Ochem Lab Benzophenone

2044 WordsApr 16, 20129 Pages
Experiment Date: 3/12/2012 Photochemistry: Photoreduction of benzophenone and rearrangement to benzpinacolone Abstract: In this experiment Benzpinacolone was synthesized in a process that contained two steps. First the photoreduction of benzophenone in 2-propanol, which was done by placing the flask under sunlightfor the absorption of the UV rays to carry out the reaction. Then the second part was the dehydration of benzpinacol to benzpinacolone, where the benzpinacol product was converted to a ketone by the acid catalyzed rearrangement of the benzpinacol to the benzpinacolone; this was done by adding iodine and acetic acid to benzpinacol. The reaction was then refluxed, cooled in an ice bath, filtered and washed with ethanol. After…show more content…
Get 50-mL RBF w/ reflux condenser: + 0.05g of iodine (2-3 sm. crystals) + 15 mL acetic acid. + 3.0g of benzpinacol and heat slowly =>boils gently. Reflux the rd sol’n 5-7 min. Cool flask. Add few mL’s of cold ethanol vac. filtrationWash crystals with cold ethanol. Weight, calc. % yield, and determine its MP. NMR spectrum + IR spectrum => analyze peaks. 4. Table of Reagents: Compound Name | Molecular weight (g/mol) | Density(g/mL) | M.P.(C) | B.P.(C) | Concentration (for sol’n.) | Benzophenone | 182 | 1.11 g/mL | 49 | 305 | ----------------- | 2-propanol | 60.1 | 0.79 g/mL | -89 | 83 | ----------------- | Glacial Acetic acid | 60.1 | 1.05 g/mL | 16-17 | 118-119 | ----------------- | Benzpinacol | 366 | 1.24 g/mL | 188 | 508 | ------------------- | IodineI2 | 127 | 4.93g/mL | 114 | 184 | --------------- | Ethanol | 46.1 | 0.79g/mL | -114 | 78 | ---------------- | Benzpinacolone | 348 | N/A | 179 | N/A | ----------------- | 5. Results:(Data/Calculations included) Part 1: Photoreduction of Benzophenone Mass of Benzpinacol: 2.11g MP of Benzpinacol: 179-180°C Theoretical MP Benzpinacol: 188°C Part 2: Mass of benzpinacolon used: 2.11g Mass of product (benzpinacolone): 1.42g Theoretical Yield of product: 2.01 g Percent Yield: 70.6% = 71% Experimental (observed) melting point: 164-165°C Theoretical MP:

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