Binary mixtures of dimethyl sulfoxide with methanol, ethylene glycol, and glycerol as solvent: Solvatochromism and chemical kinetics study

Article abstract of DOI:10.1016/j.molliq.2018.03.039

The understanding of solvent effects on chemical reaction requires precise knowledge of solute-solvent interactions. Since solute-solvent interactions are much more complex in mixed solvents, the study of chemical kinetics can be valuable because of the p

Full text of DOI:10.1016/j.molliq.2018.03.039

Accepted Manuscript
Binary mixtures of dimethyl sulfoxide with methanol, ethylene
glycol, and glycerol as solvent: Solvatochromism and chemical
kinetics study
Ali Reza Harifi-Mood, Hasan Khorshahi
PII:
DOI:
Reference:
S0167-7322(17)36027-0
doi:10.1016/j.molliq.2018.03.039
MOLLIQ 8813
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28 February 2018
10 March 2018
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ACCEPTED MANUSCRIPT
Binary mixtures of dimethyl sulfoxide with
methanol, ethylene glycol, and glycerol as solvent:
Solvatochromism and chemical kinetics study
Ali Reza Harifi-Mood*, Hasan Khorshahi
Department of Chemistry, Kharazmi University, Tehran, Iran.
Corresponding authors:
Ali Reza Harifi-Mood: harifi@khu.ac.ir & alireza.harifi@gmail.com
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Abstract
The understanding of solvent effects on chemical reaction requires precise knowledge of solute-
solvent interactions. Since solute-solvent interactions are much more complex in mixed solvents, the
study of chemical kinetics can be valuable because of the possibility of preferential solvation. In this
work, binary mixture of methanol-DMSO, ethylene glycol-DMSO, and glycerol-DMSO were
selected as solvent systems to determine solvatochromic polarity parameters and investigate the
solute-solvent and solvent-solvent interactions. Results showed that the variation of parameters
respect to solvent composition in these mixtures were compatible with those of in deep eutectic
solvents-DMSO mixtures including ethylene glycol and glycerol. Aromatic nucleophilic substitution
reaction of 1-fluoro-2,4-dinitrobenzene with piperidine was also investigated in the mentioned
mixtures. Kinetic data showed that the reaction strongly follows the based-catalyzed mechanism in
DMSO rich region. The partial catalytic and non-catalytic rate coefficients demonstrated reasonable
correlations with solvatochromic parameters.
Keywords: Aromatic nucleophilic substitution; 1-Fluoro-2,4-dinitrobenzene; Solvatochromic
parameters; Preferential solvation; Solvent effect.
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1. Introduction
Solvent can have an effect on solubility, selectivity, and reaction rates and choosing the suitable
solvent allows for thermodynamic and kinetic control over a chemical reaction [1–4]. The effect of
solvent on chemical reactivity has previously been explained on the basis of the dielectric constant,
viscosity, dipole moment, internal pressure and so on. However it has been proved that the solvent
effects are related to the nature of solute-solvent interactions. These interactions can be influenced
by the attributes of solvent molecules. The ionic or non-ionic nature of the molecules and the
existence of functional groups determine the type and strength of solute-solvent interactions [5].
Therefore, solvent effects are commonly interpreted as resulting from changes in media polarity, a
general term that is related to the overall solvating capability of the solvent [6]. Due to the
complexity of the solvation phenomena and solute-solvent interactions, there are no reliable and
exact methods for a quantitative description and prediction of these interactions. Empirical
parameters of solvent polarity are of great value in this respect and can be derived with the aid of the
principle of linear free energy relationships [7–11]. We have continuously studied the
solvatochromism of solvatochromic indicators and also the kinetics of chemical reactions in pure
and binary solvent mixture consisting of ionic liquids (ILs) or deep eutectic solvents (DESs) [12–
15].
Solute-solvent interactions are much more complex in mixed solvents than those of in pure solvents
because of the possibility of preferential solvation and solvent-solvent interactions [16–20]. Our
research group has tried to investigate these interactions in binary mixtures including new solvents
such as ILs or DESs. In recent contribution [21], we have found that DESs have a dramatic effect on
the rate of aromatic nucleophilic substitution (SNAr) reaction. A similar trend has been observed in
the variation of rate coefficient when 1-butyl-3-methyl imidazolium tetrafluoroborate as an ILs was
added to molecular solvents. [22].
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In this work, we have determined the solvatochromic parameters of binary mixture of ethylene
glycol and glycerol, as basic component of two DESs, with dimethyl sulfoxide (DMSO). Binary
mixtures of methanol-DMSO have been also studied to compare the effect of methanol on
solvatochromic parameters with that of polyols. In order to investigate the influence of solvent
effects on the chemical reaction rate, the chemical kinetics of a selected SNAr reaction were studied
in the binary solvent mixture of methanol, ethylene glycol, and glycerol with DMSO.
2. Experimental section
2.1. Materials
Methanol (≥99.8%), ethylene glycol (≥99.8%), glycerol (≥99.5%, spectrophotometric grade), and
spectroscopic grade of DMSO were purchased from Merck. All solvents were dried by 3Å molecular
sieve. The water content of the dried materials was determined by coulometric Karl Fisher titration
yielding < 1000 ppm residual water. 4-Nitroanisol and 4-Nitroaniline (> 99%) were recrystallized
