EXP226

=Researcher= Sozit Kurtu =Objective= To determine the concentration of //t//-cinnamic acid in ethanol at 20C, 25C and 30C using density measurements and NMR spectroscopy. The additivity of volumes is an [|assumption] and the density of the solid is obtained from ChemSpider prediction. =Procedure= =Results= [|Measurements] =Discussion= =Conclusion= =Log=
 * [Make spreadsheet editable by anyone - also missing pure solvent densities - you must use these for the calculation. JCB]**
 * [Provide SAMS sheet JCB]**
 * [Report the final measurements here on the wiki as well.JCB]**

2011-10-31
12:15 - Measured 1.502g //t//-cinnamic acid. 12:18 - Made solution in 4mL volumetric flask. 12:31 - Submerged solution in 34C hot water bath. 12:35 - Bath temp 33C. 12:40 - Bath temp 31C. 12:43 - Bath temp 30C. Solution is not dissolving. Moving to Rotovap bath. 13:04 - After attempting several other methods, including sonicator bath and water drawn from a different tap, placed sample in a beaker of water on a hotplate. 13:15 - Increased temp to 100C to facilitate heating with greater speed. 13:25 - Increased temp to 150C. Heating of water bath is unusually slow, possibly due to the cooling effect of the hood fan, the relatively small size of the beaker, or a malfunction of equipment. 13:35 - Water bath reached 50C. Stable. 13:40 - Measured 9.477g //t//-cinnamic acid to ensure a larger sample size. 13:42 - Made solution in 25mL Erlenmeyer flask, as a volumetric of that size was not readily available, and a great degree of precision was not necessary for a saturated solution. 13:44 - Submerged solution in a separate beaker of hot water. Starting temp 34C. First solution of 4mL discarded. 13:49 - Bath of 25mL solution reached 50C, stable. 14:35 - Decanted solutions into three screw-top vials. Withdrew <0.5mL for NMR analysis. Added CDCL3 to NMR tube. Solution precipitated quickly, so the vials were returned to the bath while NMRs were taken. 14:52 - Took NMR spectrum of solution.(NMR-1) 15:03 - Set vials of solution aside in hood for further analysis at a later date.

2011-11-01
12:30 - Put sample A in 20.5C bath. 12:39 - Equilibrated to 20C with ice. 12:42 - Put samples B and C in heating bath. Starting temp: 34C. Again, set hot plate relatively high (150C). 12:48 - Hot bath at 50C and cold bath at 20C. 13:12 - Transferred B and C to 25C and 30C, respectively. 13:14 - Empty flask A0 (5mL) weighs 12.768g. 13:15 - Visually determined that there was Not enough sample A for 5mL. Pipetted sample A into 2mL volumetric flask (A2mL), also transferring ~3-400nm to an NMR tube. Added CDCl3 to NMR tube. 13:16 - Empty flask A1 (2mL) weighs 17.444g. 13:17 - Weighted flask A1 (2mL) weighs 19.154g. Did not notice any immediate precipitation. 13.19 - Empty flask A2 (1mL) weighs 20.378g. 13:20 - Transferred 1mL sample from flask A1 to flask A2. Weighted flask A2 weighs 21.234g. 13:26 - Noted that 30C bath dropped to approx. 29.75C, while 25C bath still stable. 13:36 - 30C bath dropped to 29.25C. Equilibrated to 30C with hot tap water. 14:12 - Empty flask B1 weighs 18.206. Though the same flasks were used for all three samples, cleaning between uses, the stoppers were mixed up. 14:13 - Pipetted sample B into 2mL volumetric flask (B1), also transferring ~3-400nm to an NMR tube. Added CDCl3 to NMR tube. Bath B stable at 25C. Bath C stable at 30C. 14:15 - Weighted flask B1 weighs 19.937g. Did not notice any immediate precipitation. 1417: - Empty flask B2 weighs 20.379g. 14:18 - Transferred 1mL of sample from flask B1 to flask B2. Weighted flask B1mL weighs 21.244g. Some crystals forming. 14:20 - Empty flask C1weighs 18.206. 14:21 - Pipetted sample C into 2mL volumetric flask (C1), also transferring ~3-400uL to an NMR tube. Added CDCl3 to NMR tube. Bath C stable at 30C. 14:23 - Weighted flask C1 weighs 19.994g. **[Didn't you use the scale accurate to 0.1 mg? JCB]** 14:24 - Empty flask C2 weighs 20.383g. Small amounts of precipitation in C2. 14:23 - Transferred 1mL sample from flask C1 to flask C2. Weighted flask C1mL weighs 21.276g. Increased precipitation. 14:30 - Took NMRs of samples A, B, and C. (NMR2, NMR3, NMR4).