a particular application, assuming availability of the necessary data. As noted, with a good set of molecular models, and with patient attention t o detail, many shapes could be generated and stored on disk hy means of the internal coordinate method. Exemplary presentations of this method, and of the Cartesian technique, are presented in the tutorials. Once the technique of shape generation has been mastered, the results are rewarding, for in addition t o the facilities for rotating the shape and changing its size, one can also view the shape with either the spheres (atoms) or lines (bonds) erased. Spheres are presented in three formats: small open, for hydrogen; large open, for carbon, and large filled (inverse video) for other atoms. I t was not feasible for a review of this product t o he undertaken in conjunction with a course, but a junior chemistry major, Therese Roy, graciously accepted the assignment to test the program and to enter the data for several fairly complex molecules. These data came from publications by John Ricci, Chairperson of this Department, and an X-ray and neutron crystallographer a t Brookhaven National Laboratory. The structures used were 1. alpha-Bis(p-nitraphenyl)disulfide. 2. A polycyclic tetraoayazaphospharane. 3. A polynuclear transition metal hydride; [Rha(sS-CsMes)4Hd(BF4)z. 4. A tricyclic sulfur-containing polyene. Roy rapidly became proficient a t operating the program. As a general rule, the Cartesian technique is easier to use for shape generation, provided the necessary data are available. Puhlications that provide details of crystal structure often indude "positional parameters", based on the unit cell dimensions, and can he entered far shape generation via the Cartesian Coordinate method. The Internal Coordinate procedure uses a dummy atom ($to), in order to assist the evaluation of subsequent dihedral angles. However, thesame procedure is not used for the Cartesian method, a distinction which is not made sufficiently clear in the Cartesian tutorial; perhaps a note t o this effect could he added to the introduction on p 8. The problem of "how often to SAVE" is often troublesome. An editor file that has been (painstakingly) entered is indeed retained intact after branching elsewhere and returning, for example t o the calculation mode. If an erroroccnrs during that process, the file is erased, or a t least could not be retrieved. A note to this effect could be printed perhaps on p 10 of the manual, or the user could he directed to save the editor file before proceeding t o calculation. As noted earlier, the program would only accept 46 atoms of a 48-atom species. No error message had been generated when "48" was entered in response to the prompt:
"How many atoms to be added?" in setting up the editor file for this molecule. Same additional advice would be useful regarding the decision on which set of three prior atoms to use in determining the dihedral angle far the Internal Coordinates method. In 3-ethyl-2-methylhexane, for eaample, the ethyl carbons can each be referred back along a t least two different sets of three connecting atoms, presuming a cyclohexane-like structure, with an isopropyl ''s~de-chain". . Trial-and-error will, of course, sort out the correct choice, but this could he tediously repetitious in larger structures. Editing the values of an individual atom in an editor file is made somewhat more bothersome by the lack of numbering of the atoms in the screen display. Perhaps an arbitrary (in terms of orientation) static display could he provided, with numbering, supplied by the user. An additional useful feature, in this writer's opinion, would be the provision of additional figures in the manual, to make clearer the essential distinction between clockwise and eounterclockwise ("+"/"") dihedral angles, espeeiallv for beginners. One u r ~ f u nl m k w on thr graphic5 wrem would bea irnalltlgure (prrhapiin theL,rer left rurner,, which w d d nlwoys s l rhe~ screen representation of the three-coordinate axes. Finally, although Roy was generally favorable in her comments. She observed a preference for a model set, based on its portability, compactness, and availability, i.e., not having to compete with other students for access t o the computer. Despite this reservation-an assumedly temporary (and local) one due t o resource allocation-this reviewer recommends the product highly to those instructors (and their students) willing to make the necessary and patient effort t o generate and store shapes with many potential uses. The results were often striking and always rewarding.Therather minor difficultiescited herein cannot detract from the intrinsic merit of the product. Alan G. Smith University of Souihsrn Maine Portland. ME 04103
Organlc Chemistry, Thlrd Edltlon Ralph Fessenden and J. Fessenden. Brooks/Cole: Monterey, CA. 1986. xxi 1129 pp. Figs. and tables. 18 X 26 cm.
+
1150, of such varied type and difficulty that this hook can serve awidevariety of instructional approaches. The greatest strength of this text is its conversational style. Many explicit questions are raised just where the student should be asking them. This feature should encourage and guide those students who have not developed the discipline to ask good questions. Another helpful feature of this edition is the unusually frequent use of electron dot formulas and curved arrows in representing reaction mechanisms. The text consists of three parts: (1)bonding, (2) reactions and mechanisms, and (3) special topics. A feature of the first part is unusually thorough directions for writing structural formulas. The logic is quite sound for introducing mechanisms with a study of ionic substitution and elimination react i m i Thrre IF ,no clear renam tiw treating alkenes and nlkyncsw late Chnprcr Y J The uecisim todrvudiarusiimof hioloriral tree radicals from -the chapter an free-radical chemistry is apoor one in light of the rapidly increasing importance of this topic and the frequent confusion ahout it. Although the authors claim that biological applications of organic logic are a feature ~of this text, relatively few applications are found in the part on reactions and mechanisms. For example, the chemistry of aldehydes and ketones is replete with biological applications apart from carbohydrates. However, the text presents only two applications: transamination of amino acids and tautomerism in carbohydrate metabolism. Spectroscopy (IR and NMR) is introduced as soon a s it is feasible (Chapter 8) after a few functional groups have been described. The attention is on spectral interpretation. Very little consideration is given t o the oriein of soeetra. Thp si)eclill Inpica ~ e c l i min~ludesquite mnnagtablr chapters ou pulycycl~cand hetm q r l i r nromatirs "nd pericycliv reactions. There are conventional chapters on earhohydrates, proteins, and lipids. The treatment of nucleosides and nucleotides is superficial. The schematics and block diagrams used are more appropriate for an introductory biology text than for the end of a year of organic chemistry. This text will appeal most t o students whose primary study is the biological sciences. The text will not serve well as a reference. Relatively little attention is given t o modern methods of organic synthesis. Yet, a majority of students should find this teat t o be a helpful guide.
.~
Don E. Gibbs Rockhurst College Kansas City. MO 64110
$32.00.
The first and second editions of this texthook for the year course in organic chemistry have been reviewed in this Journal (February 1980 and May 1983). The basic organization has been retained with expanded discussion (a total of 60 additional pages) of s few topics, mainly regarding structure and bonding. The number of summaryfigures and reaction summary tahles,a useful feature of the earlier editions, has been increased significantly. The valuable 21-page appendix on nomenclature has been retained. Some drill problems have been replaced with problems from the primary literature (hut without references). There are enough unsolved problems, about Volume 64
~~
E s s a y s o n t h e Hlstory of Organlc Chemistry in t h e United States, 1875-
1955 Dean Stanley Tarbell and Ann Tracy TarbeN Folio Publishers: Nashville. TN, 1986. x 443 pp. Figs. and tables. 15.5 X 23.5 cm. $19.95.
+
(Continued on page A288) Number 11
November 1987
A287
