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Benzene is an aromatic hydrocarbon that is produced by the burning of natural products. Its molecular formula is C6H6. Benzene is a component of products derived from coal and petroleum and is found in gasoline and other fuels. It is an organic chemical compound which is a colourless liquid at room temperature with a density of 0.87 g/cm3 at 20oC. It has a relatively low boiling point, a high vapour pressure, highly flammable, can evaporate into the air very quickly and dissolves slightly in water.
It is mainly used in industries to produce other chemicals which are used to make plastics, resins, and nylon and other synthetic fibres.
Triveni Chemicals is one of the leading industrial chemicals manufacturer and supplier. They deal in both organic and inorganic chemicals. They are engaged in the manufacture and supply of Fluoride, Sulphate, Carbonate, Chloride, Benzene and many more.
Toshi Group is a well known manufacturer and trader of well formulated range of chemicals, lubricating oils, Lubricating oils, thinners, diluents & solvents.
Benzene International Pte Ltd is involved in manufacturing procurement distribution and export of commodities and products. They are mainly focused on Petro-Chemical Division.
Caldic Belgium N V are distributors of various chemicals such as acid, alkyl benzene, benzoic acid, boric acid, caustic soda, castor oil, cellulose gum, ether,
formic acid and many more.
Star Chemicals are the largest manufacturer of acid slurry.
Benzene has many products/by-products, the main products produced from benzene is Styrene or vinyl benzene (53%), Cumene (22%), Cyclohexane (12%), Nitrobenxe (5%), Detergent Alkylate (3%) and Chlorobenzenes and other products (5%), it is also used as an additive in gasoline because it occurs naturally in crude oil and is a by-product of oil refining processes.
From these main products of benzene they are then used to create everyday products, there are three main branches which are:
One of the types of products made is called Expanded Polystyrene (EPS). The chemical makeup of polystyrene is a long chain hydrocarbon with every other carbon connected to a phenyl group. Polystyrene's chemical formula is (C8H8).
Expanded Polystyrene consists of carbon, hydrogen, and oxygen.
The benefits of using this product is its superior product protection and reduced damage and replacement costs. Expanded Polystyrene is lightweight, insulates temperature sensitive products and is water resistant. Expanded Polystyrene foam is also environmentally sound and is recyclable.
Expanded Polystyrene is made from 95% air and 5% plastic (Polystyrene, Ethylene and Benzene).
To manufacture EPS, styrene is made by combining ethylene and benzene. Then styrene is subjected to suspension polymerization and treated with a polymerization initiator, which converts it into polystyrene. Once a polymer chain of the desired length has formed, the reaction with terminating agents is stopped, resulting in polystyrene beads. Then they are heated and expanded and after that they leave them to sit for 24 hours so that they can cool and harden.
Benzenes Role: The properties benzene gives the Expanded Polystyrene is:
High melting points
Good electrical properties
Excellent resistance to gamma radiation.
Process of Benzene
One of the processes of benzene is the conversion of toluene to benzene. In this hydrogen-intensive process, toluene is mixed with hydrogen then passed over a catalyst at 600 °C and 60 atmospheric pressure under these conditions. Toluene undergoes de-alkylation to benzene and methane:
C6H5CH3 + H2 â†’ C6H6 + CH4
This irreversible reaction is then used to produce biphenyl.
2 C6H6 H2 + C6H5-C6H5
If the raw material stream contains much non-aromatic components, those are likely decomposed to lower hydrocarbons such as methane, which increases the consumption of hydrogen.
Health and Safety
Exposure to benzene has serious health effects. The short term effects of breathing high levels of benzene can result in death, where as low levels can cause drowsiness, headaches and unconsciousness. Eating or drinking foods containing high levels of benzene can cause vomiting, irritation and death.
The long term effects of benzene are chronic exposure through the blood. Benzene targets vital organs and can cause DNA strand breaks, chromosomal damage, it can also damage the bone marrow causing a decrease in red blood cells, leading to anaemia.
The United States Environmental Protection Agency has a maximum permissible level of benzene in drinking water at 0.005 milligrams per litre and has also a permissible exposure limit of 1 part of benzene parts per million of air in the workplace during an 8-hour workday, 40-hour workweek and a short term exposure limit for airborne benzene is 5 parts per million for 15 minutes.
Benzene is both produced chemically and naturally occurring from processes such as volcanic eruptions, wild fires, joining of chemicals. It is considered a human carcinogen and the most common route of benzene exposure is through inhalation of air emissions from tobacco smoke and motor vehicle exhaust.
