Molecular interaction studies on thermophysical and excess properties of formamide with n-propanol

doi:10.21203/rs.3.rs-1952089/v1

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Molecular interaction studies on thermophysical and excess properties of formamide with n-propanol

https://doi.org/10.21203/rs.3.rs-1952089/v1

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Static dielectric constants at (293.15, 298.15, 303.15 K), densities and refractive indices at (293.15 K) of binary mixtures of formamide with n-propanol have been measured over the entire range of mole fractions. The variation in measured parameters with respect to temperature and composition are discussed in detail. Excess dielectric constants, Kirkwood and Bruggeman factors were estimated from experimental dielectric data to confirm molecular structure, orientation of electric dipoles, intermolecular interaction and hydrogen bonding in the binary mixtures. Excess molar volume V^E, deviation in molar refraction Δ_R, related thermophysical parameters, excess properties have also been estimated and analyzed. The nonlinear variation in dielectric constants, deviation in linear relation in Bruggeman factor, negative V^E and Δ_R suggest the presence of molecular interaction and formation of hydrogen bonds between formamide and n-propanol molecules.

Thermophysical properties

Excess properties

Formamide

n-propanol

Molecular interactions

The thermophysical properties of pure liquids and their mixtures such as dielectric constants, densities and refractive indices are very important for accurate design and the proper development of many industrial processes [1]. Variation in these physical properties with composition, temperature and frequency gives important information about molecular structure, intermolecular interactions and hydrogen bonding. There are wide ranges of possible interactions may take place among the components of a mixture, such as hydrogen bonding, molecular associations, charge transfer, dipole-dipole and dipole induced dipole interactions [2].

Formamide is an acid amide obtained from condensation of formic acid and ammonia. It is a solvent in various chemical processes. It is used in agrochemical, pharmaceutical industry, and as a solvent in polymers and resins industry. N-propanol is a primary alcohol, also called as 1- propanol, n-propanol alcohol, propan-1-ol and propyl alcohol. It is a clear, colorless and transparent liquid soluble in water. It is used as a solvent in manufacturing of pharmaceutical industry and as a chemical intermediate. The knowledge of thermophysical properties of the corresponding liquid mixtures plays an important role in analytical sciences and pharmaceutical processes like design, synthesis, extraction, purification and their involved processes [3]. However, reports are available on the thermophysical properties of formamide and n-propanol with other compounds with different techniques. High frequency dielectric response study of the binary mixtures of formamide with butylene glycol using TDR technique was reported by Navarkhele et al [4]. Moreover, the densities and excess molar volumes of ethanol, methanol and n-propanol in pure water at different temperatures were reported by Kabir et al [5]. Static permittivity, refractive index, density and related properties of binary mixtures of pyridine with 1-propanol at different temperatures were reported by Trivedi et al using a LCR meter technique [6]. Dielectric and excess properties of glycols with formamide by using the same technique explained in this manuscript was reported by Navarkhele [7]

In this study, we reported static dielectric constants $\left(\text{s}\right)$ at 293.15, 298.15 & 303.15 K temperatures and densities (ρ), refractive indices (n) at 293.15 K temperature over entire composition range. The related properties like excess dielectric constant (ε^E), effective Kirkwood correlation factor (g^eff), Bruggeman factor (f_B), atomic polarization, electronic polarization, permittivity at higher frequency, molar volume, molar refraction, polarizability, solvated radii, molar polarization, deviation in molar refractivity, excess density (d^E), excess refractive index (n^E), excess molar polarization (P_m)^E and excess molar volume (V^E) were estimated from the experimental data using appropriate equations to confirm molecular interaction, hydrogen bonding, and other possible interactions between the components of the mixture.

2.1. Chemicals

Chemicals formamide and n-propanol were obtained from a pharmaceutical company –Aurangabad - Maharashtra. The chemicals used were of 99.9% purity and used without extra purification. The final compositions were prepared by adding n-propanol in formamide at eleven different stages. All mixtures were prepared just before the experimental use.

2.2. Equipments

Experimental static dielectric constants were obtained using a wet sensor make by Delta-T Devices Ltd. UK, which is based on the principle of frequency domain reflectometry technique. Measurement of each sample was repeated at least five to six times and the average value of that reading was taken as a dielectric constant of that mixture. The details about the apparatus have been described in our earlier paper [7]. The uncertainty in dielectric constant given by the manufacturer is about ± 3%. The temperature controller arrangement with water bath has been used to sustain a constant temperature within the correctness limit of ± 1°C.

The refractive indices of the mixtures were measured using digital pocket refractometer PAL- RI, make by Atago-Japan. The apparatus measures the refractive index in the range of 1.3306 to 1.5284. The uncertainty in the measurement of refractive indices given by the manufacturer is of ± 0.0003.

The densities of the binary mixtures were measured using the Anton Paar oscillation U-tube densitometer (model DMA- 35, Austria), calibrated with double-distilled water and air. Densities of pure liquids and their mixtures were measured at 293.15 K temperature only. The uncertainty in density given by the firm is of ± 10^− 3 g·cm^− 3.

