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[ CAS No. 24932-48-7 ]

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Chemical Structure| 24932-48-7
Chemical Structure| 24932-48-7
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CAS No. :24932-48-7 MDL No. :MFCD00082743
Formula : C8H8Br2 Boiling Point : 279.1°C at 760 mmHg
Linear Structure Formula :- InChI Key :-
M.W :263.96 g/mol Pubchem ID :34347
Synonyms :

Safety of [ 24932-48-7 ]

Signal Word:Warning Class:N/A
Precautionary Statements:P261-P273-P305+P351+P338 UN#:N/A
Hazard Statements:H315-H319-H335-H412 Packing Group:N/A
GHS Pictogram:

Application In Synthesis of [ 24932-48-7 ]

  • Upstream synthesis route of [ 24932-48-7 ]
  • Downstream synthetic route of [ 24932-48-7 ]

[ 24932-48-7 ] Synthesis Path-Upstream   1~9

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Reference: [1] Chemische Berichte, 1884, vol. 17, p. 2374
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Reference: [1] European Journal of Organic Chemistry, 2011, # 2, p. 341 - 354
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YieldReaction ConditionsOperation in experiment
75% With N-Bromosuccinimide In neat (no solvent) at 20℃; for 1.5 h; Milling; Green chemistry General procedure: 1-Methoxy-3,5-dimethylbenzene(100mg, 0.73 mmol), N-Bromosuccinimide (NBS,260 mg,1.46 mmol) and one ball (5 mmdiameter, stainless steel) were transferred to a milling jar (10 mL, stainlesssteel). The ball-milling operation was performed and the progress of reaction was monitored by TLC/1H NMR.[1]After completion, the reaction mixture was transferred into 30 mL ethyl acetate and cooled at 0 °C. The product was isolated as filtrate upon paper filtration and waste succinimide as precipitate. The resulting filtrate were concentrated in vacuo to isolate 250 mg (yield: 85percent) of 2b as colourless powder. To test the efficiency in large scale, the reaction was also performed for the mono-bromination of 1-methoxy-3,5-dimethylbenzene in 1.3 g scale for 1 h and the product was isolated in 87percent yield.[1] The milling apparatus was stopped and small portion of the sample was collected from the reaction jar to study either TLC/ proton NMR. Following, the reaction was started again andthis operation time was excluded for reporting the reaction timing.
75% With N-Bromosuccinimide In neat (no solvent) at 20℃; for 1.5 h; Milling; Green chemistry General procedure: 1-Methoxy-3,5-dimethylbenzene (100mg, 0.73 mmol), N-Bromosuccinimide (NBS,260 mg,1.46 mmol) and one ball (5 mmdiameter, stainless steel) were transferred to a milling jar (10 mL, stainlesssteel). The ball-milling operation was performed and the progress of reactionwas monitored by TLC/1H NMR.[1]After completion, the reaction mixture was transferred into 30 mL ethyl acetateand cooled at 0 °C. The product was isolated as filtrate upon paper filtrationand waste succinimide as precipitate. The resulting filtrate were concentrated in vacuoto isolate 250 mg (yield: 85percent) of 2bas colourless powder. To test the efficiency in largescale, the reaction was also performed for the mono-bromination of1-methoxy-3,5-dimethylbenzene in 1.3 g scale for 1 h and the product wasisolated in 87percent yield.[1] Themilling apparatus was stopped and small portion of the sample was collectedfrom the reaction jar to study either TLC/ proton NMR. Following, the reaction was started again andthis operation time was excluded for reporting the reaction timing.
67% at 0 - 20℃; Inert atmosphere 4 mL Br2 was added dropwise to a solution of I2 (20 mg) in o-xylene (4.6 mL, 38mmol) at 0oC within 30 min. The resultant was left overnight at room temperature,followed by dissolving in Et2O (20 mL), washing with 2 N NaOH (2 X 10 mL), H2O(2 X 10 mL) and dring over MgSO4. The organic solvents were then concentrated invacuo to afford a faintly pink colored oil, which was further purified byrecrystallization in methanol to give 6.8 g pure 4,5-dibromo-o-xylene in 67percent yield.1H NMR (400 MHz, CDCl3) δ 7.37 (s, 2H), 2.18 (s, 6H).
62%
Stage #1: Cooling with ice
Stage #2: at -5 - 0℃; for 20 h;
Iodine (1.6g, 6.3mmol) was added to o-xylene (40g, 0.38mol) and stirred under ice-water mixture, then bromine (124g, 0.77mol) was dropped slowly to keep the temperature at −5 to 0°C. After stirring for 20h, the mixture was dissolved in ether, washed with aqueous potassium hydroxide and fresh water for three times, dried with anhydrous MgSO4 and evaporated the solvent to obtain a semi-solid crude product. After recrystallization from alcohol, 61.5g pure 4,5-dibromo-o-xylene 1 was obtained (yield, 62percent). Mp: 85–88°C; 1H NMR (DMSO-d6, 400Hz): 7.36 (s, 2H), 2.18 (s, 6H) ppm; MS-EI (m/z): 264 (M+), 185 (M+−Br), 104 (M+−2Br).
62% With bromine; iodine; iron In dichloromethane at 0 - 20℃; for 50 h; Will be o-Xylene 24 ml (0.2 mol)Dissolved in 30mlIn dry methylene chloride,Iodine was added to the solution while stirring2.5 g (10 mmol) and reduced iron powder(10 mmol).The mixture was cooled to zero degrees with an ice bath.Another liquid bromine 20.5 ml (0.4 mol)Was dissolved in 10 ml of dry methylene chloride,The solution was slowly added dropwise over a period of six hours using a dropping funnelThe reaction mixture,The released hydrogen bromide gas was absorbed in a funnel inverted in a 10percent sodium hydroxide solution.The reaction was stirred continuously at 0 ° C for 38 hours,Followed by stirring at room temperature for 6 hours.The reaction mixture was washed with 5percent sodium hydroxide solution until colorless,Separating the organic layer;And then washed with 5percent sodium bisulfite solution to neutral,The organic layer was separated,And dried over anhydrous sodium sulfate.After standing overnight, the filtrate was evaporated under reduced pressure on a rotary evaporator to give a light brown oily liquid.To the liquid was added 8-10 times the volume of methanol,Stirring heated to boiling, and then stop stirring,Cooled to zero degrees recrystallization.32.7 g of a transparent acicular crystal was obtained in a yield of 62percent.

