Joe A. Vinson' Shippensburg State College Shippensburg, Pennsylvania 17257
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Hydrolysis of Latex Paint in Dimethyl Sulfoxide
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An organic laboratory experiment
Commercial latex paint is an aqueous suspension of a copolymer of vinyl acetate and &-ylic ester monomers along with pigments and other inorganic materials.
e
0
0 H20=CH OR acrylic ester
HnO=CHO !l CH, vinyl acetate
The purpose of this experiment is to hydrolyze the est.er groups and identify the R group of the acrylic ester. The reaction is the following
I
-
+ KOH HxO-DMSO
The use of dimethyl sulfoxide (DMSO) as a solvent in ester hydrolysis has been shown to greatly increase the rate relative to that of water (1,s). In this experiment the use of DMSO instead of water eliminates the need for a separate hydrolysis step, such as refluxing, and allows the reaction to proceed to completion during steam distillation. The only volatile product of the reaction is the alcohol ROH which is steam distilled from the reaction mixture, isolated, and finally identified by its infrared spectmm, boiling point, and economic feasibility for low-cost polymerization. 'Present address: Chemistry Department, Washington and Jefferson College, Washington, Pennsylvania 15301. This procedure is an improved modification of an experiment published in Roberts and Caserio (6). The author gratefully acknowledges Professor Caserio for helpful discussions.
Experimental"
Add 20-60 g of latex paint to a 500 ml &necked round bottom flask fitted for steam distillation and containing a magnetic stirring bar. Use 30 ml of water and 50 ml of DMSO to transfer the paint from the flask used for weighing. Pour a solution of 10 g of potassium hydroxide and 10 ml of water into the flask. Commence heating the flask while stirring and passing steam through it. Collect the distillate (50-80 ml) until foaming becomes excessive indicating all the alcohol has distilled. Saturate the water layer with anhydrous sodium carbonate, cool to room temperature, and extract the alcohol in a separatory funnel by shaking with 2-25 ml portions of pentane. Run the pentane layer into a small flask and dry with about 1 g of anhydrous sodium sulfate. Decant the pentane into a tared flask and evaporate the solvent on a steam bath in the hood. The yield is about 0 . 2 4 . 3 g per 20 g of flat latex paint. Transfer some of the alcohol into a micro boiling point apparatus (5) and determine the boiling point with a calibrated thermometer. Run an infrared film of the alcohol using the C-O stretch region (1000-1100 cm-') to determine whether the alcohol is primary, secondary, or tertiary. Consult the "Handbook of Chemistry and Physicsn-Tables for Identification of Organic Compounds (4) for possibilities. A final choice can he made by checking the price of the alcohol in a chemical catalog to determine if its use is economically feasible. Literature Cited (1) TOMMILA, E., AND MURTO,M. L., Aela Chem. Scand., 17,1947 ,,Of?, \-*""I.
(2) ROBERTS, D. D., J. Org. Chem., 29, 2039 (1964). (3) CHERONIS, N . D., in "Techniques of Organic Chemistry," (Editor: WEISSBERGER, A,), Vol. VI, Intemcience (division of John Wiley & Sons, Inc.), New York, 1954, p. 180. (4) "Handbook of Tables for Organic Compound Identification" (3rd ed.), Chemical Rubber Co., Cleveland, Ohio, 1967. (5) ROBERTS, J. D., AND CASERIO, M. C., "ExperimentalOrganic Chemistry," W. A. Benjamin, Inc., New York, 1967, p. 61.
Volume 46, Number 12, December 1969
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877
