Abstract
A new Schiff base ester, 4-{[(4-methoxyphenyl)imino]methyl}-3-hydroxyphenyl 4-(hexadecanoyloxy)benzoate was synthesized and its IR, 1H NMR, 13C NMR and MS spectroscopic data are presented.
Much attention has been focused on Schiff base derivatives owing to their thermochromic and photochromic properties [1,2,3,4,5]. Schiff bases are also well recognized for their liquid crystal properties since the discovery of MBBA which exhibited room temperature nematic phase [6]. An appropriate length of the alkyl chain at the para position of the aldehyde or aniline fragment of N-benzylidene-anilines has also been identified as one of the main requirements which favours the existence of liquid crystal phase (or mesophase) [7,8,9]. Different terminal substituents can also significantly influence the anisotropic properties of liquid crystals [7]. In this continuation work, we report here a new liquid crystal, 4-{[(4-methoxyphenyl)imino]methyl}-3-hydroxyphenyl 4-(hexadecanoyloxy)benzoate.
Experimental
4-(4-n-Hexadecanoyloxybenzoyloxy)-2-hydroxybenzaldehye was prepared according to a method that was described in our previous work [10]. In a round-bottom flask, a mixture of the aldehyde (2.48 g, 5.0 mmol), 4-methoxyaniline (0.62 g, 5.0 mmol) and absolute ethanol (40 mL) was refluxed with stirring for 3 h. The reaction mixture was filtered and the solvent was removed from the filtrate by evaporation. Recrystallization from absolute ethanol gave the title compound as a yellow solid (2.08 g, 69%).
Melting point: 221–222 °C.
MS (EI): m/z (rel. int. %) = 602 (1) (M+).
IR (KBr): νmax/ cm–1 2953, 2916, 2848 (C-H, aliphatic), 1753 (C=O of C15H31COO- fragment), 1742 (C=O of phenyl benzoate), 1624 (C=N), 1605 (C=C, aromatic), 1284 (C-O).
1H NMR (400 MHz, CDCl3): δ/ppm 0.90 (t, 3H, J = 6.8 Hz, CH3-), 1.24–1.45 (m, 24H, CH3-(CH2)12-), 1.80 (quint, 2H, J = 7.6 Hz, -CH2-CH2COO-), 2.63 (t, 2H, J = 7.4 Hz, -CH2-COO-), 3.88 (s, 3H, Ar-OCH3), 6.84 (dd, 1H, J = 2.1, 8.3 Hz, Ar-H), 6.91 (d, 1H, J = 2.1 Hz, Ar-H), 6.99 (d, 2H, J = 8.8 Hz, Ar-H), 7.26–7.31 (m, 4H, Ar-H), 7.45 (d, 1H, J = 8.5 Hz, Ar-H), 8.26 (d, 2H, J = 8.7 Hz, Ar-H), 8.65 (s, 1H, CH=N), 13.83 (s, 1H, OH).
13C NMR (100 MHz, CDCl3): 172.09 (C=O of C15H31COO-), 164.31 (C=O of phenyl benzoate), 159.94 (C=N), 162.87, 159.33, 155.51, 154.48, 144.90, 133.25, 132.26, 127.05, 122.70, 122.32, 117.60, 115.06, 113.19 and 110.90 for aromatic carbons, 55.96 (Ar-OCH3), 34.83 (-CH2COO-), 25.25 (-CH2CH2COO-), 32.33, 30.10, 30.06, 30.00, 29.85, 29.76, 29.65, 29.50, 23.10 (CH3(CH2)12), 14.52 (CH3(CH2)12).
Elemental analysis: Calcd. for C37H47NO6, 73.85%, H, 7.87%, N, 2.33%; Found: C, 73.90%, H, 7.86%, N, 2.30%.
Supplementary materials
Supplementary File 1Supplementary File 2Supplementary File 3Acknowledgments
Authors would like to thank Universiti Tunku Abdul Rahman and Universitit Sains Malaysia for the financial supports and research facilities.
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