Question

1. The Wittig reaction is useful to replace carbonyl groups with alkenes. Use the following reaction scheme, and the reaction's procedure to answer the questions: Dissolve 0.97 mmol of Wittig reagent and 0.90 mmol of aldehyde with ImL DCM Add 0.5 mL conc. NaOH & stirr for 20 mins Transfer the crude to a test tube, add 3 mL of water Extract with 2 portions of DCM, transfer organic layers to another tube Add enough MgSO4 to cover the bottom of the tube and filter. Ph. Ph S Ph Ph . NaOH Ph Ph + 0 Bra Ph Php DCM 206.28 g/mol Wittig's Reagent a. From the previous process diagram, identify the limiting reagent. b. From the limiting reagent, how many grams of product are expected if the reaction went to completion? c. If a group obtained 0.0351 g of product, what was their yield? d. During the extraction procedure, you expect to have what is left of the excess reagent, 1,4-diphenyl-buta-1,3- diene and triphenyl phosphine oxide. Using the following drawing, specify what do you expect to extract in each layer. (Assume that phosphorus salts and oxides are soluble in water). Aqueous layer: Organic layer: e. Why did you add anhydrous magnesium sulphate to the collected organic layers?

Answer 1

locoent = (0) Limiting reagent = aldehyde al Ovom product grams of product = mmol of limiting reagent X moky mass of = 0.90 mnpox 206.8 g = 186.12 mq = 0.1869 mor

(6) ) yield = Observed yield Theoreticed yield xloo Thu 30 = 0.03515 xloo 0.186 ay = 18.87% yield = 18-87% (d, Aqueous layer = wiltig reagent and triphonyl phosphine oxide Organic layer = 1,4-diphenye-buta-1,3-diene (e) anhydrous magnesium sulphate is added to remove the - Water present in the organic layer.