吸热型碳氢燃料热沉测定装置研究

根据傅立叶定律径向系统的一维传热模型结合Tian's方程建立了一套高温流动型热量计,用于吸热型碳氢燃料的热沉测定和引发剂筛选;考察了系统的热稳定性能,用电标定的方法对仪器在500、550、600、650、700、750、800 ℃时的量热系数进行了标定,绘制了正庚烷在800 ℃、载气流速为0.04 m3/h条件下热裂解的热谱曲线,以正庚烷为模型化合物测定了其热沉.实验证明仪器基线稳定,数据可靠,复现性能良好,有较高的灵敏度和测量精度,能够满足实验需要和工作要求.     

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利用分子动力学方法模拟了碳原子与碳氢薄膜的作用过程。探讨了不同入射能量对碳原子与碳氢薄膜相互作用的影响。模拟结果表明碳原子与碳氢薄膜作用会在表面形成碳薄膜。随着入射能量的增加,碳薄膜厚度变薄。在碳薄膜中碳原子的成键形式主要为Csp2-Csp2和Csp2-Csp3,随入射能量的增加,碳原子键价结合形式从Csp2-Csp2向Csp2-Csp3转化。     

1, 1'-双(二苯基膦基)二茂铁介导的芳烃碳氢键芳基化反应制备联芳基骨架

The broad existence of the biaryl linkage in bioactive organic molecules and functional materials makes it an attractive synthesis target via construction of aryl-aryl carbon bonds. Transition metal catalyzed cross-coupling reactions of two pre-functionalized aryl partners, e.g., Suzuki-Miyaura cross-coupling and Negishi cross-coupling reactions, are the main methods typically used for the construction of biaryl linkages. Since the end of the last century, transition metal catalyzed direct C―H arylation of unactivated arenes has emerged as a practical alternative to the well-established cross-coupling strategies. However, the use of transition metal catalysts and/or organometallic reagents would lead to problems, such as the disposal of waste from large-scale syntheses and the removal of heavy metal contaminants from pharmaceutical intermediates. In this regard, the base-promoted homolytic aromatic substitution (BHAS) reaction of aryl halides with unactivated arenes offers a simpler strategy for the synthesis of biaryl scaffolds, and avoids the use of transition metals. Although the BHAS reaction can proceed to a small extent without any additives, particularly at elevated temperatures, the addition of organic promoters would significantly accelerate the reaction rate and improve the overall efficiency of the process. Over the past ten years, a wide variety of N- and O-based organic promoters have been developed to promote the BHAS reaction in the presence of the tert-butoxide base. The mechanism of the BHAS reaction has been studied extensively, and is accepted as occurring via a radical chain process involving an aryl radical. However, the role and mode of initiation of most organic promoters studied remain controversial. The development of more and varied organic promoters will surely promote the mechanistic understanding and further development of the BHAS reaction. Herein, we report that 1, 1'-bis(diphenylphosphino)ferrocene (dppf, or DPPF) can act as a P-based promoter to facilitate the direct arylation of unactivated arenes with aryl iodides using potassium tert-butoxide as the base and electron donor. A broad range of aryl iodides and arenes reacted smoothly under the optimized reaction conditions, giving arylated products in good yields and with high regio-selectivity. Intramolecular C―H arylation also worked well following a sequence of single electron transfer (SET)/initiation, 5-exo-trig aryl radical addition, ring expansion, deprotonation, and re-aromatization/propagation. A mechanistic study indicated that the diphenylphosphino group of dppf played a vital role in the initiation step by enhancing the SET-inhibiting ability of the tert-butoxide anion. A primary kinetic isotope effect was observed in the parallel reactions between 4-methoxy-iodobenzene with benzene and deuterated benzene, implying that the deprotonation of the cyclohexadienyl radical intermediate by tert-butoxide was the rate-determining step in the radical chain pathway.     

