共查询到20条相似文献,搜索用时 46 毫秒
1.
三光气法制备均苯三甲酰氯 总被引:3,自引:0,他引:3
常温下,采用三光气与均苯三甲酸在催化剂作用下制备均苯三甲酰氯(TMC),最佳收率可达88%。产品熔点为32.5~33.6℃,w(TMC)>99.2%,IR图谱与标准谱基本一致。通过对催化剂、溶剂和反应底物配比等影响因素的研究发现:(1)在常温下单一催化剂,如N,N-二甲基甲酰胺、吡啶、咪唑、三乙胺等不能让反应进行完全,收率<32%;而用复合催化剂,如吡啶/N,N-二甲基甲酰胺、咪唑/三乙胺等在常温下能反应完全,收率>60%。(2)溶剂的溶度参数与均苯三甲酰氯的溶度参数相差越小,反应速度越快。(3)反应底物配比n(三光气)/n(均苯三甲酸)<1.2时,几乎得不到产品,随着n(三光气)/n(均苯三甲酸)增大,收率增高;当n(三光气)/n(均苯三甲酸)>3后,其增大对产品收率影响不大。 相似文献
2.
Feng Wang Jie Xu Xiaoqiang Li Jin Gao Lipeng Zhou Ryuichiro Ohnishi 《Advanced Synthesis \u0026amp; Catalysis》2005,347(15):1987-1992
We conducted the liquid phase oxidation of toluene with molecular oxygen over heterogeneous catalysts of copper‐based binary metal oxides. Among the copper‐based binary metal oxides, iron‐copper binary oxide (Fe/Cu=0.3 atomic ratio) was found to be the best catalyst. In the presence of pyridine, overoxidation of benzaldehyde to benzoic acid was partially prevented. As a result, highly selective formation of benzaldehyde (86% selectivity) was observed after 2 h of reaction (7% conversion of toluene) at 463 K and 1.0 MPa of oxygen atmosphere in the presence of pyridine. These catalytic performances were similar or better than those in the gas phase oxidation of toluene at reaction temperatures higher than 473 K and under 0.5–2.5 MPa. It was suggested from competitive adsorption measurements that pyridine could reduce the adsorption of benzaldehyde. At a long reaction time of 4 h, the conversion increased to 25% and benzoic acid became the predominant reaction product (72% selectivity) in the absence of pyridine. The yield of benzoic acid was higher than that in the Snia‐Viscosa process, which requires corrosive halogen ions and acidic solvents in the homogeneous reaction media. The catalyst was easily recycled by simple filtration and reusable after washing and drying. 相似文献
3.
Kinetics of in situ epoxidation of soybean oil in bulk catalyzed by ion exchange resin 总被引:1,自引:0,他引:1
Snežana Sinadinović-Fišer Milovan Janković Zoran S. Petrović 《Journal of the American Oil Chemists' Society》2001,78(7):725-731
The kinetics of the epoxidation of soybean oil in bulk by peracetic acid formed in situ, in the presence of an ion exchange resin as the catalyst, was studied. The proposed kinetic model takes into consideration
two side reactions of the epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups as well as the
reactions of the formation of the peracid and epoxy groups. The catalytic reaction of the peracetic acid formation was characterized
by adsorption of only acetic acid and peracetic acid on the active catalyst sites, and irreversible surface reaction was the
overall rate-determining step. Kinetic parameters were estimated by fitting experimental data using the Marquardt method.
Good agreement between the calculated and experimental data indicated that the proposed kinetic model was correct. The effect
of different reaction variables on epoxidation was also discussed. The conditions for obtaining optimal epoxide yield (91%
conversion, 5.99% epoxide content in product) were found to be: 0.5 mole of glacial acetic acid and 1.1 mole of hydrogen peroxide
(30% aqueous solution) per mole of ethylenic unsaturation, in the presence of 5 wt% of the ion exchange resin at 75°C, over
the reaction period of 8 h. 相似文献
4.
烷基多苷硫酸酯铵盐的合成及性能 总被引:1,自引:0,他引:1
以烷基多苷为原料,用氨磺酸为硫酸化试剂,合成了烷基多苷硫酸氨。通过正交实验及优化实验确定了反应温度、反应时间、原料配比、溶剂、催化剂种类、催化剂用量等因素对产率的影响。得出了最佳合成条件为:以V(甲苯)∶V(吡啶)=7∶3为溶剂,以尿素为催化剂,m(APG)∶m(NH2SO3H)=1∶1.10,反应温度105℃;反应时间3.5 h。该条件下的烷基多苷硫酸铵收率达到86.6%。产品的水溶性、起泡性、增溶性较烷基多苷显著提高。 相似文献
5.
