From toukie \\at// zui.unizh.ch Thu Nov 3 06:23:24 1994 Received: from rzusuntk.unizh.ch for toukie:~at~:zui.unizh.ch by www.ccl.net (8.6.9/930601.1506) id FAA26655; Thu, 3 Nov 1994 05:33:14 -0500 Received: by rzusuntk.unizh.ch (4.1/SMI-4.1.9) id AA25869; Thu, 3 Nov 94 11:33:11 +0100 X-Nupop-Charset: British Date: Thu, 3 Nov 1994 11:27:30 +0100 (MET) From: "Hr Dr. S. Shapiro" Sender: toukie -x- at -x- zui.unizh.ch Reply-To: toukie: at :zui.unizh.ch Message-Id: <41250.toukie -x- at -x- zui.unizh.ch> To: chemistry # - at - # ccl.net Subject: Rate of rotation of methyl groups Dear Colleagues: I am seeking information on the rate of rotation of methyl groups: (i) firstly, I am seeking information/references describing the rate of rotation of the terminal methyl groups of n-alkanes at ca. room temperature (either experimental or theoretical). (ii) secondly, I am seeking information/references describing the rate of rotation of the C-19 methyl groups of steroids (or the rate of rotation of methyl groups attached to structurally related, hindered quaternary carbon atoms) at ca. room temperature (either experimental or theoretical). (iii) finally, I am seeking information/references on the RELATIVE rates of rotation of perhydro and isotopically substituted methyl groups. For example, what would one expect to be the rate of rotation of a chiral methyl group (CHDT) RELATIVE to a nonchiral perhydro methyl group (CH3) in the same molecule at the same temperature? I thank all responders for generously sharing their information/calcula- tions with me. Yours respectfully, (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: toukie*- at -*zui.unizh.ch FAX-nr: ( ... + 1) 261'56'83