Secondary is a term used in organic chemistry to classify various types of compounds (e. g. alcohols, alkyl halides, amines) or reactive intermediates (e. g. alkyl radicals, carbocations).
The reactivity of molecules varies with respect to the attached atoms.
Thus, a primary, secondary, tertiary and quaternary molecule of the same function group will have different reactivities.
[citation needed] which is the loss of the single proton bonded to the middle nitrogen.
Secondary phosphines have two 'R' groups attached to a phosphorus atom and again, a P-H bond.