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Short Note

2-[4-(Hexadecyloxy)-3-methoxyphenyl]-1,3-benzothiazole

1
Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, Jln Universiti, Bandar Barat, 31900 Kampar, Perak, Malaysia
2
Department of Science, Faculty of Engineering & Science, Universiti Tunku Abdul Rahman, Jln Genting Kelang, Setapak 53300 Kuala Lumpur, Malaysia
*
Author to whom correspondence should be addressed.
Molbank 2009, 2009(4), M634; https://doi.org/10.3390/M634
Submission received: 10 October 2009 / Accepted: 15 October 2009 / Published: 16 October 2009

Abstract

:
A new heterocycle, 2-[4-(hexadecyloxy)-3-methoxyphenyl]-1,3-benzothiazole, was prepared and its IR, 1H NMR, 13C NMR, elemental analysis and MS spectroscopic data are reported.

Graphical Abstract

Interest in the study of mesomorphic heterocyclic compounds has dramatically increased in recent years due to their wider range of structure templates, as well as their optical and photochemical properties [1]. Heterocyclic compounds, if designed properly, offer an opportunity to produce metal-containing mesogenic materials (metallomesogens) [2]. By modifying the molecular template of the existing heterocyclic compounds [3,4,5] to generate calamitic liquid crystals, we synthesized the title compound via (i) cyclization of benzothiazole and followed by (ii) Williamson etherification. Unfortunately, the presence of lateral methoxy group tends to diminish the mesogenic properties by disrupting the molecular packing [6].
Molbank 2009 m634 g001
In analogy to a recently published procedure [6], 2-aminothiophenol (5.01 g, 40 mmol) and vanillin (6.09 g, 40 mmol) in ethyl alcohol (40 mL) was heated under reflux for 6 h. The reaction mixture was subsequently cooled to room temperature. Then, distilled water (60 mL) was added slowly until the mixture turned cloudy. The mixture was kept overnight at about 20 oC and benzothiazole 1 formed was filtered and washed with cold ethanol/water (1:1.5) and dichloromethane. Then, benzothiazole 1 (5.15 g, 20 mmol) in acetone (40 mL), was added to a solution of potassium hydroxide (1.12 g, 20 mmol) in distilled water (5 mL). This was followed by addition of a small amount of potassium iodide into the mixture. The reaction mixture was heated under reflux for 1 h with stirring. 1-Bromohexadecane (7.63 g, 25 mmol) was then added to the flask and reflux was continued for 20 h. The solid obtained was filtered and recrystallized from absolute ethanol whereupon the pure compound was isolated as a white solid (6.17 g, 64%).
Melting point: 82 oC.
MS (EI): M+ (m/z) = 481 (50), 257 (100), 228 (8), 57 (9), 43 (15).
IR (KBr, cm-1): 3074, 3000 (C-H aromatic); 2922, 2849 (C-H aliphatic); 1603 (C=N thiazole); 1499 (C=C aromatic); 1267 (C-O ether).
1H NMR (400 MHz, CDCl3): δ/ppm 0.9 (t, 3H, J = 7.0 Hz, CH3-), 1.4-1.6 (m, 26H, CH3-(CH2)13-), 1.9 (quint, 2H, J = 7.0 Hz, -CH2-CH2-O-), 4.0 (s, 3H, CH3O-), 4.1 (t, 2H, J = 6.9 Hz, -CH2-O-), 7.0 (d, 1H, J = 8.4 Hz, Ar-H), 7.4 (t, 1H, J = 8.2 Hz, Ar-H), 7.5 (t, 1H, J = 8.4 Hz, Ar-H), 7.6 (dd, 1H, J = 8.4, 2.1 Hz, Ar-H), 7.7 (d, 1H, J = 2.1 Hz, Ar-H), 7.9 (d, 1H, J = 8.5 Hz, Ar-H), 8.0 (d, 1H, J = 8.1 Hz, Ar-H).
13C NMR (100 MHz, CDCl3): δ/ppm 126.6, 125.2, 123.2, 121.9, 121.5, 112.6, 110.5 for aromatic carbons, 69.5 (-O-CH2-), 56.6 (CH3O-), 32.3, 30.1, 30.0, 29.9, 29.8, 29.7, 29.5, 26.3, 23.1[-(CH2)14-CH2-O-], 14.5 (-CH3).
Elemental analysis: Calculated for C30H43NO2S: C, 74.80%, H, 9.00%, N, 2.91%; Found: C, 74.93%, H, 8.95%, N, 2.84%.

Supplementary materials

Supplementary File 1Supplementary File 2Supplementary File 3

Acknowledgements

The author (S.-T. Ha) would like to thank Universiti Tunku Abdul Rahman (UTAR) for the research facilities and financial support through UTAR Research Fund (Vote No. 6200/H02). T.-M. Koh would like to acknowledge UTAR for the award of the research and teaching assistantships.

References and Notes

  1. Lai, C.K.; Liu, H.C.; Li, F.J.; Cheng, K.L.; Sheu, H.S. Heterocyclic benzoxazole-based liquid crystals. Liq. Cryst. 2005, 32, 85–94. [Google Scholar] [CrossRef]
  2. Meyer, E.; Zucco, C.; Gallardo, H. Metallomesogens: Synthesis and properties. J. Mater. Chem. 1998, 8, 1351–1354. [Google Scholar] [CrossRef]
  3. Ha, S.T.; Koh, T.M.; Yeap, G.Y.; Lin, H.C.; Boey, P.L.; Yip, F.W.; Ong, S.T.; Ong, L.K. Synthesis and mesomorphic properties of 2-(4-alkyloxyphenyl)benzothiazoles. Mol. Cryst. Liq. Cryst. 2009, 506, 56–70. [Google Scholar] [CrossRef]
  4. Ha, S.T.; Koh, T.M.; Ong, S.T.; Lee, T.L.; Sivasothy, Y. Synthesis of 2-(4-propyloxyphenyl)benzothiazole. Molbank 2009, 3, M609. [Google Scholar] [CrossRef]
  5. Ha, S.T.; Koh, T.M.; Ong, S.T.; Ong, L.K. Synthesis of a new heterocycle with liquid crystal properties: 2-(3-Methoxy-4-hexadecanoyloxyphenyl)benzothiazole. Molbank 2009, 2009, M606. [Google Scholar] [CrossRef]
  6. Collings, P.J.; Hird, M. Introduction to Liquid Crystals; Taylor & Francis Ltd.: London, UK, 1998. [Google Scholar]

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MDPI and ACS Style

Ha, S.-T.; Koh, T.-M.; Ong, S.-T.; Win, Y.-F. 2-[4-(Hexadecyloxy)-3-methoxyphenyl]-1,3-benzothiazole. Molbank 2009, 2009, M634. https://doi.org/10.3390/M634

AMA Style

Ha S-T, Koh T-M, Ong S-T, Win Y-F. 2-[4-(Hexadecyloxy)-3-methoxyphenyl]-1,3-benzothiazole. Molbank. 2009; 2009(4):M634. https://doi.org/10.3390/M634

Chicago/Turabian Style

Ha, Sie-Tiong, Teck-Ming Koh, Siew-Teng Ong, and Yip-Foo Win. 2009. "2-[4-(Hexadecyloxy)-3-methoxyphenyl]-1,3-benzothiazole" Molbank 2009, no. 4: M634. https://doi.org/10.3390/M634

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