| 66% |
|
EXAMPLE 1 (i) Synthesis of Small Molecular Thiophene Compound (I) The preparation of precursor, 5,5'-bis(3-dodecyl-2-thienyl)-2,2'-dithiophene, (10), is illustrated in Scheme 1. A solution of 2-bromo-3-dodecylthiophene (15.36 grams, 46.36 mmol) in 40 milliliters of anhydrous tetrahydrofuran (THF) was added slowly over a period of 20 minutes to a mechanically stirred suspension of magnesium turnings (1.69 grams, 69.50 mmol) in 5 milliliters of anhydrous THF in a 250 milliliter round-bottomed flask under an inert argon atmosphere. When reaction was initiated, the reaction mixture was stirred at 60 C. for 3 hours before cooling down to room temperature. The resultant mixture was then added via a cannula to a mixture of 5,5'-dibromo-2,2'-dithiophene (6.01 grams, 18.54 mmol) and [1,2-bis(diphenylphosphino)ethane]dichloronickel (II) (0.37 gram of (dppe)NiCl2, 0.70 mmol) in 80 milliliters of anhydrous THF in a 250 milliliter round-bottomed flask under an argon atmosphere, and then refluxed for 48 hours. Subsequently, the reaction mixture was cooled down to room temperature and washed with water. The crude product was extracted with ethyl acetate and dried with anhydrous sodium sulfate. A dark brown syrup, obtained after evaporation of the solvent, was purified by column chromotography on silica gel to yield crude 5,5'-bis(3-dodecyl-2-thienyl)-2,2'-dithiophene (10), which was recrystallized from a mixture of dichloromethane (10 ml), isopropanol (250 ml) and methanol (100 ml), yielding a yellow crystalline product in 66 percent yield, m.p. 58.9 C. The NMR spectrum of the above obtained compound was recorded at room temperature using a Bruker DPX 300 NMR spectrometer: 1H NMR (CDCl3): δ 7.18 (d, J=5.4 Hz, 2H), 7.13 (d, J=3.6 Hz, 2H), 7.02 (d, J=3.6 Hz, 2H), 6.94 (d, J=5.4 Hz, 2H), 2.78 (t, 4H), 1.65 (q, 1.65, 4H), 1.28 (bs, 36H), 0.88 (m, 6H). 13C NMR (CDCl3, ppm): δ 139.78, 136.73, 135.26, 130.26, 129.99, 126.43, 123.75, 123.71, 31.86, 30.59, 29.62, 29.61, 29.54, 29.46, 29.40, 29.30, 29.20, 22.63, 14.05. |
| 66% |
|
(i) Synthesis of Small Molecular Thiophene Compound (I) The preparation of precursor, 5,5'-bis(3-dodecyl-2-thienyl)-2,2'-dithiophene, (10), is illustrated in Scheme 1. A solution of 2-bromo-3-dodecylthiophene (15.36 grams, 46.36 mmol) in 40 milliliters of anhydrous tetrahydrofuran (THF) was added slowly over a period of 20 minutes to a mechanically stirred suspension of magnesium turnings (1.69 grams, 69.50 mmol) in 5 milliliters of anhydrous THF in a 250 milliliter round-bottomed flask under an inert argon atmosphere. When reaction was initiated, the reaction mixture was stirred at 60 C. for 3 hours before cooling down to room temperature. The resultant mixture was then added via a cannula to a mixture of 5,5'-dibromo-2,2'-dithiophene (6.01 grams, 18.54 mmol) and [1,2-bis(diphenylphosphino)ethane]dichloronickel(II) (0.37 gram of (dppe) NiCl2, 0.70 mmol) in 80 milliliters of anhydrous THF in a 250 milliliter round-bottomed flask under an argon atmosphere, and then refluxed for 48 hours. Subsequently, the reaction mixture was cooled down to room temperature and washed with water. The crude product was extracted with ethyl acetate and dried with anhydrous sodium sulfate. A dark brown syrup, obtained after evaporation of the solvent, was purified by column chromotography on silica gel to yield crude 5,5'-bis(3-dodecyl-2-thienyl)-2,2'-dithiophene (10), which was recrystallized from a mixture of dichloromethane (10 ml), isopropanol (250 ml) and methanol (100 ml), yielding a yellow crystalline product in 66 percent yield, m.p. 58.9 C. The NMR spectrum of the above obtained compound was recorded at room temperature using a Bruker DPX 300 NMR spectrometer: 1H NMR (CDCl3): δ 7.18 (d, J=5.4 Hz, 2H), 7.13 (d, J=3.6 Hz, 2H), 7.02 (d, J=3.6 Hz, 2H), 6.94 (d, J=5.4 Hz, 2H), 2.78 (t, 4H), 1.65 (q, 1.65, 4H), 1.28 (bs, 36H), 0.88 (m, 6H). 13C NMR (CDCl3, ppm): δ 139.78, 136.73, 135.26, 130.26, 129.99, 126.43, 123.75, 123.71, 31.86, 30.59, 29.62, 29.61, 29.54, 29.46, 29.40, 29.30, 29.20, 22.63, 14.05. |
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