27
卷
4
期
2
∞
8.4
结构
fι
学
CJIEGOU
HUAXUE)
Chinese
J.
Struct.
Chem.
Vo
l.
27
,
No
.4
491-497
Prediction of Infinite Dilution Activity Coefficients
of Halogenated Hydrocarbons in Water
XU
Hui-Ying
(
MIN
Jian-Qing
(College
of
Biology & Environment Engineering,
Zh
写
;iang
Shuren
Universi
η"
Hangzhou 310015, China)
ABSTRACT Geometrical optimization and electrostatic potential calculations have been per-
formed for a series
of
halogenated hydrocarbons
at
the
HFI
Gen-6d level. A number
of
electrostatic
poten
出
Is
and the statistically based structural descriptors derived from these electrostatic potentials
have been obtained. Multiple linear regression analysis and artificial neural network are employed
simultaneously
in
由
is
paper. The result
shows
由
at
the parameters deri ved from electrostatic
potentials
σLt
，
Vsmd
Z
町，
together with the molecular volume
(V
mc) can
be
used to ex-
press the quantitative structure-infinite dilution activity coefficients
(y
∞)
relationship of halogenated
hydrocarbons
in
water. The result also demonstrates that the model obtained by using BFGS
qu
臼
i
Newton neural network method has much better predictive capability
than
出
at
from multiple linear
regression.
The goodness
of
the model has been validated through exploring the predictive power
for the extemal test set.
The model obtained via neural network may be applied to predict
y
∞
of
other halogenated hydrocarbons not present in the data se
t.
Keywords: halogenated hydrocarbons, molecular electrostatic potentials,
iI
ñmite
dilution
activity coefficients
(1'
勺，
QSPR
, artiflcial neural networks
1 INTRODUCTION
Kn
owledge
of
the thermodynamic behavior
of
dilute aqueous solutions is extremely important for
the design
of
many
separ
四
on
processes like those
involving the separation
of
a dilute pollutant from a
waste stream.
In the environinen
ta1
area
，出
e
sep
缸
a
tion of solvents and other hazardous chemicals
at
very luw
concentration
仕
om
drinking water
is
of
greatly important operations
, such
as
halogenated
organic chemicals in water.
The thermodynamic be-
havior of dilute aqueous solutions conducts how
these separation
pr
∞
esses
can be carried out suc-
cessfully.
Received 24 July
2
∞
'7;
accep
臼
d
6 November 2007
①
Corr
，臼
pαlding
au
血。
r.
Xu Hui.Ying,
bom
in 1965, associate professor,
m
电
joring
in
quantum chemical sludy. E-mail: xuhy65@163.com
f provide means to
s
阳
dy
this behavior
and
can
determine directly the phase equilibria
of
dilute
aqueous solutions. A number
of
different ex-
perimental methods are available
now
for
the
mea-
surement
of
f
[l
-3].
f
of
some halogenated
hydr
，。
carbons were also
measured(4].
Nonetheless, due to
the time-consuming and high expense
, it
is
nearly
impossible to determine experimentally
f for all
halogenated organic chemicals. UNIFAC (UNI-
QUAC functional group activity coefficientsp] and
ASOG (analytical solution
of
groupsi
6
]
are
the
most
commonly used prediction methods for liquid phase
activity coefficients
, and both
of
them are group-
contribution methods.
Though these methods
may
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