{{Short description|Chemical group (–C3H7) derived from propane}} thumb|300px|From left to right: the two isomeric groups propyl and 1-methylethyl (iPr or isopropyl), and the non-isomeric cyclopropyl group.
In organic chemistry, a '''propyl group''' is a three-carbon alkyl substituent with chemical formula '''{{chem2|\sCH2CH2CH3}}''' for the linear form. This substituent form is obtained by removing one hydrogen atom attached to the terminal carbon of propane.<ref name="IUPAC A-1">{{Cite web |url=http://www.acdlabs.com/iupac/nomenclature/79/r79_34.htm |title=IUPAC Nomenclature - Acyclic Hydrocarbons Rule A-1. |access-date=2022-07-31 }}</ref> A propyl substituent is often represented in organic chemistry with the symbol '''Pr''' (not to be confused with the element praseodymium).
An isomeric form of propyl is obtained by moving the point of attachment from a terminal carbon atom to the central carbon atom, named '''isopropyl''' or 1-methylethyl. To maintain four substituents on each carbon atom, one hydrogen atom has to be moved from the middle carbon atom to the carbon atom which served as attachment point in the ''n''-propyl variant, written as {{chem2|\sCH(CH3)2}}.<ref name="IUPAC A-2">{{Cite web |url=http://www.acdlabs.com/iupac/nomenclature/79/r79_36.htm |title=IUPAC Nomenclature - Acyclic Hydrocarbons Rule A-2. |access-date=2022-07-31 }}</ref>
Linear propyl is sometimes termed normal and hence written with a prefix ''n''- (i.e., ''n-''propyl), as the absence of the prefix ''n''- does not indicate which attachment point is chosen, i.e. absence of prefix does not automatically exclude the possibility of it being the branched version (i.e. ''i''-propyl{{Citation needed|date=July 2022|reason=unverified c- usage in names}} or ''isopropyl'').<ref name="IUPAC A-1"/>{{Not in citation|date=July 2022}} In addition, there is a third, cyclic, form called cyclopropyl, or ''c''-propyl{{Citation needed|date=July 2022|reason=unverified c- usage in names}}. It is not isomeric with the other two forms, having a different chemical formula ({{chem2|\sC3H5}} vs {{chem2|\sC3H7}}), not just a different connectivity of the atoms.
==Examples== ''n''-Propyl acetate is an ester which has the ''n''-propyl group attached to the oxygen atom of the acetate group. thumb|center|Chemical structure of propyl acetate.
=== Other examples === * Isopropyl alcohol * Isopropylamine
==References== {{reflist}}
{{Functional group}}
Category:Alkyl groups