We published an article on introduction to hydrocarbons here and we mentioned some of the common hydrocarbons there. It might interest you to know that alkanes, alkenes, and alkynes are not the only hydrocarbons in organic chemistry and we would mention more of them in this section.
Cyclic aliphatic hydrocarbons are compounds in which carbon atoms are bonded together in a cyclic fashion. They are called cycloalkanes if only saturated carbon atoms form the ring, and cycloalkenes if there is at least a carbon-carbon double bond within the ring of carbon atoms.
Monocycloalkanes have the general formula with the open-chain alkenes CnH2n however, for the simplest mono cycloalkane, n = 3. A mono cycloalkane has two hydrogen atoms less than the corresponding open-chain alkane.
Polymerization
Polymerization is the process whereby small molecules of an organic compound combine repeatedly, in a regular fashion, to form a long-chain molecule. The small molecules are called monomers, while the product of polymerization is called a polymer.
A polymer is a long-chain molecule obtained when monomers combine repeatedly. Polymers have high relative molecular masses; hence, they are called macromolecules or giant molecules. Polymerization takes place at high temperatures ad pressures, and in the presence of catalysts.
There are two main types of polymerization namely: addition and condensation polymerization.
Addition Polymerization
Addition polymerization occurs in organic molecules containing carbon-carbon double bonds, as in alkenes, and those with triple covalent bonds, such as alkynes. In addition polymerization reactions, numerous monomers link in a highly regular fashion, to form a polymer without a gain or loss of materials. Under this condition, the monomer and the corresponding polymer have the same empirical formula.
The polymerization of ethene would give polyethene and this occurs at high temperature in the presence of peroxide catalyst. Another example is the polymerization of propane which gives polypropene as the output and polypropylene is used to make plastic tiles, electric wire insulators, chairs, and ropes.
Plastics & Natural Rubber
Plastics are polymers whose molecules can slide over one another when stretched, with the molecules remaining in their new positions when the stretching force is removed, i.e for the material to be deformed. Plastics of all kinds are synthetic polymers. They are light, soft or hard, flexible, tough, and with great tensile strengths. They are waterproof and resistant to chemicals and heat.
There are two types of plastics namely:
Thermoplastics: These are polymers that can be softened or melted when subjected to heat or pressure, and be remolded into any shape. For such polymers, their plasticity(plastic property) increases as the heat or pressure applied increases.
Thermosets: Thermosets are polymers that cannot be softened or melted by heat or pressure. Once formed, they become set(rigid), and cannot be remolded again.
Rubbers & Its Types
There are two types of rubber namely natural and synthetic rubber. Rubber-tree plantations are found in the southern part of Nigeria and when tapped, rubber tree gives a naturally occurring milky and sticky fluid called latex. When latex is coagulated or smoked by the use if methanoic or ethanoic acid, it gives, raw rubber, which is tough, hard, and elastic. Synthetic rubbers/artificial rubbers are obtained from 1,3-butadiene and substituted 1,3-butadiene.