SPECTROSCOPIC AND COMPUTATIONAL STUDIES OF SYNTHESIZED 2, 4-DINITROPHENYL HYDRAZONES OF SELECTED KETONES AND THEIR DERIVATIVES

Abstract

Hydrazones are versatile class of organic compounds with the general structure, R1R2C=NNHR3. Hydrazones of acetone, acetophenone, benzophenone, 2,2,2-trifluoroacetophenone and 2,2,2-triphenylacetophenone were synthesized and characterized by spectroscopic and computational methods using density functional theory (DFT) at B3LYP/6-31G*(d,p) basis set with SPARTAN 14 software. Results from spectroscopic analysis were compared with computational results. The compounds were all coloured with percentage yield 82.1, 82.6, 73.5, 69.4 and 88.4% respectively. UV-Vis spectra showed max in the UV region (355-385nm) and high molar absorptivity with the range going to the visible with high absorptivity. Mostly, high values of oscillator strength were recorded both in the experimental and calculated. Calculated vibrational frequencies assigned to C=N, N-N and N-H; 1706, 1147 and 3492; 1686, 1132 and 3467; 1665, 1128 and 3456; 1678, 1132 and 3489; 1664, 1115 and 3472cm-1 were in agreement with experimental IR vibrational frequencies: 1620.8, 1102.4 and 3456.0; 1618.4, 1129.0 and 3450.4; 1613.6, 1126.6 and 3462.4; 1618.4, 1109.0 and 3476.0; 1625.6, 1064.8 and 3440.0cm-1for all the hydrazones respectively. Variation of the substituent attached to the carbonyl carbon affected the values of the vibrational frequencies and bond lengths; this is as a result of distortion due to electronic and steric effects. The molecules exhibited high dipole moment from 6.69 to 8.38 Debye. High electrophilic index values were recorded from 5.5385 to 6.5504eV showing (2,2,2-trifluoroacetophenone with highest and 2,2,2-triphenylacetophenone with the lowest values, respectively). Polar surface area values range from 88.3 to 90.84 Å2 and calculated log P values from-0.42 to 3.77.