Nitroaromatics are usually prepared using a mixed acid of nitric acid with strong acids. However, the use of strong acids caused dangerous work-up and the disposal of large amounts of acid-waste. Therefore, much effor...Nitroaromatics are usually prepared using a mixed acid of nitric acid with strong acids. However, the use of strong acids caused dangerous work-up and the disposal of large amounts of acid-waste. Therefore, much effort has been made on the improvement of nitration process without strong acids. We examined solid-phase aromatic nitration with Mg(NO3)2 on silica gel in order to establish the nitration process without strong acids. The nitration of 1,2- and 1,3-, 1,4-dimethoxybenzenes and 4-methylanisole with Mg(NO3)2 proceeded by heating on silica gel at 150°C for 4 - 5 h to produce the nitroaromatics. The nitration of 1,3,5-trimethoxybenzene produced the nitrated dimer, 2,4,6,2’, 4’,6’-hexamethoxy-3-nitrobiphenyl, which was not isolated in other solid-phase nitration. In the cases of naphthalene derivatives, the α-nitrated compounds were obtained. In the cases of p-cresol and 2-naphthol, the esterification occurred at the hydroxyl group to give 4-tolyl nitrate and 2-naphthyl nitrate, respectively. It is synthetic interest to note that nitrate esters were isolated in solid phase. Thus Mg(NO3)2-SiO2 composite was mild reagent for solid-phase nitration. Acidity of Mg(NO3)2-SiO2 composite was determined to be pH 0.96 by the measurement of absorption spectra on a micro spectrophotometer using meso-tetra(p-cyanophenyl)porphyrin as a pH-indicator. Mg(NO3)2-SiO2 composite made acidic conditions. Therefore, it was suggested that Mg(NO3)2 reacted with proton on silica gel to form the NO+2. Thus, electron-rich aromatic hydrocarbons led the efficient nitration through electrophilic attack of NO+2. After the nitration, acidic Mg(NO3)2-SiO2 composite could be turned into neutrality by exposing wet conditions and disposed safely since the composite did not involve harmful elements. Thus the solid-phase nitration using Mg(NO3)2-SiO2 composite will provide safety and environmentally conscious chemical process.展开更多
Napiegrass (Pennisetum purpureum Schumach) was treated with a low-moisture anhydrous ammonia (LMAA) pretreatment by adding an equal weight of water and keeping it under atmospheric ammonia gas at room temperature for ...Napiegrass (Pennisetum purpureum Schumach) was treated with a low-moisture anhydrous ammonia (LMAA) pretreatment by adding an equal weight of water and keeping it under atmospheric ammonia gas at room temperature for four weeks. After the removal of ammonia and washing with water, a simultaneous saccharification and fermentation (SSF) was conducted for the LMAA-pretreated napiergrass (1.33 g) in a buffer solution (8 mL) using a mixture of a cellulase (80 mg) and a xylanase (53 mg) as well as the cell suspension (0.16 mL) of Saccharomyces cerevisiae. Ethanol and xylose resulted in 91.2% and 62.9% yields, respectively. The SSF process was scaled up using LMAA-pretreated napiergrass (100.0 g) to give ethanol (77.2%) and xylose (52.8%). After the removal of ethanol, the pentose fermentation of the SSF solution (40 mL), which contained 1.00 g of xylose, using cell suspension of Escherichia coli KO11 (70 mL) gave 86.3% yield of ethanol. Total ethanol yield reached 68.9% based on xylan (21.4 wt%) and glucan (39.7 wt%) of the LMAA-pretreated napiergrass.展开更多
Fuelization of Italian ryegrass and Napier grass was examined by the combination of biological treatments and photocatalytic reforming (photo-Reform). The alkali-pretreated Italian ryegrass and Napier grass were subje...Fuelization of Italian ryegrass and Napier grass was examined by the combination of biological treatments and photocatalytic reforming (photo-Reform). The alkali-pretreated Italian ryegrass and Napier grass were subjected to the enzymatic saccharification using cellulase and xylanase. Xylose and glucose were produced in 56.6% and 71.1% from Italian ryegrass and in 49.5% and 67.3% from Napier grass, respectively. Xylose and glucose were converted to hydrogen by the photo-Reform using a Pt-loaded titanium oxide (Pt/TiO2) under UV irradiation. Moreover, a low-moisture anhydrous ammonia (LMAA) pretreatment was performed for Italian ryegrass and Napier grass by keeping moist powdered biomass under NH3 gas atmosphere at room temperature for four weeks. The Italian ryegrass and Napier grass which were pretreated by LMAA method were subjected to simultaneous saccharification and fermentation (SSF) using a mixture of cellulase and xylanase as well as Saccharomyces cerevisiae in acetate buffer (pH 5.0). Ethanol and xylose were produced in 91.6% and 51.6% from LMAA-pretreated Italian ryegrass and 78.6% and 68.8% from Napier grass, respectively. After the evaporation of ethanol, xylose was converted to hydrogen by the photo-Reform. In the case of saccharification→photo-Reform, energy was recovered as hydrogen from the alkali-pretreated Italian ryegrass and Napier grass in 71.9% and 77.0% of energy recovery efficiency, respectively. In the case of SSF→photo-Reform, the energy was recovered in 82.7% and 77.2% as ethanol and hydrogen from the LMAA-pretreated Italian ryegrass and Napier grass, respectively.展开更多
