In organic chemistry, a propyl group is a three-carbon alkyl substituent with chemical formula −CH2CH2CH3 for the linear form. This substituent form is obtained by removing one hydrogen atom attached to the terminal carbon of propane.[1] A propyl substituent is often represented in organic chemistry with the symbol Pr (not to be confused with the element praseodymium).

From left to right: the two isomeric groups propyl and 1-methylethyl (iPr or isopropyl), and the non-isomeric cyclopropyl group.

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 −CH(CH3)2.[2]

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] or isopropyl).[1][failed verification] In addition, there is a third, cyclic, form called cyclopropyl, or c-propyl[citation needed]. It is not isomeric with the other two forms, having a different chemical formula (−C3H5 vs −C3H7), not just a different connectivity of the atoms.

Examples

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n-Propyl acetate is an ester which has the n-propyl group attached to the oxygen atom of the acetate group.

 
Chemical structure of propyl acetate.


Other examples

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References

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  1. ^ a b "IUPAC Nomenclature - Acyclic Hydrocarbons Rule A-1". Retrieved 2022-07-31.
  2. ^ "IUPAC Nomenclature - Acyclic Hydrocarbons Rule A-2". Retrieved 2022-07-31.