The trans isomer is almost completely eliminated in the first 24h, while the cis isomer
is eliminated by day 8 from liver and kidney, and in days 12, 17, 24 and 28 from fatty tissue (Crawford et al.
Remarkably, according to our calculations the cis isomer
seems to be slightly more stable than the trans one, probably because of some hydrogen bond like interaction between the hydrogen atom and the opposing oxygen.
While maleic acid, the cis isomer
, is a synthetic organic compound, its trans isomer, fumaric acid, is an organic acid widely found in nature (Felthhouse et al.
We can see that the cis isomer
is almost fully consumed irrespective of the distance from the air surface, whereas the trans isomer only cures near the surface.
The cis isomer
is much higher lactone described as having an earthy, concentrations.
NPG, the [alpha]-proton of the cis isomer
is found at 2.
Regular amino acids form secondary amides, in which the trans isomer is considerably more stable than the cis isomer
(Figure 3), resulting in a linear chain.
Additionally, some of the C=C double bonds along the NR backbone have changed configuration from the cis isomer
to 1,2-pendant and vinyl-terminated isomers.
In all cases, the chemical shift of the C-1 methine proton of the cis isomer
is more deshielded (larger ppm value) than the methine proton of the trans isomer.
o] (a low value is preferable) and the percentage of cis isomer
(which should be high).
According to Otsuka (1974)(1) the cis isomer
is much more flavor active with an odor threshold of 0.
12]MDI, the difference in molecule linearity between the cis isomer
and the trans isomer is not very obvious, as shown in figure 1.