EXP292

=Researcher= Rida Atif =Objective= To determine the recrystallization yield of the purified cinnamic acid (291a) from the puirfied crystals from EXP291. Expecting an 85% recrystallization yield because the hypothesis of impure crystals in EXP281 is being tested.

=Results= 0.057M solubility of the cinnamic acid in boiling hexane. This was calculated by converting mass of crystals obtained after the recrystallization to moles and dividing by the liters of solvent used. Only 54% of the cinnamic acid was able to be recrystallized.

=Discussion= The results of this experiment do not coincide with the with expected recrystallization yield of 85% as predicted in EXP291. The apparent solubility according to this experiment is 0.057M which disagrees previously determined solubilities of 0.13M and 0.18M.

=Conclusion= This experiment's yield of 54% is close to the EXP281's yield of 64%. Because of the close yield's, we can negate the theory that the low yield in EXP281 could have been due to an impurity in the cinnamic acid. If it was due to an impurity, the yield in this experiment would have been close to 85%.

=Log=

2012-06-04
11:40 - 0.3539g of 291a (purified cinnamic acid) was put into a 50mL Erlenmeyer flask. 11:42 - Turned hot plate on to 190C 11:54 - Added 5mL of n-hexane into erlenmeyer flask and set on hot plate with loose cap on (to prevent hexane from evaporating and escaping the flask). 11:59 - Added approximately 1mL of hexane into flask 12:00 - Turned down hot plate to 125C 12:02 - Added 1mL of hexane into flask. 12:04 - Added 1mL of hexane into flask. 12:06 - Added 1mL of hexane into flask. 12:07 - Turned hot plate up to 200C because the hexane slowed down boiling tremendously. 12:09 - Added 1mL of hexane into flask. 12:12 - Added 1mL of hexane into flask. 12:15 - Added 1mL of hexane into flask. 12:17 - Added 1mL of hexane into flask. 12:22 - Set another erlenmeyer flask with pure n-hexane onto hotplate 12:23 - Added 1mL of hexane into flask. 12:25 - Added 1mL of hexane into flask. At this point there is a total of 15mL of hexane in the flask. 12:30 - Added 1mL of hexane into flask. 12:34 - Added 1mL of hexane into flask. Some crystals are sticking to the inside wall of the flask. 12:36 - Added 1mL of hexane into flask 12:40 - Added 1mL of hexane into flask. 12:43 - Added 1mL of hexane into flask. 12:44 - Added 1mL of hexane into flask. The crystals have clumped together to appear larger than the original "salt crystal" size. 12:47 - Added 1mL of hexane into flask 12:51 - Added 1mL of hexane into flask. 12:54 - Added 1mL of hexane into flask 12:56 - Added 1mL of hexane into flask. at this point there is a total of 25mL of hexane in the flask. 1:00 - Added 1mL of hexane into flask. 1:04 - Added 1mL of hexane into flask. 1:07 - Added 1mL of hexane into flask. 1:10 - Added 1mL of hexane into flask. 1:13 - Added 1mL of hexane into flask. 1:21 - Added 1mL of hexane into flask. 1:23 - Added 2mL of hexane into flask. 1:26 - Added 1mL of hexane into flask. 1:28 - Added 1mL of hexane into flask. At this point there is a total of 35mL of hexane in the flask. 1:30 - Added 1mL of hexane into the flask 1:35 - Added 1mL of hexane into the flask 1:37 - Added 1mL of hexane into the flask. 1:39 - Added 1mL of hexane into the flask. 1:45 - Added 1mL of hexane into the flask. 1:49 - Added 1mL of hexane into the flask 1:53 - Added 1mL of hexane into the flask. All of the crystals have gone into the solution. There is a total of 42mL of hexane in the flask. 1:54 - Removed flask from hot plate and set down to cool so crystals form 2:05 - mass of filter paper 0.1688g 2:09 - suction filtered crystals in flask 2:12 - mass of empty vial with cap 13.5939g 2:19 - the crystals are very light and easily fly away. they seem very static. 2:20 - mass of vial with cap with crystals 13.7878g 2:20 - mass of crystals obtained after recrystallization 0.1931g