PHASE-BEHAVIOR OF THE REACTANTS, PRODUCTS AND CATALYSTS INVOLVED IN THE ALLYLIC EPOXIDATION OF TRANS-2-HEXEN-1-OL TO (2R,3R)-(-3-PROPYLOXIRANEMETHANOL IN HIGH-PRESSURE CARBON-DIOXIDE())
Ba. Stradi et al., PHASE-BEHAVIOR OF THE REACTANTS, PRODUCTS AND CATALYSTS INVOLVED IN THE ALLYLIC EPOXIDATION OF TRANS-2-HEXEN-1-OL TO (2R,3R)-(-3-PROPYLOXIRANEMETHANOL IN HIGH-PRESSURE CARBON-DIOXIDE()), The Journal of supercritical fluids, 12(2), 1998, pp. 109-122
The possible phase behavior of a reaction mixture is an important cons
ideration when evaluating CO2 as an alternative solvent to replace tra
ditional organic compounds. To address this issue we present phase equ
ilibrium measurements and modeling of primarily binary mixtures with C
O2 of the reactants, products and catalysts present in the allylic epo
xidation of trans-2-hexen-1-ol to (2R,3R)-(+)-3-propyloxiranemethanol.
This reaction occurs with very high enantiomeric selectivity in liqui
d CO2, yields a high value product, and would normally be carried out
in an organic solvent like benzene. Thus, it is a promising candidate
for CO2 solvent replacement. The systems studied are trans-2-hexen-1-o
l-CO2, tert-butyl hydroperoxide (in decane)-CO2, (2R,3R)-(+)-3-propylo
xiranemethanol-CO2, tert-butyl alcohol-CO2, diisopropyl L-tartrate-CO2
, vanadium(V)tri-i-propoxy oxide-CO2 and titanium(IV) isopropoxide-CO2
. The compositions of the liquid phases were determined as a function
of pressure, at temperatures between 303.15 and 323.15 K and pressures
between 31.5 and 110.2 bar. Liquid/liquid immiscibility regions were
found for the trans-2-hexen-1-ol-CO2 and (2R,3R)-(+)-3-propyloxiraneme
thanol-CO2 binaries. This region is located between 310.9 K (the lower
critical end point) and 315.3 K (a type-k point) and the correspondin
g pressures of 79.5 and 86.7 bar for trans-2-hexen-1-ol-CO2. The (2R,3
R)-(+)-3-propyloxiranemethanol-CO2 liquid/liquid immiscibility region
ranges from 315.1 K (a type-k point) to below 293.7 K, at the correspo
nding pressures of 86.1 to 55.8 bar. All of the other binaries exhibit
ed simple vapor/liquid equilibrium (VLE). Modeling with the Peng-Robin
son equation of state (PREOS) gave reasonably good results for the two
phase regions for all of the systems, using just one temperature-inde
pendent parameter for each binary system. The PREOS did predict LLV th
ree phase regions for the trans-2-hexen-1-ol-CO2 and (2R,3R)-(+)-3-pro
pyloxiranemethanol-CO2 binaries, but generally at conditions different
from those observed experimentally. Finally, we present some prelimin
ary predictions of the multicomponent phase equilibria based on the bi
nary measurements and models. (C) 1998 Elsevier Science B.V.