氰酸钠法合成磺酰脲类除草剂苄嘧磺隆 总被引:1,自引:0,他引:1
研究了以邻甲酸甲酯苄基磺酰氯、2-氨基-4,6-二甲氧基嘧啶和氰酸钠为原料,乙腈为溶剂,在吡啶催化下合成除草剂苄嘧磺隆的新方法。考察了溶剂种类、催化剂用量、氰酸钠用量、反应时间、反应温度等因素对反应的影响。结果表明:邻甲氧羰基苄基磺酰氯、2-氨基-4,6-二甲氧基嘧啶、吡啶和氰酸钠摩尔比为1∶1∶1∶1.2,乙腈为溶剂,在40°C下搅拌反应3 h,产品收率67.8%,纯度97.0%(HPLC)。该方法避免了剧毒光气,简化了工艺路线,是一个对环境友好的磺酰脲除草剂的合成方法。 相似文献
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以对甲苯磺酰氯(TSC)和邻氨基苯甲酸(ATRA)为原料,吡啶为溶剂,乙醇钠为催化剂,合成紫外长波草绿荧光功能材料.产品的性状为淡黄色粉末状晶体.通过原料物质的量配比、催化剂用量、反应温度、反应时间等四个方面的条件试验,找出了最佳工艺条件,收率大于20%.同时对该产品进行了初步的表征分析. 相似文献
8.
5-氯甲酰氧基异肽酰氯的制备 总被引:4,自引:0,他引:4
以三光气(简称BTC)为酰氯化剂,与 5 -羟基异酞酸在复合催化剂作用下制备了 5- 氯甲酰氧基异肽酰氯(简称CFIC),收率最高可达 42 .3%。分析了反应条件的改变对产品收率的影响。反应物量比R〔n(三光气)∶n(5- 羟基异酞酸)〕≤1 .1时,产品收率很低,几乎得不到产品; 1. 11 7时,影响不大。溶剂极性越大,反应越快,收率越高。复合催化剂(三乙胺 /咪唑、吡啶 /咪唑)的催化效果远远优于单一催化剂(N,N -二甲基甲酰胺、三乙胺、吡啶和咪唑)。反应适宜在 5 ~20℃操作,温度高于 30℃时,反应很难进行。反应时间较短时,对产品收率影响较大,当时间大于 24h后,影响不大。利用正交实验确定的最佳工艺条件为:反应物量比为 1. 67;催化剂为m(咪唑)∶m(吡啶) =1∶4及m(吡啶+咪唑)∶m(三光气) =0. 08∶1;反应温度5~10℃。用红外光谱仪分析产品的主要官能团:在 1785. 24、1764 .12、1603 .20cm-1和 1557. 99cm-1处有强吸收峰,它们分别为Ar—OCOCl、Ar—COCl与三取代基苯环。用高效液相色谱仪测得w(CFIC) =99. 4%,用数字熔点仪测得产品熔点为 56. 7~57. 0℃。推测了三光气在催化剂作用下的反应机理。 相似文献
9.
有机碱催化Knoevenagal法合成肉桂酸及其工艺优化 总被引:1,自引:0,他引:1
本文以苯甲醛和丙二酸为原料,吡啶等有机碱为催化剂,利用Knoevenagal反应合成肉桂酸,从而降低了反应温度,提高了产率和产品纯度,简化了合成工艺。同时,比较和分析了不同弱碱催化剂对肉桂酸合成产率的影响,结果表明吡啶的催化效果最好,并通过正交试验探讨了有机碱催化作用下,不同工艺参数对肉桂酸产率的影响,确定反应的最佳工艺条件为:以吡啶为催化剂,反应物苯甲醛/丙二酸摩尔比取1:3,催化剂用量0.02mol,反应时间为90min,肉桂酸产率可达90%。 相似文献
10.
以茴脑为原料,有机溶剂与水复合溶剂为溶剂,室温下通过臭氧化分解反应制取茴香醛,并通过GC-MS、FT-IR和1H-NMR对产品进行了表征.对该溶剂体系与传统溶剂体系下茴香醛的产率进行了对比,并确定了丙酮/水体系为最佳溶剂体系.实验详细考察了溶剂用量、臭氧气流量、混合溶剂中水含量和反应时间等工艺参数.优化的工艺条件为:丙酮和水为溶剂,m(茴脑)∶m(混合溶剂)=1∶3,臭氧气流量0.06 m3·h-1,混合溶剂中水的质量含量为15%,反应时间100 min,茴香醛产率82.70%.该反应在水的存在下实现了室温下一步法合成茴香醛,避免了茴脑臭氧化物的分离及还原步骤,工艺简单,洁净环保. 相似文献
11.