2.3. Excess permittivity (ε^E)

Excess dielectric permittivity (ε^E) gives qualitative information about the formation of a new structure in the binary mixtures [8]. Excess dielectric constant is calculated using the equation:

$${\epsilon }^{E}=\left({\epsilon }_{sm}\right)-[{\epsilon }_{1}.{\varPhi }_{1}+{\epsilon }_{2}.{\varPhi }_{2}]$$

Where (${\epsilon }_{sm})$ is the static dielectric constants of mixtures, ${\epsilon }_{1},{{\epsilon }_{2},\varPhi }_{1}and {\varPhi }_{2}$ are the static dielectric constants and mole fractions of liquid 1 (formamide) and liquids 2 (n-propanol) respectively.

2.4 The Kirkwood factor

The Kirkwood correlation factor (g) provides information about orientation of the electric dipoles in polar liquids [9]. The modified form of Kirkwood correlation factor that is, effective Kirkwood correlation factor (g^eff) given by [10, 11] was estimated by the equation:

$$\frac{4{\Pi }\text{N}}{9\text{K}\text{T}}\left(\frac{{{\mu }}_{1}^{2}.{ {\rho }}_{1}. {{\Phi }}_{1}}{{\text{M}}_{1}}+\frac{{{\mu }}_{2}^{2}.{ {\rho }}_{2}.{ {\Phi }}_{2}}{{\text{M}}_{2}}\right){\text{g}}^{\text{e}\text{f}\text{f}}=\frac{\left( {\epsilon }_{sm}-{{\epsilon }}_{{\infty }\text{m}}\right)(2{\epsilon }_{sm}+{{\epsilon }}_{{\infty }\text{m}} )}{{\epsilon }_{sm}{({{\epsilon }}_{{\infty }\text{m}}+2)}^{2}}$$

Where “g^eff” is the effective Kirkwood correlation factor for the binary mixtures.

In Eq. (2) N, K, T, ${\epsilon }_{sm} and {{\epsilon }}_{{\infty }\text{m}}$ ,${{ \mu }_{1}}^{2}, {{\mu }_{2}}^{2}, {\rho }_{1}$,${ \rho }_{2}$, ${M}_{1},$ ${M}_{2}$, ${\varPhi }_{1}, {\varPhi }_{2},$are Avogadro number, Boltzmann constant, temperature, static dielectric constant of mixture and dielectric constant at high frequency, dipole moment, density, molecular weight, mole fraction of liquid 1 and 2 respectively.

2.5 Bruggeman factor (f_BM)

Molecular interactions in polar binary mixtures can be confirmed from the Bruggeman mixture formula. The static dielectric constant${ (\epsilon }_{sm}$) of two binary mixtures is related to this formula with the volume fraction of solute${ (\epsilon }_{sB}$) that proves the interaction between the solute (${\epsilon }_{sB}$) and solvent (${\epsilon }_{sA}$) of the mixtures by the equation [12]:

$${f}_{BM=}\left[\frac{{\epsilon }_{sm}-{\epsilon }_{sB}}{{\epsilon }_{sA}-{\epsilon }_{sB}}\right]{\left[\frac{{\epsilon }_{sA}}{{\epsilon }_{sm}}\right]}^{\frac{1}{3}}=1-V, \left(3\right)$$

In above equation (V) is the volume fraction. According to this equation a linear relationship is expected in Bruggeman factor (f_BM) and (V), deviation from this linear relation indicates presence of molecular interaction and hydrogen bonding in the mixtures.

2.6. Molar refraction, Atomic polarization, Permittivity at higher frequency, Polarizabilty, Solvated radii, molecular polarization and deviation in molar refraction

From experimental densities (d) and refractive indices (n) data of pure liquids and mixtures, the molar refraction (R_m) was calculated by the equation [13]:

$${\text{R}}_{\text{m}}=\left(\frac{{\text{n}}^{2 }-1}{{\text{n}}^{2}+2}\right){\text{V}}_{\text{m}}={\text{P}}_{\text{A}}+{\text{P}}_{\text{E}}={\text{P}}_{\text{T}}={\text{P}}_{\text{D}}$$

Where “n” is the refractive index of the liquid and ${\text{V}}_{\text{m}}$ = (M/d) is molecular volume, in this ‘M’ and ‘d’ is the molecular weight and the density of the pure liquids respectively. The right hand side of Eq. (4) is equal to the summation of both atomic polarization (P_A) and electronic polarization (P_E) and that is equal to total polarization (P_T) or distortion polarization (P_D).

The atomic polarization (P_A) was calculated from the refractive indices (n) of pure substances and mixtures by the equation [14]:

$${\text{P}}_{\text{A}}=1.05 {\text{n}}^{2}$$

The permittivity at higher frequency${ (\epsilon }_{\infty })$ is the square of the refractive index and it was calculated by the equation:

$${ {\epsilon }}_{{\infty }}={\text{n}}^{2}$$

Where (n) is the refractive index of the binary mixtures.

