共查询到19条相似文献,搜索用时 137 毫秒
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作为氢氟烯烃(HFO)类物质,顺-1,1,1,4,4,4-六氟-2-丁烯(Z-HFO-1336)的臭氧消耗潜值(ODP)为零,温室效应潜值(GWP)极低,对环境影响很小,因其性能与前几代发泡剂相近,被看作新一代绿色环保发泡剂,其合成方法受到氟化工界的广泛关注。至今,Z-HFO-1336的合成方法主要可分为:①直接氟化C4化合物合成;②氟利昂类化合物CFC-113、HCFC-123经偶联反应制备;③由卤代甲烷与卤代烯烃经调聚反应制备。其中直接氟化法虽然路线短,但产物选择性低、催化剂稳定性差;而氟利昂类化合物偶联法污染大,调聚合成存在工艺复杂、收率低等问题。提出了两种具有学术和工业价值的研究路线:①HCFC-123自偶联一步合成Z-HFO-1336,反应涉及C—Cl键的活化、单电子转移(SET)等过程,极具理论研究意义;②以乙烯、三氟丙烯为原料经调聚反应合成,原料来源广泛,催化合成可连续进行,具有很强的工业价值。 相似文献
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《应用化工》2022,(9):2257-2260
在氟化镁基催化剂作用下,以催化氟化1,1,1,3-四氯-4,4,4-三氟丁烷(HCFC-343jfd)合成反式-1,1,1,4,4,4-六氟-2-丁烯(E-HFO-1336mzz)为研究对象,开展了反应温度、物料比、接触时间及催化剂的寿命实验。结果表明,最佳反应条件为反应温度300℃,HF与HCFC-343jfd的摩尔比为15∶1,停留时间6 s,在该条件下,HCFC-343jfd的转化率为100%,E-HFO-1336mzz的选择性为95.1%,且连续反应300 h后,HCFC-343jfd的转化率>99.0%,E-HFO-1336mzz的选择性>94.5%。采用新型无铬催化剂,获得了最佳E-HFO-1336mzz反应工艺,具有较高的氟化工业应用前景。 相似文献
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叙述了2-溴七氟丙烷的性质及其制备方法,1种是六氟丙烯先和溴反应制得1,2-二溴六氟丙烷,1,2-二溴六氟丙烷与KF反应得到2-溴七氟丙烷;另1种是六氟丙烯先与HF反应制备1,1,1,2,3,3,3-七氟丙烷(HFC-227ea),HFC-227ea与溴反应得到2-溴七氟丙烷。目前实现工业化的方法实质上都是六氟丙烯法。介绍了2-溴七氟丙烷在医药农药中间体领域的应用情况。认为今后研究重点是将2-碘七氟丙烷参与的反应尽可能地用2-溴七氟丙烷代替,以合成更多的医药农药关键中间体;2-溴七氟丙烷制备的医药农药关键中间体主要是4-七氟异丙基苯胺衍生物,而其中2-甲基-4-七氟异丙基苯胺是合成氟虫酰胺的关键中间体,应重点关注。 相似文献
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The hydrodehalogenation of halon 1211 over Ni, Pd and Pt supported on γ-alumina was studied. The effect of reaction temperature and hydrogen/halon 1211 input ratio was examined. Steady state catalytic activities of Pd and Pt are very similar, and much higher than that of Ni. Hydrodehalogenation over Pd favours the formation of CH2F2, while Pt and Ni produce primarily CH4 and CH3F, respectively. Product profiles suggest that the hydrodehalogenation of halon 1211 over Pd and Pt follows a reaction mechanism which is similar to hydrodehalogenation of CFC-12. Over Ni catalysts, the primary hydrodehalogenation reactions are those which first remove one halogen (Cl or Br) and then remove two halogens (one F and either Br or Cl). The higher mobility of hydrogen atom on the surface of Pt is consistent with the observation that only trace amounts of C2+ hydrocarbons were detected when Pt was used compared with Pd and Ni. Increasing selectivity to CH2F2 with time on stream over Pd and Pt is mainly ascribed to the transformation of support alumina to partially fluorinated alumina. 相似文献
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灭火剂发展现状与未来 总被引:3,自引:0,他引:3
合理选择灭火剂是即时有效扑灭燃烧火焰和防火防爆的关键。对常用的物理灭火剂和化学灭火剂的特点、灭火机理和适用范围作了归纳 ,着重介绍了哈龙和哈龙替代品的灭火机理 ,并对物理灭火剂和化学灭火剂之间的协同作用作了重点阐述 相似文献
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Eric M. Kennedy Kai Li Behdad Moghtaderi Bogdan Z. Dlugogorski 《Chemical Engineering Communications》1999,176(1):195-200
We report the results of an experimental and kinetic modeling study of gas-phase reaction between methane and halon 1301 (CBrF3). At 1000 K, with an equimolar feed of CH4 and CBrF3 and at a residence time of 1 second, CHF3 and CH3Br are produced at selectivities in excess of 90%. Other reaction products detected include C2H2F2, C2H2, C2H2, and CHBrF2. Very good agreement between kinetic modeling and experimental results was obtained. 相似文献
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Nicola Silvestris Giovanni Simone Giulia Partipilo Emanuela Scarpi Vito Lorusso Anna Elisabetta Brunetti Evaristo Maiello Angelo Paradiso Anita Mangia 《International journal of molecular sciences》2014,15(9):15767-15777
