五氧化二碘辅助亲电碘化1-甲基萘制备高残炭沥青（英文）
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摘要
以1-甲基萘(1-MNP)为原料,采用碘化/脱碘聚合法成功制备了新型高残炭沥青,研究了溶剂种类、碘化温度和反应物摩尔比对碘化样品的影响。GC-MS结果表明当1-MNP、I_2和I_2O_5以1∶0.75∶0.18的摩尔比在60℃乙酸溶液中反应24 h,碘化产物主要由1-碘-4-甲基萘组成,选择性高达96.4%;碘化样品经130~180℃热处理发生脱碘化氢缩合反应。对所制沥青的甲醇可溶组分分析结果表明,脱碘化氢过程中有芳环加氢产物(四氢萘、5-甲基四氢萘等)和甲基迁移产物(2-甲基萘、二甲基萘、三甲基萘等)生成。通过TG、~1H-NM R和FT-IR等手段对沥青结构进行表征,结果表明该沥青具有较高的聚合度(甲苯可溶组分低于12 wt.%)、较高的残炭率(54~66 wt.%)以及较复杂的甲基萘分子组装方式(包括α-α'、α-β'和β-β')。脱碘聚合显著提高了沥青的聚合度和残炭率,这种沥青可用于高性能炭材料的制备。
Novel high-carbon-yield pitches were prepared through the iodination of 1-methylnaphthalene( 1-MNP) followed by dehydroiodination/polycondensation. 1-MNP was first iodinated by I_2 with the aid of I_2O_5,yielding mainly 1-iodo-4-MNP. Then,a thermal-dehydroiodination reaction at a comparatively low temperature of 130-180 ℃ was carried out to condense the iodinated products to obtain the pitches. The structures of the iodinated products and pitches were investigated by TG,GC-MS,1H-NMR and FTIR. Results indicated that the iodination selectivity(Smb) reached 96. 4% when 0. 75 mol I_2 and 0. 18 mol I_2O_5 reacted with 1 mol1-MNP at 60 ℃ for 24 h in acetic acid. Ring-hydrogenation products(tetralin,5-methyltetralin) and methyl migration products(2-MNP,dimethylnaphthalene and trimethylnaphthalene) were found in the pitches by analyzing their methanol-soluble fractions. Dehydroiodination substantially increased the degree of polymerization and carbon yield of the pitches. The pitches exhibited high polymerization degrees( toluene soluble fraction less than 12 wt%),high carbon yields(54-66 wt%) and complicated 1-MNP molecular assembly patterns including α-α',α-β',β-β',depending on dehydroiodination temperature and time. The iodination/dehydroiodination approach is simple,mild and clean for preparation of high quality pitches for high performance carbon materials.
Novel high-carbon-yield pitches were prepared through the iodination of 1-methylnaphthalene( 1-MNP) followed by dehydroiodination/polycondensation. 1-MNP was first iodinated by I_2 with the aid of I_2O_5,yielding mainly 1-iodo-4-MNP. Then,a thermal-dehydroiodination reaction at a comparatively low temperature of 130-180 ℃ was carried out to condense the iodinated products to obtain the pitches. The structures of the iodinated products and pitches were investigated by TG,GC-MS,1H-NMR and FTIR. Results indicated that the iodination selectivity(Smb) reached 96. 4% when 0. 75 mol I_2 and 0. 18 mol I_2O_5 reacted with 1 mol1-MNP at 60 ℃ for 24 h in acetic acid. Ring-hydrogenation products(tetralin,5-methyltetralin) and methyl migration products(2-MNP,dimethylnaphthalene and trimethylnaphthalene) were found in the pitches by analyzing their methanol-soluble fractions. Dehydroiodination substantially increased the degree of polymerization and carbon yield of the pitches. The pitches exhibited high polymerization degrees( toluene soluble fraction less than 12 wt%),high carbon yields(54-66 wt%) and complicated 1-MNP molecular assembly patterns including α-α',α-β',β-β',depending on dehydroiodination temperature and time. The iodination/dehydroiodination approach is simple,mild and clean for preparation of high quality pitches for high performance carbon materials.
引文
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[22]Ogata Y,Aoki K.Iodination of aromatic compounds with a mixture of iodine and peracetic acid.III.Autocatalysis and relative rates[J].Journal of the American Chemical Society,1968,90(22):6187-6191.
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[24]Maccoll A.Heterolysis and the pyrolysis of alkyl halides in the gas phase[J].Chemical Review s,1969,69(1):33-60.
[25]Szwarc M,Ghosh B N,Sehon A H.The C–Br bond dissociation energy in benzyl bromide and allyl bromide[J].The Journal of Chemical Physics,1950,18(9):1142-1149.
[26]Masuda K,Okuma O,Nishizawa T,et al.High-temperature nmr analysis of aromatic units in asphaltenes and preasphaltenes derived from Victorian brow n coal[J].Fuel,1996,75(3):295-299.
[27]Korai Y,Nakamura M,Mochida I,et al.Mesophase pitches prepared from methylnaphthalene by the aid of HFBF3[J].Carbon,1991,29(4-5):561-567.
[28]Ida T,Akada K,Okura T,et al.Carbonization of methylenebridged aromatic oligomers[J].Carbon,1992,30(2):165-171.
