[organic]

I need to calculate the Pka of an organic base.
Is there any method by which we can calculate Pka value experimentally? say for example Pka of N-methyl imidazole.
Thanks in advance for your help.

[Borek]

No idea what you mean by "calculate experimentally". pKa values are either calculated from the molecule structure (difficult task, I have never seen satisfactory description of the method) or determined experimentally (most often using Henderson-Hasselbalch equation).

[AWK]

For the case of organic compounds there are possibility to estimate some pKa values

[organic]

I was just looking for an experimental procedure to calculate Pka value
thanks for the reply

[AWK]

Experimental procedure means measurements

[Kryolith]

pKa values are (classically) determined by titration. Have a look at the titration curve of CH₃COOH with NaOH.

http://newarkbioweb.rutgers.edu/bio301s/Lab%202-2.gif

[organic]

thanks very much

[organic]

Experimental procedure means measurements

if i have N-methyl imidazole hydrochloride salt, how do i calculate the Ka value? and how do i know what buffer do i need? can i use NaOH solution for titration?

[AWK]

Procedures for an exact determination of pKa are quite complex. But aproximate pKa you can calculate from titration. This subject was discussed many times on this forum. Borek is especially competent on this subject.

[optimusprime]

Isoelectric focusing?