文摘Nitroaromatics are usually prepared using a mixed acid of nitric acid with strong acids. However, the use of strong acids caused dangerous work-up and the disposal of large amounts of acid-waste. Therefore, much effort has been made on the improvement of nitration process without strong acids. We examined solid-phase aromatic nitration with Mg(NO3)2 on silica gel in order to establish the nitration process without strong acids. The nitration of 1,2- and 1,3-, 1,4-dimethoxybenzenes and 4-methylanisole with Mg(NO3)2 proceeded by heating on silica gel at 150°C for 4 - 5 h to produce the nitroaromatics. The nitration of 1,3,5-trimethoxybenzene produced the nitrated dimer, 2,4,6,2’, 4’,6’-hexamethoxy-3-nitrobiphenyl, which was not isolated in other solid-phase nitration. In the cases of naphthalene derivatives, the α-nitrated compounds were obtained. In the cases of p-cresol and 2-naphthol, the esterification occurred at the hydroxyl group to give 4-tolyl nitrate and 2-naphthyl nitrate, respectively. It is synthetic interest to note that nitrate esters were isolated in solid phase. Thus Mg(NO3)2-SiO2 composite was mild reagent for solid-phase nitration. Acidity of Mg(NO3)2-SiO2 composite was determined to be pH 0.96 by the measurement of absorption spectra on a micro spectrophotometer using meso-tetra(p-cyanophenyl)porphyrin as a pH-indicator. Mg(NO3)2-SiO2 composite made acidic conditions. Therefore, it was suggested that Mg(NO3)2 reacted with proton on silica gel to form the NO+2. Thus, electron-rich aromatic hydrocarbons led the efficient nitration through electrophilic attack of NO+2. After the nitration, acidic Mg(NO3)2-SiO2 composite could be turned into neutrality by exposing wet conditions and disposed safely since the composite did not involve harmful elements. Thus the solid-phase nitration using Mg(NO3)2-SiO2 composite will provide safety and environmentally conscious chemical process.
文摘Napiegrass (Pennisetum purpureum Schumach) was treated with a low-moisture anhydrous ammonia (LMAA) pretreatment by adding an equal weight of water and keeping it under atmospheric ammonia gas at room temperature for four weeks. After the removal of ammonia and washing with water, a simultaneous saccharification and fermentation (SSF) was conducted for the LMAA-pretreated napiergrass (1.33 g) in a buffer solution (8 mL) using a mixture of a cellulase (80 mg) and a xylanase (53 mg) as well as the cell suspension (0.16 mL) of Saccharomyces cerevisiae. Ethanol and xylose resulted in 91.2% and 62.9% yields, respectively. The SSF process was scaled up using LMAA-pretreated napiergrass (100.0 g) to give ethanol (77.2%) and xylose (52.8%). After the removal of ethanol, the pentose fermentation of the SSF solution (40 mL), which contained 1.00 g of xylose, using cell suspension of Escherichia coli KO11 (70 mL) gave 86.3% yield of ethanol. Total ethanol yield reached 68.9% based on xylan (21.4 wt%) and glucan (39.7 wt%) of the LMAA-pretreated napiergrass.
文摘Fuelization of Italian ryegrass and Napier grass was examined by the combination of biological treatments and photocatalytic reforming (photo-Reform). The alkali-pretreated Italian ryegrass and Napier grass were subjected to the enzymatic saccharification using cellulase and xylanase. Xylose and glucose were produced in 56.6% and 71.1% from Italian ryegrass and in 49.5% and 67.3% from Napier grass, respectively. Xylose and glucose were converted to hydrogen by the photo-Reform using a Pt-loaded titanium oxide (Pt/TiO2) under UV irradiation. Moreover, a low-moisture anhydrous ammonia (LMAA) pretreatment was performed for Italian ryegrass and Napier grass by keeping moist powdered biomass under NH3 gas atmosphere at room temperature for four weeks. The Italian ryegrass and Napier grass which were pretreated by LMAA method were subjected to simultaneous saccharification and fermentation (SSF) using a mixture of cellulase and xylanase as well as Saccharomyces cerevisiae in acetate buffer (pH 5.0). Ethanol and xylose were produced in 91.6% and 51.6% from LMAA-pretreated Italian ryegrass and 78.6% and 68.8% from Napier grass, respectively. After the evaporation of ethanol, xylose was converted to hydrogen by the photo-Reform. In the case of saccharification→photo-Reform, energy was recovered as hydrogen from the alkali-pretreated Italian ryegrass and Napier grass in 71.9% and 77.0% of energy recovery efficiency, respectively. In the case of SSF→photo-Reform, the energy was recovered in 82.7% and 77.2% as ethanol and hydrogen from the LMAA-pretreated Italian ryegrass and Napier grass, respectively.
