edited by G E O R ~ EL. GILBERT Denisan University Granville. Ohio 43023
A Modification of the Copper Catalysis Demonstration Apparatus SUBMITTEO BY: Edwln S. Olson and R. E. Ashmore South Dama State Un vsrw, Brwkings. SD 57077 CHECKED BY: Darrell D. Axtell Eastern Montana College
shown to undergo a similar oxidation if the alcohol is heated in the water bath to within lo0 of its boiling point. These other alcohols have more of a tendency to "pop" especially if you try to test the effluent gases, thus testing the oxidation product from alcohols other than methanol should he done with extreme caution. With methanol, use care in bubbling gases through the concentrated HqSOa - .solutions. and take care not t o inrale the formaldehyde or methanol vapors. Never use oxygen gas, only air. ~~~
Billings, MT 59101
The demonstration reported by one of us several years ago has been used successfullv in introducina and illnstratine the oxidation of alcohols to carbonyl comp&nds over a copper catalyst.' We should like to suggest amodification in the ap. paratus which gets a little more out of the demonstration. If the reaction chamber is constructed with a constricted neck 4 cm from the top, the Nichrome holder for the copper coil can rest there, and then a rubber stopper with a lead out tube can he inserted in the top after the reaction has started. Thus, the effluent gaseous products can be huhhled into tuhes containing testing reagents.
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' Ashmore, R. E., J. CHEM.EDUC.,45,243 (1968).
Feigl. F.. "Spot Tests in Organic Analysis," Elsevier, New York, 1966. 0. 434. ~ k n e rR. , L., Fuson. R. C.. and Curtin, D. Y.. T h e Systematic
ldentificat~on of Organic Compounds," 5th Ed., John Wiley and Sons, York,19649 P. 126.
Lecture Experiments in Gas-Liquid Chromatography with a Simple Gas Chromatograph at Room Temperature m
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Adalbert Wollrab Institute Didaktik der Chemie at the Justus Llebig University 63 Giessen Federal Republlc of Gwmany
TO TEST N E E
arorm 8":
Rlchard R. Doyle Denison University Granville.OH 43023 ..
A thick-walled mhher tube isconnected with one end to the outlet of a reduction valve which reaulates the flow of hvdrogen from agas cylinder. The othe'end of the rubber tuge is connected to a glass tube (about 30 in. long and 'Izin. diameter) filled with salt which is coated with a layer of hexadecane. A short glass tube, drawn out a t one end into a c a ~ i l lary (inner diameter about 1 mm) bent up at a right ang];, is joined by a short rubber connection to the glass tube packed with salt.
,, TO BUBBLER
Copper catalysis apparatus. Thus, one can show that the product of the copper-catalyzed oxidation of methanol is indeed formaldehyde by the specific chromotropic acid test and simultaneously exhibit some chemical properties of formaldehvde. T o test for foimaldehyde, the gases are huhhled into concentrated sulfuric acid for about half a minute and then a few milligrams of c~romotropicacid are added, Formaldehyde forms a violet dye with chromotropic acid2Another good test is t o bubble the gases into 2,4-dinitro~henylhydrazine reagent.3 The yellow precipitate of the 2,4-dinitrophenylhydrazone is formed. After arousing interest with these colorful demonstrations, the nature of the condensation of formaldehvde with Dhenolics (such as chromotrooic acid) and ~~~~~~, ~with -.-~ hydiazines can he developed in the lecture in addition to a discussion of the oxidation. Other volatile alcohols (ethyl, propyl, isopropyl) can be a
1042
Journal of Chemical Education
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Coating o f t h e Salt and Packing 0' the Column Material: one 250-ml beaker, 1Petri dish (10-15 in. in diameter), 1mortar, 1spatula, 1glass tube (about 30 in. long and 'h in. diameter), cotton wool, 100gsodium chloride, 1.5 ml hexadecane, 30 ml chloroform. Procedure: 100 g sodium chloride is ground in a mortar in 10 g portions to a very fine powder. 1.5 g of hexadecane is mixed with 30 ml chloroform and the liquid poured onto the sodium chloride in a 250.ml beaker. ~h~ salt is thoroughly mixed with the liquid and placed in alarge Petri dish. The mixture is stirred and blended with a spatula in the fume cupboard until the saltlwks dry and is no longer lumpy. The dish is left 2 hr in the fume cupboard. The glass tube is clased with a wad of cotton wool at one end and filled with the coated ~ salt ~ by means ofafunnel connected to theelass - tube hvambber tube
' Wollrab, A., J. CHEM.Eouc. 52,200 (1975).
