* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
Stage #1: With n-butyllithium In tetrahydrofuran at -78℃; for 2 h; Stage #2: at -78 - 20℃; for 15 h;
1,4-Dibromo-2,5-dimethoxybenzene (2.0 g, 6.76 mmol) was added dissolved in THF 35 mL, it was added dropwise a 1.6 M BuLi slowly at -78 . After stirring the reaction solution for 2 hours at -78 , it was added dropwise to DMF (2.8 mL, 33.7 mmol). The reaction solution is stirred at room temperature for 15 hours (20 ). 2 N HCl in a 20 mL reaction mixture was stirred slowly dropping off. The resulting solid was then filtered under reduced pressure, dried to obtain a 2,5-dimethoxyterephthalaldehyde 267 mg (30percent).
Reference：
[1] Organic Letters, 2011, vol. 13, # 19, p. 5208 - 5211
[2] Angewandte Chemie - International Edition, 2018, vol. 57, # 35, p. 11310 - 11315[3] Angew. Chem., 2018, vol. 130, p. 11480 - 11485,6
[4] Organic and Biomolecular Chemistry, 2003, vol. 1, # 7, p. 1157 - 1170
[5] Patent: KR101493823, 2015, B1, . Location in patent: Paragraph 0107-0109
[6] Journal of Materials Chemistry A, 2017, vol. 5, # 44, p. 22933 - 22938
[7] Journal of Materials Chemistry A, 2018, vol. 6, # 2, p. 374 - 382
2
[ 4394-85-8 ]
[ 2674-34-2 ]
[ 7310-97-6 ]
Reference：
[1] Journal of the American Chemical Society, 2003, vol. 125, # 37, p. 11241 - 11248
3
[ 2674-34-2 ]
[ 68-12-2 ]
[ 31558-41-5 ]
Reference：
[1] Journal of the American Chemical Society, 2002, vol. 124, # 5, p. 773 - 775
4
[ 150-78-7 ]
[ 2674-34-2 ]
Yield
Reaction Conditions
Operation in experiment
85%
With bromine In chloroform at 0℃; for 3 h;
Example 2: Preparation of 2,5-dibromo-1 ,4-dimethoxybenzene (2); [00103] In a one liter round-bottom flask, a solution of bromine (35.2 g, 220 mmol) in chloroform (50 ml) was added dropwise to a solution of 1 ,4- dimethoxybenzene (13.8 g, 100 mmol) in chloroform (400 ml) under 00C. After stirring for 3 hours, 100 ml of saturated Na2CO3 solution was added. The organic layer was washed with water, brine, and dried over sodium sulfate. The solvent was removed on a rotary evaporator and the residue was performed recrystallization from ethanol to afford pure 2,5-dibromo-1 ,4- dimethoxybenzene (25.8 g, 85percent). 1HNMR (CDCI3) 57.128 (s, 2 H), 3.873 (s, 6 H).
83.6%
at 20℃; for 4 h; Sonication
In a 250 ml reaction flask, 20.0 g (0.145 mol, 1.0 eq) of hydroquinone dimethyl ether and 55 ml of glacial acetic acid were added and dissolved by ultrasonic; A solution of 15 ml of Br2 (0.290 mol, 2.0 eq) and 15 ml of glacial acetic acid was added dropwise at room temperature. After 1.5 hours, the mixture was stirred at room temperature for 2.5 h. Placed in the upper refrigerator to 10 below the temperature (not to acetic acid curing) filter; and petroleum ether washing filter cake to give a white solid, vacuum drying and then weight 35.6g, the yield of 83.6percent.
68%
for 16 h; Cooling with ice
1,4-dimethoxybenzene (1.66 g, 12.0 mmol) was dissolved in 25 mL glacial acetic acid and cooled in an ice bath. Bromine (1.3 mL, 25 mmol) was carefully added. The cooling bath was removed and the reaction was stirred for 16 h and then poured over ice. The reaction mixture was extracted 3 x with 100 mL of CHCl3. The combined organics were dried over MgSO4, filtered, and the solvents were removed under vacuum. The product was isolated via recrystallization in absolute ethanol to yield white needles (2.40 g, 68percent), mp 140-142 C (lit.5 mp 144-145 C). 1H NMR (CDCl3): δ 7.12 (s, 2H), 3.86 (s, 6H). The 1H NMR matches the known spectrum.5
63%
With bromine In acetic acid at 20℃; for 2 h;
To a solution of 1,4- dimethoxybenzene Q-8 (7.5 g, 53.57 mmol) in acetic acid (25 mL) was added a solution of bromine (17.4 g, 108.9 mmol) in acetic acid (5 mL) at room temperature. After stirring for 2h, the solution was cooled to 10 0C. The resulting fine precipitate was filtered, washed with water (20 mL), and dried under vacuum to obtain compound Q-9 (1Og, 63percent) as a white solid. TLC Rf = 0.5 (petroleum ether - EtOAc, 9.9:0.1); 1H NMR (CDCl3) δ 7.10 (s, 2H), 3.84 (s, 6H).