Write a report which explains the alkylation of benzene using the Friedel Crafts reaction
Friedel Crafts reaction is a substitution reaction, catalyzed by aluminium chloride, in which an alkyl group or an acyl group replaces a hydrogen atom of an aromatic nucleus. This general reaction is the most important member of a larger group of aromatic substitution reactions known to be catalyzed by conventional or Lewis acids.
Haloalkane reacts with benzene in the presence of an aluminium halide. The resulting products are alkyl benzene and hydrogen halide. This reaction is called the Friedel-Crafts alkylation of benzene.
With primary halides, the reaction begins with coordination of the acid to the halogen of the Haloalkane. This coordination places a partial positive charge on the halogen-bearing carbon, rendering it more electrophilic. Attack on the benzene ring is followed by proton loss giving the observed product.
With secondary and tertiary halides, free carbocations are usually formed as intermediates.
Benzene is treated with a chloroalkane in the presence of aluminium chloride as a catalyst.
Substituting a methyl group gives methylbenzene - once known as toluene.
Aluminium chloride AlCl3 is used in this reaction but it is not shown because as it's a catalyst.
The formation of the electrophile
The electrophile is CH3+. It is formed by reaction between the chloromethane and the aluminium chloride catalyst.
Toluene C6H5CH3 is a clear, colourless, flammable liquid with a sweet odour it is an aromatic hydrocarbon that is widely used as an industrial feedstock and as a solvent.
Industrial uses of toluene include dealkylation to benzene. It is also used as a carbon source for making Multi-Wall Carbon Nanotubes. Toluene can be used to break open red blood cells in order to extract haemoglobin in biochemistry experiments. Toluene can be used as an octane booster in gasoline fuels used in combustion engines.
Industrial uses of Toluene
How it is used
Carpet adhesive solvents
Solvents - Dilution
Solvents - Extraction
Solvents - Paint Stripping
Pesticide Mfg (Insecticides)
Solvents - Insecticide Manufacture
Solvents for Gravure Printing
Solvents - Rubber Manufacture
Wood Stains and Varnishes
Machinery Mfg and Repair
Solvents - Machinery Manufacture and Repair
Solvents - Metal Degreasing
Properties of Benzene
0.8765 g/mL3 at 20oC
Solubility in water
0.8 g/L (25 °C)
0.652 cP at 20 °C
Properties of Toluene
0.8669 g/mL at 25oC
Solubility in water
0.47 g/l (20-25°C)
0.560 cP at 25°C
Write a report which explains an industrial process associated with a petrochemical.
Fractional Distillation of Crude Oil
Fractional distillation is the separation of a mixture into its component parts, or fractions, such as separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate.
Crude oil is the main source of organic chemicals. It was produced over millions of years by the breakdown of plant and animal remains at the high pressures and temperatures deep below the sea. It is called a fossil fuel and is not renewable.
Crude oil is a mixture mostly of alkanes, both unbranched and branched. Crude oils from different sources have different compositions.
To convert crude oil into useful products the mixture has to be separated. The first step is heating it and collecting the fractions that boil over different ranges of temperatures. Each fraction is a mixture of hydrocarbons that have a similar chain length and therefore similar properties. The process is called fractional distillation and it is done in a fractionating tower.
The crude oil is first heated in a furnace so that it vaporises.
The vapours pass into a tower that is cooler at the top than at the bottom.
They pass up the tower via a series of trays containing bubble caps until they arrive at a tray that is sufficiently cool (at a lower temperature than their boiling point). Then they condense to liquid.
The mixture of liquids that condenses on each tray is piped off.
The shorter chain hydrocarbons condense in the trays nearer to the top of the tower, where it is cooler, because they have lower boiling points.
The thick residue that collects at the base of the tower is called tar or bitumen and is used for road surfacing
Industrial distillation performed in large, vertical cylindrical columns called distillation towers, with diameters ranging from 65 centimetres to 6 meters and heights ranging from 6 meters to 60 meters or more. The distillation towers have liquid outlets at intervals up the column which allow for the withdrawal of different fractions or products having different boiling points or boiling ranges. The products with the lowest boiling point exit from the top of the columns and the products with the highest boiling point exit from the bottom of the column.
Fractional distillation is used in oil refineries to separate crude oil into useful substances having different hydrocarbons of different boiling points. The crude oil fractions with higher boiling points:
have more carbon atoms
have higher molecular weights
are darker in colour
are more viscous
are more difficult to ignite and to burn
Fractions from Crude Oil
Name of fraction
Boiling range (oC)
Length of carbon chain
Liquefied petroleum gas
Up to 25
Gas oil (diesel)
Central heating fuel
Lubricating oil petrochemicals
Fuel for ships
The amount of each fraction distillation provides from crude oil:
Fractional distillation of crude oil
percent from distillation
Petrol and Naphtha
Fuel oil and bitumen