ORGANIC CHEMISTRY in BEGINNING CHEMISTRY COURSES* GLEN WAKEHAM University of Colorado, Boulder, Colorado
HEMISTRY teachers are generally aware that the proportion of time allotted to organic chemistry in beginning courses is gradually increasing. Time was when high-school and freshman courses coutained no organic chemistry; i t was assumed that the students would take organic chemistry later on. It was presently realized, however, that the majority of students in beginning courses would never take any more
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* Presented before the Divisions of History of Chemistry and Chemical Education at the Midwest Regional Meeting of the A.C.S., Omaha, Nebraska, April 29-May 1, 1937.
chemistry; also that organic chemistry is of just as much general importance, common interest, and cultural value as inorganic chemistry. Hence the gradual encroachment of organic chemistry into beginning courses. Textbooks which formerly contained five or ten pages of organic chemistry now devote from fifty to a hundred to that branch of the subject. The time will probably come when high-school and freshman courses will he divided about half and half between the two suhjects. In the meantime, however, chemistry teachers are ex-
periencing some difficulty in crowding in the organic subject matter without dropping any of the inorganic topics or getting any increase in the amount of time available for chemistry. In the end, it will doubtless be necessary to reorganize the whole subject as "general
"organic" view of the whole field, as a single, closely inter-connected unit-not simply a chaotic mass of unintelligible empirical formulas to be memorized. It includes a fairly representative range of the substances in which the student is most likely to be inter-
TABLE 1 OUTLINEOF ORGANICWMISTRY I. ,ALIPHATIC(CHAIN)COMPOUNDS
Hydrocarbons Po~afins H
I I
Halogen Subdilution Producls CH. L Cl. =
.
Alcohols AgOH = i- AgCl
Aldehvdes CHIOH 4- 0 = HCHO 4- H 2 0
++ +
C,HbOH 0 = CHsCHO HZO (CxHaO) C-Hs.0 Sugars 6 CHIO = CaHllOs 2 GHi20e - HIO = CL~HZZOU Starch and Cellulore nC6H120s- nH1O = (GH,oOa).
CFT.CI L
"
HCHO 4- 0 = H . COOH(CH20J
H-C-H
CHIS
H
GHe f C12 = HCI GHCl
H
+
I H-C-H I H-C-H I
A lnkm
H
CHdn
+ 1)
Illuminating gas, Gasoline, Mineral and L u b r i c a t i n g oils, Vaseline, P a r a f i n waxes
Unsaturated &carbons
C,H,NHn, etc. Proteins Complexes of aminoacids such as: CHnNHnCOOH Ethers ZC*H& - H,O = (C,HdlO
Hydro-
CnHsCl AgOH = GHrOH AgCl C&I, 10 Glycerol H
I I H-C-OH I H-C-OH I H-C-OH
++
+
CHCHO 0= CH8COOH(GH602) Fatty Acid Type: C.Hs.OJ C,BHJ%OS (Palmitic) C M H ~ (Stearic) O~ ClsHnOl (Oleic, unsaturated) Fals end Oils C I H ~ O H )-t~ 3CtaHnOn = CaHs(C!sHaOJr 3Hn0 (Tri-oalnntml . . Soaps C,H,(CX&,O,)~ 3 NaOH = 3 NaC~sHarOz CJHI(OH).
+
++
H Nitroglycerine
Glycerol TrCNitrete CaHs(NOa)a
Acetylene CaG HIO = HCI CH Ca(OH)r
+ +
Hydrocarbons Benzene
F ,cH'cH
Chlorobeneenc GHsCl Nitrobensene
qWi0,
(Exploswes, Like "TN-T") Trinitrc-
Phcnol ("Carbolic acid." somewhat like alcohol) CHrOH
Bcnsaldehyde C6H6CH0
Benemc Acid C&COOH Salicylzc Acid CsH40HCOOH ("Aspirin" derived from this)
I
HC
%' chemistry," to choose the most desirable topics from all branches of the subject. For the present, however, it seems necessary to compromise by trying to discover the neatest, most effectiveway of giving beginning students some intelligent idea of the scope and importance of the organic field in a minimum of time. The outline here presented is admittedly a provisional makeshift. I t has been praised by many experienced high-school teachers who attended the writer's class in the teaching of elementary chemistry as "just what they were looking for." Its possible advantages, when competently presented, may be suggested. I t gives the student a compr+ensive, integrated,
ested, and shows their relationships with each other. It presents a skeleton outline which any teacher can amplify according to his own ideas, or the special needs of his class. I t illustrates the chief ideas and nomenclature of organic chemistry which the student is likely to meet in intelligent general reading--organic synthesis through a series of reactions; substitution; homologous series; isomerism, and so forfh. I t builds up the system structurally from the simplest compounds. It can be completely presented in a relatively short time.
It is easy,of course, to criticize or ridicule this outline from various viewpoints. It can be (and has been!) called "organic chemistry on one page," "dilettante chemistry," "pseudo-chemistry," "organic chemistry in half an hour," and so forth. The only reply is that it has been used by a number of teachershard-pressed for t i m e w i t h results which they and their students deemed satisfactory and gratifying.
series of substitution syntheses. General importance of the alcohols. 6. Continuing substitution in organic synthesis. "Alcoholisdehydrogenatw," intermediate step between alcohols and organic acids. 7. Further synthesis by oxidation, forming organic acids. Importance of "fatty" acids. 8. Simple sugars as polymers of formaldehyde, probably synthesized by nature from formaldehyde. NOTES ON PRESENTATION Higher sugars and polysaccharides as condensations of 1. Point out the almost universal tetravalence of simple sugars, with loss of water. The reverse process carbon and the unique power of carbon atoms to unite of hydrolysis in nature and industry. with each other to form "chain" and "ring" compounds. 9. Fats as esters (organic salts) of glycerol (an alco2. Classification of all important carbon compounds hol) and fatty acids. Soaps as alkali salts of fatty into "chain" (aliphatic) and "ring" (aromatic) com- acids. pounds. 10. Amines are mentioned simply as an introduction 3. Methane as the "great-grandfather" of all chain to some knowledge of proteins. compounds. The paraffins as a typical homologous 11. Ethers, unsaturated hydrocarbons, and nitroseries. Common substances included in the paraffins. glycerine may be included, or omitted, a t the teacher's "Cracking," and so forth. discretion. 4. "Substitution" of chlorine for hydrogen in 12. Benzene derivatives are treated as parallel anamethane. Importance of this and analogous methods logues to the paraffin derivatives. Many teachers will in organic "synthesis." want to extend this part of the course somewhat. 5. Further substitution of hydroxyl group f i r halo13. Most students enjoy learning a few "structural" gen. "Evolution" of organic compounds through a formulas.
