Sandra C. Thomason
and Donald G. ~ u b l e r ' Furman University Greenville, south Carolina 29613
The oxidation of aldehydes to acids by silver(1) oxide is a well-known p r o c e d ~ r e ,as ~ is the Tollen's Test for the qualitative detection of aldehydes3 as well as variations for the quantitative analysis of ald e h y d e ~ . ~While both hydrogen peroxide and potassium permanganate are standard reagents to convert aldehydes to acid derivative^,^ we have not found procedures in the literature using silver oxides for this purpose. Inasmuch as silver(1) oxide does not affect carbon-carbon double bonds nor many other functional groups sensitive to oxidation, this reagent should be superior to either hydrogen peroxide or potassium permanganate for preparing acid derivatives of aldehydes. We have evaluated silver(1) oxide and silver(I1) oxide Grateful acknowledgment is made for support of this work by the Undergraduate Research Participation Program, National Science Foundation (GE-2578). R. B., A N D ZOOK,H. D., "Synthetic Organic ChemWAGNER, istry," John Wiley & Sons, Inc., New York, 1953, p. 419. a S ~R . L., ~ FUSON, ~ ~R. C., ~ AND , CURTIN,D. Y., "The Systematic Identification of Organic Compounds,'' (Ah ed.), John Wiley & Sons, Inc., New York, 1964, p. 173. ' SIGGIA,S., IND SEOUL,E., Anal. Chem., 25, 640 (1953).
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Journol of Chemical
Education
Acids as Derivatives of Aldehydes Prepared with Silver Oxides
for this purpose and find the procedure is simple and rapid and provides good yields of the acids. For these reasons this technique is the method of choice to prepare an aldehyde derivative whenever the acid so formed is a solid. The aldehyde is added to a slight excess of a silver oxide and aqueous sodium hydroxide in a test tube and stirred for a few minutes. The unreacted silver oxide and the silver are removed by filtration and the filtrate is acidified to separate the acid derivative. The acid may be identified by its melting point, its neutralAldehyde Derivatives by Oxidation with Ag20
.
.. -Ag,O 0ridn;,As. m.p. m.,,.
Product p-Ac,etln!idobenmic acid Amne acid Beneoio acid pBromobenroio acid Cinnamio acid Cmtonio soid p-Cyanobenroio acid Furoio acid p-Nitrobenzoio acid Salicylic wid Sorbic aoid p T o l u i o acid 3.4.5-Trimethoxybenzoio aoid
Reorystallieed from
water.
251 253-254 184 184-185 121 120-123a 251 257-260 133 131-134 72 71.5-72.5 214 214-216 133 127-1300 241 240-243 157 156158b 134 133-134 177 180-181 168 167-170
a Reorystailized from a ~&r-aieohol mixture.
-As0
and
Ago
Oxidn.:
ization equivalent, or spectral characteristics. Treat,ment of each of thirteen aldehydes with silver(1) oxide and with silver(^^) oxide provided acceptable yields of pure acids (see the There appears to be no chemical advantages of one reagent over the other, but because of availability and cost silver(1) oxide is the preferred reagent. Experimental
oneml (or 1 of solid) of the aldehyde was to a suspension of 1.1-1.4 g of silver oxide in 3.0 ml of 10Yosodium hydroxide
and 5 ml of water in a. test tube. The mixture was stirred with a glass rod until the dark, fine silver oxide was converted to the flocculant, brown silver. The reactions were all exothermic. The silver and unreacted silver oxide were removed by filtration, and the filtrate was acidified with concentrated hydrochloric acid to precipitate the acid derivative. The acid was filtered 08, washed with ice water, and air-dried. For those acids (furoic acid and crotonic acid) which have relatively high solubilities in water, the acids were recovered irom the water via ether extreetion. The melting points of most of the acids in the table were obtained without further purification. A few were purified by crystallization from waler or water-alcohol mixtures.
Volume 45, Number 8, August 1968
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