I need to find the web site that had the following information on it.

FUNDAMENTALS

A strong acid  is one that is ca.100% dissociated in H2O and it’s pKa
is approximately 0.  Examples would include HCl, HClO4, HNO3, H2SO4
(first dissociation), sulfonic acids:  C-SO3H, monoesters of sulfuric
acid:  C-O-SO3H.  H3PO4 (first dissociation) is weaker than these
strong acids, but stronger than most weak acids.  A weak acid  is one
that is usually  <10%  dissociated in H2O.  Usuall, pKa’s are in the
range of 4.0 to 7.0.  Common examples would include:  H2CO3 (first
dissociation), H3PO4 (second dissociation, i.e., H2PO4- ), carboxylic
acids (C-CO2H) and monophosphate esters (second dissociation): 
C-O-PO3H -A very weak acid is one that is usually  <1% dissociated in
H2O.  Usual pKa’s are in the range of  9.0 to 12.0.  Examples are
NH4+, HCO3-, H3PO4 (third dissociation, i.e., HPO42- ), H2S (first
dissociation)
phenols:  Ar-OH, thiols:  C-SH, conjugate acids of amines:  RNH3+,
R2NH2+, R3NH+


In the case of phosphoric acid, there are four seperate species :
H3PO4, H2PO4- , HPO42- , and PO43-
The 3 pKa's are 2.14, 7.20, 12.48.  In the case of phosphomonoesters 
(R-OPO3H2) there are three possible species and two pKa's: ca. 2, ca.
7.  Phosphodiesters ( R-O-PO2H) exist in an equilibrium of two species
with the pKa  ca. 2
B.	SPECIFICS
	--	dissociation (and association) are equilibrium processes; in water
these equilibria are usually achieved instanteously.
	--	ionic state of an acidic (or basic) functional group is determined
by the presence or absence of H+
	--	presence or absence of H+ is determined by [H+] in the bulk of the
solution if the environment is                  aqueous.

When a particular functional group is close to a second functional
group, the two groups interact (this is called the inductive effect);
this is true when the functional groups are parts of the same molecule
(as in amino acids, nitrophenols and citric acid) when the effect is
rationalized as a “through-the-bonds” effect, and also when the
functional groups are positioned close to one another in 3-space even
if they belong to different molecules (as in tertiary and quaternary
structures of proteins), when the inductive effect is “through-space”.
 The acid strength of each group may be altered.  For example, compare
acetic acid (pKa = 4.76 for CO2H) and glycine (pKa = 2.34 for CO2H).

 	
See the Table in your text book for specific pKa's of 
some amino acids commonly found in proteins .

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Request for Question Clarification by bobbie7-ga on 17 Sep 2002 23:44 PDT

Can you tell us anything else?

Could this be at a University website?

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Clarification of Question by drtom-ga on 18 Sep 2002 07:56 PDT

This was from a University web site and was most likely some type of
on-line class notes.  The site was accessable to the general public
and I origionally accessed the site in August of this year.  I was
trying differant search parameters with Google when I found it.  I
have been unable to duplicate that search.

On this site, there is a statement "In the case of phosphomonoesters 
(R-OPO3H2) there are three possible species and two pKa's: ca. 2, ca.
7.  Phosphodiesters ( R-O-PO2H) exist in an equilibrium of two species
with the pKa  ca. 2"  I need to either find a differant referance that
makes that same statement or find this site, contact the individual
who wrote it and find out where he got the information.

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Request for Question Clarification by tehuti-ga on 19 Sep 2002 05:24 PDT

I have found a place that simply states the two pKa values for the
monoesters. This is also from some study/lecture notes, and it is
possible to get to a contact page for the author. However, there is no
mention of diesters.

Otherwise, I have tried searching for various combinations taken out
of the quotation you provide, but without success.

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Clarification of Question by drtom-ga on 20 Sep 2002 07:40 PDT

I would accept as a complete answer a contact or referance(s) that
validates the following statement...

In the case of phosphomonoesters 
(R-OPO3H2) there are three possible species and two pKa's: ca. 2, ca.
7.  Phosphodiesters ( R-O-PO2H) exist in an equilibrium of two species
with the pKa  ca. 2

If one referance makes the statement about the phosphomonoesters and
another makes it about the phosphodiesters - great.

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Request for Question Clarification by tehuti-ga on 24 Sep 2002 08:16 PDT

I have found a cached document with many pKa values, including
phosphoric acid and diverse organic phosphates at
http://216.239.39.100/search?q=cache:ZkIKQJiOuD8C:icg.harvard.edu/~chem206/Fall_2001/lectures/18_Acid_Based_Properties_of_Organic_Molecules/pKa_compilation.pdf

The actual pdf file on the Harvard web site cannot be opened without a
password. The cache does not show the complete document, so the
bibliography of citations is not visible.  However, you might be able
to contact one of the compilers of the document to obtain further
information:

FH Westheimer is Emeritus Professor at the Department of Chemistry and
Chemical Biology, Harvard   http://www.chem.harvard.edu/
WP Jencks is Emetirus Professor of Biochemistry at Brandeis 
http://www.bio.brandeis.edu/pages/faculty/jencks.html

The pKa data themselves were compiled by R Williams, but I'm afraid
that name is less readily identifiable.

I hope you might find something of use in this information. I have
drawn a blank in all other attempts at searching on this topic.

This does look very much like an extract from notes prepared by a
lecturer for students.  If so, there is a possibility that the page is
on an intranet accessible only by members of the university.  Also,
the course might have been changed and these notes might have been
substituted with a revised set.

The source was a University Web site that was open to the public.  In
chemistry, the general rule is that notes for classes don't change
unless there has been some additional research on the subject that
will change the conclusions or that the notes were unclear.  This was
very clear and represents a significant amount of research by the
author - not likely to change.  However, notes go on and off, the
possibility is that they may have been pulled.

I posted a comment that there may be a differant way to get at the
answer.