In chemistry

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

 vicinal (from Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 vicinus = neighbor) stands for any two functional group

Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

s bonded to two adjacent carbon

Carbon

Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 atoms. For example the molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 2,3-dibromobutane carries two vicinal bromine

Bromine

Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...

 atoms and 1,3-dibromobutane does not.

Likewise in a gem-dibromide the prefix gem, an abbreviation of geminal

Geminal

In chemistry, the term geminal refers to the relationship between two functional groups that are attached to the same atom...

, signals that both bromine atoms are bonded to the same atom. For example, 1,1-dibromobutane is geminal.

Like other such concepts as syn

Syn addition

In organic chemistry, syn and anti addition are different ways in which two substituents can be added to a double bond or triple bond. This article will use alkenes as examples....

, anti, exo or endo, the description vicinal helps explain how different parts of a molecule are related to each other either structurally or spatially. The vicinal adjective is sometimes restricted to those molecules with two identical functional groups. The term can also be extended to substituents on aromatic rings.