三芳基膦配体的合成研究

从间溴苯酚出发, 利用新的合成方法经五步反应合成了一系列具有不同烷氧基的芳基膦配体. 改进后的方法可方便地通用于在苯环上具有各种不同基团基的膦配体衍生物的合成, 且有原料易得、操作简单、产率较高的优点.     

双膦配体修饰铑催化乙酸乙烯酯氢甲酰化反应(英文)

研究了双膦配体对铑催化的乙酸乙烯酯氢甲酰化反应的促进作用,结果表明,在优化反应条件下,以双膦化合物2,2’-二(二苯膦甲基)-1,1’-联苯(BISBI)为配体时,铑催化乙酸乙烯酯氢甲酰化反应的TOF(转化频率)值达到4000h1,生成2-乙酰氧基丙醛的选择性99%.当在较温和的条件下Rh/BISBI催化乙酸乙烯酯氢甲酰化反应较长时间时TON(转化数)值达到9200,成醛率超过90%,2-乙酰氧基丙醛选择性仍保持99%.     

硅胶键合膦的制备及其对铑络合物催化1-辛烯氢甲酰化反应的影响

以硅胶为载体, 采用键合接枝法将2-(二苯膦基)乙基三乙氧基硅烷(DPPES)共价键合于硅胶表面, 制备了性能优良的硅胶键合型膦配体(以SiO₂(PPh₂)表示). 以SiO₂(PPh₂)为配体, Rh(acac)(CO)₂ (acac:乙酰丙酮)为催化前体, 负载铑膦络合物催化剂(SiO₂(PPh₂)/Rh)在1-辛烯氢甲酰化反应中原位生成. 对生成的负载型催化剂和硅胶键合型膦配体进行了傅里叶变换红外(FTIR)光谱表征, 考察了膦/铑摩尔浓度比([P]/[Rh])、温度等因素对铑催化的长链1-辛烯氢甲酰化反应的影响. 结果表明, 膦/铑摩尔浓度比的增加能显著提高反应的成醛选择性, 降低铑的流失. 在[P]/[Rh]=12、363 K、2.0 MPa、1.5 h 的温和反应条件下, 1-辛烯转化率和成醛选择性分别可达98.4%和95.3%, 其催化活性与DPPES或三苯基膦(TPP)作配体时的均相铑催化相近. 催化剂循环4 次后, 反应活性无明显下降, 1-辛烯转化率均在97.0%左右, 经电感耦合等离子体原子发射光谱(ICP-AES)检测,有机相中铑流失低于0.1%.     

十六烷基三羟乙基溴化铵促进1-辛烯氢甲酰化水/有机两相反应研究

研究了水/有机两相体系中表面活性剂十六烷基三羟乙基溴化铵(CTHAB)对Rh/TPPTS (TPPTS: 三[间-磺酸钠基苯基]膦)催化的1-辛烯氢甲酰化反应的促进作用, 初步证实了CTHAB分子中的羟基可与催化活性物种的铑之间发生配位. 与传统表面活性剂十六烷基三甲基溴化铵(CTAB)相比, 表面活性剂CTHAB的添加不仅加速了水/有机两相1-辛烯氢甲酰化反应, 而且提高了成醛的正/异比, 促进作用明显. 在 [Rh]=0.8 mmol/L, [TPPTS]/[Rh]=40, [CTHAB]=4.0 mmol/L, 90 ℃, 0.5 MPa, 1.5 h时, 生成醛的TOF为497 h^-1, 正/异比(L/B)可达25.6. 催化剂经7次循环后, 反应活性和成醛正/异比无明显下降. 该催化体系对不同长链烯烃氢甲酰化反应同样具有促进作用.     

一场科学的辩论赛——谣言有罪盐无罪

Amid five tastes, only salt is indispensable. As a kind of essential nutrition, salt plays a vital role in our daily life. Although the salt is in small particle size, yet it received a lot of rumors. In recent years, rumors on salt have sprung like mushrooms including sea salt, iodized salt, low sodium salt, additive in salt and so on. To stop the rumors from spreading and to clarify that the salt is innocent, a debate competition was applied to tell the truth:rumors are guilty rather than salt!     

咖啡因女神的复仇

通过虚构咖啡因女神的复仇计划,以奇幻的手法介绍了咖啡因的历史、化学性质、提取方法、体内代谢途径及生理功能特征。用通俗易懂的语言和扣人心弦的情节科普了咖啡因在体内的作用机制。文中一个少年因无知而顶撞了咖啡因女神,引发女神复仇行动,她引诱少年提取、销售毒品级咖啡因,又因少年的道歉而心软,在交易已经达成之时决定停止复仇。然而少年销售咖啡因却是因其药物性质而非毒品性质,女神的复仇计划落空,皆大欢喜。     

点石成金——人造钻石的真相

"A diamond is forever", diamond is not only seen as a kind of precious stones, but also used in industry. With technology and science continuing to develop, synthetic diamond is developing rapidly. To answer readers' confusion of synthetic diamond, there is a wonderful story, which tells readers about structure and properties of graphite and diamond, the basic method and catalysis of synthetic diamond.     

一闪一闪亮晶晶,我们身体需要锌

Although their contents in the human body are extremely low, even less than 0.01 wt%, trace elements are essential for the human body. As a kind of trace element, zinc plays an important role in human growth and development, reproductive inheritance, immunity, endocrine and other important physiological processes. At the same time, zinc deficiency is also a common phenomenon among Chinese children. Through the fictional experience of the fictional Zinc Gu Cheng, this article uses the anthropomorphic approach to popularize the role of zinc. Finally, the story ends with a little girl's dream. We hope that through this short story, people can understand the importance of zinc to the human body and realize the indispensable role of trace elements.     

室温有氧条件下高稳定性Pd(P-Phos)Cl2配合物催化Suzuki-Miyaura交叉偶联反应

制备了新型Pd(P-Phos)Cl₂配合物, 并通过¹H, ¹³C和³¹P核磁共振及X射线单晶衍射对其结构进行了确认及表征. 结果表明, 该配合物是室温有氧条件下Suzuki-Miyaura交叉偶联反应的高稳定高效催化剂, 并具有广泛的底物适用性. 催化剂用量较低, 且转化数(TON)最高可达49000.     

联苯类手性双膦配体的合成方法改进

从易获得的间溴苯甲醚出发, 利用改进后的方法经六步反应合成了手性双膦配体(R)-和(S)-6,6-二甲氧基-2,2-二(二芳基膦基)-1,1'-联苯[(R)-和(S)-6], 改进后的方法简化了合成步骤, 提高了收率, 可方便地用于在苯环上具有不同取代基的联苯类手性双膦配体衍生物的合成.