from water/ethanol and water/acetone, respectively, Reichardt’s betaine dye (>90%) was obtained
from Sigma-Aldrich and was used without further purification.
2.2. Spectrophotometric measurements
In order to determine the maximum absorption of 4-nitroanisole, 4-nitroaniline, and Reichardt’s
betaine dye, aliquot of their primary solutions were transferred into a 1 cm quartz cuvette. The
binary mixtures of solvents over the entire range of mole fractions were gravimetrically prepared
(±0.1mg uncertainty in mixture composition). Each binary mixture was transferred into the quartz
cell and the solution was vigorously stirred, so that a homogeneous solution was prepared. UV-vis
absorption spectra of the solutions were recorded in the suitable range of wavelength, using a GBC
UV-vis cintra 101 spectrophotometer at 25˚C.
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2.3. Kinetic measurements
The kinetic of the reaction between 1-flouro-2, 4-dinitrobenzene (FDNB) and piperidine (Pip) was
spectrophotometrically studied in the mixtures of DMSO with methanol, ethylene glycol, and
glycerol at 25˚C. Prior to kinetic investigations, the product of the reaction was synthesized by
adding of Pip to FDNB directly and then the recrystallizing of the produced precipitate from hot
ethanol. The stability of product was tested in all solvents for 24h. Solvent mixtures were closely
prepared as described in previous section. After transferring the aliquot of primary solutions of the
reactants, the variation of solution absorption was recorded at a wavelength around 360-370 nm
depending on the solvent composition. The concentrations of FDNB and Pip were chosen in
significant difference to study the reaction under pseudo-first-order conditions. The rate coefficients
of the reaction were calculated according to the procedure reported in elsewhere [23,24].
3. Results and discussion
3.1. Solvatochromic parameters in binary solvent mixtures
The solvatochromic parameters of pure methanol, ethylene glycol, glycerol, and their mixtures with
DMSO including hydrogen bond donor ability, α, hydrogen bond acceptor ability, β,
dipolarity/polarizability, π*, and normalized polarity,퐸푇푁, of media over the entire composition range
have been determined based on the procedure reported elsewhere [12]. Eqs 1–4 show the related
equations used to determine the solvatochromic parameters:
−1
(
)⁄
( )
1
퐸푇 30 kcal. mol = 2.8592 휗퐵
(
)
(
)
퐸푇 solvent − 퐸푇 TMS
퐸푇푁 =
( )
2
(
)
(
)
퐸푇 water − 퐸푇 TMS
∗
(
)
( )
3
휋 = 0.427 34.12 − 휗퐴푁푆
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31.10 − 3.14휋∗ − 휗퐴푁퐼
( )
훽 =
훼 = 0.186 10.91 − 휗퐵 − 0.72휋
where 휗퐵, 휗퐴푁푆 , and 휗퐴푁퐼 are the wavenumbers of maximum absorbance Reichardt’s betaine dye, 4-
4
2.79
∗
(
)
( )
5
(
)
nitroanisole, and 4-nitroaniline, respectively, in kK. 퐸푇 30 is empirical polarity and refers to charge
transfer energy of Reichardt’s betaine dye in solvent that its values have been reported as normalized
parameters (퐸푇푁) in this contribution. TMS denotes tetramethyl silane. Determined solvatochromic
parameters based on recent equation were reported in Table 1. Fig. S1 of the supplementary
materials shows that the trends of present data are in good agreement with solvatochromic
parameters of ethaline-DMSO and glyceline-DMSO mixtures recently published by our research
group [14]. Ethaline and glyceline, as two usual DESs, are consisting of ethylene glycol and
glycerol, respectively. With relative deviations generally <12%, except for the β parameter of
glycerol, solvatochromic parameters of pure ethylene glycol and glycerol demonstrate a relative
agreement with the solvatochromic parameter value of pure DESs. On the other hand, the similar
trend of data variation respect to mole fraction, with relative deviation between 5.2-41.5% (exhibited
in Fig. S1), confirms that ethylene glycol and glycerol are dominant components which determine
the polarity of DESs. It is worth mentioning that the determining factor of media polarity is polyol
moiety and DESs.
Deviation from ideal behaviour produces an excess values for solvatochromic parameters which can
be concluded the probes are not equally solvated by the two components of the binary solvent
mixture and a preferential solvation of the probe is occurred. These conditions arise when the
composition of bulk solvated differs from the solvation microsphere.
3.2. Preferential solvation model
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As it can be found in various reports, preferential solvation model is based on a simple exchange of
two solvents in microsphere solvation of an indicator (solute) according to the following equations:
I (S1)2 + 2S2
I (S1)2 + S2
I (S2)2 + 2S1
I (S12)2 + S1
(6)
(7)
where I stands for the solute, S1 and S2 for the pure solvents, and S12 for the solvent formed by the
interaction of solvents 1 and 2. I(S1), I(S2) and I(S12) represent the solute solvated by the S1, S2
and S12 species. Eq. (6) reflects the total exchange of solvent 1 by solvent 2 in the solvation sphere
of the solute, and Eq. (7) corresponds to the exchange by the double-structure solvents. The
constants of two processes are defined by the preferential solvation parameters f2/1 and f12/1 according
to the Eqs (8) and (9) [25–27]:
푥2푠/푥1푠
(푥20/푥10)2
( )
8
푓
2/1
=
푥1푠2/푥1푠
푥20/푥10
( )
9
푓
12/1
=
where 푥1푠, 푥2푠, and 푥1푠2 are the mole fractions of the solvent 1, 2, and composite solvent, respectively,
in solvation microsphere. 푥10 and 푥20 represents the bulk mole fractions of solvent 1 and 2,
respectively. According to this model, the physio-chemical properties (Y) in the solvent mixtures are
calculated as an average of these properties in pure and composite solvents (Y1, Y2, and Y12) as
follows:
0
0
푌 1 − 푥 + 푌 푓 ⁄ 푥2 + 푌2푓12 1(1 − 푥0)푥0