Enzymatic activation of irinotecan (CPT-11) is due to carboxylesterase (CES), and its pharmacological behavior is influenced by drug resistance-related proteins. We previously reported that the clinical response and prognosis of metastatic colorectal cancer (mCRC) patients did not differ in tumors with different thymidylate synthase (TS) or topoisomerase-I (Topo-I) expression. Using immunohistochemistry (IHC), we evaluated the biological role of CES2 and the expression of breast cancer resistance protein (BCRP/ABCG2) in 58 consecutive mCRC patients, who had undergone a first-line CPT-11/5-FU/leucovirin (FOLFIRI) regimen. The expression of these proteins was also examined in a group of synchronous lymph nodes and liver metastases. Furthermore, all samples were revaluated for TS and Topo-I expression. High expression of CES2, ABCG2, TS and Topo-I was observed in 55%, 56%, 38% and 49% of patients, respectively. There was a significant association between high TS and high ABCG2 expression (p = 0.049). Univariate analysis showed that only TS expression significantly impacted on time to progression (p = 0.005). Moreover, Cox’ multivariate analysis revealed that TS expression was significantly associated with overall survival (p = 0.01). No significant correlation was found between investigated markers expression and clinical response. Topo-I expression resulted in being significantly higher in liver metastases with respect to the corresponding primary tumors (p < 0.0001), emphasizing the role of Topo-I expression in metastatic cancer biology. In primary tumor tissues, CES2 expression tended to be higher than that observed in liver metastasis tissues (p = 0.05). These preliminary data may suggest CES2 over-expression as a potential marker of malignant phenotype. In light of these findings, we suggest that Topo-I expression together with TS expression could be associated with metastatic progression of CRC. Further studies are warranted with the aim of evaluating the potential predictive and prognostic role of CES2 and ABCG2 in larger series of patients. 相似文献
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Photocatalytic water splitting for hydrogen production (H2) is one of the main potential applications of photocatalytic technology, which can use solar energy as the energy required for chemical reactions to alleviate the energy crisis. In this work, zero-dimensional/two-dimensional (0D/2D) contact surface CdS/α-Fe2O3 (CF) heterojunction photocatalyst was synthesized via a simple solvothermal method. Photocatalytic hydrogen production experiments revealed that the CF-15 sample shows the optimal photocatalytic H2 rate (1806 (μmol·h-1·g-1)) and apparent quantum efficiency (AQE = 13.7% at λ = 420 nm). The enhancement of photocatalytic performance is mainly attributed to the contact of 0D/2D interface and the synergistic effect of Z-scheme electron transfer mechanism. This work provides an effective way for modified composite semiconductor photocatalyst by constructing special interface heterojunction to achieve highly efficiently catalysis. 相似文献
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氟胺类物质是最有希望作为哈龙替代品的含氮化合物之一,全氟三乙胺作为典型的氟胺类物质具有良好的灭火效果。为研究全氟三乙胺热解机理,在管式加热炉内对全氟三乙胺进行热分解,通过GC-MS分析全氟三乙胺在不同温度条件下的热解产物,并用Gaussian软件对其热解反应路径进行理论计算。结果表明:保持停留时间为10 s,全氟三乙胺的初始热解温度为600℃,750℃完全热解,热解产物有C4F9N、C3F7N、C2F6和C3F8,热解温度较低时C4F9N体积分数最大,热解温度较高时C3F7N体积分数最大。在全氟三乙胺热解反应路径计算中,全氟三乙胺分子中的C—C键断裂后存在1条反应路径,可生成实验产物中的C3F8;全氟三乙胺分子的C—N键断裂后存在3条反应路径,可生成实验产物中的C3F7N、 C4F9N和C2F6。全氟三乙胺热解后产生的CF3自由基可与H、OH自由基发生反应,从而产生灭火作用。此外,其热解产物C4F9N和C3F7N具有CN双键,更容易与燃烧活泼自由基·OH、·H发生化学作用,对研究全氟三乙胺的灭火机理具有十分重要的意义。 相似文献