Propyl group
Chemical group (–C₃H₇) derived from propane / From Wikipedia, the free encyclopedia
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).
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/c/c7/Propyl_groups.svg/640px-Propyl_groups.svg.png)
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.