(
)
(
2 2 1
)
⁄
1
2
2
2
(
)
10
푌 =
0
0
1 − 푥2 2 + 푓 ⁄ 푥2 + 푓12 1(1 − 푥0)푥0
(
)
(
)
⁄
2 1
2
2
In this study, Y refers to the wavenumber of solvatochromic indicators in solution. In the continuing
of this contribution, 푥20 has been demonstrated with xCoS that refers to the mole fraction of methanol,
ethylene glycol, and glycerol in binary solvent mixtures. Solvent effects on the solvation of indicator
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can be observed with the hypso- or batho-chromic band shift of the absorbance spectra. Deviations
from the ideal trends of wave numbers are related to difference between the solvation microsphere
and bulk compositions.
A pronounced trend with a regular sequence is observed for the absorbance wave numbers of 4-
nitroanisole, that is, methanol-DMSO mixtures show fast variation while glycerol-DMSO mixtures
demonstrate a negligible variation (Fig. 1a). On the other side, the wave numbers of 4-Nitroaniline
show a similar trend in all mixtures (Fig. 1b). It is clear that the Reichardt's betaine dye presents an
increasing trend with a positive deviation from ideality, minimum deviation in methanol-DMSO and
maximum deviation in glycerol-DMSO mixtures (Fig. 1c)
The measured wave numbers of solvatochromic probes have been fitted to the proposed Eq. (10) and
the calculated parameters are given in Table 2. In all probes and mixtures, data shows that f2/1 values
are little more or less than unit except for betaine dye in ethylene glycol-DMSO and glycerol-
DMSO. It means that this indicator is preferentially solvated by ethylene glycol or glycerol. On the
other hand, high f12/1 values in the majority of data demonstrate that also the indicators (especially
betaine dye) can be preferentially solvated by the composite solvents compared to pure DMSO. A
comparison of the preferential solvation of betaine dye in this work with previous contribution [21]
indicates that this probe is preferentially solvated by the polyol moiety of DESs.
3.3. Kinetic results
In order to investigate the influence of solvent polarity parameters and compare the solvent effects in
ethylene glycol-DMSO and glycerol-DMSO with DESs-DMSO media, the SNAr reaction between
FDNB and Pip was studied in methanol-DMSO, ethylene glycol-DMSO, and glycerol-DMSO
mixtures. The mentioned media were selected regarding to similar study recently published [21] in
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order to determine the influence of molecule solvent or salt moiety in DESs as a dominant
component which affects on chemical kinetics of the reaction.
The suggested reaction mechanism of FDNB with Pip has been shown in Scheme 1 with apparent
rate coefficient according to Eq. (11) [24]:
[ ]
푘1(푘2 + 푘3 퐵 )
(
)
11
푘퐴 =
푘−1 + 푘2 + 푘3[퐵]
where kA is the apparent second-order rate coefficient and B is Pip as both nucleophile and base
catalyst. It has been proved that if the decomposition of the intermediate to products is slow, Eq. (11)
will be rearranged to Eq. (12):
푘1푘2 푘1푘3
[ ]
퐵
(
)
12
푘퐴 =
+
푘−1
푘−1
It is clear that the apparent rate coefficient is related to Pip concentration. On the other word, the
reaction follows a base-catalyzed mechanism. It was confirmed that base-catalyzed or non-catalyzed
mechanism of the reaction is related to not only the nature of the reactants but also the solvent
properties [22–24].
In order to determine the mechanism of the reaction, the influence of Pip concentration, as a base, on
the reaction rate was studied over the entire range of DMSO mole fractions in methanol-DMSO,
ethylene glycol-DMSO, and glycerol-DMSO mixtures. The obtained second order rate coefficients
of the reaction are summarized in Table 3 as a function of Pip concentration in all solvent mixtures.
Data shows that the reaction follows the base-catalyzed mechanism in the most of solvent mixtures.
Fig. S2 shows the influence of solvent composition on the reaction rate. Also, it demonstrates
different kinetics response depending on the solvent composition. The dependence of kA values on
Pip concentration in the DMSO region is higher than those of methanol, ethylene glycol, or glycerol
regions. In all mixtures, the statistical parameters reveal a satisfactory linear dependence of the rate
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coefficient on the change in Pip concentration (Table 4). On the other hand, the observable changes
are clear in the trends of rate coefficient when the solvent composition changes. The kA values
decrease smoothly with increasing mole fraction of methanol in methanol-DMSO mixtures while it
decreases sharply with adding the ethylene glycol and glycerol as a co-solvent to DMSO. Fig. S3
demonstrates the similarity trend between data in this contribution with previous report [21] reported
in ethaline-DMSO and glyceline-DMSO mixtures. It confirms that ethylene glycol and glycerol in
ethaline and glyeline, respectively, are effective moieties on the reaction mechanism. Data in Table 4
shows that reaction has the highest value of k1k3/k-1 in pure DMSO compared with in all solvent
mixtures. Like ethaline-DMSO and glyceline-DMSO, which exhibit and exponential increasing of
k1k3/k-1 with respect to DMSO mole fraction [21], a sharp enhancement of k1k3/k-1 values is clear
when the mole fraction of solvent mixture increases respect to DMSO in all mixtures. The results in
the pure solvents indicate that the reaction is clearly base-catalyzed in DMSO and it is less influence
by catalysis in methanol, ethylene glycol, and glycerol (Table 3). In all mixtures, the k2/k3 values
reveal that the reaction is base-catalyzed over the whole range of mixed solvent compositions. On
the other word, the reaction is susceptible to be base-catalyzed when it is performed in pure DMSO
