Subject: Three questions

From: "Hr Dr. S. Shapiro" <[email-masked]>
Date: Thu, 17 Nov 1994 09:55:47 +0100 (MET)

Dear Colleagues:

     I have three questions, as follows:

     (i) Does anyone know substituent pi constants (used for calculating
partition coefficients) for the isobutyl {-CH2CH(CH3)2} and/or sec-butyl
{-CH(CH3)CH2CH3} groups?  If so, kindly advise me of the values and the
reference(s) in which these experimental values can be found.  I would like
to use these pi-values to estimate the partition coefficients of some
phenolic derivatives.

    (ii) With respect to the Hammett substituent constants (sigma)m and
(sigma)p, is it legitimate to assume that the sigma constant for an ortho-
substituted derivative, "(sigma)o" will be (approximately) the same as the
(sigma)p value?  Why or why not?  Any published references specifically ad-
dressing this question would be most sincerely appreciated.

     My third question is NOT a computational chemistry one, but whilst I
have your attention I tought that I might as well ask it:

   (iii) Does anyone know of any commercial source anywhere of reagent-grade
o-, m-, and/or p-isobutylphenol and any types of o-, m-, and/or p-pentyl-
and/or hexylphenols?  If so, kindly send details.

     I thank all responders in advance for kindly sharing their experience
(and data) with me.

Sincerely,

(Dr.) S. Shapiro
Institut fuer orale Mikrobiologie und allgemeine Immunologie
Zentrum fuer Zahn-, Mund, und Kieferheilkunde der Universitaet Zuerich
Plattenstrasse 11
Postfach
CH-8028 Zuerich, Switzerland

Internet: [email-masked]
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