[2]Mochida I,Yoon S H,Takano N,et al.Microstructure of mesophase pitch-based carbon fiber and its control[J].Carbon,1996,34(8):941-956.
[3]Maeda T,Zeng S M,Tokumitsu K,et al.Preparation of isotropic pitch precursors for general purpose carbon fibers(GPCF)by air blow ing-I.Preparation of spinnable isotropic pitch precursor from coal tar by air blow ing[J].Carbon,1993,31(3):407-412.
[4]Chen C,Kennel E B,Stiller A H,et al.Carbon foam derived from various precursors[J].Carbon,2006,44(8):1535-1543.
[5]White J L,Sheaffer P M.Pitch-based processing of carbon-carbon composites[J].Carbon,1989,27(5):697-707.
[6]Huang S,Guo H,Li X,et al.Carbonization and graphitization of pitch applied for anode materials of high pow er lithium ion batteries[J].Journal of Solid State Electrochemistry,2013,17(5):1401-1408.
[7]Greinke R A,Lewis I C.Carbonization of naphthalene and dimethylnaphthalene[J].Carbon,1984,22(3):305-314.
[8]Mochida I,Nakamura E,Maeda K,et al.Carbonization of aromatic hydro carbons-III:carbonization catalyzed by alkali metals[J].Carbon,1975,13(6):489-493.
[9]Mochida I,Kudo K,Fukuda N,et al.Carbonization of pitchesIV:Carbonization of polycyclic aromatic hydrocarbons under the presence of aluminum chloride catalyst[J].Carbon,1975,13(2):135-139.
[10]Mochida I,Shimizu K,Korai Y,et al.Structure and carbonization properties of pitches produced catalytically from aromatic hydrocarbons w ith HF/BF3[J].Carbon,1988,26(6):843-852.
[11]Kim B J,Kil H,Watanabe N,et al.Preparation of novel isotropic pitch w ith high softening point and solvent solubility for pitch-based electrospun carbon nanofiber[J].Current Organic Chemistry,2013,17(13):1463-1468
[12]Ge C,Yang H,Miyawaki J,et al.Synthesis and characterization of high-softening-point methylene-bridged pitches by visible light irradiation assisted free-radical bromination[J].Carbon,2015,95:780-788.
[13]Blanksby S J,Ellison G B.Bond dissociation energies of organic molecules[J].Accounts of chemical research,2003,36(4):255-263.
[14]Stavber S,Jereb M,Zupan M.Electrophilic iodination of organic compounds using elemental iodine or iodides[J].Synthesis,2008,2008(10):1487-1513.
[15]Wing-Wah S.Iodination of methoxyamphetamines with iodine and silver sulfate[J].Tetrahedron letters,1993,34(39):6223-6224.
[16]Orito K,Hatakeyama T,Takeo M,et al.Iodination of alkyl aryl ethers by mercury(II)oxide-iodine reagent in dichloromethane[J].Synthesis,1995(10):1273-1277.
[17]Sathiyapriya R,Karunakaran R J.A convenient procedure for the iodination of arenes[J].Journal of Chemical Research,2006(9):575-576.
[18]Lulinski P,Skulski L.Oxidative iodination of arenes with manganese(IV)oxide or potassium permanganate as the oxidants[J].Bulletin of the Chemical Society of Japan,1999,72(1):115-120.
[19]Olah G A,Wang Q,Sandford G,et al.Iodination of deactivated aromatics w ith N-iodosuccinimide in trifluoromethanesulfonic acid(NIC-CF3SO3H)via in situ generated superelectrophilic iodine(I)trifluoromethanesulfonate[J].Journal of organic chemistry,1993,58(11):3194-3195.
[20]Brazdil L C,Cutler C J.Selective production of diiodobenzene and iodobenzene from benzene[J].The Journal of Organic Chemistry,1996,61(26):9621-9622.
[21]Brazdil L C,Fitch J L,Cutler C J,et al.Kinetics of aromatic iodination reactions using iodine,diiodine pentoxide and sulfuric acid in acetic acid[J].Journal of the Chemical Society,Perkin Transactions 2,1998(4):933-936.
[22]Ogata Y,Aoki K.Iodination of aromatic compounds with a mixture of iodine and peracetic acid.III.Autocatalysis and relative rates[J].Journal of the American Chemical Society,1968,90(22):6187-6191.
[23]Ogata Y,Nakajima K.Iodination of aromatic compounds with a mixture of peroxyacetic acid and iodine[J].Tetrahedron,1964,20(1):43-47.
[24]Maccoll A.Heterolysis and the pyrolysis of alkyl halides in the gas phase[J].Chemical Review s,1969,69(1):33-60.
[25]Szwarc M,Ghosh B N,Sehon A H.The C–Br bond dissociation energy in benzyl bromide and allyl bromide[J].The Journal of Chemical Physics,1950,18(9):1142-1149.
[26]Masuda K,Okuma O,Nishizawa T,et al.High-temperature nmr analysis of aromatic units in asphaltenes and preasphaltenes derived from Victorian brow n coal[J].Fuel,1996,75(3):295-299.
[27]Korai Y,Nakamura M,Mochida I,et al.Mesophase pitches prepared from methylnaphthalene by the aid of HFBF3[J].Carbon,1991,29(4-5):561-567.
[28]Ida T,Akada K,Okura T,et al.Carbonization of methylenebridged aromatic oligomers[J].Carbon,1992,30(2):165-171.