The propylene or propene at room temperature and atmospheric pressure is in the gaseous state and, like other alkenes, is colorless. It has an odor similar to oil but less intense. It presents a dipole moment since, although it lacks a strong polar bond, its molecule is asymmetric.
Likewise, propylene is a structural isomer of cyclopropane (they have the same chemical formula C3H6). It occurs in nature as a consequence of the processes of vegetation and fermentation. It is artificially produced during the processing of fossil fuels such as oil, natural gas and, to a lesser extent, carbon.
Similarly, ethylene and propylene are products of petroleum refining in a process of splitting large hydrocarbon molecules to generate small hydrocarbons in great demand..
Propylene can also be obtained using different methodologies:
- By reversibly reacting ethylene and butene, where the double bonds are broken and reformulated to give propylene.
- Through a process of dehydrogenation (loss of hydrogen) of propane.
- As part of a program to produce olefins from methanol (MTO), propylene was produced from methanol. This was passed through the zeolite catalyst, which promotes its dehydration and leads to the formation of ethylene and propylene..
3CH3OH (methanol) => CH3CH = CHtwo (propylene) + 3HtwoO (water)
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In the upper image you can see the chemical structure of propylene, in which its asymmetry stands out (the right side is different from the left). Its carbon skeleton, excluding the H atoms, can be seen as a boomerang.
This boomerang has an unsaturation or double bond on one of its sides (the C1) and is therefore flat due to sp hybridizationtwo of carbon atoms.
However, the other side is occupied by the methyl group (-CH3), whose hybridization is sp3 and has a tetrahedral geometry. Thus, seen from the front, the boomerang is flat with the H atoms protruding from it at approximately 109.5º.
In the gas phase, the molecule weakly interacts with others by dispersion forces. Likewise, the interactions between the double bonds (π-π) of two propylene molecules are prevented by the methyl group.
This results in a decrease in its intermolecular forces, which is reflected in its physical properties. Only at very low temperatures, propylene can adopt a solid structure, in which the boomerang remain grouped with their weak interactions.
It is a colorless gas with an aromatic odor. It is transported in the form of liquefied gas and, when it escapes from the containers that contain it, it does so in the form of a gas or liquid. At low concentrations it forms an explosive and flammable mixture with air, the density of propylene being greater than that of air..
42.081 g / mol
53.9ºF at 760mmHg
48 ºC to 760 mmHg
301.4 ºF
185 ºC
162ºF
44.6 ml / 100 ml in water.
1,250 ml / 100 ml in ethanol.
524.5 ml / 100ml in acetic acid.
200 mg / l 25 ºC
0.609 mg / ml at -52.6º F
0.5139 at 20º C
1.46 at 32ºF (relative to air taken as reference).
1.49 (air = 1).
1.91 kg / m3 at 273.15 ºK
1 mmHg at -205.4ºF
760 mmHg at -53.9ºF
8.69 × 103 mmHg at 25 ºC (extrapolated value).
1,158 kPa at 25 ºC
15.4 atm at 37 ºC
851ºF
455 ºC
83.4 micropoise at 16.7 ºC.
16,692 BTU / lb
10,940 cal / g
104.62 cal / g (at boiling point)
16.7 dynes / cm at 90 ° C
Polymerizes at high temperatures and high pressures in the presence of catalysts.
185.25 ° C.
10-50 mg / m3 (detection)
100 mg / m3 (recognition)
It is used in the petrochemical industry as a fuel and alkylating agent. In the chemical industry it is used as a raw material for the production and synthesis of numerous derivatives.
It is mainly useful in the production of polypropylene, acrylonitrile (ACN), propylene oxide (PO), alcohols, cumene and acrylic acids.
Polypropylene is one of the main plastic materials used in electronics and electrical accessories, household items, bottle caps and suitcases..
The laminated material is used in the packaging of sweets, labels, compact discs, etc., while the fibers are used to make folders and clothes..
Elastomeric polymers and fibers are obtained from acrylonitrile. These fibers are used for the manufacture of different forms of clothing, such as sweaters, socks and sportswear. They are also used in home furnishings, folders, upholstery, cushions and blankets..
Propylene oxide participates as a component in the synthesis of polyurethane. This is used in the manufacture of flexible foam and rigid foam. Flexible foam is used as a filler in home furniture and in the automotive industry.
On the other hand, rigid foam is mainly used as a building insulation material..
Also, propylene oxide is used in the production of propylene glycol. This compound is used in the manufacture of unsaturated polyester resins and as an antifreeze.
Additionally, propylene oxide is used in the production of propylene glycol ether. This ether has application in the manufacture of paints, clothes, inks, resins and cleaners.
Propylene allows the obtaining of some alcohols, among them isopropanol, used as a solvent in cosmetics and personal care products. In addition, it fulfills the function of an antiseptic agent.
- Isopropanol is involved in the manufacture of paints, resins, inks and adhesive tapes. It is also used in the pharmaceutical industry.
- Oxo-alcohol2-ethylhexanol is used in the production of phthalate, plasticizers, adhesive materials and paints.
- Butanol is used in the manufacture of paints, coatings, resins, colorants, pharmaceuticals and polymers.
On the other hand, cumene is produced from the combination of propylene and benzene. Cumene is the main compound in the manufacture of phenol and acetone, used in a variety of products, such as polycarbonates, phenolic resins, epoxy resins, and methyl methacrylate..
Finally, acrylic acid - another product derived from propylene - is used in the production of acrylic esters and resins for paints, coating and adhesive applications..
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