Laboratory experiments for undergraduate organic chemistry. I. The

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LABORATORY EXPERIMENTS for UNDERGRADUATE ORGANIC CHEMISTRY I . THE PREPARATION OF D1ACETYLETHYL;ENEDIArNINE

LAWRENCE H . AMUNDSEN Connecticut State College, Storm, Connecticut

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T HAS often been a source of annoyance to teachers add 45 g. (42.9 cc.) of glacial acetic acid. The mixture of organic chemistry that a larger portion of labora- will get hot and may boil. Attach the flask to a plain tory manuals than of textbooks is usually devoted fractionating column. Fit the column with a cork to aromatic compounds. For this reason and also be- holding a thermometer and connect the side-arm to a cause of the industrial growth of aliphatic chemistry water-cooled condenser set downward for distillation. in recent years perhaps it might be well to h d more Use a graduated cylinder to receive the distillate, and heat the flask quite rapidly so that the distillate colaliphatic compounds suitable for preparation. The preparation of diacetylethylenediamine (N,N1- lects at a rate of about 1 cc. per minute. Continue the ethyleuebis-acetamide) bas been found by us to be un- distillation until 23 to 25 cc. of the distillate has colusually satisfactory. I t gives a fair yield of a very lected. This operation need not require more than pure product in a reasonable length of time. It is, in twenty or thirty minutes. The temperature a t the fact, an experiment in the aliphatic series comparable top of the column seldom goes much above 110°, but to the preparation of acetanilide in the aromatic even if the temperature is allowed to rise considerably series. If it is regarded as an alternative to the prepa- higher, it seems to have little effect on the purity or ration of acetamide by the heating of ammonium yield of the product. Cool the flask by placing it in acetate, it has the advantage of requiring much less cold water, and stir the contents with a glass rod to time and of giving more satisfactory results in the prevent the formation of a solid mass which will be hands of students. Diacetylethylenediamine has been difficult to dissolve for recrystallization. When the prepared by the action of acetic anhydride upon eth- contents has solidified and the flask has cooled to near ylenediamine,' by the action of ethyl acetate upon room temperature, add 55 cc. of alcohol, place the ethylenediamine.hnd by the action of acetic acid flask under a reflux condenser, and boil the contents upon ethy1enediamine.l After experimenting in this until the product dissolves. When the solid material laboratory with all three methods we have found has dissolved, pour the solution into a 250-cc. beaker, that the last method is in every way the most place 5 cc. of alcohol in the flask, warm it and rinse it satisfactory. Experiments with various methods of with the alcohol which should then be added to the purification have convinced us that better results are solution in the beaker. Allow the solution to cool obtained by crystallization from 95 per cent. alcohol to room temperature. Finally cool the solution for than by any of the methods that have been prop~sed.'.~.~some time with ice, if it is available, and filter off the Ethylenediamine has recently been made available in crystals with suction. Wash them twice with enough commercial quantities a t a reasonable price, and the ethyl acetate to cover them, filter, and place them beother materials are among the cheapest substances used tween filter paper or porous tile plates to dry. When in the organic laboratory. If, however, one wishes to they are thoroughly dry, determine the yield and economize on materials, one half the stated quantities melting point. The yield is usually 25-35 g. The may be used with equally satisfactory results. melting point should be near that of the pure substance which is 175.6°.S.t A few grams of slightly impnre zu " which 20 indicates that it contained 68 per cent. ethylenediamine.' Therefore, the number of cubic centimeters of distillate to be collected and the theoretical yield of the product were calculated on the assumption that the ethylenediamine content of the commercial product was 68 per cent. WILSON,A. L., "New aliphatic amines," Ind. Eng. Chcm.,27, 867 (Aug., 1935). t Other melting points which have been reported are 173173.5",' 175",' and 172".l The melting point of the products obtained according to the above directions has usually been 172.5-174" corr. The samples used by us bad a specific gravity of 0.981

Place 30 g. (30.6 cc.) of commercial 60-70 per cent. ethylenediamine* in a 200 cc. round-bottom flask and -

1 HOFXANN, A. W., "Notiz iiber Anhydrobasen der aliphatischen Diamine." Ber.. 21.2332 (1888). ' TUCKER,N. B.." ~ o r m afatty i acid amides of ethylenediamine." J.Am. C h .Sac., 57,1989 (Oct., 1935). < m o o n , H. C. AND Rsm, E. E., "Some alkyl-glyoxalidines." ibid.. 57.2424 (Dec.. 1935). his product canbe ol;tain&d from the Carhide and Carbon Chemicals Corporation, 30 East 42nd Street, New York City.

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product may be obtained by adding ether to the alcohol filtrate after crystallization. The theoretical yield should be based upon ethylenediamine, as acetic acid 6FRANCmONT, A, ?, N, AND DUB SgY, V,,..SUr

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tion de quelques acitamide substitutuies." Rcc. tram chim., 30, 184 (1911).

has been used in excess. Experiments have indicated that this practice yields a purer product. The author wishes to express his appreciation for the aid of his organic chemistry students in testing this procedure.