Paraisomers

Paraisomers are a specific type of isomer in chemistry. The term "paraisomer" is not a standard or widely recognized term in chemical nomenclature. It's possible it is a neologism, a term used within a very specific research group, or a misspelling of a more common term. However, if interpreted as a portmanteau of "para" and "isomer," it likely refers to isomers where substituent groups are positioned at the 1,4-positions of an aromatic ring, such as a benzene ring. In such a case, they would be a subset of positional isomers.

Positional isomers are molecules with the same molecular formula and the same functional groups but differ in the location of these groups on the carbon skeleton or in the position of a double or triple bond. For a disubstituted benzene ring, there are three possible positional isomers: ortho (1,2-substitution), meta (1,3-substitution), and para (1,4-substitution). Therefore, if "paraisomer" is used, it most likely denotes the 1,4-substituted isomer in relation to other positional isomers of the same compound. For example, p-dichlorobenzene would be the "paraisomer" of o-dichlorobenzene and m-dichlorobenzene. The distinct positioning of substituents significantly impacts the physical and chemical properties of these isomers, including their melting points, boiling points, solubility, and reactivity.