61%
With N-Bromosuccinimide In water; N,N-dimethyl-formamide at 20 - 80℃; for 6 h;
General procedure: To a stirred solution of starting compound (0.5–1.2 mmol) in DMF–H2O (95:5, v/v, 8–12 mL) mixture was added NBS (4.0–4.2 mmol) at room temperature. The contents were stirred at room temperature about 10 min and then heated for appropriate duration mentioned in Table 2. Progress of the reaction in every case was monitored by TLC analysis. After completion of the reaction, the reaction mixture was cooled to room temperature and quenched with aqueous NaHCO3 (20percent, 20–30 mL) solution. The insoluble precipitate was isolated by filtration and dried in vacuo. It was further purified by either recrystallization with ethyl acetate/n-hexane mixture or short pad silica gel column chromatography led to pure product.
Reference：
[1] Tetrahedron, 1999, vol. 55, # 36, p. 11127 - 11142
[2] Tetrahedron Letters, 1998, vol. 39, # 35, p. 6349 - 6350
[3] Organic Process Research and Development, 2016, vol. 20, # 2, p. 284 - 296
[4] Journal of the American Chemical Society, 2003, vol. 125, # 37, p. 11241 - 11248
[5] Journal of Materials Chemistry A, 2017, vol. 5, # 44, p. 22933 - 22938
[6] Journal of Materials Chemistry A, 2018, vol. 6, # 2, p. 374 - 382
[7] Synlett, 2005, # 17, p. 2664 - 2666
[8] Tetrahedron, 1997, vol. 53, # 30, p. 10357 - 10400
[9] New Journal of Chemistry, 2014, vol. 38, # 6, p. 2229 - 2232
[10] Journal of Organic Chemistry, 1998, vol. 63, # 11, p. 3764 - 3768
[11] Patent: WO2006/93467, 2006, A1, . Location in patent: Page/Page column 26
[12] Synthetic Communications, 2001, vol. 31, # 13, p. 2021 - 2027
[13] Patent: CN106397468, 2017, A, . Location in patent: Paragraph 0012; 0018; 0022
[14] Synthetic Communications, 1998, vol. 28, # 3, p. 499 - 505
[15] Chemical Communications, 2016, vol. 52, # 74, p. 11088 - 11091
[16] Tetrahedron, 2001, vol. 57, # 24, p. 5109 - 5121
[17] Journal of Organic Chemistry, 1980, vol. 45, # 3, p. 378 - 384
[18] Tetrahedron, 2015, vol. 71, # 2, p. 283 - 292
[19] Journal of Organic Chemistry, 2011, vol. 76, # 20, p. 8501 - 8507
[20] Patent: WO2010/129049, 2010, A1, . Location in patent: Page/Page column 111; 113
[21] Tetrahedron Letters, 2014, vol. 55, # 24, p. 3511 - 3515
[22] Synthetic Communications, 1998, vol. 28, # 11, p. 2087 - 2095
[23] Austral. J. scient. Res., 1949, vol. <A> 2, p. 595,599
[24] Chemische Berichte, 1878, vol. 11, p. 1036
[25] Journal of the Chemical Society, 1925, vol. 127, p. 2003
[26] Chemische Berichte, 1878, vol. 11, p. 1036
[27] Synthetic Communications, 2002, vol. 32, # 20, p. 3233 - 3239
[28] Macromolecules, 2002, vol. 35, # 13, p. 4975 - 4982
[29] Organic Letters, 2001, vol. 3, # 3, p. 445 - 447
[30] Canadian Journal of Chemistry, 2008, vol. 86, # 10, p. 976 - 981
[31] Polymer, 2010, vol. 51, # 3, p. 632 - 638
[32] Angewandte Chemie - International Edition, 2018, vol. 57, # 35, p. 11310 - 11315[33] Angew. Chem., 2018, vol. 130, p. 11480 - 11485,6
