The ring-opening of ECH from the acidolysis reaction with neodecanoic
acid (NDA), which was catalyzed by tetramethylammonium chloride (TMAC)
in our experiments, is shown in Scheme 2 . Different amounts of
TMAC were added to study the effect of catalyst content on the reaction
performances
(see Figure 2 ). Figure 2(A) shows the curves of NDA conversion
versus reaction time. It is acceptable that the reaction rate,
especially at the early stage, increases when more TMAC is used. To be
more detailly, as the amount of TMAC increases to 5% (molar ratio to
NDA), the reaction time for 99% conversion of NDA basically doesn’t
change with the further increment of TMAC. And when using 1% TMAC, the
reaction time of 20 hours is needed, which is too long to be accepted.
Therefore, it is a better option to add TMAC in the molar ratio of
0.05:1 to NDA. Figure 2(B) shows the GC analysis results of the samples
taken at the end of the reactions. Because of the increment of TMAC, the
concentration of dichloropropanol (DCP) greatly increases from 3.7% to
7.2%, resulting in the decline of \(\eta_{\text{ECH}}\) by 7.1%.
Temperature is another factor that greatly influences the reaction
performances (see Table 1 ). As the temperature rises from 50oC to 110 oC, the required reaction
time is reduced from 1200 min to 90 min, however, the concentration of
side-product dichloropropanol (DCP) in the final reaction system rises
from 3.7 w % to 8.5 w %, leading to the decline of\(\eta_{\text{ECH}}\) by 9%. Taking both the factors of reaction time
and selectivity into consideration, it is a better option to apply the
temperature condition in the range of 70~90oC.
Table. 1 Effect of temperature on the reaction performances.