Benzene is an important organic compound that has proved itself to be incredibly important for various industrial applications. The synthesis of a large number of compounds starts with benzene. From rubbers, plastics and dyes to drugs, explosives and pesticides; almost all the chemical industries have to deal with benzene at some point or the other. It is even added into gasoline to make sure that the engines function as smoothly as possible.
Benzene comprises of six carbon and six hydrogen atoms which are bonded in a particular way. Scientists understood this empirical formula but it was difficult to determine the structure of benzene because carbon can bond to one to four other atoms. The structure could have been linear, branched or cyclic, with single bonds or double bonds and single rings or multiple rings. During the period of benzene’s discovery, methods were not available to scientists that could have been employed to understand the structure by looking directly at the carbon atoms. Thus, speculations had to be made and these had to be supported by observations to put forth the structure of benzene as it appears in nature.
Then, a German chemist named Friedrich Kekule had a day-dream while working in his laboratory. He imagined a snake biting its own tail and it led him to suppose the same scenario in case of the benzene structure. He refined and presented this idea, backed with proper scientific evidence to the amazement of the organic chemistry world. His discovery led to rapid developments in the niche of benzene study. Many honors were bestowed upon him for the vision he provided to the scientific community.
The structure of the benzene molecule consists of its six carbon atoms and six hydrogen atoms all lying in a single plane. It has a hexagonal shape. There are three double bonds and three single bonds between the carbon atoms but with a difference. The electrons that are responsible for the carbon-carbon bond do not stay attached or “belong” to the carbon atom which actually contributed them. The electrons behave as if they belong partially to each of the six carbon atoms. This is called delocalization. Delocalization makes the benzene ring very stable. The stability offered by delocalization is very much desired by the benzene molecule and any changes which seek to disrupt the delocalization are resisted strongly.
From benzene to plastics
Like we have mentioned before, benzene is used to make a number of industrially important products. There are various benzene derivatives which can have either a single substituent for a hydrogen atom or up to six substituents, which will effectively replace all the hydrogen atoms. When a substituent is placed on the benzene ring, the carbon right next to it on either side is called the ortho-position carbon. The next carbon in the cycle is called para-position carbon and the third one is called meta-position carbon. Compounds that are derived from benzene such as styrene are used in plastic industry to make polystyrene. The plastic cups and plates you use are, in a way, products of benzene.