基于双重碳氢活化的γ,δ-不饱和酰胺与炔烃的脱氢环化反应

吡啶酮是一类重要的含氮杂环骨架,广泛存在于天然产物和药物分子中,是重要的化学转化中间体,其合成与修饰是现代医药学及化学领域的研究热点之一。杂环母核的官能团化修饰是该类化合物较为常见的衍生方式,但要求特定位点的反应基团预组装。相较而言,两个片段分子的直接偶联环化,是更为直接且具备较高实用性的合成类似杂环分子库的方式。近年来,过渡金属催化的丙烯酰胺与炔烃的氧化偶联制备吡啶酮类化合物取得了长足进展,关键活化步骤为过金属催化剂对酰胺β位sp2碳氢键的活化。然而,通过对更加易得的烷基酰胺进行sp3碳氢键活化制备杂环骨架依然具有较高的挑战性。其原因主要在于较低的α-酸性使得酰胺的脱氢反应变得异常困难。本课题组最近报道了温和条件下,铱催化的酰胺、酸及酮的空气脱氢反应。反应中产生的烯丙基-铱中间体被认为提高了酰胺的α-酸性,从而加速了脱氢过程。在此基础上,我们报道一种铑(Ⅲ)催化的γ,δ-不饱和酰胺与炔烃类化合物的脱氢环化新方法,制备一系列多取代的吡啶酮类化合物。催化循环历经酰胺导向铑(Ⅲ)对底物β位点的sp3碳氢活化,进而脱氢生成共轭的双烯酰胺中间体,随后酰胺基团再次导向铑(Ⅲ)对β位的sp2碳氢活化,进而与炔烃进行插入,环化获得吡啶酮。该反应对各种官能团具有较好的容忍性。γ-烯基结构不但促进第一步的酰胺脱氢,而且是杂环产物后修饰的重要位点。机理实验表明双烯酰胺的确为反应中间体之一。核磁实验显示酰胺脱氢迅速,而控制实验则表明炔烃的插入过程的选择性与其电性有密切的关系,有可能参与了该反应的速控步。     

无金属参与的氧原子邻位C(sp~3)—S键的构筑

以二叔丁基过氧化物(DTBP)为氧化剂,苯硫酚为硫化试剂,在无金属参与的条件下,于120℃下采用一步法合成了硫代苄醚.这种构筑C(sp~3)—S键的方法具有高原子经济性和高选择性的优点,并以较高的收率获得了一系列目标化合物.     

羰基兼容的氟代反应及远端氟代脂肪酮合成的近期进展

含氟化合物在医药、农药以及材料领域有着广泛的应用, 然而温和而高效的构建sp³碳氟键却极具挑战性. 氟代脂肪酮类化合物是一类重要的含氟合成砌块. 本文将从碳氢键氟化、脱羧脱硼氟化、双键氟化、开环氟化四个方面简要概述近年来羰基兼容的氟代反应以及在合成远端氟代脂肪酮方面取得的重要进展.     

十氢萘的超临界裂解性能分析

以十氢萘为吸热型碳氢燃料的模型化合物,研究其在550~610 ℃和0.1~3.5 MPa条件下的热裂解过程.实验表明：不同温度（特别是相对较高的590和610 ℃）下,十氢萘在0.1~2.0 MPa压力下的转化率增加较为显著;十氢萘热裂解的主要气体产物有甲烷、乙烷、乙烯、丙烷、丙烯和碳原子数大于3的组分（C3⁺）等;在相同温度条件下,甲烷、乙烯的含量随压力增加而降低;乙烷、丙烷、丙烯和C3⁺的含量随压力增加而增加.裂解的气相产物中烯烃含量随温度升高而降低.液相产物主要包括环戊烷类、环戊烯类、环己烷类、环己烯类、苯类、茚类、萘类和十氢萘异构化产物等.根据液相产物的主要成分,推测了可能的裂解过程.由十氢萘双自由基引发,自由基通过氢转移、β-断裂、异构化、脱氢和加成反应等方式继续反应形成目标产物.     

超临界条件下吸热型碳氢燃料氧化安定性研究

采用超临界反应装置测定了吸热型碳氢燃料HDF-1的氧化安定性能．结合吸光度分析结果、红外谱图以及氧化沉积量的测定结果,考察了2,6-二叔丁基对甲酚（BHT）对燃料氧化安定性能的影响．结果表明,如果反应时间为3h,BHT能够将燃料的氧化沉积量降低64％,有效地提高燃料的氧化安定性能,但BHT对缓解燃料颜色变化并无明显效果．     

乳液中结晶与溶解的超声监测

许多油-水乳液的性质与分散相的固、液态有关。例如,食品乳液中液滴与悬浮粒子之间小分子的分布和聚集受到分散相阶段的强烈影响。有许多技术被用来监测乳液的结晶过程,它们包括:膨胀测定法、宽带核磁共振、X射线衍射、各种热学分析法及电子自旋共振。本文所描述方法的原理是测量乳液中的超声声速和声衰减。该方法与其它现有方法相比,具有成本低、