Introduction
Benzene is an organic chemical compound known as benzol. It has a sweet smell and is a colourless, flammable liquid. Benzene is a major industrial solvent and is used in the production process of plastic, oil, synthetic rubber and many dyes.
Properties of benzene
Identification
Benzene has a molecular formula of C6H6 and a molecular weight of 78.11.
Physical Properties
Benzene's solubility in water is 1750 mg/L at 25 degrees C. It readily mixes with ethanol, ethyl ether, acetone and chloroform. Its melting point is 5.5 deg C and the boiling point is 80.1 degrees C. It has a flash point of -11 degrees C.
2) What industries use benzene? (5)
Industries that use Benzene
Triveni Chemicals
Triveni is a chemical industry and deals with industrial chemicals, organic chemicals, inorganic chemicals, fluoride and fluoborat.
Zhejiang Zanyu Technology Co Ltd
Leading surfactant manufacturer and exporter in China. Mainly produce SLES, SLS, LABSA, LSA, CDEA, AOS, CMEA, CAB, MES etc., they own 4 set of 3.8mt per hour and 2 set of 1.6mt per hour sulphonation line, production capacity more than 150,000mt annually.
Advance Surfactants India Limited
Advance Surfactants India Limited are a leading and outstanding manufacturer, exporter, importer and service provider of sophisticated chain of products like Linear Alkyl Benzene Sulphonic Acid (LABSA), Linear Alkyl Benzene Sulphonate (LAS).
M S MEHTA & CO
They are suppliers of chemicals such as (TOLUNE, BENZENE, SODIUM HEXA META PHOSPHATE, POLY ELECTROLYTE,XANTHAN GUM, CELLULOSE ACETATE PTHLATE).
A V Plastic Equipments Pvt Ltd
They are in the field of manufacturing various types of plastics equipments. The Spirall tank process involves extruding a special grade of High Density Polyethylene (HDPE) and P.P. (Copolymer) into a strip and then winding it spirally and continuously over a rotating mandrel to form a homogeneous, seamless shell.
Above are five different industries that use benzene or produce for there final outcome product.
3) What products are made using benzene? (10)
Benzene is ranked in the top 20 chemicals for production volume. Some industries use benzene to make other chemicals and products which are used to make:
Tire/Rubber Manufacturing
Benzene is used in the production of tires and rubber:
Manufacturers use products that contain benzene as solvents in various steps of the production.
The adhesives used to attach soles to shoes contain benzene.
Printing/Painting
Benzene is contained in products used in the printing industry:
For cleaning and maintaining printing equipment.
Ink that is used in printing frequently contains benzene.
Benzene is an ingredient of a variety of painting products, such as:
Spray paints,
Sealers
Most of these products contain solvent containing benzene that keeps them in liquid form until they are ready for use.
Chemicals/Plastics
Benzene is used in manufacturing chemical and plastic products. Examples include:
Resins,
Adhesives
Synthetic products such as:
Nylon
Styrofoam.
Chemicals manufactured that use benzene include:
Pesticides
Dyes.
Some examples of specific products that contain benzene include:
Weed and Vegetation Killer,
Formula M 62 Insecticides.
4) Briefly explain the process of each of the products that you find (7)
Below are four products that contain benzene form the list above, below will explain the Composite properties that are enhanced and the disadvantages and advantages by benzene used on the product.
Resins,
Nylon
Benzene is mainly used as an intermediate to make other chemicals. Its most widely-produced derivatives include.
Phenol for resins and adhesives (via Cumene), 20% is used in the production of Cumene
Cyclohexane, which is used in the manufacture of Nylon. 15% of benzene is used in the production of Cyclohexane (eventually to nylon).
Resins
Phenol can be made from the partial oxidation of benzene, the reduction of benzoic acid, by the cumene process,
Phenol is an important petrochemical used in the production of phenolic resins, nylon, polycarbonate resins, and many other chemicals. Cumene (i.e. isopropyl benzene) is produced primarily by alkylation of benzene with propylene. Cumene is then converted to phenol and acetone by peroxidation.
Phenolic resin can include any of various synthetic thermosetting resins such as Bakelite, obtained by the reaction of phenols with simple aldehydes such as formaldehyde.
Phenolic properties
Excellent dielectric strength
Good machinability
Light weight
Heat and wear resistant
Resists corrosion and chemicals
Good mechanical strength & dimensional stability
Low moisture absorption
Benzene processes
Four chemical processes contribute to industrial benzene production: catalytic reforming, toluene hydrodealkylation, toluene disproportionation, and steam cracking.
Below will explain the process toluene hydrodealkylation
Toluene hydrodealkylation
Toluene hydrodealkylation converts toluene to benzene.
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 → C6H6 + CH4
This irreversible reaction is then used to produce biphenyl.
2 C6H6 H2 + C6H5-C6H5
If the raw material stream contains much paraffins or naphthenes, these are likely decomposed to lower hydrocarbons such as methane, which increases the consumption of hydrogen.
Health and safety
The US Department of Health and Human Services (DHHS) classifies benzene as a human carcinogen. Long-term exposure to excessive levels of benzene in the air causes leukemia, a potentially fatal cancer of the blood-forming organs, in susceptible individuals. In particular, Acute myeloid leukemia or acute non-lymphocytic leukaemia (AML & ANLL) is not disputed to be caused by benzene
Conclusion
In conclusion benzene is a chemical with advantages and disadvantages, benzene can enhance properties of different materials but also cause health and safety effects. But these effect can are manly cause over long term use of benzene, industrial worker that work with benzene have a higher risk them consumers, in my opinion without benzene most product today would not be as good as they are such as plastic and polyester our hole life runs around them. Benzene is made mostly from petroleum. Because of its wide use, benzene ranks in the top 20 in production volume for chemicals produced.
