The enthusiastic acceptance of this newsletter by the alumni, as well as by the college community, has made this a worthwhile undertaking. It should be noted, however, that no solicitations for funds are ever made to the alumni. This is an imvortant element to consider, since its usefulness dependsin receiving news from all the alumni it represents. without the restrictions imposed by a membership fee. G o n e interested in starting i n alumni newsletter computerizing an existing one, should contact the author for the necessary software. A sample newsletter also will be provided, if requested.
Figure 3. This is the "Limit Report" screen used with the "Select Index" of Figure 1 for printing a report or address labels. on the monitor as the information screen. At this point, the material can be edited or a memo screen can be accessed, with a field of 5000 characters (not shown). To print a listing of alumni information or mailing labels, one returns to the main screen and selects the appropriate "print" letter followed by the indexing mode desired under "select index". When the "K" key is pressed, the limit report screen is accessed and shown here as Figure 3. In this particular example, if "D" of the main screen (Fig. 11, is pressed, an alumni report will be printed out for all chemistry majors, in alphabetical order by last name, for those whose addresses &e currently known. In a similar fashion, by simply hghlighting any one of the four letters under index" of the main menu of Firmre 1,with .~ - - - - - the ~ - "select - ~ any combination of the limit report of ~ i g u r e 3it, is possible to obtain a printed report or a set of labels in the specified manner. One of the most useful aspects of this program is that it can print out a large number of mailing labels in ascending order of postal zip code greatly facilitating the use of bulk mailing. For a nonprofit educational institution, this means a significant saving of postage fees, on the order of 66%. ~
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The Newsletter The format of this newsletter consists of a cover sheet, a letter, and four main sections-College News, Department News, Faculty News, and Alumni News. Administrative, faculty and alumni profiles are also included, with a photograph of those profded. Requirements to Use the Alumni Program A dBASE I11 PLUS software package is needed. The minimum requirements to use dBASE I11 PLUS is a PC or PC clone with 256K of memory with 2 disk drive monitor and a PGDOS 2.0. Of course, to get as much as possible from this database program, an 80-column printer and extra memory is needed. A hard disk will make the application run faster, and increased board memory will allow greater freedom in using this package. Our machine is an IBM-AT with 1.5 megabytes of memory and a 80megabyte hard disk. An IBM Proprinter 111is the printer we are currently using. Discussion The preparation of a departmental alumni newsletter requires a fair amount of uncompensated effort. However, it can be reasonably edited by a single member of a department, if a simple and efficient computerized database management program is used. In addition, an institution needs to provide the services of a typist, the printing shop, and mailroom facilities. 44
Journal of Chemical Education
Acknowledgment The author expresses his thanks to John T. Fox for his invaluable assistance in the preparation of the computer program, and for his continuing interest in this project. Thanks are also due to Louis J. Bodi for his enthusiastic support of this newsletter.
Proton and Carbon43 NMR Simulation of Mixtures Harold M. Bell Virginia Polytechnic institute and State University Blacksburg, VA 24061 Programs for computer simulation of NMR spectra have been available for some time (5). These were originally written for large machines, but in recent years versions that run on personal computers have been reported (6).We recently found it necessary to simulate proton and carbon spectra of mixtures, e.g. CHZOWCH~OD, and in the course of this work modified Castellano and Bothner-By's program FREQUINT for proton analysis and wrote a new program for carbon-13. This note announces the availability of these programs for use on the IBM PC or compatible computer. Proton NMR The program for simulation of spectra of mixtures can accommodate five components, each containing as many as six coupled nuclei. The user is prompted to enter the chemical shifts and coupling constants for each component, and the mole percent of each. Then for each component the frequencies and intensities corresponding to all transitions are calculated in the usual way, and the results are either printed or stored to disk. Finally a plot of the spectrum is presented on the video display. Here the user svecifies the chemical shiR rance. the plot size, and the Ilnewidth; spectrum integration is provided upon request. T h ~ dot s mav then be dlrected to a Hewlett-Packard Color Pro, or compatible, plotter, or dumped to a dot matrix printer. The program was written because of the need to simulate overlapping spin-spin splitting patterns of mixtures,
Figure 4. Simulated proton spectrum of paint remover.
and it functions exactly as intended. However, two other useful applications should be noted. First, it simulates the spectra of campounds containing two or more separate spin systems. For example, the spectrum of ethyl propionate, with two AzX3spin systems, is created by treating the compound as a 50150 mixture of two separate five-spin "molecules". Similarly, the spectrum of t-butyl acetate is obtained by simulating an equimolar four-component mixture, with one component containing the acetate methyl and the other three each having one of the t-butyl methyls. Second, the ability to integrate affords instructors the option of creating mixture spectra for use in problem sets or exams. For examole. ~.the 90 MHz simulated s~eetrumof a mixture of 11.9r~ m~thdnul.33 W r arrlonr, 11.2'; rduene, and 13 3% methyhe chloride, shown m F ~ ~ m 1, r e is nmrl?. ~ndisr~npmshahlr from the spectrum of a sampled huusehold pninr remover.
