Benzene (C6H6, PhH) is an organic chemical compound, a colourless liquid with a pleasant sweet odour. It is the simplest aromatic hydrocarbon. Benzene is included in petrol, is widely used in industry, is a raw material for production of medicines, various plastics, synthetic rubber and dyes.
Benzene
C6H6
Solvents
Organic Intermediates, Hydrocarbon Solvents
Although benzene is part of crude oil, it is synthesised in industrial scale from its other components. It is toxic and carcinogenic. Benzene refers to unsaturated hydrocarbons (homologous series CnH2n-6), but in contrast to the hydrocarbons of ethylene series C2H4, it displays properties typical for unsaturated hydrocarbons (reactions of addition are typical for them) only under adverse conditions, whereas benzene is more prone to substitution reactions. This “behaviour” of benzene is explained by its special structure: all bonds and molecules are located on one plane and the presence of a conjugated 6π-electron cloud in the structure.
| FRACTION SORTS | Top Grade | First Grade |
|---|
| Appearance | Clear liquid free of impurities and water | Clear liquid free of impurities and water |
| Color | The liquid is not darker than an aqueous solution of potassium dichrome acid with a mass concentration of 0.003 g/dm³ | The liquid is not darker than an aqueous solution of potassium dichrome acid with a mass concentration of 0.003 g/dm³ |
| Density at 20°С, g/cm³ | 0.878–0.880 | 0.877–0.880 |
| Crystallization temperature, °С, not lower | 5.40 | 5.30 |
| Mass fraction of the main substance, %, not less than | 99.9 | 99.5 |
| Mass fraction of the sum of non-aromatic hydrocarbons, %, max | 0.07 | 0.15 |
| Mass fraction of toluene, %, max | Not standardized | 0.03 |
| Staining of sulphuric acid, model scale number, max | 0.1 | 0.15 |
| Mass fraction of total sulfur, %, max | 0.00005 | 0.00005 |
| Water extraction reaction | Neutral | Neutral |
| Note | The mass fraction standard for the sum of non-aromatic hydrocarbons is set only for benzene intended for caprolactam production. | The mass fraction of toluene is specified for grade 1 benzene intended for styrene production. |
