Post Lab Questions slowly oxidize in air to form benzoic acid. If dehyde is yell
ID: 1089529 • Letter: P
Question
Post Lab Questions slowly oxidize in air to form benzoic acid. If dehyde is yellow or contains crystals, then it is contaminated with benzoic acid that 1 Benzaldehyde, when stored for long periods, may the benzal needs to be removed before u sing in the reaction. To purify, benzaldehyde is shaken in a separatory funnel with equal volumes of 5% sodiurm carbonate until the evolution of CO2 no longer occurs. The similar) and used upper, benzaldehyde, layer can then be dried over magnesium sulfate (or Why might the presence of benzoic acid be deleterious to this reaction? Fully Explain Your Answer!-be specific. a. How does treatment with sodium carbonate remove the benzoic acid? Show a balanced chemical equation to explain your answer. b. How many electrons are in the thiazoline ring (5-membered ring) of thiamine hydrochloride? Of thiamine? Are these rings anti-aromatic, non-aromatic, or aromatic? Explain your answer. What would be the product of this reaction if 4-tolualdehyde, shown below, was used in place of benzaldehyde. Would you expect the reaction with 4-tolualdehyde to be faster or slower than the reaction with benzaldehyde? (Explain your reasoning.) 3 4-tolualdehyde Write Up Write up the experiment in the usual mannerExplanation / Answer
1. Removal of benzoic acid from benzaldehyde
a. Benzoic acid has an ionizable proton and thus acts as an acid. If benzoic acid is present in the system, it would neutralize the basic reagent and we would have no more any active reagent for the reaction left.
b. C6H5COOH + Na2CO3 ---> 2C6H5COONa + CO2 + H2O
CO2 is released as a gas and shows the extent of reaction.
2. Thiazoline ring has 4 pi-electrons in it. the ring is aromatic as lone pair of electron on S is used to complete the aromaticity of 6pi electron count as needed by Huckel rule.
3. If p-tolualdehyde is used instead for the reaction, the reaction is expected to be slower. p-tolualdehyde has a -CH3 group on it, which is an electron donating group by resonance, makes the carbonyl carbon less electrophilic and less reactive towards nucleophilic attack.
[The reaction is not specified, so product cannot be written here. But it will be similar to benzladehyde product except for an -CH3 group at para position of the ring]