[Big-Daddy]

What is the definition of "hydrogen abstraction" and how do we tell the order of ease of abstraction for different H atoms? Is it just another term for how easily is the hydrogen atom in question dissociated off the compound, i.e. acidity of the H? My Google search was inconclusive on this point.

[Archer]

 Hydrogen extraction may be referring to hydrogen radicals (i.e. a proton and an electron)

Proton abstraction relates to the pKa of the hydrogen.

[Big-Daddy]

Hydrogen extraction may be referring to hydrogen radicals (i.e. a proton and an electron)

Proton abstraction relates to the pKa of the hydrogen.

Ah thanks. Frustrating (but I think you're right in the context I'm looking at). So how do we predict the stability of free radicals then (Know any good sources for this info?)

[Archer]

This is the only book on free radicals I have ever needed. I have not done much radical chemistry though.

An Introduction to Free Radical Chemistry
Andrew F. Parsons
ISBN: 978-0-632-05292-9

The book orders the relative rate of hydrogen abstraction from a C-H bond as tertiary> secondary > primary which is due to bond strenght and radical stability.