or DMSO-rich mixtures. On the other hand, it is partially base-catalyzed or non-catalyzed in pure
alcohol and alcohol-rich region.
These results are compatible with the similar influences of hydrogen bond donor (HBD) or non-
HBD solvents on the base catalysis in SNAr reactions [22,24,28,29]. The performed reaction in
solvents with HBD ability (such as methanol) exhibits non-catalyzed mechanism while it follows
base-catalyzed mechanism in some hydrogen bond acceptor (HBA) solvents.
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3.4. Solvent effects on partial rate coefficients
As it was mentioned above, solvent composition controls the reaction mechanism and it will be truly
in relation with solvent properties. In order to find relationship between the base-catalyzed
mechanism and solvent effects, we analyzed the influence of the microscopic solvent properties on
the base catalysis rate coefficients k1k3/k-1 and k1k2/k-1, in which the former is related to the catalyzed
step and the later refers to the non-catalyzed step of the reaction. The variation of these partial rate
coefficients were investigated as a function of solvent composition and also solvatochromic
parameters (퐸푇푁, α, β, and 휋∗). The results have been exhibited in Figs. 2-4.
The plot k1k3/k-1 vs xCos (co-solvent is methanol, ethylene glycol, or glycerol) shows that the partial
rate coefficient k1k3/k-1 non-linearly decreases with mole fraction of co-solvent (Fig. 2a-4a).
Inset curves of Figs. 2-4 demonstrate a similar pattern for the variation of k1k2/k-1 vs xCos in all
mixtures. It is clear that there is an obvious difference among the changes in rate coefficients so that
k1k3/k-1 and k1k2/k-1 decrease smoothly from pure DMSO to pure methanol while they diminish
sharply from pure DMSO (in while the base catalysis is effective) to pure ethylene glycol or glycerol
(in which the non-catalyzed mechanism is possible). These results refer to the tendency of reaction
to follow the base-catalyzed mechanism over the entire range of mole fractions in methanol-DMSO
mixtures (Fig. 2a). Similar tendencies are observed in ethylene glycol-DMSO and glycerol-DMSO
mixtures (Figs. 3a and 4a).
In order to investigate and evaluate the solvent effects on the partial rate coefficients, the relationship
between k1k3/k-1 or k1k2/k-1 and solvatochromic parameters was studied (Figs. 2-4). The plots show
increases in both k1k3/k-1 and k1k2/k-1 with increments in the dipolarity/polarizability while both of
them decrease with increasing the HBD ability of the media in methanol-DMSO and ethylene
glycol-DMSO. It is worth mentioning that the dipolarity/polarizability and HBD ability of the media
have opposite effects on the reaction rate. Since the intermediate of the reaction has zwitterionic
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character and the activated complex of the reaction has higher polarity than reactants, the reaction
rate increases with the dipolarity/polarizability. On the other hand, hydrogen bond donor solvents
interact with nucleophile through the hydrogen-bonding interactions. Therefore, the nucleophile is
stabilized and the reaction rate decreases when HBD ability of the media increases. The decreasing
trend of kA with mole fraction of methanol and ethylene glycol in methanol-DMSO and ethylene
glycol-DMSO, respectively, confirms that the HBD ability of media which affects on the reaction
rate is the most effective factor as a rate coefficient controller. Although Fig. 4 shows the different
pattern of partial rate coefficients vs dipolarity/polarizability, correlation between reaction
coefficients and HBD ability of the media is the same. Consequently, the influence of the HBD
ability on the reaction rate can be interpreted in the same way.
On the other hand, these plots show that k1k3/k-1 and k1k2/k-1 enhance with increasing HBA ability of
the media. It means that high HBA solvents are suitable media for base catalysis condition in the
reaction.
The correlation of partial rate coefficients with empirical polarity (퐸푇푁 ) is present in Figs. S4-S6 in
which decreases in partial rate coefficients are observed with increment in 퐸푇푁. since there is a dual
parameter regression for 퐸푇푁 as a function of dipolarity/polarizability and HBD [9], it is expectable
that a particular pattern is observed like dipolar/polarizability or HBD pattern. It shows that the
reaction is performed in the solvent media with low polarity (not low polarizability) with the highest
partial base catalyzed and non-catalyzed rate coefficients. The adding of co-solvent with different
characterization decreases sharply the rate coefficients.
4. Conclusions
The comparison of solvatochromic parameters determined in binary mixtures of methanol-DMSO,
ethylene glycol-DMSO, and glycerol-DMSO with those of in binary mixtures of ethaline and
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glyceline with DMSO shows that it can be concluded similar trend of parameters with solvent
composition in the most of them. On the other hand, it confirms that the ethylene glycol and glycerol
in their corresponding DESs, ethaline and glyceline, respectively, are the most effective moieties of
DESs which determine the physico-chemical properties of DESs.
The SNAr reaction of 1-fluoro-2,4-dinitrobenzene with piperidine performed in the mixtures of
methanol, ethylene glycol, and glycerol with DMSO showed a similar pattern with DESs-DMSO
mixtures. Empirical polarity and HBD ability of the media have parallel and positive effects on the
both apparent and partial rate coefficients. On the other hand, the reaction follows the catalyzed
mechanism by piperidine in DMSO and DMSO-rich mixtures.
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16

