Date: January 24, 2012 Reaction: Brominating Alkenes (trans-­‐cinnamic acid) O
Br
NH
OH
+
Br
Br
O
acetic acid
reflux
Br
Reference: Wigal, C. T. Brominating Alkenes. In Signature Labs Series: Chemistry Lab Experiments CHEM 226; Jeffers, J., Ed.; Cengage Learning: Mason, OH, 2008; p 167-­‐176. Materials: Compound MW (g/mol) Mass Moles Mole Ratio trans-­‐Cinnamic acid 148.16 * * 1 Pyridinium tribromide 319.84 * * 1 Acetic acid 60.05 * ** ** Product Name * * * 1 Procedure:*** § Add trans-­‐cinnamic acid, pyridinium tribromide, and acetic acid to 5 mL conical vial § Add stir bar § Reflux for 15 minutes § Add 2.5 mL of distilled water to vial § Chill in ice bath for 15 minutes § Filter crystals § Check product with silver nitrate test and melting point Yield: Theoretical Yield Calculation: Repeat for each reactant. Whichever reactant yields the lowest moles of product is the limiting reagent. (g reactant) x (1/MW of reactant) x (stoichiometric ratio)= moles of product Once limiting reagent is found convert lowest moles of product to grams of product (Moles of product) x (MW product) = Theoretical Yield Example: 2 H2 + 1 O2 à 2H2O Used: 1.512g H2 and 32g O2 (1.512g H2) x (1/2.016g/mol H2) x (2 mol H2O/2 mol H2) = 0.75moles H2O (32g O2) x (1/32g/mol O2) x (2 mol H2O/1 mol O2) = 2moles H2O Hydrogen is the limiting reagent OH
Br
(2moles H2O)*(16g/mol H2O) = 32g H2O The theoretical yield is 32g H2O Percent Yield Calculation (actual yield g/theoretical yield g) x 100 = percent yield Product Theoretical Actual Percent Limiting Literature Actual Yield Yield Yield Reagent Melting Melting Point Point Product Name * * * * * * Spectra: None. Observations: A white precipitate formed during the silver nitrate test. Datasheet Example CHM 226 The datasheet example given is a guideline to follow. You will need to write your own datasheets for the experiments conducted during this semester. Datasheets will be provided on the website for the techniques that will be learned. All datasheets for experiments should be hand written in your laboratory notebook. Each datasheet should include the date, reaction, reference, materials, procedure, yield, spectra, and observations All information presented on this example datasheet is based on using trans-­‐cinnamic acid for the brominating alkenes experiment. Please adjust the given information and missing information as necessary to represent YOUR actual experiment and data. * Write your actual values in these spaces. Double check your calculations. ** This information for the solvent is usually not included as it does not participate in the reaction taking place. *** When writing your procedure, be sure that you understand all the steps. You can abbreviate the procedure from what is given to you.