A Computer Program for Identifying
William Gosser and John 1. Emmons Quincy College Quincy, lllinois 62301
Organit Compounds
A
computer program has been developed as an aid in the identification of organic compounds, particularly in the organic qualitative analysis course. The basic method of identifying organic compounds is by recourse to chemical reactions, the so-called "wet chemistry" techniques. Although these techniques are still used to some extent, methods for carrying out the separation and identification of organic compounds have undergone a dramatic revolution with the advent of spectral and instrumental methods of analysis. I n the chemical reactions technique, as exemplified by Shriner, Fuson, and Curtin,' the scheme normally followed by the student in identifying an organic compound is as follows; melting point/hoiling point, ignition test, elemental analysis, solubility, classification and derivative formation. This computer program is written in IITRANa and is based upon five determinations; melting point or boiling point; elemental analysis for nitrogen, sulfur, and halogen; and the aluminum chloride-azoxybenzene test to determine the presence of inert compounds such as aromatic hvdrocarbons derived from benzene and their halogen "derivatives. These determinations are the input parameters. The numeral "0" is used to denote a negative test and the numeral "1" is used to denote a positive test. Table 1.
97 193 132 238 118 146 118 122
0 0 0 1 1 0 0 0 0 1 0 0 0 0 0
n
0 1 0 1 0 1 0 0
0 0
0 0 1 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0
Table 2. 120 99 233
Compound
henzoir arid
The computer is programmed with a data list as shown in Table 1. The columns, from left to right, in the table represent boiling point/melting point, inertness, nitrogen, halogen, sulfur, and name of the comPresented before the 3rd Great Lakes Regional Meeting of the American Chemical Societv. DeKdb. Illinois. June 5 . 1969. 'SHRINER. R. L.. us&. R. C..'ANDC"RTIN. D. Y.. "The Systematic identifibation df 0rga;io Compounds," (5th ed.), John Wiley & Sons, Inc., New York, 1964. BAWER, C. R., PELUSO, A. P., AND WOBLEY, W. S., "IITRAN 360," Addison Wesley Publishing Co., Inc., Reading, Mass., 1967.
0 1 1
0
0 0 0
Dingman Ressa. Guest
0
1
0
Typical Output Based on Input of Table 2 Inert
beta-naphthol allvl deohol toluene isobutyraldehyde methvl salicvlate n-prabyl dlebhol N,N-dimethyl aniline chlorobenzene ohthdimide icetic acid ilnthrrtnilic acid n-butyl alcohol
Typical lnput Data of Three Students 0 0
Table 3.
Sample Data List
Nitro- HaloInert gen gen Sulfur -
pound, respectively. The boiling point/melting point parameter is programmed to read plus or minus five degrees. The computer scans the data list and prints out all compounds whose parameters match those of the input. Where several compounds are printed out, the student may have to resort to one or more of the classification tests to completely identify the compound. The program permits input of several sets of data for the same student or different students simultaneously. The program can be modified in many ways to suit the instructor. For example, instead of printing out the name of the compound, the program can be modified to print out molecular weight and percent composition; or type of compound, i.e., ester, acid, carhonyl, amine, etc.; or some literature reference such as Beilstein. The program can be adapted further to other tests, chemical or spectral, and the data list can be expanded to include any number of compounds. Table 2 shows typical input data of three students, and Table 3 shows typical output data based upon this input.
0
0 0 0 0
Nitroeen Hdoeen Sulfur
Name
0 0 0 0 0
Dingman beta-naphthol aceticacid n-butyl alcohol benzoic acid
0 0 0 0 0
0
0 0 0 0
0 1 0 1 Ressa No compound fits your data. Run tests again. 233 238
0
0
1 1
0
0
0
0
Guest ~bthslimide
The computer program accomplishes several things.