The molecular dipole polarizability (α) was calculated from the experimental densities and refractive indices of pure substances and mixtures using Lorentz- Lorentz formula [15]:

$$\left(\frac{{\text{n}}^{2 }-1}{{\text{n}}^{2}+2}\right)=\left(\frac{4}{3}\right){\Pi }\text{n}{\prime }{\alpha }$$

Where ${n}^{{\prime }}=\frac{N}{{V}_{m}}$, N is Avogadro’s number, ${V}_{m}$ is molar volume, and (n) is refractive index of the binary mixtures.

Considering spherical form of the solvated molecules, the solvated radii of the pure liquids and binary mixtures were calculated using the equation [16]:

$$\text{V}= \left(\frac{4}{3}\right){\Pi }{\text{r}}^{3}$$

From experimental dielectric constants and densities of pure substances and mixtures the molecular polarization (Pm) was estimated using the equation [17]:

$${\text{P}}_{\text{m}}={\text{V}}_{\text{m}}\left(\frac{{{\epsilon }}_{\text{s}}-1}{{{\epsilon }}_{\text{s}}+2}\right)$$

Where (ε_s) and (${\mathbf{V}}_{\mathbf{m}}$) is the static dielectric constants and molecular volume of the binary mixtures.

The deviation in molar refraction was determined from the experimental density and refractive indices by the well-known equation [18]:

${\varDelta }_{\text{R}}={\text{R}}_{\text{m}\text{i}\text{x}}-\sum _{\text{i}}{{\Phi }}_{\text{i}}{\text{R}}_{\text{i}}$ Where i= 1, 2, (10)

In above equation (${\text{R}}_{\text{m}\text{i}\text{x}}$) is the molar refractivity of the mixtures (Φ_i) and (${\text{R}}_{\text{i}}$) are volume fraction and molar refractivity of pure liquids 1 and 2 respectively.

2.7. Excess Parameters (excess density (d ^E ), excess refractive index (n ^E ), excess molar polarization (P _m ) ^E and excess molar volume (V)^E

From experimental densities, the excess density (d^E) was calculated using the equation:

$${\text{d}}^{\text{E}}={\text{d}}_{\text{m}\text{i}\text{x}}-\left({{\Phi }}_{1}{\text{d}}_{1}-{{\Phi }}_{2}{\text{d}}_{2}\right)$$

Where ${\text{d}}_{\text{m}\text{i}\text{x}}$ are the values of densities of mixtures,${\varPhi }_{1},$ ${\varPhi }_{2}$ d₁, d₂ are the mole fractions and densities of the first and second liquids respectively.

From experimental refractive indices (n), the excess refractive index (n^E) was estimated by the equation:

$${\text{n}}^{\text{E}}={\text{n}}_{\text{m}\text{i}\text{x}}-\left({{\Phi }}_{1}{\text{n}}_{1}-{{\Phi }}_{2}{\text{n}}_{2}\right)$$

Where ${n}_{mix}$ are the values of refractive indices of the mixtures$\text{a}\text{n}\text{d} {\varPhi }_{1},$ ${\varPhi }_{2},$ ${n}_{1}$ $,{n}_{2}$ are the mole fractions and refractive indices of the first and second liquids respectively.

The excess molar polarization (P_m)^E of the mixtures was determined by the equation:

$${P}_{m}^{E} ={\text{P}}_{\text{m}\text{i}\text{x}}-[{\text{P}}_{\text{m}1} .{\varPhi }_{1}+{\text{P}}_{\text{m}2} .{\varPhi }_{2 } ]$$

Where P_mix is polarization of mixtures, P_m1, P_m2, Φ₁ and Φ₂ are polarization and mole fraction of liquid 1 and 2 respectively.

From experimental densities, the excess molar volume (V)^E was estimated using following equation [19]:

${ \text{V}}^{\text{E} }= {{V}_{m}}_{\text{m}\text{i}\text{x}}-\sum _{\text{i}=1}^{\text{n}}{{\Phi }}_{\text{i}} {.\text{V}}_{\text{m}\text{i}} \text{W}\text{h}\text{e}\text{r}\text{e} \text{i}=1, 2$ , 3---- (14)

Where ${{V}_{m}}_{\text{m}\text{i}\text{x}}$ is the molar volume of the mixtures${{\Phi }}_{\text{i}}$represents volume fraction and ${\text{V}}_{\text{m}\text{i}}$ is the molar volume of the components 1 and 2 respectively.

3.1. Static dielectric constant

A comparison of experimental dielectric constant${ (\epsilon }_{s})$, density (ρ, g·cm^− 3) and refractive index (n) of pure liquids at 293.15 K temperature to literature data is appears in Table 1 [20].

