From: Jacob Zabicky (zabicky$##$bgumail.bgu.ac.il)
Date: Thu Apr 29 1999 - 06:18:59 EDT
Hello Richard,
IMHO you should do both, starting if possible with an astimate, that will
point to the experimental difficulties awaiting you when attempting actual
measurement. Now, investment of capital, time and intellectual effort in
the determinataion of the actual pKa of acetonitrile has to be justified by
some retionale. Otherwise, knowing that it is very high, as estimated by
this or that method, should usually be sufficient, and the precise
knowledege of whether that pKa is 16, 24 or 30 does not add to the primary
impression that dissociation is scant.
All the best,
Jacob
>To List:
>
>In response to the following two posts in the recent interesting discussion
>on acetonitrile catalysed deuterium exchange.....ya just can't trust those
>computer prediction programs for physicochemical properties!! Instead of
>"Go figure...." the watchword should be "Go measure...."
>
>Richard
>>------------------------------
>>
>>Date: Wed, 28 Apr 1999 10:14:49 +0800
>>From: Leslie J Harrison <chmhl$##$leonis.nus.edu.sg>
>>Subject: acetonitrile pKa
>>
>>
>>The pKa of MeCN is approx. 25.
>>
>>------------------------------
>>
>>Date: Wed, 28 Apr 1999 12:19:24 -0400
>>From: Hart_MacPherson$##$hc-sc.gc.ca
>>Subject: Re: ORGLIST: acetonitrile pKa
>>
>>just out of interest i ran CH3CN on PALLAS 1.2 for a pKa estimate. the
>>results
>>were "no acid groups" and "no basic groups", hence no pKa value was estimated.
>>
>>h. macpherson
>>health canada
>>ottawa, ontario
>>
>>------------------------------
>
>Richard J. Prankerd, PhD
>Senior Lecturer
>School of Pharmacy
>University of Queensland Phone: INT + (617) 3365-3179
>St Lucia QLD 4072 Fax: INT + (617) 3365-1688
>AUSTRALIA richard$##$pharmacy.uq.edu.au
> http://www.uq.edu.au/pharmacy/rprank.html
>(including photo)
>
>
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