Task 4.2
Friedel- Crafts Alkyltion is the substituation of an alkyl group into benzene ring.
Benzene is treated with a chloroalkane in the presence of aluminium chloride as a catalyst.
Substituting a methyl group gives methylbenzene known as toluene.
or better:
Aluminium chloride isn't added into the equation as aluminium chloride is a catalyst
Toluene is more recative then benzene, this mean there is more to the reation and you can get further hethyl groups substituted around the ring.
The formation of the electrophile is CH3+. It is formed by reaction between the chloromethane and the aluminium chloride catalyst.
The electrophilic substitution mechanism
Stage one
The benzene electrons are strongly attached to the positive charges of CH3+ ion when approaching the delocalised electrons in the benzene
Two electrons from the delocalised system are used to form a new bond with the CH3+ ion. Because those two electrons aren't a part of the delocalised system any longer, the delocalisation is partly broken, and in the process the ring gains a positive charge.
The hydrogen shown on the ring is the one which was already attached to that top carbon atom and will be removed in the second stage.
Stage two
The second stage involves the AlCl4-, which was produced at the same time as the CH3+ ion.
One of the aluminium-chlorine bonds breaks and both electrons from it are used to join to the hydrogen. This removes the hydrogen from the ring to form HCl, and re-generates the aluminium chloride catalyst in the process. The electrons which originally joined the hydrogen to the ring are now used to re-establish the delocalised system.
Toluene is:
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 are
the dealkylation to benzene
Also used for paper coating as t is used as a solvent.
Used as an octane booster in gasoline fuels used in combustion engines.
Paint Stripping used as a solvent
Printing used as solvents for gravure printing
Properties of Benzene
Properties of Toluene
Molecular formula
C6H6
C6H5CH3
Molar mass
78.11 g/mol
92.14 g/mol
Appearance
Colourless liquid
Colourless liquid
Density
0.8765 g/mL3 at 20oC
0.8669 g/mL at 25oC
Melting point
5.5 °C
−93 °C
Boiling point
80.1 °C
110.6 °C
Solubility in water
0.8 g/L (25 °C)
0.47 g/l (20-25°C)
Viscosity
0.652 cP at 20 °C
0.560 cP at 25°C
Dipole Moment
0 D
0.375
Task 4.3
Isomerisation Process
The above diagram is a schematic of a oil refinery process, Isomerization this is what will be looked at. The main Isomerization process is to convert low octane n-paraffin to high-octane iso-paraffins to produce gasoline as the final outcome, but before that happens other persudes must take place.
When crude oil enters it is heated and then distillated once the distillation producer is complete, then moves to the naphtha hydrotreating process once complete move to the isomerization process.
The Primary Process Technique is that isomerization occurs in a chloride promoted fixed bed reactor where n-paraffins are converted to iso-paraffins. The catalyst is sensitive to incoming contaminants (sulfur and water).
Below is the Isomerization processes schematic, below will explain what is happening.
Desulfurized n-paraffin feed and hydrogen are dried in fixed beds of solid desiccant prior to mixing together
The mixed feed is heated and passes through a hydrogenation reactor to saturate olefins to paraffins and saturate benzene
The hydrogenation effluent is cooled and passes through a isomerization reactor
The final effluent is cooled and separated as hydrogen and LPGs which typically go to fuel gas, and isomerate product for gasoline
blending
Isomerization converts the following:
n-butane
n-pentane
n-hexane
Into their respective iso-paraffins of largely higher octane number
Straight chain paraffin's are converted to their breached-chain counterparts, these component atoms are the same but have different geometric structure.
Isomerization is important for the conversion of n-butane into iso-butane, to provide additional feedstock for alkylation units, and the conversion of normal pentanes and hexanes into higher branched isomers for gasoline blending.
Isomerization is similar to catalytic reforming in that the hydrocarbon molecules are rearranged, but unlike catalytic reforming, isomerization just converts normal paraffin's to iso-paraffins.
There are three distinct isomerization processes:
Butane
Pentane
Hexane
Butane Isomerization produces feedstock for alkylation.
There are two types of processes
Low temperature (contains Aluminium chloride plus hydrogen chloride)
High temperatures (contain Platinum or any other metal catalyst)
In a typical low-temperature process, the feed to the isomerization plant is n-butane or mixed butanes mixed with hydrogen and pass to the reactor at 230o-340oFand 200-300psi.
The hydrogen chloride removed in a stripper column as Hydrogen is flashed off in a high-pressure separator and
The resultanting butane mixture is sent to separate n-butane from the iso-butane product to the fractionators (deisobutanizer) .
Pentane/hexane isomerization increases the octane number of the light gasoline components n-pentane and n-hexane, which are found in abundance in straight-run gasoline.
In a typical pentane/hexane isomerization process,
Dried and desulfurized feedstock is mixed with a small amount of organic chloride and recycled hydrogen, and then heated to reactor temperature.
It is then passed over supported-metal catalyst in the first reactor where benzene and olefins are hydrogenated.
The feed next goes to the isomerization reactor where the paraffins are catalytically isomerized to isoparaffins.
The reactor effluent is then cooled and subsequently separated in the product separator into two streams:
Liquid product (isomerate)
Recycle hydrogen-gas stream.
The isomerate is washed (caustic and water), acid stripped, and stabilized before going to storage.
Isomerization Process
Feedstock
From
Process
Typical products - to - unit
n-Butane
Various processes
Rearrangement
Isobutane To Alkylation
n-Pentane
Various processes
Rearrangement
Isopentane To Blending
n-Hexane
Various processes
Rearrangement
Isohexene To Blending
Gas To Gas Plant
Schematic of butane isomerization
