A multicomponent reaction is a reaction where three or more reactants react ... then obtained (20.0 — Analytical Chemistry Chemistry Question

9.1 A partial scheme for the formation of the 2-nitrophenol starting from the nitronium ion NO₂ + is proposed below. Draw the missing intermediates and products.

9.2 Give at least two products other than 2-nitrophenol and 4-nitrophenol that could explain the low yield.

Various characterizations of the 2-nitrophenol and 4-nitrophenol were performed:
9.3 Using the NMR data, determine which product (2-nitrophenol or 4-nitrophenol) corresponds to A and B. To justify your answer, interpret the NMR chemical shifts of the products.

9.4 Which interaction(s) between B and water can explain the higher solubility in comparison to A? Choose the correct answer(s).
 Intermolecular hydrogen bonds
 Intramolecular hydrogen bond
 Electrostatic interaction
 Van der Waals interactions
 Covalent bond

To check the purity of A and B, a Thin Layer Chromatography (TLC) on silica was performed. The eluent is a mixture of pentane/diethylether (7:3 in volume). After visualization of the TLC using a UV light, the retention factor was calculated for the two spots (0.4 and 0.9).
9.5 Choose the correct statement(s).
A has a ☐lower or ☐higher retardation factor (Rf) than B on the TLC because:

9.6 Which is the color of a solution of 4-nitrophenol in neutral water? Choose the correct answer.
Blue  Green  Pink  Purple  Red  Yellow

9.7 Choose the correct answer.
 4-nitrophenol has a longer absorption wavelength than its conjugated base because its conjugation is more important.

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9.10 Which alternative method(s) can be used for the titration of 4-nitrophenol? Choose the correct answer(s).
 UV^-Visible spectroscopy
 Potentiometry
 NMR
 Conductometry