From chemistry-request@server.ccl.net Mon Mar 31 04:31:15 2003 Received: from mailrelay1.lrz-muenchen.de ([129.187.254.101]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id h2V9VEs31782 for ; Mon, 31 Mar 2003 04:31:14 -0500 Received: from eeb04.cup.uni-muenchen.de by mailrelay1.lrz-muenchen.de with ESMTP for CHEMISTRY@ccl.net; Mon, 31 Mar 2003 11:30:53 +0200 Received: from localhost by eeb04.cup.uni-muenchen.de (8.8.8/1.1.22.3/02Jul99-1017PM) id LAA0000024207; Mon, 31 Mar 2003 11:30:52 +0200 (MET DST) Date: Mon, 31 Mar 2003 11:30:52 +0200 (MET DST) From: Stefan Seidler To: Subject: Re: Calculation of chemical reactivity Message-Id: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII > I was asked to investigate the relative reactivities of various aniline > derivatives in the following reaction: > > Ph-NH2 -> Ph-NHOH -> Ph-NO > > where Ph are differently substituted Phenyl or Azaphenyl (Pyridine, Pyrimidine...) rings. > The reactivity of cmpds in redox reactions could be estimated by thermodynamic considerations: deltaG = nF(Udon - Uacc) U: redox potential For sure the oxidative reactions of organic cmpds include complex reaction mechanisms, but the most important step in the mechanism of the oxidation of aromatic amines is actually the electron transfer itself (no H transfer, no O addition; see german "Organikum" D.6). The redox potential is directly related to the energies of the frontier orbitals: a substrate should be more easy oxidizeable the higher the energy of the HOMO. Therefore the calculation of the HOMO energies might be useful for estimating the reactivity and ordering your series. Additional information regarding reactivity could be found in the bibliographies of "synthesis planning tools" like EROS (Gasteiger) and CAMEO (Jorgensen). Quantitative Prediction of Chemical Reactivity: http://www2.chemie.uni-erlangen.de/publications/publ_topics/publ_topics-10.html Regards, Stefan --- stefan.seidler AT cup.uni-muenchen.de