ScienceHideout - 19-8-2014 at 12:38
As we all know, organic compounds are generally reducing agents. What I want to figure out is how to classify and quantify their strength as such. For
example, it is easily understood that ascorbic acid is a stronger reducing agent than methyl alcohol... but is there an actual way to quantify that?
Would ORP work, or could I titrate it somehow, or is it purely theoretical?
Thank you very much in advance!
Dean
EDIT: I could have sworn that I posted this in beginnings... Oh well 
[Edited on 19-8-2014 by ScienceHideout]
Oscilllator - 19-8-2014 at 16:52
You can measure the strength of a reducing agent relative to another reducing agent fairly simply. If substance A reduces substance B but substance C
does not, then substance A is a stronger reducing agent than substance B.
This is similar to the old-school way of finding the reactivity of metals. An example is that Zinc metal reduces Cu2+ but lead metal does not.
Therefore Zinc is a more reactive metal than lead.
Templar - 20-8-2014 at 02:58
This is difficult... its not just the reducing potention of the reducing agent (boro,LAH, Al/Hg, Na/Hg etc) its also the intermediates that are formed
during the process.
For example, DNA polymerase is an enzyme that can do what it normally takes acyl chlorides or PCl3 to do, make peptide bonds. There are other
biological reducers too, I think yeast will turn ketones and aldehydes into their alcohols, but is limited by reagent concentration.
I think the reaction mechanism is very important for testing the reducing potential, but there is also the very clear differences in reactivity, LAH
vs boro.
Maybe on the susceptibility of attack from other groups (or to attack other groups) and reduce them. Nucleophiles attack LAH pretty readily? But not
so much borohydride.
ScienceHideout - 20-8-2014 at 06:16
I guess the problem is that what I am trying to test are very weak in the first place... reducing saccharides. Comparing it to the reactivity series
would theoretically work, but anything that theoretically works doesn't practically work. It is not very difficult to reduce silver complexes with any
of them (Tollen's Test) or copper complexes (Benedict's, right?), but it is obvious that lead, tin, nickel, cobalt, iron, etc. will not. So they all
are very close, the sugars, I just want to be able to put them into some order and assign quantitative data to them. Ribose, xylose, dextrose,
galactose, fructose, lactose, maltose, sucrose. I know that sucrose is non reducing because there is no hemiacetal, it is just a matter of sorting
them after that.