Reference: [1] Tetrahedron, 2002, vol. 58, # 46, p. 9413 - 9422
[2] Tetrahedron Letters, 2014, vol. 55, # 13, p. 2154 - 2156
[3] Tetrahedron Letters, 2015, vol. 55, # 13, p. 2154 - 2156
[4] Journal of the American Chemical Society, 1993, vol. 115, # 13, p. 5422 - 5429
[5] Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 2006, vol. 45, # 1, p. 227 - 231
[6] Synlett, 2015, vol. 26, # 14, p. 1991 - 1996
[7] Tetrahedron Letters, 2004, vol. 45, # 37, p. 6851 - 6853
[8] Dyes and Pigments, 2014, vol. 109, p. 144 - 150
[9] Patent: CN105541850, 2016, A, . Location in patent: Paragraph 0030; 0031; 0032; 0033
[10] Patent: WO2016/100754, 2016, A1, . Location in patent: Paragraph 0289
[11] Tetrahedron, 2008, vol. 64, # 50, p. 11370 - 11378
[12] Chemical Science, 2017, vol. 8, # 12, p. 8164 - 8169
[13] Russian Chemical Bulletin, 2008, vol. 57, # 8, p. 1665 - 1670
[14] Bulletin de la Societe Chimique de France, 1965, p. 3537 - 3544
[15] Synthesis, 1972, p. 29 - 30
[16] Molecular Crystals and Liquid Crystals (1969-1991), 1988, vol. 154, p. 9 - 26
[17] Journal of the Chemical Society. Perkin Transactions 2, 1999, # 7, p. 1503 - 1512
[18] Chemische Berichte, 1884, vol. 17, p. 2374
[19] Tetrahedron, 2009, vol. 65, # 39, p. 8113 - 8119
[20] Journal of Organic Chemistry, 2012, vol. 77, # 3, p. 1308 - 1315
[21] Synthesis (Germany), 2016, vol. 48, # 15, p. 2449 - 2454
[22] Journal of Coordination Chemistry, 2017, vol. 70, # 16, p. 2916 - 2928
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Reference: [1] Journal of the Chemical Society, 1930, p. 2510,2520
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Reference: [1] Journal of the Chemical Society, 1930, p. 2510,2520
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Reference: [1] Journal of the Chemical Society, 1930, p. 2510,2520
  • 7
  • [ 583-71-1 ]
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  • [ 24932-48-7 ]
Reference: [1] Chemische Berichte, 1884, vol. 17, p. 2374
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  • [ 95-47-6 ]
  • [ 7726-95-6 ]
  • [ 7553-56-2 ]
  • [ 583-71-1 ]
  • [ 24932-49-8 ]
  • [ 24932-48-7 ]
  • [ 2810-69-7 ]
Reference: [1] Chemische Berichte, 1884, vol. 17, p. 2374
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YieldReaction ConditionsOperation in experiment
90% With potassium permanganate In water 4,5-o-o-xylene6.5 g (0.025 mol)Adding 200ml of water, stirring to form a suspension,Heated to boiling.15.8 g (0.1 mol) of potassium permanganate powder was divided equally into three equal portions,The reaction mixture was added to the reaction mixture once every two hours,Co-reaction for 6 hours. The reaction mixture was cooled to room temperature, The slow addition of sodium bisulfite reduction of the remaining potassium permanganate,Until the magenta completely disappear.Potassium hydroxide was added to the reaction mixture to adjust the pH to above 12.The reaction mixture was filtered through a Buchner funnel,A clear colorless filtrate was obtained,The filtrate was a solution of potassium 4,5-dibromophthalate.The residue was washed twice with 1percent KOH solution,The washings were combined into the filtrate.To the filtrate slowly dropping concentrated hydrochloric acid (18M) acidification to pH is about equal to 2, the precipitation of a large number of white flocculent4,5-dibromophthalic acid.With a Buchner funnel filter,The filter cake was washed with a small amount of 1percent hydrochloric acid solution,And then placed in a desiccator silica gel drying.Obtained as a shiny white solid 7.3 g, 90percent.
Reference: [1] Patent: CN105541850, 2016, A, . Location in patent: Paragraph 0034; 0035; 0036
[2] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1980, p. 1834 - 1840
[3] Journal of the Chemical Society, 1952, p. 4615,4618
[4] J. Gen. Chem. USSR (Engl. Transl.), 1980, vol. 50, # 5, p. 907 - 915[5] Zhurnal Obshchei Khimii, 1980, vol. 50, # 5, p. 1122 - 1131
[6] Acta Crystallographica Section B: Structural Science, 1999, vol. 55, # 4, p. 530 - 542
[7] Journal of the American Chemical Society, 2012, vol. 134, # 7, p. 3411 - 3418
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