Table 1

Comparison between experimental values of static dielectric constant, density and refractive index of pure components with literature values
Chemical name	Static dielectric constant (${\epsilon }_{s})$		Density (ρ) (g·cm^− 3)		Refractive index (n)
Chemical name	This work	Literature	This work	Literature	This work	Literature
Formamide	112.78 (20⁰C)	110.87 [4] (20⁰C)	1.1332 (20⁰C)	1.1290 [20] (25⁰C)	1.4494 (20⁰C)	1.4455 [20] (25⁰C)
n-propanol	21.54 (20⁰C)	19.76 [6] (20⁰C)	0.8033 (20⁰C)	0.7930 [13] 25⁰C	1.3872 (20⁰C)	1.3761 [13] (25⁰C)

Table 2 lists the experimental dielectric data at 293.15 K to 303.15 K at 5 K intervals for the binary mixtures which are graphically illustrated in Fig. 1. The Dielectric constants of the binary mixtures decrease with an increase in temperature and mole fraction of n-propanol for the studied temperatures. This may be due to the orientation polarization. With an increased thermal motion there is fall in orientation polarization that reduces the alignment of the permanent dipoles that may results in decrease in dielectric constants [21]. The decrease in dielectric constants with an increase in mole fraction of n-propanol may be due to increase in size and shape of the complex molecules after hydrogen bonding. This may reduce mobility and number of dipoles in the binary mixtures that may decrease the volume of the rotating molecules. The experimental results are in agreement with the results given by [22].

Table 2

Experimental static dielectric constants ${(\epsilon }_{s})$of formamide + n-propanol mixtures at different temperatures.
Mole fraction of n-propanol	Static dielectric constant T = 293.15K	Static dielectric constant T = 298.15K	Static dielectric constant T = 303.15K
1	112.78	109.51	107.34
0.95	103.35	100.15	98.18
0.89	93.80	90.78	88.76
0.83	84.18	81.28	79.30
0.76	74.02	71.15	69.24
0.68	63.68	60.94	59.12
0.59	54.01	51.58	50.32
0.48	45.60	43.56	42.15
0.35	37.77	35.91	34.58
0.19	29.91	28.21	26.74
0	21.54	19.89	18.51

Figure 1 shows, variation in dielectric constants against mole fraction of n-propanol. From Fig. it is noted that, the variation in ${ (\epsilon }_{s})$is non- linear with increasing concentration of n-propanol. In polar mixtures, if molecular association is taking place a non-linear variation in the dielectric constants with concentration is expected and the same is confirmed from the same Fig. 1. This shows that an intermolecular association is taking place in the studied binary system [23].

Table 3 lists the experimental densities and refractive indices of formamide - n-propanol binary mixtures at 293.15 K. Densities of the binary system decrease with an increase in mole fraction of n-propanol. Increasing concentration of n-propanol in formamide may weaken intermolecular bonds and new bonds may form between dissimilar and similar molecules that may increase the volume of the mixtures, as a result the density may decrease. The results are in agreement with the earlier results of Farid [13, 24].

Table 3

Experimental densities and refractive indices of formamide + n-propanol mixtures at 293.15 K temperature
Mole fraction of n-propanol	Density T = 293.15K (g·cm^− 3)	Refractive index T = 293.15K
1	1.1332	1.4494
0.95	1.1001	1.4430
0.89	1.0670	1.4367
0.83	1.0341	1.4307
0.76	1.0011	1.4244
0.68	0.9680	1.4181
0.59	0.9350	1.4119
0.48	0.9021	1.4056
0.35	0.8690	1.3994
0.19	0.8361	1.3933
0	0.8033	1.3872

From Table 3, it is also noticed that refractive indices of the binary system decreases with an increase in composition of (n-propanol) over the entire range, this may be due to decrease in density and number of dipoles per unit volume of the binary mixtures.

3.2. Excess permittivity (ε^E)

The (ε^E) provides information about formation of new structure and intermolecular interaction between polar binary mixtures. The (ε^E) values were estimated by Eq. (1) and tabulated in Table 4.

Table 4

Estimated excess dielectric constants of formamide + n-propanol mixtures at different temperatures
Mole fraction of n-propanol	Excess dielectric constant T = 293.15K	Excess dielectric constant T = 298.15K	Excess dielectric constant T = 303.15K
1	0.00	0.00	0.00
0.95	-0.30	-0.39	-0.27
0.89	-0.73	-0.80	-0.81
0.83	-1.22	-1.34	-1.39
0.76	-2.26	-2.51	-2.56
0.68	-3.48	-3.76	-3.80
0.59	-4.02	-4.15	-3.72
0.48	-3.31	-3.21	-3.00
0.35	-2.01	-1.90	-1.69
0.19	-0.75	-0.64	-0.65
0	0.00	0.00	0.00

The (ε^E) values of the binary mixtures are negative over the entire mole fraction range at the studied temperatures. This shows, in the mixtures the solutions interact in such a way that the effective dipole moment decreases. In addition, the number of dipoles in the mixture might be smaller than the corresponding average number in the pure liquids, which give an idea about the formation of new structure leading to a lower macroscopic permittivity. The results are in agreement with the earlier results reported by Hosmani et al and Navarkhele et al [25, 26].

