CHEM 125A: FRESHMAN ORGANIC CHEMISTRY II - Lecture 25 - Professor J. Michael McBride
C-13 and 2D NMR – Electrophilic Aromatic Substitution
Proton decoupling simplifies C-13 NMR spectra. Dilute double labeling
with C-13 confirmed the complex rearrangement scheme in steroid
biosynthesis. Two-dimensional NMR yields correlations between NMR
signals that underlie structural determination of proteins and
identification of the mechanism of a rapid carbocation rearrangement.
Substitution of an electrophile for a proton on an aromatic ring
proceeds by a two-step association-dissociation mechanism involving a
cyclohexadienyl cation intermediate. The relative rates of forming
various products from substituted benzenes correlates with the
substituents' influences on the stability of the various cyclohexadienyl
cation intermediates. The spectrum of electrophile reactivities is very
broad. Important contributions for activating electrophiles were made
by Friedel and Crafts working in Paris.
Please recommend us on Facebook, Twitter and more:
Other social media tools
Tell us what you think of Chemistry 2011 -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Chemistry2011 is an informational resource for students, educators and the self-taught in the field of chemistry. We offer resources such as course materials, chemistry department listings, activities, events, projects and more along with current news releases.
The history of the domain extends back to 2008 when it was selected to be used as the host domain for the International Year of Chemistry 2011 as designated by UNESCO and as an initiative of IUPAC that celebrated the achievements of chemistry. You can learn more about IYC2011 by clicking here. With IYC 2011 now over, the domain is currently under redevelopment by The Equipment Leasing Company Ltd.
Are you interested in listing an event or sharing an activity or idea? Perhaps you are coordinating an event and are in need of additional resources?
Within our site you will find a variety of activities and projects your peers have previously submitted or which have been freely shared through creative commons licenses.
Here are some highlights: Featured Idea 1, Featured Idea 2.
Ready to get involved? The first step is to sign up by following the link: Join Here. Also don’t forget to fill out your profile including any professional designations.