are often present in the resin, and many laboratories are not equipped for infrared spectrophotometric analysis, the subsequent procedure is suggested. PROCEDURE Saponification, Acidification, and Extraction. Dissolve 20 to 50 grams of vehicle with 25 ml. of benzene in a 1-liter Erlenmeyer flask. Add approximately 300 mi. of 0.51V alcoholic potassium hydroxide, attach an air condenser, and reflux over a 95°F. water bath for 1.5 hours. Filter off the dipotassium phthalate, using a fritted-glass funnel of medium porosity, and transfer the filtrate to a 800-ml. beaker. Drive off the solvents in a water bath, keeping the volume between 100 and 200 ml. by addition of water. Transfer the solvent-free sample to a 500-ml. separatory funnel, add 6N sulfuric acid in 1-ml. portions until the sample tests acid to litmus, then add 1 ml. more of acid. Cool, then extract with at least three 100-ml. portions of ether. Collect the ether washings and wash them with four 25-ml. portions of water. Combine the original water layer with the water washings. Evaporate the combined water layers over a steam bath to approximately 150 ml.Reflux Distillation. Place the above water layer in a 250-ml.round-bottomed single-necked 24/40If flask. Add 50 ml. of xylene and a few boiling chips. Attach a Dean and Stark (Barrett type) receiver trap (20-ml. capacity), 24/40T, and a water condenser (400 mm. long) with a male 24/40"f" joint with a drip tip. Place the assembly over a controllable heat source and apply heat. Reflux, drawing off the water layer from the trap until approximately 100 ml. have been recovered. Evaporate the water sample to 5 to 10 ml. by any convenient method. Glycol Detection. Place 4 to 5 ml. of OTA periodic acid in a test tube, add 3 to 4 drops of concentrated nitric acid, and shake. Add 1 ml. of the evaporated water sample (above) and shake thoroughly. Add 2 to 3 ml. of 0.1 A silver nitrate. The formation of a white precipitate, silver, silver iodate (AglCR), indicates the presence of a vicinal glycol. DISCUSSION
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