3.3. The Kirkwood factor (g^eff)

In the mixtures, the dipole pairs are formed and orient in parallel and antiparallel directions that is confirmed from Kirkwood correlation factor (g). The effective Kirkwood correlation factor (g^eff) of the binary system was calculated using Eq. (2) and reported in Table 5 that is graphically illustrated in Fig. 2. As Fig. 2 shows, the g^eff values are greater than 1( g^eff >1 ) over entire range of n-propanol for the studied temperatures. This indicates parallel orientation of electric dipoles in the formamide molecules. The plot of g^eff show nonlinear variation over the entire composition range at the studied temperatures. This confirms the net increase in dipole ordering due to H- bond complexation. The results are in agreement with earlier results of Hosamani et al and Trived et al [27, 6].

Table 5

Estimated effective Kirkwood correlation factor (g^eff ) of formamide + n-propanol mixtures at different temperatures
Mole fraction of n-propanol	Kirkwood correlation factor T = 293.15 K	Kirkwood correlation factor T = 298.15 K	Kirkwood correlation factor T = 303.15 K
1	1.83	1.81	1.80
0.95	1.86	1.83	1.83
0.89	1.89	1.86	1.85
0.83	1.92	1.88	1.87
0.76	1.94	1.89	1.87
0.68	1.94	1.88	1.86
0.59	1.97	1.91	1.90
0.48	2.08	2.01	1.98
0.35	2.27	2.19	2.14
0.19	2.60	2.49	2.39
0	3.40	3.18	3.00

3.4. Bruggeman factor (f_BM)

The Bruggeman factor (f_BM) values are estimated using Eq. (3) that is listed in Table 6, and graphically illustrated in Fig. 3. As Figure shows, there is deviation from linear relation is taking place over the entire composition range of the binary mixtures at the studied temperatures, shows presence of molecular interaction and hydrogen bonding in the binary system.

Table 6

Estimated Bruggeman factor of formamide + n-propanol mixtures at different temperatures
Volume fraction of n-propanol	Bruggeman factor T = 293.15K	Bruggeman factor T = 298.15K	Bruggeman factor T = 303.15K
0	1.000	1.000	1.000
10	0.923	0.922	0.923
20	0.842	0.842	0.842
30	0.756	0.756	0.757
40	0.661	0.660	0.660
50	0.558	0.556	0.557
60	0.454	0.454	0.463
70	0.356	0.359	0.363
80	0.256	0.259	0.263
90	0.142	0.145	0.147
100	0.000	0.000	0.000

3.5. Molar volume (V _m ), molar refractions (R _m ), polarizabillty (α), solvated radii (r), molar polarization (P _m ), deviation in molar refraction (Δ _R ), atomic polarization (P _A ), electronic polarization (P _E ) and permittivity at higher frequency ( )

Table 7 list, estimated values of the molar volume (V_m), molar refractions (R_m), polarizabillty (α), solvated radii (r), molar polarization (P_m), deviation in molar refraction (Δ_R), atomic polarization (P_A), electronic polarization (P_E) and permittivity at higher frequency () of formamide - n-propanol mixtures. As from Table 7 it is seen that, nearly all parameters are increasing over the entire composition range of n- propanol except (P_A) and (). Since (P_A) and () depends on the refractive indices of the mixtures. The (R_m) values is a measure of volume occupied with an atom or molecule and depends on the refractive indices, it was noticed that the (V_m) and (R_m) of the studied binary mixture increases as refractive indices decrease and the same is noticed from Tables 7 and 3.

Table 7

Estimated molar volume (V_m), molar refraction (R_m), polarizability (α), solvated radii (r) molar polarization (Pm), deviation in molar refractivity (Δ_R), atomic polarization (P_A), electronic polarization (P_E) and permittivity at higher frequency (ε_∞) of formamide + n-propanol mixtures at 293.15K temperature.
Mole fraction of n-propanol	${\text{V}}_{\text{m}}$ (cm³/mol)	R_m (cm³/mol)	α (10²⁴) cm/mole	(r) A⁰	(Pm) cm³/mole	Δ_R cm³. mol^− 1	(P_A)	(P_E)	ε_∞
1	39.745	10.668	4.23	2.11	38.702	0.00	2.20	8.46	2.10
0.95	42.310	11.217	4.47	2.16	41.105	-0.14	2.18	9.03	2.08
0.89	45.034	11.791	4.67	2.20	43.624	-0.26	2.16	9.62	2.06
0.83	47.923	12.397	4.91	2.25	46.255	-0.35	2.14	10.24	2.04
0.76	51.007	13.226	5.16	2.30	48.994	-0.42	2.13	10.89	2.02
0.68	54.375	13.688	5.42	2.34	51.827	-0.45	2.11	11.57	2.01
0.59	57.835	14.387	5.70	2.39	54.737	-0.45	2.09	12.29	1.99
0.48	61.614	15.121	5.99	2.45	57.730	-0.41	2.07	13.04	1.97
0.35	65.693	15.904	6.30	2.50	60.738	-0.32	2.05	13.84	1.95
0.19	70.080	16.737	6.36	2.55	63.491	-0.18	2.03	14.69	1.94
0	74.816	17.622	6.98	2.61	65.281	0.00	2.02	15.60	1.92

The deviation in molar refraction (Δ_R) against mole fraction of n-propanol is graphically illustrated in Fig. 4 and given in Table 7. The (Δ_R) values are negative over the entire mole fraction range at the studied temperature. As from Fig. 4, it is seen that (Δ_R) values exhibit a parabolic shape with a minimum value locate between 0.68 and 0.59 mole fraction of n-propanol. This mole fraction deviation in (Δ_R) represents the electronic perturbation due to orbital mixing of the components of the mixtures. Therefore (Δ_R) can be used as a measure of strength of the interaction between the components of the mixtures and is strongly dependent on composition and temperature [28, 29]. Negative values of (Δ_R) indicate greater dispersive forces in the mixtures than pure components [30].

