Passage IV

Introduction

Nitrobenzene (C₆H₅NO₂) is a molecule consisting of a nitro group (-NO₂) attached to a benzene ring (a ring of 6 carbon atoms connected by alternating single and double covalent bonds). A teacher asked 4 students to predict what carbon-containing products are formed when nitrobenzene and bromine (Br₂) react in the presence of solid ferric bromide (FeBr₃), and also how fast those products are formed. Figure 1 shows a representation of this reaction; each C atom is labeled with a number.

Student 1

The -NO₂ partially donates electrons to the benzene ring, resulting in a relatively fast reaction between nitrobenzene and Br₂. A new C-Br covalent bond is formed when electrons from a carbon atom of the benzene ring are transferred to one of the Br atoms of Br₂. The reaction produces only 1 carbon-containing product: the H atom bound to C-2 is replaced by a Br atom.

Student 2

The-NO₂ partially pulls electrons from the benzene ring, resulting in a relatively slow reaction between nitrobenzene and Br₂. A new C-Br covalent bond is formed when electrons from a Br atom of Br₂ are transferred to one of the carbon atoms of nitrobenzene. The reaction produces only 1 carbon-containing product: the H atom bound to C-3 is replaced by a Br atom.

Student 3

The-NO₂ partially pulls electrons from the benzene ring, resulting in a relatively fast reaction between nitrobenzene and Br₂. A new C-Br covalent bond is formed when electrons from a carbon atom of the benzene ring are transferred to one of the Br atoms of Br₂. The reaction produces only 1 carbon-containing product: the H atom bound to C-4 is replaced by a Br atom.

Student 4

The-NO₂ partially donates electrons to the benzene ring, resulting in a relatively slow reaction between nitrobenzene and Br₂ . A new C-Br covalent bond is formed when electrons from a Br atom of Br₂ are transferred to one of the carbon atoms in nitrobenzene. The reaction produces 2 carbon-containing products, and each product has only 1 Br atom. In one product, the H atom bound to C-2 is replaced by a Br atom, and in the other product, the H atom bound to C-4 is replaced by a Br atom.