Matthew McBride


To recrystallize caffeine using a sintered glass funnel to allow for the removal of the 1-octanol and maximize the recovery yield of the 0.75M solution


A 0.75M solution of caffeine in 1-octanol was created in a sinter glass funnel and the caffeine was dissolved in the 1-octanol using a heating mantel. The crystals were recovered by cooling at room temperature.


Recrystallization Sheet
Concentration: 0.75M


Originally, a 1.0M solution of 1-octanol was created, but the 1-octanol began boiling and all the crystals did not enter the solution. Additional 1-octanol was added to the solution to create the 0.75M solution and all of the crystals entered the solution. However, after the caffeine crystals recrystallized, the 1-octanol could not be forced through the filter. It seemed that the crystals had recrystalized in the filter and blocked the filter so none of the liquid could pass through. From this, it was determined that future experiments must perform the recrystallization in a test tube and then transfer the solution to the filter to remove the 1-octanol.


The recrystallization cannot be completed in the sinter glass funnel because the formation of the crystals in the filter causes the filter to be blocked so that no liquid can pass through. The 1-octanol could not be removed from the sample and no product was recovered.



11:39 The weight of a sintered glass funnel was measured to be 22.3481 g.
11:51 0.4945 g of anhydrous caffeine was added to the funnel.
11:58 1.7940 g of 1-octanol was added to the funnel. The funnel was set in a beaker containing 1-octanol, so that the 1-octanol in the funnel would not flow through the filter.
12:01 Clamped the funnel over the beaker of 1-octanol in the hood. Placed a wrap around heating mantel around the funnel.
12:33 Turned the heating mantel on to a setting of 70. Placed aluminum foil over the mantel and funnel to reduce the escape of heat.
12:42 Turned the setting to 100.
12:52 The solution was observed to bubble, but crystals were still visible in the solution. The heat was turned off.
13:08 0.7124 g of 1-octanol was added to the funnel. Heat was turned on to a setting of 120.
13:10 Heat was set to max.
13:41 It was difficult to observe if all of the crystals had entered the solution using the heating mantel. The heating mantel was removed and a heat gun was used. The 1-octanol was observed to boil slightly but all of the crystals entered the solution. Heat gun was turned off and the crystals were allowed to cool. A few drops of 1-octanol pass through the filter.
13:45 Crystals came out of the solution.
14:11 The 1-octanol would not pass through the filter. Air was used to try and push the liquid through the filter, but the crystals were too tightly packed across the filter and would not allow the 1-octanol to pass through.