This preview shows page 1. Sign up to view the full content.
Rules of the Day 12809
1.
Adjacent nuclei have magnetic fields associated with their spins
.
The spins of equivalent
adjacent nuclei can be either +1/2 or 1/2, and at room temperature they are found in about a
50:50 mixture at any given nucleus (very slight excess of lower energy +1/2). These can add to
give n+1 different spin combinations in the proportions predicted by Pascal's triangle. Each
different spin combination produces a different magetic field, which leads to
n+1 splittings
in
the peaks of the NMR spectra of the adjacent (no more than three bonds away) nuclei.
2. The distance between peaks split in this way is called the
coupling constant ("J")
.
Rules of the Day 13009
1.
THEORY:
When there are
two sets of adjacent H atoms, the number of peaks multiply.
For example, a CH
2
group with a CH
2
group and a CH
3
group on either side should show 3 x 4 =
12 splittings! You can say this group is a "triplet of quartets" (or a "quartet of triplets").
2.
This is the end of the preview. Sign up
to
access the rest of the document.
This note was uploaded on 09/22/2010 for the course CH 53200 taught by Professor Bocknack during the Spring '10 term at University of Texas at Austin.
 Spring '10
 BOCKNACK

Click to edit the document details