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Table 1. Solvatochromic parameters for binary solvent mixtures of methanol, ethylene glycol, and
glycerol with DMSO at 25˚C (xCoS refers to the mole fraction of methanol, ethylene glycol, or
glycerol).
DMSO
Methanol
β
Ethylene glycol
Glycerol
β
흅∗
흅∗
훑∗
푬퐓퐍
푬퐓퐍
푬퐓퐍
xCoS
α
α
β
α
0
0.12 0.91 1.12 0.45
0.31 0.95 1.03 0.52
0.43 0.96 1.00 0.56
0.52 0.98 0.97 0.60
0.62 0.95 0.95 0.64
0.71 0.92 0.92 0.67
0.78 0.91 0.88 0.69
0.87 0.86 0.83 0.71
0.94 0.82 0.79 0.73
0.99 0.81 0.77 0.75
1.04 0.78 0.74 0.76
0.12 0.91 1.12 0.45
0.36 0.90 1.09 0.56
0.49 0.91 1.06 0.61
0.62 0.90 1.03 0.66
0.66 0.87 1.00 0.67
0.73 0.83 1.00 0.70
0.79 0.81 0.99 0.73
0.86 0.80 0.96 0.75
0.90 0.79 0.93 0.76
0.94 0.71 0.91 0.77
0.95 0.61 0.95 0.79
0.12 0.91 1.12 0.45
0.42 0.86 1.12 0.59
0.51 0.83 1.14 0.64
0.58 0.74 1.15 0.68
0.60 0.67 1.17 0.70
0.66 0.61 1.17 0.73
0.68 0.57 1.15 0.73
0.74 0.53 1.14 0.75
0.81 0.47 1.11 0.78
0.82 0.38 1.15 0.79
0.86 0.36 1.12 0.81
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
18