5
[ 150-78-7 ]
[ 2674-34-2 ]
[ 25245-34-5 ]
Reference：
[1] Monatshefte fuer Chemie, 1931, vol. 58, p. 92,104
[2] Chemical Papers, 2018, vol. 72, # 11, p. 2893 - 2898
Reference：
[1] Monatshefte fuer Chemie, 1931, vol. 58, p. 92,104
[2] Journal of the Chemical Society, 1927, p. 74
[3] Monatshefte fuer Chemie, 1924, vol. 45, p. 582
9
[ 150-76-5 ]
[ 2674-34-2 ]
[ 74076-59-8 ]
Reference：
[1] Journal of the Chemical Society, 1927, p. 74
10
[ 31405-34-2 ]
[ 77-78-1 ]
[ 2674-34-2 ]
Reference：
[1] Journal of the Chemical Society, 1927, p. 74
[2] Monatshefte fuer Chemie, 1924, vol. 45, p. 582
[3] Monatshefte fuer Chemie, 1931, vol. 58, p. 92,104
11
[ 7377-91-5 ]
[ 2674-34-2 ]
Reference：
[1] Monatshefte fuer Chemie, 1931, vol. 58, p. 92,104
12
[ 123-31-9 ]
[ 2674-34-2 ]
Reference：
[1] Monatshefte fuer Chemie, 1924, vol. 45, p. 582
13
[ 106-51-4 ]
[ 2674-34-2 ]
Reference：
[1] Monatshefte fuer Chemie, 1924, vol. 45, p. 578
14
[ 7726-95-6 ]
[ 64-19-7 ]
[ 150-76-5 ]
[ 2674-34-2 ]
Reference：
[1] Monatshefte fuer Chemie, 1924, vol. 45, p. 582
15
[ 7789-69-7 ]
[ 150-78-7 ]
[ 2674-34-2 ]
[ 25245-34-5 ]
Reference：
[1] Chemische Berichte, 1931, vol. 58, p. 92,101
16
[ 150-78-7 ]
[ 2674-34-2 ]
[ 25245-34-5 ]
Reference：
[1] Monatshefte fuer Chemie, 1931, vol. 58, p. 92,104
[2] Chemical Papers, 2018, vol. 72, # 11, p. 2893 - 2898
17
[ 7789-69-7 ]
[ 150-78-7 ]
[ 2674-34-2 ]
[ 25245-34-5 ]
Reference：
[1] Chemische Berichte, 1931, vol. 58, p. 92,101
18
[ 2674-34-2 ]
[ 14753-51-6 ]
Yield
Reaction Conditions
Operation in experiment
79%
With boron tribromide In dichloromethane for 24 h; Reflux
In a 100 ml single-necked flask, 7.1 g (24.2 mmol, 1.0 eq) of 1,4-dibromo-2,5-dimethoxybenzene and 30 ml of dichloromethane were added. After the addition of the addition of BBr3 4.6ml (49.6mmol, 2.05eq), reflux reaction 24h. The methylene chloride was distilled off, and 50 ml of water was added with stirring. The filter cake was washed with water and washed with water. And dried in vacuo to give 5.08 g of a white solid in 79percent yield.
Reference：
[1] Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals, 2001, vol. 365, p. 481 - 489
[2] Journal of Materials Chemistry, 2011, vol. 21, # 28, p. 10472 - 10481
[3] Patent: CN106397468, 2017, A, . Location in patent: Paragraph 0012; 0019
[4] Monatshefte fuer Chemie, 1924, vol. 45, p. 578
[5] Macromolecules, 2002, vol. 35, # 13, p. 4975 - 4982
With boron tribromide; In dichloromethane; for 24h;Reflux;
In a 100 ml single-necked flask, 7.1 g (24.2 mmol, 1.0 eq) of 1,4-dibromo-2,5-dimethoxybenzene and 30 ml of dichloromethane were added. After the addition of the addition of BBr3 4.6ml (49.6mmol, 2.05eq), reflux reaction 24h. The methylene chloride was distilled off, and 50 ml of water was added with stirring. The filter cake was washed with water and washed with water. And dried in vacuo to give 5.08 g of a white solid in 79% yield.
