Question

1. The synthesis of Grignard reagent is challenging. a) Draw the product that is expected to be formed if the Grignard reagent was in contact with water prior to the reaction with MgBr CO2? (2 pts) b) Circle the correct answer. In the reaction in 1 a), phenyl magnesium bromide acts as a (nucleophile/electrophile/base/acid). (1 pt) Consider the following reaction and circle the correct answer. In this reaction, phenyl magnesium bromide acts as a, Oo MgBr MgBr (nucleophile/electrophile/base/acid). (1 pt) coz I 3. What is incorrect about the product; benzoic acid that is obtained in today's experiment? (2 pts) TOO MgBr C ooha) The product will produce a singlet around 11-12 1. Mg, ether ppm in NMR HCI, H2O b) The product will have a low solubility in water 2. CO2 c) The product will have a low solubility in ether d) The product will produce a broad peak around 2500 cm 1 - 3100 cm 1 in IR 4. Consider the following extraction scheme. HCI, H20 addition refers to the step in the box in question number 3. HCI H2O separate layers NaOH H2O transfer aqueous repeat NaOH extraction 2x

Answer 1

Ans-1(a): Benzene [C6H6] $1584946641000_image.png$

(b): Nucleophile

Ans-2: Nucleophile

Ans-3: "the product will have low solubility in ether" is the incorrect statement. In fact it is highly soluble in ether but low solubility in water at room temperature.

Ans-4: The extraction scheme separates the pure benzoic acid from the reaction mass. The layers are as follows:

First tube = A = Ether + B = Aq. Layer

Second Tube = ether layer (A) having most of the crude benzoic acid

Third tube = After extracting with NaOH/Water + ether the C will be ether and the D = aq,. layer having most of the benzoic acid as sodium salt in ionic form.

Fourth Tube = The ether layer is again extarcted with the aq. NaOH to get the maximum recovery of benzoic acid in the separated layer in fourth tube as E.

Fifth tube: The extracted aq. sodium salt of the benzoic acid is then acidified with aq. HCl in this tube to get the pure benzoic acid as F.