regioselective

This is a technical term used exclusively in chemistry, specifically organic chemistry. It describes a reaction where the chemical bond is formed at one specific location (region) of a molecule rather than another possible location. It is used in formal academic papers, textbooks, and laboratory reports.

It is crucial to distinguish regioselectivity from stereoselectivity. While regioselectivity concerns which atom in a molecule is reacted upon, stereoselectivity concerns the spatial arrangement (geometry) of the resulting atoms. A reaction can be regioselective without being stereoselective, or vice versa.

In a practical sense, high regioselectivity is highly desirable because it minimizes the production of unwanted isomers (by-products), which simplifies the purification process and increases the overall yield of the target compound.