3.6. Excess density (d ^E ), excess refractive index (n ^E ), excess molar polarization (P _m ) ^E and excess molar volume (V^E)

Table 8 list, estimated excess density excess (d^E), excess refractive index (n^E), excess molar polarization (P_m)^E and excess molar volume (V^E) against the mole fraction of n-propanol. As Table 8 shows, the (d^E) values of the binary mixtures are negative over the entire composition range at the studied temperature. This is due to increase in molar volume of the binary mixtures.

Table 8

Estimated excess density, excess refractive index, excess molar polarization and excess molar volume of formamide + n-propanol mixtures at 293.15 K temperature
Mole fraction of n-propanol	Excess density T = 293.15K (D)^E	Excess Refractive index T = 293.15K (n)^E	Excess molar polarization (P_m )^E	Excess Molar volume (V^E)
1	0.0000	0.00000	0.000	0.00
0.95	-0.00011	-0.00018	-0.254	-0.94
0.89	-0.00022	-0.00026	-0.393	-1.73
0.83	-0.00013	-0.00004	-0.420	-2.35
0.76	-0.00014	-0.00012	-0.339	-2.77
0.68	-0.00025	-0.00020	-0.164	-2.99
0.59	-0.00026	-0.00018	0.087	-2.97
0.48	-0.00017	-0.00027	0.422	-2.69
0.35	-0.00028	-0.00024	0.772	-2.13
0.19	-0.00019	-0.00012	0.867	-1.24
0	0.00000	0.00000	0.000	0.00

From Table 8, it is also observed that the (n^E) values of the binary mixture are negative over the entire composition range for the studied temperature. The excess refractive indices indicates maximum solvent- solvent interaction and depends mainly on different physical properties of the solvents such as dielectric constant, dipole moment, donor number, chemical structure, basicity and polarizability. The results are in agreement with the earlier reported results of Farid [13].

The estimated values of (P_m) ^E of the binary mixture are given in Table 8. The (P_m) ^E values are negative in formamide rich region and positive in n-propanol rich region at the studied temperature.

The (V^E) of the binary mixtures were estimated by Eq. (14) that is given in Table 8 and graphically illustrated in Fig. 5. The (V^E) values are negative over the entire composition range of n-propanol at the studied temperature. The negative behavior of excess molar volumes may be due to the volume contraction after mixing. The (V^E) is generally used as a signal of non-ideal behavior of real mixtures. Negative values of excess molar volumes show strong intermolecular interaction, hydrogen bonding, charge transfer complexes and other complex forming interactions including strong dipole-dipole interactions between the components of molecules in the mixture. [18].

This study provides fundamental static dielectric constants, densities and refractive indices data of the binary mixtures of formamide with n-propanol over the entire composition. It is found that for increase in temperature and mole fraction there was decrease in dielectric constants of the binary mixtures. For the studied temperature, the density and refractive index data also decreases with an increase in mole fraction of n-propanol in formamide. At the studied temperatures, the dielectric data shows an excellent non-linear behavior with mole fraction supporting to an intermolecular association in the studied binary system. From experimental results, several important properties have been derived to confirm molecular interaction, hydrogen bonding, and other possible interactions between the components of the mixtures.

The excess dielectric constants of the binary mixture are found to be negative, which shows decrease in dipole moment of the mixtures after interaction over the entire composition range and at studied temperatures. The (g^eff) data show parallel orientation of electric dipoles in the mixtures over the entire composition range and at studied temperatures. The (f_BM) values of the binary mixtures are deviating from the linear relations confirm presence of molecular interactions and hydrogen bonding in the binary mixtures.

The estimated parameters molar volume, molar refraction, polarizability, solvated radii, molar polarization, electronic polarization of this binary mixtures increases, where as permittivity at higher frequency and atomic polarization decreases with increase in mole fraction since they depends on refractive indices of the binary mixtures. The molar refractivity deviations (Δ_R) of the studied mixtures are also negative as a result of greater dispersive forces in the mixtures than pure components.

The excess densities (d^E), excess refractive indices (n^E), excess molar polarizations (P_m)^E and excess molar volumes (V^E) of the binary mixtures are found to be negative over the entire composition range for the studied temperature. The negative excess molar volumes (V^E) confirm volume contraction after mixing of formamide and n-propanol. From molecular interaction perspective, we suggest that the contributors to (V^E) are most likely from the hydrogen bonding formation interactions, charge transfer complexes and other complex forming interactions.

