nitration of methyl benzoate quiz

reactant

methyl benzoate

reagents used in the reaction

HNO3/H2SO4

product

methyl m-nitrobenzoate

what kind of reaction is this?

electrophilic aromatic substitution

characteristics of methyl benzoate

• MW = 136.15 g/mol

• bp = 200 deg C

• density = 1.09 g/ml

characteristics of methyl m-nitrobenzoate

• MW = 181.15 g/mol

• mp = 78 deg C

when the nitronium ion is added to the benzene ring, it temporarily interrupts its aromaticity and forms…

a carbocation, also known as:

• cyclohexadienyl cation

• sigma complex

• arenium ion

how is arenium ion re-stabilized?

via resonance and deprotonation (via HSO4-)

electron donating groups (EDG)…

activate the ring and direct substitution in o/p

electron withdrawing groups (EWG)

deactivate the ring and direct substitution in m

the ester group of methyl benzoate is a…

EWG, which means it is meta-directing

what flask was used at the start of the experiment?

25-mL erlenmeyer flask

step 1

cool 3 mL of H2SO4 to 0-3 deg C; then add 2.5 mL methyl benzoate

step 2

cool 2 mL of H2SO4 and 2 mL of HNO3 in a 10-mL graduated cylinder

using a ____, add the HNO3/H2SO4 solution dropwise to the erlenmeyer flask

pasteur pipette

what temperature should the flask be kept while adding the reagents to it?

5-20 degrees C

allow flask to warm up to…

room temperature and let it stand for 15 minutes

where is the reaction mixture transferred to?

50-mL beaker containing crushed ice (about 10 g); rinse out reaction flask w/ a little water and add to the beaker

what happens after the ice has melted?

• product is isolated via vacuum filtration

• determine melting point of the crude product

• calculate the weight of the crude material w/ a pre-weighed flask

recrystallize the product by adding…

minimum 5-10 mL of methanol

what does heating the mixture do?

an attempt to dissolve the crude

what happens if the crude does not dissolve?

if undissolved after 2 minutes, add dropwise methanol until it does

steps after heating of the recrystallized product?

• solution is cooled

• product obtained via vacuum filtration

• melting point and yield of the product obtained