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Table 2. Parameters and standard deviation obtained by using of the preferential solvation model
based on Eq. (10).
Indicator
Solvents
Y1
Y2
Y12
f2/1
f12/1
N
r2
σ
31.54
31.51
32.39
31.94
32.01
31.90
2.49
1.71
11
11
0.980
0.951
0.002
0.001
4-Nitroanisole
DMSO/methanol
DMSO/ethylene
glycol
1.10
1.00
31.50
31.50
31.27
1.00
1.10
11
0.959
0.002
DMSO/glycerol
25.09
25.06
26.61
26.43
25.53
25.74
0.72
0.42
1.00
1.61
11
11
0.992
0.991
0.002
0.002
4-Nitroaniline
Betaine dye
DMSO/methanol
DMSO/ethylene
glycol
25.06
26.57
25.92
0.55
1.09
11
0.994
0.002
DMSO/glycerol
15.91
15.88
19.36
19.68
18.64
18.81
1.00
2.53
2.28
5.02
11
11
0.993
0.997
0.009
0.005
DMSO/methanol
DMSO/ethylene
glycol
15.90
19.91
18.82
2.84
8.04
11
0.988
0.007
DMSO/glycerol
19

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Table 3. Second-order rate coefficients, 풌푨 / Lmol-1 s-1, for the reaction between 1-fluoro-2,4-
dinitrobenzene (2×10-5 mol L-1) and piperidine in binary solvent mixtures, measured at 25˚C.
[pip] / mol L-1
0.0002
0.0004
0.001
0.0014
0.002
0.0024
solvent
푥퐶표푆
400.0
3
-
460.0
5
8.1
520.0
6
9.4
610.0
7
10.7
-
7.5
12
-
8.3
14.75
DMSO
0.0
methanol
ethylene glycol
glycerol
-
2
3
5
5
6.13
350
-
370
426
485
540
232.6
586
270.2
DMSO+methanol
DMSO+ethylene glycol
0.1
78.25
71.5
150.1
90
195.8
100
-
DMSO+glycerol
116.5
141
252
290
42.04
11.7
315
56.7
16.7
343
67.8
20.1
365
95.7
23.7
412
105
30.2
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
-
-
141
162
18.7
2
194
20
242
22.2
4.1
255
33.6
5.2
291
34.4
7
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
-
-
2.6
102
120
6.0
1.3
149
7.1
2.3
173
8.4
3.7
186
12
214
13.7
5.9
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
-
-
4.2
170
7.1
5
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
53.3
-
-
75
2
111
3.5
128
4.1
150
5
1.5
2.1
3.2
3.8
38
-
-
54
1.3
1.2
60
2.7
2
82
3
92
4.3
3.3
104
6.8
4.1
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
2.8
25
-
-
32
1
42
2.5
1.9
47
2.9
2.3
55
4.2
3.2
62
6
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
1
4.3
12
-
-
13
0.6
1.4
24
1.5
2.4
30
2
37
3.1
3.5
40
4
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
3.1
4.6
7
-
-
10
2
12
5.5
2.8
15
8.1
4.2
17.5
10.8
4.9
19
14.1
5.9
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
1.8
20