It provides a rapid means of identifying an organic compound, it releases considerable laboratory time which can be used on other instrumental techniques and on the identification of more difficult compounds, it requires a minimum knowledge of programming, and it gives the student an understanding and appreciation of what the computer can do. Program and student formats are available upon request by writing to Dr. William Gasser, Department of Chemistry, Quincy College, Quincy, Illinois. Acknowledgmenls
This program came about as a result of a cooperative Volume 47, Number 2, February 1970
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137
venture in course and curriculum development between several colleges and universities in the greater Chicago area based on a regional computer network. Funding
was provided in part by National Science Foundation Grants GJ-281 through GJ-290. The computer is located a t the Illinois Institute of Technology.
5. Penzes
Research Council of Alberta Edmonton, Alberta, Canada
A Simple Cell for Preparation of Electrolytes
Most laboratory workers have a t one time or another been confronted with the problem of producing concentrated aqueous solutions of metal salts containing minimum amounts of foreign ions. The preparation of such solutions often requires elaborate experimental technique. An attractive preparation method is the anodic dissolution of a metal in an electrolyte. It is clear, however, that this method is applicable only when a suitable electrolyte can be found and when the electrochemical characteristics of the metal permit anodic dissolution. A severe shortcoming of this method is the elaborate cell required to prevent the cathodic deposition of the anodically dissolved metal. This difficulty was overcome using a simple cell which can produce a high concentration of the anodically dissolved metal (see figure). The cell was a cylindrical glass tube approximately 300 mm long. It was supplied with two side arms, and the bottom was formed so as to allow drainage and cleaning. One side arm incorporated the electrical contact to the anode, while the other served to withdraw the concentrate. The anode (the metal or metal-alloy to he dissolved) was placed a t the bottom of the electrolyte; the cathode, made of platinum, was placed near the surface. It is important that the cathode he positioned near, and perpendicular to, the surface, to allow the gas to escape. The cell was then connected to a direct current source. The electrode reactions are anode: cathode:
+ e2H+ + 2e-- HZ M
+M+
The electrolyte fraction surrounding the anode (anolyte) has higher metal ion concentration and, since it is more dense, remains in the lower part of the reaction cell. If conditions are maintained so as to avoid mixing of electrolyte layers, there will be essentially two electrolyte fractions: the anolyte at the lower section, containing the majority of the metal ions, and the initial electrolyte in the upper part of the cell. 138
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Journal o f Chemical Education
The current density will depend greatly on the particular conditions, hut, as a general rule, it should be chosen so that its heating effect will he minimized. The formation of a thermal gradient can lead to mixing of the electrolyte layers. The concentrate withdrawal tube should he of small diameter to assure minimum disturbance when the concentrate is removed. The concentration can be estimated from the weight loss and the concentrate volume, or, if the current is monitored, from the number of coulombs passed through the cell. The estimated concentration is always higher than the actual value, due to the diffusion of metal ions to the upper electrolyte layer. With a slight modification, the cell may be operated continuously. The fresh electrolyte is introduced through small holes of the anode, while withdrawal of the concentrate is continuous, but dropwise, via the side arm. The cell operates best when the anolyte is allowed to build up until i t covers the anode and the l introduction and withdrawal is balanced with , current density in such a manner that the interface of the anolyte-initial electrolyte remains a t nearly the same position, i.e., a t approximately one-half of the anode-cathode distance. Both arrangements were F~KT~o~vrr successfully used for dis, solving tin in fluoboric acid solution, and a concentration of approximately 500 g/l was obtained. It was ~cc~,om~ also possible to use a leadtin alloy for the anode; thus, a concentrate for solder plating could be prepared in a single step. =A,mOG
WT~SACF
"0T"Dt.W.L
Eledrolyrir cell for preporation.
oloctrolyto
venture in course and curriculum development between several colleges and universities in the greater Chicago area based on a regional computer network. Funding
138
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Journal o f Chemical Education
was provided in part by National Science Foundation Grants GJ-281 through GJ-290. The computer is located at the Illinois Institute of Technology.
