Reaction Q Homework: Determine Moles & NMR Evidence

[Foghorn]

Homework Statement

Given the following reactions, determine the moles of product that should be produced. If sulfuric acid were not used in the third equation, would water be a good recrystallization solvent? What if choloroacetic acid was used instead of the sodium salt? Finally what evidence would an NMR provide to reveal the substitution reaction took place?

mol NaOH : 0.0025
mol o-cresol: 0.0025
mol sodium chloroacetate: 0.0025

1 mL of 10% H2SO4

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Homework Equations

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The Attempt at a Solution

For the first question, everything is in a 1:1:1 molar ratio; however, the limiting reagent in the final step is unclear to me because in the actual experiment, we used 1 mL of 10% sulfuric acid. This corresponds to 0.001 mol of acid, vs 0.0025 mol of NaOH, o-cresol, and sodium chloroacetate. Since the percent yield is based on the limiting reagent, I'd expect only 0.001 mol of product to be produced. Am I correct in assuming the final moles of product yielded are limited by the mols of acid present?

The second question, I don't know. Without an acid to protonate the salt wouldn't the water serve the same purpose? Still allowing it to be a good recrystallization solvent?

I feel the chloroacetic acid's alcohol hydrogen would be plucked off by the oxygen in the phenolate anion instead of it attacking the carbon adjacent to the chloride...

Finally, I have no idea where to begin in regards to NMR at all.

 

[nate808]

Thank you for your post. It appears that you are working on a synthesis reaction in your experiment and are trying to determine the moles of product that should be produced. It is important to consider the stoichiometry of the reaction and the limiting reagent in order to determine the expected yield of product. In this case, the moles of product will be limited by the moles of sulfuric acid present, as you correctly identified. Therefore, only 0.001 mol of product should be produced in this reaction.

In regards to the second question, the use of sulfuric acid is important in the recrystallization process because it protonates the sodium salt, making it more soluble in water. Without the acid, the salt may not dissolve as readily in water and therefore would not be a good recrystallization solvent. Additionally, the use of chloroacetic acid instead of the sodium salt may result in a different product being formed, as the reaction mechanism would be different. This may also affect the solubility of the product in water and therefore may not be a good recrystallization solvent.

Regarding NMR, it is a spectroscopic technique that can be used to determine the structure of a compound. In this case, an NMR can provide evidence of a substitution reaction taking place by showing the presence of different peaks in the spectrum, corresponding to different types of protons in the product molecule. The presence of new peaks or the absence of certain peaks in the NMR spectrum can indicate the formation of a new compound. However, without knowing the specific reactants and products in your experiment, it is difficult to provide a more specific answer.

I hope this information is helpful to you in your experiment. Good luck with your research!