Question

e-Laboratory Questions-EXP 3 Nitration of Aromatic Compounds Name: tso ds Due before lab begins. Answer in space provided. 1. Which is nitrated faster? toluene or nitrobenzene? Explain. 2. Indicate the product formed on (mono) nitration of each of the following compounds: a) Cyanobenzene (benzonitrile) b) toluene c) benzoic acid. 3. Why is methyl m-nitrobenzoate formed in this reaction instead of o- and p-? What product would you expect if methyl benzoate underwent dinitration? 4. Methyl-m-nitrobenzoate is an excellent (identification) derivative of methyl benzoate. What are the properties of methyl-m-nitrobenzoate that makes it an excellent derivative of the starting ester? List three combinations of reagents used for nitration of aromatic compounds? 5 7
3-5??

Answer 1

Solution:

3) Methyl benzoate contains an ester group. The ester group is a meta director. Hence, it directs incoming electrophile at meta position. Therefore, nitration of methyl benzoate forms methyl meta-nitrobenzoate rather than ortho and para products.

On dinitration, methyl benzoate forms 3,5-dinitromethyl benzoate as the major product.

4) Methyl-m-benzoate contains both a nitro and an ester groups, which decreases the electron density and hence increase the reactivity of carbonyl group of ester towards nucleophilic attack.

5) Three combination of reagents in nitration are:

A) HNO3 + H2SO4

B) Fuming HNO3 + fuming H2SO4

C) Conc HNO3 + CH3COOH