Tested Overhead Projection Series Compiled by
HUBERT N. ALYEA Princeton University
22. ORGANIC CHEMISTRY
A. General Dem. 6 6 1-Ammonium
Cyanaie fram Urea
To show; Formation of ammonium and cyanate ions by heating urea-aq; a reversal of the classical Wohler's synthesis: (NH)&=O urea
~1NIL,+
+ OCN-
rtrnmo~uumeyanate
Materials: 1 molar urea, device E-1 or Me-amps for measuring current. Procedure: (a) Project two culture tubes half-filled with 1 M urea in H-3. Boil tube B for 5 min. Now transfer the tubes to Me-amps, project, and test for conductivity. (b) Ditto, but add two drops of AgN03aq to each. Observations: (a) The unboiled tuhe (urea) does not conduct; the boiled tuhe (NH,+ and OCN-) conducts. (b) Tube 1, no reaction with Ag+; tube 8 precipitates white (macro) AgOCN. Reference: WALKER, J., and HAMBLEY, 13. J., J. Chem. Soc., 87, 746 (1894); SCHEER, R., P rmis Chem., 5, 56 (1956); SEETHAHAMAN, P. A,, J. Chem. Igduc., 39, A8.19, 1962 uses urea which reverts to ammonium cyanate.
B. Chain Compounds Dem. 662-Amylene
+ Bramine
To shoto: The addition of bromine to unsaturated hydrocarbons. Material:
Bromine, amylene (I-pentene), H-3, cotton.
Procedure: Push a loose wad of steel wool into the bottom half-inch of a culture tube, and to this add four drops of mineral oil. Project in H-3. Heat until white clouds (hydrocarbons) appear. Now tilt an unstoppered bottle of Brs to let the reddish-brown vapor spill into the culture tuhe. Immediately stopper. Let stand a few seconds. Observations: The reddish-brown color disappears. Reason: The steel wool catalyzes the crackiug of the hot oil, giving unsaturated products; the double bonds in the latter add bromine which disappears. Bn 7 CCnHzn A
Reactions:
CnHzn+z
Dem. 664-Cracking
C,H&b
Bacon Fai
To show: The high-temperature cracking of bacon fat, and reaction of the unsaturated products with bromine. Materials: Bacon, forceps, H-3, two culture tube stoppers, bromine. Procedure: Tilt an unstoppered bottle of bromine to spill the vapor into two culture tubes; stopper at once. Project in H-3. Into tube one drop a strip of bacon, about 3 X '/%X in. Holding in the forceps, heat a similar strip of bacon in H-3, and when the bacon sputters and drips, drop it into the bromine in culture tube 2; stopper at once. Observations: Tube 2 becomes colorless in a few seconds. Reason: Heating bacon fat cracks it into unsaturated acrolein (CH,=CH-CHO; this causes the acrid choking odor from burned bacon); the double bond of the unsaturated compound adds bromine, decolorizing the tube. Dem. 665-Preparaiian
To show:
af Aceiylene
Preparation and combustion of acetylene.
Materials:
Fresh calcium carbide, cell H-1.
Procedure: Project two culture tubes in H-3. Tilt an unstoppered bottle of bromine over each, so as to fill them with the reddish-brown vapor; then quickly stopper them with small plugs of cotton. Now put two drops of amylene into tube 2, stopper it again.
Procedure: Project cell H-1 with the generator containing 1 lump (5 mm3, no larger, CARE)of CaC2, and water in the medicine dropper and the receiver. Collect gas in the holder; test with a lighted match.
Observations: Tube 2 becomes colorless as the bromine in i t adds to the unsaturated bond in amylene.
Observations: Acetylene, caught in the gas holder, explodes with air when a match is applied to it.
Reaction: CHFCH-CH1-CH,-CH3 CH2Br-CHBr-CH1-CH3-CH3 Dem. 663-Cracking
+ Br,
-
Mineral Oil
+ +
-+
+
Reactions: CaC2 2HOH Ca(0H)s C%H,t ; 2C2Hz 50%-+ 4C02 2H20. Dem. 666-Acefylene
Formed in a Ballaon
Experiment developed by Ken.neth V. Jaclcman.
Experiment developed by Carl J. Maneuso.
To sh,ow: The cracking of mineral oil, using Fe as catalyst, to give unsaturates which add bromine.
To show: in it.
Materials: Steel wool, H-3, mineral oil, dropper, bromine.
Materials: Rubber balloon, lump of fresh CaCz, thread, medicine dropper, Bunsen burner.
Balloon swelling as acetylene is generated
Volume 46, Number 9 , September 1969
/ A633
