MediumChemistryHigh School (11–12)Organic Compounds with Functional Groups › Aldehydes, Ketones and Carboxylic AcidsNumerical

5.31 g of benzaldehyde (106.12 g/mol) is heated at about 453 K with ethanoic anhydride and sodium…

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$5.31\ \text{g}$ of benzaldehyde ( $106.12\ \text{g/mol}$ ) is heated at about $453\ \text{K}$ with ethanoic anhydride and sodium ethanoate. After acidification, cinnamic acid ( $148.16\ \text{g/mol}$ ) is isolated in a $60\ \%$ yield. Write the equation. Find the amount of benzaldehyde and the mass of cinnamic acid. How many carbon atoms does the reaction add to the aldehyde?

Need a reminder? The key ideaShow

Wolff-Kishner and Clemmensen turn C=O into CH $_2$ (base and acid). Perkin: ArCHO, (CH $_3$ CO) $_2$ O and CH $_3$ COONa at 453 K give ArCH=CHCOOH. Haloform: CH $_3$ CO- with 3 X $_2$ and 4 NaOH gives CHX $_3$ and the carboxylate with one carbon fewer. A crossed aldol with an aldehyde that has no alpha hydrogen is a Claisen-Schmidt reaction. For a gas, $V = nRT/P$ with $R = 8.314$ kPa L/(mol K).

The worked solution

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