40 MISC. PUBLICATION 679, U. S. DEPT. OF AGRICULTURE 



advisable to employ enough flasks, beakers, and graduated cylinders so 

 that each can be used for its specific purpose throughout the operation 

 without needing to be cleaned or dried out. 



2. Place the separatory funnel in the ring stand and pour into it in- 

 hibited monomer until it is slightly less than one-half full. Add an 

 equal volume of 2-percent aqueous sodium hydroxide solution. 



3. Remove the separatory funnel from the ring stand, and, while 

 holding its stopper in place, shake it vigorously and intermittently 

 until the two liquids are thoroughly mixed. It is advisable to loosen 

 the stopper once or twice during this operation to release any vapor 

 pressure that may have been built up. 



4. Replace the funnel in the ring stand and allow the two liquids to 

 separate by gravity. The lower liquid is the hydroxide solution which 

 is now brownish in color because it contains the hydroquinone. When 

 separation is practically complete, draw off this lower liquid and discard 

 it. While doing so, remove the stopper temporarily from the top of the 

 funnel to admit air for replacing the liquid drawn off. 



5. Repeat steps 3 and 4 after adding a fresh quantity of hydroxide 

 solution to the separatory funnel. If the lower liquid now remains 

 colorless it is safe to assume that the hydroquinone has all been removed. 

 If any trace of color appears, however, add hydroxide solution and re- 

 peat steps 3 and 4 until the alkali wash is finally colorless. 



6. In order to remove the residual alkali, pour into the funnel an 

 amount of distilled water approximately equal in volume to the monomer 

 already in it. Remove the funnel from the stand and shake it vigor- 

 ously as in step 3 until the liquids are thoroughly mixed. 



7. Again place the funnel in the stand, and when separation of the 

 liquids is practically complete , draw off and discard the lower (aqueous) 

 portion. 



8. Repeat step 6, using a fresh quantity of distilled water, and this 

 time, after shaking and subsequent separation, draw the discard portion 

 into a beaker that has been well rinsed with distilled water. Test this 

 for alkalinity with litmus paper or with pH indicator solutions or papers 

 having a range above pH 7. If the presence of sodium hydroxide should 

 be indicated by this test, repeat step 6 until a negative test is obtained. 



9. Draw all of the monomer from the funnel and transfer it to an 

 Erlenmeyer flask which contains enough anhydrous calcium sulfate or 

 calcium chloride to form a layer approximately one-half inch thick over 

 the bottom. This flask should be tightly stoppered with a tinfoil- 

 wrapped cork and stored at a temperature of 4° C. (approximately 

 40° F.) or below. The monomer should stand thus over the desiccant 

 for at least 10 hours to make sure all the water has been taken out of it . 

 It may then be transferred to clean, dry storage bottles having metal- 

 lined screw-caps, or it may be left in the desiccating flask until needed. 

 In case this monomer is to be used with a catalyst that does not neces- 

 sitate filtration, it should be filtered at this time before transfer to the 

 storage bottles so as to remove the particles of desiccant which might 

 otherwise cause haziness in the finished plastic. Continuous storage 

 at the low temperature specified is necessary as a precaution against 

 premature polymerization. 



10. If the desiccant used for drying the monomer is of a type that 

 can be reactivated, it should be spread out on a tray after use to permit 

 complete evaporation of the monomer before it is heated for reactivation, 