With hydrogen bromide; dihydrogen peroxide In methanol Heating;
98%
With tert.-butylhydroperoxide; hydrogen bromide In methanol for 6h; Heating;
98.6%
With bromine In dichloromethane at 2 - 4℃; for 2.83333h; Inert atmosphere; Large scale;
96%
With bromine In tetrachloromethane at 0℃;
94%
With bromine In chloroform
93.2%
With bromine In chloroform at 0 - 20℃; for 24h;
90%
With Galden HT135; bromine; potassium carbonate In chloroform at 20℃; for 21h;
90%
With bromine In dichloromethane at 20℃; for 1h; Darkness;
89%
With sulfuric acid; dihydrogen peroxide; potassium bromide In ethanol; water for 0.333333h; Heating;
89%
With bromine; acetic acid at 20℃; Cooling with ice;
88%
With bromine In acetic acid for 2h; Ambient temperature;
85%
With bromine In chloroform at 0℃; for 3h;
2
Example 2: Preparation of 2,5-dibromo-1 ,4-dimethoxybenzene (2); [00103] In a one liter round-bottom flask, a solution of bromine (35.2 g, 220 mmol) in chloroform (50 ml) was added dropwise to a solution of 1 ,4- dimethoxybenzene (13.8 g, 100 mmol) in chloroform (400 ml) under 00C. After stirring for 3 hours, 100 ml of saturated Na2CO3 solution was added. The organic layer was washed with water, brine, and dried over sodium sulfate. The solvent was removed on a rotary evaporator and the residue was performed recrystallization from ethanol to afford pure 2,5-dibromo-1 ,4- dimethoxybenzene (25.8 g, 85%). 1HNMR (CDCI3) 57.128 (s, 2 H), 3.873 (s, 6 H).
84%
With Oxone; potassium bromide In water; acetonitrile at 20℃;
83.6%
With bromine; acetic acid at 20℃; for 4h; Sonication;
2.1 1) Synthesis of 1,4-dibromo-2,5-dimethoxybenzene:
In a 250 ml reaction flask, 20.0 g (0.145 mol, 1.0 eq) of hydroquinone dimethyl ether and 55 ml of glacial acetic acid were added and dissolved by ultrasonic; A solution of 15 ml of Br2 (0.290 mol, 2.0 eq) and 15 ml of glacial acetic acid was added dropwise at room temperature. After 1.5 hours, the mixture was stirred at room temperature for 2.5 h. Placed in the upper refrigerator to 10 below the temperature (not to acetic acid curing) filter; and petroleum ether washing filter cake to give a white solid, vacuum drying and then weight 35.6g, the yield of 83.6%.
80.6%
With PHP In water; acetic acid for 19h;
77%
With bromine; sodium sulfite In chloroform; water at 0 - 20℃; Inert atmosphere;
74%
With bromine In acetic acid at 20℃; for 2h;
72%
With bromine; potassium acetate In acetic acid for 2h;
68%
With bromine; acetic acid for 16h; Cooling with ice;
4 2,5-dibromo-1,4-dimethoxybenzene (11).
1,4-dimethoxybenzene (1.66 g, 12.0 mmol) was dissolved in 25 mL glacial acetic acid and cooled in an ice bath. Bromine (1.3 mL, 25 mmol) was carefully added. The cooling bath was removed and the reaction was stirred for 16 h and then poured over ice. The reaction mixture was extracted 3 x with 100 mL of CHCl3. The combined organics were dried over MgSO4, filtered, and the solvents were removed under vacuum. The product was isolated via recrystallization in absolute ethanol to yield white needles (2.40 g, 68%), mp 140-142 C (lit.5 mp 144-145 C). 1H NMR (CDCl3): δ 7.12 (s, 2H), 3.86 (s, 6H). The 1H NMR matches the known spectrum.5
68%
With bromine In dichloromethane
67%
With bromine; sodium sulfite In chloroform; water at 0 - 20℃; Inert atmosphere;
63%
With bromine In acetic acid at 20℃; for 2h;
4
To a solution of 1,4- dimethoxybenzene Q-8 (7.5 g, 53.57 mmol) in acetic acid (25 mL) was added a solution of bromine (17.4 g, 108.9 mmol) in acetic acid (5 mL) at room temperature. After stirring for 2h, the solution was cooled to 10 0C. The resulting fine precipitate was filtered, washed with water (20 mL), and dried under vacuum to obtain compound Q-9 (1Og, 63%) as a white solid. TLC Rf = 0.5 (petroleum ether - EtOAc, 9.9:0.1); 1H NMR (CDCl3) δ 7.10 (s, 2H), 3.84 (s, 6H).