针对目前氟吡菌酰胺中间体(2-[3-氯-5-(三氟甲基)吡啶-2-基]乙胺(5))合成路线长、操作复杂,产品收率低、工业生产成本高等问题,本文系统开展了(5)绿色合成工艺的研发。以2,3-二氯-5-(三氟甲基)吡啶(1)为原料,选择将亲核取代、脱羧两步反应合为一锅法制得2-[3-氯-5-(三氟甲基)吡啶-2-基]乙腈(3),之后将催化加氢还原和水解连续进行得到氟吡菌酰胺中间体(5)的盐酸盐。在一锅法中详细考察了溶剂、碱、pH等重要因素对收率的影响。优选溶剂为DMF、碱为无水碳酸钾、pH为0.5~1,产品(3)收率达到88.1%,纯度98.5%。在加氢还原和水解连续反应中探索了催化剂种类、加氢反应时间和温度以及水解中盐酸用量等影响。结果表明,采用5% Pd/C催化剂(型号R5K1),在加氢反应温度15℃、反应时间12h、水解时38%浓盐酸用量为n(HCl)∶n(3)=5.5,产品(5)收率达78.8%,纯度为96.2%。同时,实现了工艺中各步溶剂以及Pd/C催化剂的高效回收套用,为该中间体的清洁工业生产提供了新技术支撑。 相似文献
12.
Chitralekha Khatri 《Fuel Processing Technology》2010,91(10):1288-1295
Synthesis of highly active nano-crystalline, thermally stabilized solid acid catalyst has been reported by loading different weight fractions of sulfated zirconia on chemically activated fly ash through two step sol-gel technique. The catalysts were characterized using powder XRD, FT-IR, N2-adsorption desorption study, CHNS elemental analysis, SEM-EDAX and their acidity were measured by pyridine adsorbed FTIR. Liquid phase benzylation of benzene and toluene with benzyl chloride was studied as test reaction for catalytic activity of SZF catalysts. A very high conversion of benzene (87%) and toluene (93%) were observed, which is attributed to significant amount of acid site on the catalyst surface. The FTIR study of the pyridine adsorbed samples reflects the presence of Brønsted as well as Lewis acid sites. The catalyst with 12 wt.% zirconia (SZF-12) was regenerated and reused up to four reaction cycles with equal efficiency as in the first run. 相似文献
13.
4,4'-二羟基二苯砜合成新工艺的研究 总被引:1,自引:0,他引:1
对苯酚磺化、脱水法合成4,4'-二羟基二苯砜(BPS)工艺进行改进。研究了使用新的催化剂(2,6-萘二磺酸)和溶剂(均三甲苯-均四甲苯混合溶剂),提高经苯酚和浓硫酸合成BPS的收率和纯度。详细研究了合成过程中所用溶剂类型及混合溶剂比例、催化剂种类及用量对BPS收率、纯度及异构体2,4'-二羟基二苯砜变化规律的影响。较好的工艺条件为:100 g均三甲苯-均四甲苯混合溶剂(二者质量比3∶1),5 g 2,6-萘二磺酸催化剂,98.5 g苯酚,在110 ℃将51.2 g硫酸滴加完成后,将反应液快速升温至回流温度172 ℃并保持5 h。BPS产品收率可达99.3%,纯度为96.49%。该方法收率高,催化剂便宜,易于工业化。 相似文献
14.
Bi-min Zhang Newby Teresa Cutright Carlos A. Barrios Qingwei Xu 《Journal of Coatings Technology and Research》2006,3(1):69-76
Zosteric acid, a natural product present in eelgrass, has been found to prevent the attachment of some bacteria and barnacles. The results indicate that it may also be effective at reducing the early stages of biofouling, such as the attachment of bacteria that lead to a biofilm. In this study, the ability of zosteric acid in reducing the early stages of fouling was evaluated using attachment studies of fresh water bacteria via two approaches. First, plain coatings were submersed in water containing zosteric acid and either enriched Lake Erie bacteria or Pseudomonas putida, a model fresh water bacteria. It was found that zosteric acid with a concentration one-tenth of its EC50 (the concentration eliminates 50% of the bacteria) was able to reduce bacterial attachment by more than 90%. The second approach incorporated zosteric acid into silicone coatings in the presence of a common solvent to achieve the slow release of zosteric acid; such coatings were then subjected to the bacterial attachment. A ~75% reduction in bacterial attachment was found for 1 wt% zosteric acid entrapped Sylgard® 184, a model silicone coating, but the reduction only achieved ~55% for 1 wt% zosteric acid entrapped in a commercial silicone coating, RTV11. 相似文献
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Acetylene as a reducing agent for the selective catalytic reduction (C2H2-SCR) of NO in the presence of excess oxygen on various Ce-exchanged zeolites was investigated for the first time. Under the conditions of 1600 ppm NO, 800 ppm C2H2, and 9.95 % O2 in He, the Ce-H-ZSM-5 (Si/Al=25) catalyst shows about 83% NO conversion to N2 at the temperatures ranged from 300 to 350 °C. It is followed by the other zeolites in the activity order of Ce-H-Y (Si/Al=2.5), Ce-H-_ (Si/A1=20∼30), and Ce-H-SAPO (Si/Al=34), Ce-H-5A (Si/Al=12). Almost no NO conversion was obtained over Ce-Na-ZSM-5 (Si/Al=25) and Na-ZSM-5 (Si/Al=25) catalyst samples. The Conversion of NO to N2 increased with O2 concentration in the range of 0.1 ∼ 9.95% over the CeH-ZSM-5 (Si/Al=25) catalyst. It is suggested that O2 plays an important role in the C2H2-SCR of NO reaction, by oxidizing NO to NO2 on acid sites in assistant with cerium species of the catalyst. A large amount of CO, which seems to be in proportion with the NO conversion to N2, was produced. Long-term experiments up to 56 h combined with a excursion of the reaction temperature up to 650 °C over the Ce-H-ZSM-5 (Si/A1=25) confirmed the catalyst’s durable performance under the reaction conditions. It is found that the de-NOx activity of Ce-H-ZSM-5 catalyst can be enhanced by the presence of 50 ppm of sulfur dioxide in the dry-feed reaction conditions. 相似文献
17.
