Cracking mineral oil. Dem. 663 - Journal of Chemical Education (ACS

Demo. Previous Article · Next Article · Table of Contents .... About Us · ACS Members · Librarians · Authors & Reviewers · Website Demos · Privacy Pol...
0 downloads 0 Views 935KB Size
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