Acknowledgements

The authors are thankful to head, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University-Aurangabad (M.S.) India, for providing the experimental facility for the said work.

Conflict of interest:

The authors declare no competing financial interest.

ORCID

Vaijanath Navarkhele http://orcid.org/0000-0002-7276-4179

Long, B., Wang, Z., Yang, H., Ding, Y.: Intermolecular interactions of 1, 2-diethoxyethane with toluene: An insight from surface and volumetric properties at different temperatures. J. Mole Liqs. 249, 1–8 (2018). https://doi.org/10.1016/j.molliq.2017.11.015
Yilmaz, H., Guler, S.: Excess properties of methanol-water binary system at various temperatures. II Nuovo Cimento. 20D, 1851–1853 (1998)
Jouyban, A., Shahla, S., Chan, H.: A simple relationship between dielectric constant of mixed solvents with solvent composition and temperature. Int. J. Pharm. 269, 353–360 (2004). doi:10.1016/j.ijpharm.2003.09.010
Navarkhele, V.V., Bhanarkar, M.K.: High-frequency dielectric response of the binary mixture formamide–butylene glycol. Phys. Chem. Liq. 48, 89–98 (2010). http://dx.doi.org/10.1080/00319100802688360
Kabir, M.H., Motin, M.A., Huque, M.E.: Densities and excess molar volumes of Methanol, Ethanol and N-Propanol in pure Water and in Water + Surf Excel solutions at different temperatures. Phys. Chem. Liq. 42, 279–290 (2004). 10.1080/0031910042000205346 ) DOI
Trivedi, C.M., Rana, V.A.: Static permittivity, refractive index, density and related properties of binary mixtures of pyridine and 1-propanol at diffenent temperature. Indian J. Pure Appl. Phys. 52, 183–191 (2014)
Navarkhele, V.V.: Dielectric and Excess properties of glycol with formamide at different temperatures. Russian Journal of Physical Chemistry A 92, 1417–1422 DOI: 10.1134/S0036024418070191. (2018)
Sengwa, R.J., Sankhla, S., Shinyashiki, S.: : Dielectric Parameters and Hydrogen Bond Interaction Study of Binary Alcohol Mixtures. J. Sol Chem. 37, 137–153 (2008). 10.1007/s10953-007-9230-6 ) DOI
Kirkwood, J.G.: The dielectric polarization of polar liquids. J. Chem. Phys. 7, 911–919 (1939)
Kumbharkhane, A.C., Puranik, S.M., Mehrotra, S.C.: Dielectric relaxation of tert- butyl alcohol–water mixtures using a time-domain technique. J. Chem. Soc. Faraday Trans. 87, 1569–1573 (1991). https://doi.org/10.1039/FT9918701569
Kumbharkhane, A.C., Puranik, S.M., Mehrotra, S.C.: Dielectric relaxation studies of aqueous N, N dimethylformamide using a picoseconds time domain technique. J. Sol Chem. 22, 219–229 (1993). https://doi.org/10.1007/BF00649245 )
Bruggeman, D.A.G.: Ann. Phys. (Leipz). 24, 636–646 (1935).
Farid, I., EI-Dossoki.: Refractive index and density measurements of selected binary protic- protic, aprotic-aprotic, and aprotic and protic syatems at temperatures from 298.15K to 308. 15 K. J Chin. Chem Soc. 54,, 1129–1137 (2007). )
Mongnaschi, E.R., Laboranti, L.M.: Association of pure polar liquids: Dielectric properties of docosanoic acid. J. Chem. Soc. Faraday Trans. 92(18), 3367–3369 (1996)
Rays, K., Rath, J., Dwivedi, C.: Excess Molar polarization in binary mixtures of polar liquids. J. Phys. Chem. Liqs. 39, 227–237 (2001)
Kim, J.I.: A Critical Study of the Ph4AsPh4B Assumption for Single Ion Thermodynamics in Amphiprotic and Dipolar-Aprotic Solvents; Evaluation of Physical Parameters Relevant to Theoretical Consideration. Z. Phys. Chem. Neue Folge. 113, 129–150 (1978)
Oswal, S.: Studies on density, viscosity, dielectric constant, and refractive indices of binary mixtures of ester in benezen and carbon tetrachloride. Can. J. Chem. 66, 111–116 (1988)
Aliaj, F., Syla, N., Kurtishaj, A., Elezaj, N., Arbneshi, T., Zeqiraj, A.: Densities, refractive indices, and derived properties of binary mixtures of ethanol with benzene and pyridine at various temperatures under atmospheric pressure. International journal of Thermophysics 41, 49. –55 (2020). https://doi.org/10.1007/s10765-020-02632-9
Gonzalez, E.J., Requejo, P.F., Maia, F.M., Dominguez, A., Macedo, E.A.: Solubility, density and excess molar volume of binary mixtures of aromatic compounds and common ionic liquids at T = 283.15 K and atmospheric pressure. Phys. Chem. Liq. 53, 419–428 (2015). https://www.tandfonline.com/loi/gpch20
Hossein, I., Zahra, B.M.: Densities, viscosities, and refractive indices for binary and ternary mixtures of formamide (1) + N,N-dimethylacetamide (2) + 2-methyl-1-butanol (3) at 298.15 K for the liquid region and at ambient pressure. Arab. J. Chem. 12, 5079–5085 (2019). http://dx.doi.org/10.1016/j.arabjc.2016.12.004
Hill, N.E., Vaughan, W.E., Price, A.R., Davies, M.: Dielectric properties and Molecular behavior,Van Nostrand Reinhold, London140–170() (1969)
Kumbharkhane, A.C., Puranik, S.M., Mehrotra, S.C.: Structural study of amide-water mixtures using dielectric relaxation technique. J. of Mole Liqs. 51, 261–277 (1992). )https://doi.org/10.1016/0167-7322(92)80088-Y
Lone, B.G., Undre, P.B., Patil, S.S., Khirade, P.W., Mehrotra, S.C.: Dielectric study of methanol- ethanol mixtures using TDR method. J. of Mole Liqs. 141, 47–53 (2008). 10.1016/j.molliq.2008.03.001 ) doi
Nasim, A., Movagharnejad, K., Mohsen, P., Mahnam, K.: Densities, Viscosities, and Refractive Indices of Poly(ethylene glycol) 300 + 1,2-Ethanediol, 1,2- Propanediol, 1,3- Propanediol, 1,3-Butanediol, or 1,4-Butanediol Binary Liquid Mixtures. J. Chem. Eng. Data. 65, 3448–3462 (2020). https://dx.doi.org/10.1021/acs.jced.9b01189
Hosamani, M.T., Fattepur, R.H., Deshpande, D.K., Mehrotra, S.C.: : Temperature-and Frequency –Dependent Dielectric studies of PFluorophenylactetonitrile –Methanol mixtures using the Time domain reflectrometry. J. Chem. Soc. Faraday Trans. 91, 623–626 (1995). )https://doi.org/10.1039/FT9959100623
Navarkhele, V.V., Bhanarkar, M.K.: Dielectric relaxation study of formamide–propylene glycol using time domain reflectometry. Phys. Chem. Liquids. 49, 550–559 (2011). DOI: 10.1080/00319104.2010.508041
Noh, H.J., Park, S.J.: Excess molar volumes and deviations of refractive indices at 298.15 K for binary and ternary mixtures with pyridine or aniline or quinoline. In J. Ind. Eng. Chem. 16, 200–206 (2010). https://doi.org/10.1016/j.jiec.2010.01.038 )
Singh, S., Parveen, S., Shukla, D., Gupta, M., Shukla, J.P.: Volumetric, Optical, Acoustical and Viscometric Study of Molecular Association in Binary Mixtures of Butylamine with 1- Butanol and Tert-Butanol. Acta Phys. Pol. A. 111, 847–858 (2007). 10.12693/APhysPolA.111.847 ) DOI
Aniya, V., Kumari, A., Reddy, R., Satyavathi, B.: Measurement and Modeling of Phase Equilibrium, Volumetric Properties and Molar Refractivity of 2-Methylpropan-2- ol + Ethane-1, 2-diol. J. Solu Chem. 46, 1177–1201 (2017). 10.1007/s10953-017-0638-3 ) DOI
Ali, A., Tariq, M., Nabi, F., Shahajahn: Density, Viscosity, Refractive Index, and Speed of Sound in Binary Mixtures of Pyridine and 1-Alkanols (C6, C7, C8, C10) at 303.15 K. Chin. J. Chem. 26, 2009–2015 (2008). https://www.researchgate.net/publication/315750205