61%
With N-Bromosuccinimide In water; N,N-dimethyl-formamide at 20 - 80℃; for 6h;
General procedure for the preparation of para-quinones:
General procedure: To a stirred solution of starting compound (0.5-1.2 mmol) in DMF-H2O (95:5, v/v, 8-12 mL) mixture was added NBS (4.0-4.2 mmol) at room temperature. The contents were stirred at room temperature about 10 min and then heated for appropriate duration mentioned in Table 2. Progress of the reaction in every case was monitored by TLC analysis. After completion of the reaction, the reaction mixture was cooled to room temperature and quenched with aqueous NaHCO3 (20%, 20-30 mL) solution. The insoluble precipitate was isolated by filtration and dried in vacuo. It was further purified by either recrystallization with ethyl acetate/n-hexane mixture or short pad silica gel column chromatography led to pure product.
50%
With N-Bromosuccinimide In dichloromethane for 24h; Ambient temperature;
With sulfuric acid; potassium bromide anschliessendes Erwaermen mit wss. H2O2;
With bromine; acetic acid
bei der Bromierung;
19.3 g
With bromine In acetic acid at 20℃; for 2h;
With bromine In tetrachloromethane at 20℃;
With N-Bromosuccinimide; sulfuric acid In tetrahydrofuran; water at 20℃; for 0.25h;
With bromine In acetic acid
With bromine In dichloromethane at 20℃;
With bromine; acetic acid at 0 - 25℃; for 13h;
With bromine; acetic acid; zinc(II) chloride at 20℃;
1,4-Dibromo-2,5-dimethoxybenzene (2.0 g, 6.76 mmol) was added dissolved in THF 35 mL, it was added dropwise a 1.6 M BuLi slowly at -78 . After stirring the reaction solution for 2 hours at -78 , it was added dropwise to DMF (2.8 mL, 33.7 mmol). The reaction solution is stirred at room temperature for 15 hours (20 ). 2 N HCl in a 20 mL reaction mixture was stirred slowly dropping off. The resulting solid was then filtered under reduced pressure, dried to obtain a 2,5-dimethoxyterephthalaldehyde 267 mg (30%).
poly(9,9-bis(6-bromohexyl)fluorene-co-alt-2,5-dimethoxy-1,4-phenylene); monomer(s): 2,7-bis[9,9-bis(6-bromohexyl)fluorenyl]-4,4,5,5-tetramethyl-[1.3.2]dioxaborolane; 1,4-dibromo-2,5-dimethoxybenzene[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
76%
With tetrakis(triphenylphosphine) palladium(0); potassium carbonate In toluene at 85℃; for 24h;
General procedure: To an N-heterocycle was added a solution of i-PrMgCl*LiCl (1.33 M, 1.8 eq. with respect to N-heterocycle, in THF) and (i-Pr)2NH (0.1 with respect to N-heterocycle). The mixture was stirred at room temperature under an argon atmosphere for 18 hours. An electrophile was added and the mixture was stirred at room temperature for 20 minutes. The reaction was quenched by addition of saturated aqueous NH4Cl (20 mL), and a saturated Na2S2O3 solution (20 mL) in the case of I2 as an electrophile. The mixture was extracted three times with EtOAc, the organic layer was dried over MgSO4, filtered and the solvent was removed under reduced pressure.
Stage #1: 1,4-dibromo-2,5-dimethoxybenzene With iodine; magnesium In tetrahydrofuran at 40℃; for 6h; Inert atmosphere;
Stage #2: carbon dioxide In tetrahydrofuran at 0℃; for 0.5h;
With tetrakis(triphenylphosphine) palladium(0); potassium carbonate In ethanol; water; toluene at 105℃; for 20h; Inert atmosphere;
5.4
Finally, the final product b was obtained by Suzuki coupling reaction: 9 mmol of 9-benzoquinone-10 borate,1.5 mmol of 1,4-dibromo-2,5-dimethoxybenzene, 0.36 mmol of tetrakis(triphenyl)phosphine palladium, 36 mL of toluene, 10 mL of ethanol,K2CO3 28 mmol (formulated with 14 mL of water) was added to the reaction flask, and then the system was evacuated and refluxed under nitrogen at 105 ° C for 20 hours.After completion of the reaction, the methanol was subjected to hot-washing filtration, toluene to recrystallization, and sublimation to obtain the final product b in a yield of 55%.
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