Chemistry Reference
In-Depth Information
bonds, which are evidenced by the presence of a minor peak at 2.8 ppm
corresponding to the protons in the methylene groups between two non-
conjugated double bonds (-CH
¼
CH-CH
2
-CH
¼
CH-). In the TOPER spec-
trum [Figure 8.2(b)], the multiplet peaks in the 3.4-3.8 ppm region belong
to the hydroxyl functional methylene protons of the polylol. The peaks at
4.0-4.4 ppm show the methylene protons of the polyol backbones
connecting to the ester structure (-CH
2
-O-(C
¼
O)-CH
2
-). The TOPERMA
product was characterized by the maleate vinyl protons at 6.3 ppm and the
peak of acid protons at 10.1 ppm [Figure 8.2(c)]. The fumarate (trans-isomer
of the maleate) peak appeared at 6.9 ppm with a very low intensity, since the
maleate-fumarate isomerization favors a higher temperature than the
reaction temperature.
21
The peak at 7.1 ppm represents the unreacted MA
vinyl protons. As the maleinization reaction of TOPER proceeded, the pro-
tons at 3.4-3.8 ppm were converted to those at 4.0-4.5 ppm, the methylene
protons of the polyol backbones connecting to the ester structure. The peaks
at 2.8 ppm belonging to the protons in the -CH
¼
CH-CH
2
-CH
¼
CH- struc-
ture became sharp, indicating the occurrence of a new similar structure.
This may result from the protons on the conjugated triene connecting to MA
via a Diels-Alder reaction [Figure 8.2(c)]. The peaks at 3.1-3.4 ppm can be
designated as the protons on the MA connecting to the conjugated triene.
Hence, the maleinated products shown in Scheme 8.2 were ideal structures
of TOPERMA, and the real products should contain the byproducts resulting
from the Diels-Alder reaction. The peak that appears at 7.28 ppm in each
spectrum represents the residual protons of CDCl
3
. The peak at 7.45 ppm
shows the aromatic protons of the N,N-dimethylbenzyl amine used as a
catalyst for the maleinization reaction.
Soft ionization combined with the inherent multiple charging mechanism
of ESI has made MS an ideal tool to determine accurate molar masses.
Figure 8.3 shows the ESI-MS spectra of TOPER and TOPERMA. The struc-
tures assigned to various mass numbers are given in Scheme 8.5. The
characteristic peaks and the possible molecular structures of the TOPER
products were correlated as 353.2[M
2
þ
H]
1
,379.2[M
2
þ
Na]
1
,397.2[M
1
þ
H]
1
,
and 435.2[M
1
þ
K]
1
, indicating the presence of monopentaerythritide and
monoglyceride. The peaks and the structures of TOPERMA were correlated as
449.2[M
4
-H]
,493.2[M
3
-H]
,547.1[M
6
-H]
,591.2[M
5
-H]
,645.1[M
8
-H]
,
689.2[M
7
-H]
, and 787.1[M
9
-H]
, suggesting the yield of several maleate half-
esters. The peaks of 645.1[M
8
-H]
obviously revealed the Diels-Alder structure
in TOPERMA, because the monoglyceride could not react with three MA
molecules without the Diels-Alder reaction. Multiplicity seen in the mass
spectra near the intense peaks is due to the natural abundance of various fatty
acids in TO.
8.3.1.2 DCPD-UPR-TO Polymers
Data of A
v
, V
s
, weight-average and number-average molar masses (M
w
and
M
n
), and polydispersity (PDI) for DCPD-UPR-TO polymers with different TO