The possibilities of producing structured phospholipids between soybean phospholipids and caprylic acid by lipase-catalyzed
acidolysis were examined in continuous packedbed enzyme reactors. Acidolysis reactions were performed in both a solvent system
and a solvent-free system with the commercially immobilized lipase from Thermomyces lanuginosa (Lipozyme TL IM) as catalyst. In the packed bed reactors, different parameters for the lipase-catalyzed acidolysis were elucidated,
such as solvent ratio (solvent system), temperature, substrate ratio, residence time, water content, and operation stability.
The water content was observed to be very crucial for the acidolysis reaction in packed bed reactors. If no water was added
to the substrate during reactions under the solvent-free system, very low incorporation corporation of caprylic acid was observed.
In both solvent and solvent-free systems, acyl incorporation was favored by a high substrate ratio between acyl donor and
phospholipids, a longer residence time, and a higher reaction temperature. Under certain conditions, the incorporation of
around 30% caprylic acid can be obtained in continuous operation with hexane as the solvent.
Presented at the 95th American Oil Chemists' Society Annual Meeting and Expo in Cincinnati, Ohio, May 10, 2004. 相似文献
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Marta Martinez-Garcia Winnie Dejonghe Lieve Cauwenberghs Miranda Maesen Karolien Vanbroekhoven Yamini Satyawali 《European Journal of Lipid Science and Technology》2021,123(2):2000225
Glucose- and xylose laurate esters are enzymatically synthesized using equimolar substrate concentrations in 2-methyl-2-butanol, comparing free lauric acid with methyl- and vinyl-laurate as acyl donors. All reactions result in ≥70% acyl donor conversions after 72 h but the activated donors are also partially hydrolyzed to lauric acid, highlighting the difficulty in controlling water presence in this particular reaction system. The esterification of xylose generates a complex product profile, with several regioisomers of monoesters and diesters. The esterification of glucose is quite selective, forming mainly the 6-O monoester (≥96%) with a small presence of two diester isomers (4%). Increasing substrate concentration up to 800 millimoles kg−1 results in lower conversion values (down to 58%) but shows that the reaction proceeds successfully even in the presence of high amounts of insoluble glucose. However, the reaction is less selective and the proportion of diester increases, becoming up to 46% (molar fraction) of the final product. Solvent recovery after esterification can be achieved by organic solvent nanofiltration through a polymeric membrane able to retain ≥80% of all reaction substrates and products. Practical Applications: The use of high substrate concentrations during the enzymatic synthesis of sugar ester biosurfactants leads to product titers that are more industrially appealing, without the need to find a solvent that can solubilize all initial substrate. The sustainability of the enzymatic conversion at mild temperatures can be enhanced by recycling of the reaction solvent through organic solvent nanofiltration, an energy efficient alternative to other traditional methods like distillation. 相似文献
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Supported 12-tungstophosphoricacid (12-TPA) and 12-tunstosilicicacid (12-TSA) were used as heterogeneous catalysts for liquid-phase
tert-butylation of m-cresol, an industrial important reaction. Alkylation reactions have been carried out with supported 12-TPA by varying different
parameters such as % loading of 12-tungstophosphoricacid onto support, mole ratio of alcohol to m-cresol, reaction temperature, amount of the catalyst, reaction time and calcination temperature to optimize the conditions.
To see the effect of the acidity on the reaction, the same reaction was studied over supported 12-TSA. Both the catalysts
give 100% selectivity for o-isomer with different % conversion. The difference in catalyst performance of both the catalyst
was correlated with the value of total acidity as well as Bronsted acidity. 相似文献