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Quiz9A - 1 CHM 2123 Quiz#9 Assigned Due before 5pm...

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1 CHM 2123, Quiz #9: Preparation of Esters Assigned: November 16, 2006 Due: November 20, 2006, before 5pm MARKING SCHEME 1. In Method B, the workup requires several steps. Briefly explain below (and with equations, if possible) why it is necessary to… (3 points) a) … wash the ether phase with a solution of NaHCO 3 ? To remove unreacted carboxylic acid : R OH O + NaOH unreacted acid (sparingly soluble in H 2 O) Na H 2 O soluble salt (+ H 2 O) RCO 2 b) … wash the ether phase with a NaCl solution ? A saturated aqueous solution of NaCl is very hygroscopic, since it has a high ionic content. This essentially removes water from the organic phase, thus lowering the amount of anhydrous Na 2 SO 4 required to dry the organic phase. c) … filter through a funnel containing approximately 3g of anhydrous Na 2 SO 4 ? To finish drying the organic phase. Na 2 SO 4 is a hygroscopic compound and readily forms a hydrate complex, which is insoluble in organic solvents.
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