Benzene Reactions
Aromatic hydrocarbon or arenes are the compounds of carbon and hydrogen which contain at least one hexagonal ring of carbon called as benzene in their molecule. Aromatic hydrocarbon can contain one or more than one benzene ring. Those compounds which contain more than one benzene ring are known as polynuclear aromatic hydrocarbon like naphthalene, anthracene etc. The aromatic compounds are generally taken as derivatives of benzene.
Benzene and its derivatives are mainly used in synthetic organic chemistry. The main source of polynuclear aromatic compounds is coal tar. For example, naphthalene is the largest single constituent (6 - 10%) of coal tar. It is mainly found in middle oil fraction of coal tar distillation. Anthracene is mainly extracted from green oil fraction of coal tar. Generally polynuclear aromatic compounds are carcinogenic and toxic in nature.
Benzene is the simplest aromatic compound with C6H6 molecular formula and contains three pi bonds arranged in alternate manner in hexagonal ring. The carbon-carbon bond length in benzene is intermediate to C - C single bond (154 pm) and C = C double bond (134 pm) that is 139 pm due to resonance in molecule. It exists in two resonating structures purposed by Kekulé in 1865.
Properties of Benzene
1. Aromatic hydrocarbons like benzene are colorless and have characteristic odor.
2. Benzene is toxic and carcinogenic in nature.
3. It is a non-polar molecule and exists in the form of colorless liquid and highly inflammable in nature.
4. That is the reason, the bottle of benzene are marketed with the warning of toxic and flammable liquid.
5. Because of the high percentage of carbon atom compare to alkanes, Benzene burns with sooty flame and less denser than water.
6. The density of benzene is 0.8765 g/cm3 and melts at 278.7 K. The boiling point of benzene is 353.3 K temperature.