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Molecular interaction studies on thermophysical and excess properties of formamide with n-propanol

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Abstract

Figures

1. Introduction

2. Experimental Sections

2.1. Chemicals

2.2. Equipments

2.3. Excess permittivity (ε^E)

2.4 The Kirkwood factor

2.5 Bruggeman factor (f_BM)

3. Results And Discussion

3.1. Static dielectric constant

3.2. Excess permittivity (ε^E)

3.3. The Kirkwood factor (g^eff)

3.4. Bruggeman factor (f_BM)

4. Conclusions

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1

Molecular interaction studies on thermophysical and excess properties of formamide with n-propanol

Status:

Version 1

Abstract

Figures

1. Introduction

2. Experimental Sections

2.1. Chemicals

2.2. Equipments

2.3. Excess permittivity (εE)

2.4 The Kirkwood factor

2.5 Bruggeman factor (fBM)

3. Results And Discussion

3.1. Static dielectric constant

3.2. Excess permittivity (εE)

3.3. The Kirkwood factor (geff)

3.4. Bruggeman factor (fBM)

4. Conclusions

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1

2.3. Excess permittivity (ε^E)

2.5 Bruggeman factor (f_BM)

3.2. Excess permittivity (ε^E)

3.3. The Kirkwood factor (g^eff)

3.4. Bruggeman factor (f_BM)