pH independent, thiol cross-linker?

Frank R. Gorga fgorga at
Tue Nov 2 08:44:35 EST 1999

Yoram Gerchman wrote in message
<381E9849.B4359018 at>...
>(This is a re-post, sorry)
>Greetings Netters
>I'm looking for a pH independent, thiol cross-linker, any idea would be
>welcome (should work at pH range 6-9)

There is no such thing... because of the basic chemistry of the SH group

The deprotonated form (RS-) is much more nucleophilic than the protonated
form (RSH). Fuethermore, the typical thiol has a pKa of around 8.5. Thus at
pH 9 thiols are more than 50% deprotonated, while at pH 6 there is
essentially no unprotonated thiol.

The bottom line... the reaction of thiols with any reagent will depend on
the pH in the range 6 to 9. Reactions will proceed quite well at pH 9 and
very poorly (if at all) at pH 6.

--- FRG

Frank R. Gorga, Ph.D.
Dept. of Chemical Sciences
Bridgewater State College
Bridgewater, MA 02325
508-531-1785 (fax)
fgorga at

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