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Table 4. Partial rate coefficients for the reaction of piperidine with 1-flouro-2,4-
dinitroflourobenzene in binary mixtures.
ퟏퟎ−ퟒ 풌ퟏ풌ퟑ/풌−ퟏ
ퟏퟎퟒ풌ퟐ/풌ퟑ
풌ퟏ풌ퟐ/풌−ퟏ
(퐋퐦퐨퐥−ퟏ퐬−ퟏ
(퐋퐦퐨퐥−ퟏ퐬−ퟏ
)
n
)
풓ퟐ
solvent
푥퐶표푆
DMSO
0.0
15.99
0.21
0.31
0.2
377.6
3.6
6.4
23.61
17.14
20.6
0.966
0.953
0.949
0.912
4
5
5
5
methanol
ethylene glycol
glycerol
1.31
6.55
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
10.78
9.33
3.29
326.5
51.0
56.43
30.29
5.5
17.15
0.997
0.983
0.973
5
5
5
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
6.35
3.30
0.87
251.3
25.9
7.9
39.57
7.8
9.08
0.965
0.983
0.976
5
5
5
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
6.57
0.92
0.25
133.1
12.0
0.6
20.26
13
2.4
0.974
0.936
0.955
5
5
5
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
4.77
0.40
0.22
98.5
3.6
0.32
20.65
9
1.45
0.980
0.956
0.960
5
5
5
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
5.04
0.23
0.17
52.4
1
0.65
10.40
4.3
3.82
0.979
0.947
0.967
5
5
5
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
2.83
0.25
0.14
36.8
0.02
0.65
13.0
0.08
4.64
0.63
0.912
0.987
5
5
5
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
1.57
0.23
0.16
24.5
0.03
0.27
15.61
0.1
1.69
0.985
0.971
0.976
5
5
5
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
1.35
0.16
0.15
9.4
0.07
0.86
6.96
4
5.73
0.984
0.979
0.970
5
5
5
DMSO+methanol
DMSO+ethylene glycol
DMSO+glycerol
0.52
0.55
0.2
7
0.02
0.98
13.46
0.4
4.9
0.974
0.996
0.981
5
5
5
21

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Scheme 1. The reaction mechanism of 1-fluoro-2,4-dinitrobenzene and piperidine
22

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Fig. 1. The maximum absorption of wavenumber of 4-Nitroanisol (a), 4-Nitroaniline (b), and
Reichardt’s dye (c) for binary solvent mixtures of DMSO with methanol (♦), ethylene glycol (▲),
and glycerol (■). Lines have been calculated by Eq. (10) from the parameter of Table 2.
23

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Fig. 2. Plots k1k3/k-1 and k1k2/k-1 (inset curves) vs xCoS, α, β, and π* for the reaction performed in
DMSO-methanol mixtures.
24

ACCEPTED MANUSCRIPT
Fig. 3. Plots k1k3/k-1 and k1k2/k-1 (inset curves) vs xCoS, α, β, and π* for the reaction performed in
DMSO-ethylene glycol mixtures.
25

ACCEPTED MANUSCRIPT
Fig. 4. Plots k1k3/k-1 and k1k2/k-1 (inset curves) vs xCoS, α, β, and π* for the reaction performed in
DMSO-glycerol mixtures.
26

ACCEPTED MANUSCRIPT
Highlights
 Polarity of methanol, ethylene glycol, and glycerol-DMSO mixtures was studied.
 Non-ideal trends in parameters were investigated by preferential solvation model.
 The reaction of 1-fluoro-2,4-dinitrobenzene and piperidine was studied in mixtures.
 The results were compared with data in deep eutectic solvents- DMSO mixtures.
27