Learn English – Constituent vs substituent

word-choice

I am a chemist, and I was writing the following sentence:

"The solvent mixture was non-polar due to the minimum amount of dipole-dipole forces in both constituents".

Constituents here was meant to refer to two compounds, molecules etc.

However generally I tend to use the word substituents, but looking up the definitions (just from dictionary.com), I now wonder if I am misusing this word.

So for constituent:

adjective
1.
serving to compose or make up a thing; component:
the constituent parts of a motor.

For substituent:

noun
3.
a constituent element, material, etc.; component.
So for substituent:

noun
1.
(chem) an atom or group that replaces another atom or group in a molecule or can be regarded as replacing an atom in a parent compound.

Interestingly, something I never noticed is that substituent doesn't seem to be used outside a chemistry context, while constituent is widely used.

So my questions, in short:

1) Is there another context where substituent may be used?

2) How interchangeable are substituent and constituent?

Best Answer

A quick search for the definition of the word substituent shows

an atom or group of atoms taking the place of another atom or group or occupying a specified position in a molecule.

In the world outside of chemistry the word substitute is used and not substituent. It means

a person or thing that takes the place of someone or something else

sports : a player who takes the place of another player during a game

Now, consider constituent

any one of the people who live and vote in an area : a member of a constituency

 one of the parts that form something

An element A can be a constituent of a compound if the compound was formed initially with the element A or has substituted another element B. So, a substituent (element A) is a current constituent of a compound that has substituted another (element B).

Personally, I would use substitute in everyday conversation and not substituent, except in chemistry related topics.