Exp 4 - 2.5 mL 6 M NaOH(aq Boiling chips Report the results...

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TA: HSIEN-PO CHIU Oct 9 & 11, 2007 Exp 4. Heating under Reflux: Synthesis of salicylic acid from wintergreen oil Principle 1. Reaction: OH O O O - O O - O - O O - H 2 SO 4(aq) OH O OH + NaOH (aq) + CH 3 OH 2. Mechanism of basic hydrolysis R 1 O O R 2 R 1 OH - O - O OH R 2 R 1 O O + H R 1 O O - R 2 O - + R 2 OH Safety cautions 1. NaOH and H 2 SO 4 are highly corrosive. Wear safety goggles and glooves. 2. Methyl salicylate can irritate the eyes, lung, and skin, too. Procedure : see p.46-47 2 mmol scale rxn (reflux for 30 mins) acidification by H 2 SO 4(aq) vacuum filtration recrystallization by water (6.7g/100mL boiling water; 0.18g/100mL cold water) Apparatus setting 1. Heating using aluminum block 2. Use air condenser for reflux 3. Control the heat rate so that the reflux ring of condensing vapor remains at least 2 cm below the top of air condenser. 5 mL conical vial air condenser 2 mmol methyl salicylate +
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Unformatted text preview: 2.5 mL 6 M NaOH (aq) + Boiling chips Report the results 1. theoretical yield (weight), MW check table on p.44 2. weight of crude product after vaccum filtration 3. crude yield (%) 4. weight of purified product after recrystallization 5. purified yield (%) 6. recrystallization yield (%) 7. melting point of the pure product Q&A 1. Why is a condenser used in Exp4 fo the formation of salicylic acid? (A) to remove dangerous vapors (B) to covert water and methyl salicylate vapors back to liquid (C) to convert methyl salicylate to vapors and evaporate of water (D) none of the above 2. When methyl salicylate undergoes a basic hydrolysisto give salicylic acid, which functional group is involved? (A) phenol (B) aromatic C-H (C) aromatic C-C (D) ester...
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