Chemical and Biomolecular Engineering

Official blog of the Lehigh University Chemical Engineers

Nitration Reaction — Orgo Lab

Leave a comment

Many reactions occur in organic chemistry involving aromatics, especially benzene. Benzene is a six ring carbon with three double bonds. Benzene rings can have groups attached to them; for example, if a methyl (CH3) is attached to a benzene ring, the molecule is called Toluene. In a recent organic lab, my partner and I synthesized methyl 3-nitrobenzoate from methyl benzoate.

Reaction

Reaction

To start, nitric acid (HNO3) is slowly added to sulfuric acid (H2SO4). This reaction is exothermal so it must be kept in an ice bath. The reaction of acids produces nitrate ion (NO2-) which will attach to the benzene ring. The substituent (molecule) that is attached to a benzene ring determines where and if another group will bond to the ring. The type of substituent determines how reactive the ring will be and is based on the resonance forms that can be formed. The COOCH3 that is on the ring above if not reactive, so it is a meta director. Groups that are reactive will cause ortho and para addition to the ring. Coming from Latin, ortho means “next to”, meta means “after that”, and para means “across”. These prefixes are used to specify where a molecule will attach to a ring based on what group is already on the ring.

The acid mixture is slowly added to the reactant, methyl benzoate. This reaction is extremely exothermic, which means it produces a significant amount of heat energy. For this reason, the acid mixture is added very slowly and the reaction is kept in an ice bath. After the reaction goes to completion, a solid is formed. These crystals are then filtered using vacuum filtration. This gives a crude product, which is recrystallized using methanol as the solvent. After heating and then cooling, this mixture is again filtered which gives the final product. We weighed the product to determine percent yield and found the melting point to determine purity. This lab was very informative and helped explain how to nitrate a benzene ring.

Methyl 3-nitrobenzoate

Methyl 3-nitrobenzoate

Advertisements

Author: Ben Dunmire

I am a sophomore Chemical Engineering major at Lehigh. On campus, I am the president of Club Baseball and a member of AIChE and NSCS. Outside of school, I enjoy the outdoors, fishing, and any type of athletic activity. You can reach me at bcd216@lehigh.edu.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s