Subray N. Bhat

Ultrasonic and thermodynamic investigations of hydrogen bondings in weakly interacting ternary liquid systems: Ketones-chloroform-cyclohexane

Abstract Sound velocities in acetone, methyl ethyl ketone, methyl isobutyl ketone, chloroform, cyclohexane and their binary and ternary systems were measured in order to study the weak molecular interaction between acetone, methyl ethyl ketone, methyl isobutyl ketone and chloroform in cyclohexane. The association constants at 25°C and the heats of complexation for the above systems are 0. 809, 1. 189 and 1. 613 dm 3 mole −1 and 13. 45, 12.49 and 11. 53 kJ mole −1 respectively.

Surface tension measurements in the study of molecular complexes

Surface tension measurements can be used to investigate molecular complex formation in liquid solutions for strong and weak complexes. The association constant and epthalpy for triethylamine-iodine, hexamethylbenzene-tetracyanoethylene and ethanol-iodine in cyclohexane are 4·55×103, 218 and 0.93M−1 at 25° C and 12·5, 7·7 and 5·1 kcal/mol respectively. These values compare well with those reported in the literature by other methods.

Studies on the iodine complexes of pyridine picolines and aminopyridine by constant activity method

Abstract The iodine complexes of pyridine, α-, β-, γ- picolines, 2-aminopyridine and 2,2′-bipyridine in cyclohexane were studied by the constant activity method, their spectral characteristics and thermodynamic parameters were determined. The equilibrium constants, molar extinction coefficients of the charge-transfer band maxima, e CT , at 25°C and heats of complexation, ΔH°, are respectively as follows: 1. (a) pyridine-iodine, 107 dm 3 mol −1 24200 dm 3 mol −1 m −1 and 31 KJ/mol; 2. (b) α-picoline-iodine, 172 dm 3 mol −1 m −1 , 49700 dm 3 mol −1 m −1 and 33 KJ/mol; 3. (c) β-picoline-iodine, 243 dm 3 mol −1 , 50300 dm 3 mol −1 m −1 and 35 KJ/mol; 4. (d) γ-picoline-iodine, 342 dm 3 mol −1 , 55900 dm 3 mol −1 m −1 and 41 KJ/m; 5. (e) 2-aminopyridine-iodine, 427 dm 3 mol −1 , 60800 dm 3 mol −1 m −1 and 47 KJ/mol; 6. (f) 2,2′-bipyridine-iodine, 6.0 dm 3 mol −1 ,−, 21 KJ/mol. The values of the blue shifted iodine band maxima of the above mentioned donors and their molar extinction coefficients are, 420 nm (1450 dm 3 mol −1 m −1 ), 419 nm (1470 dm 3 mol −1 m −1 ), 418 nm (1640 dm 3 mol −1 m −1 ), 417 nm (1570 dm 3 mol −1 m −1 ), 410 nm (1574 dm 3 mol −1 m −1 ) and 452 nm (1370 dm 3 mol −1 m −1 ) respectively. The oscillator strengths and transition dipole moments of the blue-shifted iodine bands are characterised.

Ultrasonic and thermodynamic investigations of weakly interacting systems

Abstract Ultrasonic velocity measurement method has been used to investigate the interaction between weakly interacting systems in ternary systems. The equilibrium constant and heat of formation for acetone-methanol in carbon tetrachloride is 0.33 dm 3 mol −1 at 303.15 K and 14.2 kJ mol −1 respectively.

Conductometric study of charge transfer complexes

A conductometric titration technique has been used for determining the stoichio-metry of charge-transfer complexes which ionise in polar media. The systems studied are: Iodine complexes of acetone, methyl ethyl ketone,iso-butyl methyl ketone, dimethylsulphoxide triphenyl phosphine, triphenyl arsine, triphenyl stibene, methanol, ethanol andn-propanol. The stoichiometry of the above complexes (in highly polar media) were found to be≈2:3 (except in the cases of triphenyl stibene where stoichiometry was≈1:4). The effects of temperature, concentration and dielectric constants (of the media) on conductivities of the complexes have been reported.

First experimental evidence for the existence of blue-shifted iodine band: The3π1-1∑+ transition. An anecdote

The absorption maximum of the3π1-1∑+ transition of the iodine molecule in cyclohexane is found to be at 689 nm. Derivative spectroscopic evidence for the blue shift of the above band in complexed iodine has been provided for the first time.

Viscometric studies of hydrogen bonding

The viscometric method can be conveniently used for studying the interaction between weakly interacting systems. The systems studied are: methanol-acetone, ethanol-acetone,n-propanol-acetone andn-butanol-acetone in carbon tetrachloride. At 25°C, the equilibrium constants for the above ternary systems are 0·22, 0·30, 0·38 and 0·52 M−1 respectively. However, the heats of formation of complexes obtained by the viscometric method are high and decrease from methanol-acetone-CCl4 ton-butanol-acetone-CCl4.

Viscometry in the study of molecular complexes

Viscometric method has been used to study the interaction between the weak interacting systems such as benzene-CCl4-cyclohexane, toluene-CCl4-cyclohexane ando- xylene-CCl4-cyclohexane. The equilibrium constants and other thermodynamic parameters have been reported and compared with literature data.

Transference number of charge-transfer complexes in solutions: methanol-iodine and ethanol-iodine

The majority of charge carriers in charge-transfer complexes of methanoliodine and ethanol-iodine in solutions are anion constituents. The transfer number of cation decreases with the increase in concentration of iodine.