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Carbon NMR This nronam affords the simulation of nmton-decouoled carbon-13 spectra of mixtures containing as many a s eight components, each with up to 50 carbon atoms. A separate program is first used to create a file that contains the shift data for everv comnonent in the mixture. The main program reads this fileand then prompts the user for the percent com~ositionof the mixture to be simulated. A plot of the spec&um is provided, as in the proton case, with user specification of the delta range, plot size, and linewidth. As before, integration is provided i p o n request. The optional pen plot has one feature not found in the proton simulation: If a plot height of less than three inches is chosen, a "stick plot" of each component will be drawn directly above the mixture spectrum. An example is shown in Figure 5.
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tive to hardware and the number of coupled nuclei. For example, the ABXBcase requires about 22 s to compute, 2 s to plot, and 11 s to integrate if the IBM PC is equipped with a n 8087 math coprocessor. Otherwise, the times increase to 50, 5, and 30 s, respectively. An IBM PS2 Model 60 equipped with the math coprocessor gave times of 5,2, and 4 s for the same calculations. Carbon simulations require virtually no time to calculate the pattern, but considerable time to plot, owing to the rather large spectrum widths encountered in carbon-13 NMR. A six-component mixture with 36 different chemical shifts spanning 100 ppm required 65 s to calculate the Lorentzian line shapes and display the resulting spectrum on an IBM PC with 8087 math chio. Copies ofthese programs are available on either 3 112-in. or 5 114-in. disks for $5.00 (free if formatted disks and prepaid mailer are sent). Please specify disk size desired and indicate EGA and 8087 availability. Checks should be made payable to the Virginia Tech ~ h e k i s t r y Department and should be sent to H. M. Bell, Chemistry Department, Virginia Tech, Blacksburg, VA 24060.
A Tutorial on the Use of Curved Arrows in Organic Chemistry William N. Turek St. Bonaventure University St. Bonaventure, NY 14778
The use of cuwed arrows in organic chemistj is a n excellent wav to illustrate the flow of electrons a s reactants form intermediates or products. Properly used, curved arrows also act as a mide to the mechanism of a reaction. L~nfortunatrly,some students have dittictilty using curved arrowscorrectlv At the June 1988 ACS meetinc in 'll~mnto this fact was biought out as participants critiqued current textbooks. Curved arrows, to varying degrees, appear in most textbooks but only a few devote significant space to describing the fundamentals of curved arrows (7).Since some authors do not include the nonbonding electron pairs on nucleophiles, the mistaken notion that cuwed arrows are used to move atoms and not electrons can be given. In other cases the curved arrows are imprecisely printed leading to student confusion. To complement textbooks in their treatment of curved arrows a computer tutorial has been developed. +he tutogal displays a curved arrow equation for Hz0 and HBr. The direction of the cuwed arrows is discussed in terms ofeleciron donor nucleophilic, sites and electron accentor relcetroohillc, sites. The factors that drtwminc the nucleophilicity of a site are explained. After the curved arrows are erased, the student can draw them to reinforce how curved arrows are correctly drawn. An example of curved arrows emanating from implied nonbonding electrons is included. I n addition, a n erroneous way of drawing cuwed arrows is ~ v e and n explained. ouro other examples of &wed arrow equations are given and explained: the ionization of tert-butyl chloride, the reaction of the methoxymethyl cation with water, the formation of a n acylium ion from acetyl chloride a n d aluminum chloride, a n d t h e reaction of ethene with hydrogen chloride. The last example illustrates that the chemical properties of the reactants must be known if curved arrows are to be drawn correctly. The second part of the tutorial contains 11equations in which the curved arrows are drawn correctly or incorrectly. The student is asked to indicate hisher choice; then the response is graded followed by a n explanation that is correlated with the response. The equations used are given in the following list:
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. i , . i t . i , . i , . I b . . * . n . CHEll SHIFT
Figure 5. Methyl-b-glucoside-3,6-dinitrate. OH on C2 and C4 30% deuterated. Thisis a nortion of the snedrum of methvl-b-ducoside-3.6a; C-2 and C-4 dinitrate'in acetone. he hydroxyl are nartlv deuterated, which causes the corresponding signals near 72.1 and 68.'5 to be "doubled". signal; a t 72.7 a i d 73.7 correspond to C-6 and C-5, respectively. The program is limited in that no allowance is made for different nuclear Overhauser enhancements or different degrees of saturation from carbon to carbon, or from component to component. However, even with thislimitation it still is useful in many situations involving analysis of mixtures by carbon-13 NMR. Both oroerams are written in FORTRAN and are available fo; t h i IBM-PC and compatibles, in four versions, with and without the 8087 math comocessor, and with CGA or EGAgraphics. As long a s a pen plotter is available, the choice of eranhics d i s ~ l a v is s not important. However, ~ give good-quality screen only t h e E G &aphics'w;ll dumps. Run times for proton simulations are very sensi-
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Volume 69 Number 1 January 1992
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