Grognard Reaction

Question 1

What are the reactants

Answer 1

The reactants are magnesium bromobenzene and methyl benzoate

Sulfuric a is is used on the arrow

Question 2

What are the products

Answer 2

The products are triphenyl methanol, methanol, 2 Mg, sulfate, and 2 Br

Question 3

Methyl benzoate precaution

Answer 3

Combustible

Question 4

Bromobenzene precaution

Answer 4

Flammable

Question 5

Methyl magnesium bromide

Answer 5

Flammable

Question 6

Why do you need to scrape the magnesium against the side of the test tube

Answer 6

This promotes a reaction between the bromobenzene and the magnesium

Question 7

Why did you first combine a small amount of the reactants and they test to

Answer 7

First you need to combine a small amount of the reactants in a test tube in order to start the exothermic reaction

Question 8

Why is it necessary to have an ice water bath available during the preparation

Answer 8

Because if the reaction becomes too vigorous the reaction could become too vigorous from adding from adding bromobenzene too quickly

Question 9

What signs should you look for in determining if the reaction has initialized

Answer 9

The Ether Will begin to reflux and the tube will begin to warm to the touch and the solution will turn brown

Question 10

After the formation of the Grignard reagent, why is it important to keep this reaction mixture from being exposed to air for any longer than necessary

Answer 10

It is important to keep the reaction mixture from being exposed to air because it’s exothermic

Question 11

Explain why an additional funnel was used to add bromobenzene

Answer 11

An additional funnel was needed to slowly add bromobenzene if added to quickly it can produce an unwanted compound

Question 12

Why are ether solvent s important to the success of the Grignard reagent ?

Answer 12

Because the vapors help prevent oxygen from reaching the reaction solution

Question 13

Give an explanation why the regents solvents and apparatus used for the preparation must be dry

Answer 13

They must be dry because the region is a nucleophilic and a strong base. This allows it to react with acidic compounds including water

Question 14

Can reagents be used to prepare ethanol as a solvent

Answer 14

No they cannot be used to prepare ethanol because we don’t want alcohol as solvents

Question 15

What is a Grignard reagent

Answer 15

And organomagnesium halide compound formed by the interaction of an alkyl and aryl halide and metallic magnesium in ether solvents

Question 16

After adding methyl benzoate what Is the purpose of treating the mixture with sulfuric acid and ice water mixture

Answer 16

To give the covalent ether soluble alcohol and water soluble magnesium salt

Question 17

One of the final steps and purification is to boil off the ether. Why are you careful to keep the hot plate at a low setting

Answer 17

Ether is highly flammable

Question 18

What are the five steps of recrystallization

Answer 18

1. Choose the solvent
2. Heat the solvent to a boiling
3. Dissolve your crude product
4. Cool to room temperature then an ice bath to re-crystallize
5. Isolate your product five vacuum filtration