氯化钕异丙醇合物/三异丁基铝催化剂活性中心的分离与聚合

研究了氯化钕异丙醇合物/三异丁基铝催化剂的配制方式对异戊二烯聚合和聚合产物特性的影响。 将催化剂的悬浊液分离得到清液和沉淀，分别进行聚合，并对沉淀进行了拉曼光谱表征。 结果表明，(Nd+Al)配制方式在室温和70 ℃下所得催化剂的清液均无活性，并且70 ℃下所得催化剂的沉淀也无活性。 (Nd+IP+Al)配制方式在任何条件下所得催化剂的各组分均有活性，推测该配制方式所得催化剂可能形成的是2种活性中心：(isoprenyl)2NdCl和(isoprenyl)NdCl2。 配制方式对聚异戊二烯的微观结构没有影响(96%左右)，分离前的悬浮催化剂和沉淀催化剂所得聚异戊二烯均为高分子量(Mn＞100×104)和窄分子量分布(Mw/Mn＜2.0)的聚合物，但是分离后清液所得聚合物的分子量较低(Mn＜30×104)，分子量分布很宽(Mw/Mn＞5.0)。     

马来酸酐接枝稀土异戊橡胶接枝率的测试方法

以马来酸酐(MAH)和稀土异戊橡胶(IR)聚合液为主要原料,采用溶液接枝改性反应制备了马来酸酐接枝稀土异戊橡胶(IR-g-MAH)。以IR-g-MAH接枝率的测试方法为研究对象,对比直接滴定法和返滴法,并进一步优化直接滴定法的测试条件。实验结果表明,直接滴定法测试的结果准确度高、重复性好,且测试过程简单。其较优的测试条件为:水解试剂为乙醇,样品用量为0.2~0.5g,KOH-乙醇标准溶液浓度为0.02~0.06mol/L。     

基于光腔衰荡光谱的便携式呼气异戊二烯分析仪性能评估

呼气异戊二烯是一种内源性代谢产物,其含量与人体血液中的胆固醇水平存在关联。但人体呼气影响因素众多,寻找其与胆固醇水平诊断参数的定量相关性,需要对选取的特定人群进行有效的呼吸气体分析（实时、在线、高灵敏度、高选择性、高精度的大量呼气数据获取）。光腔衰荡光谱（CRDS）是一种具有极高灵敏度、稳定性和选择性的光谱技术。采用目前市场在售的单波长紧凑型半导体紫外激光器,搭建了一套基于CRDS的呼气异戊二烯分析仪,该分析仪主要由激光系统、真空腔体、光电探测模块以及数据采集模块构成。线性拟合的结果显示所获得的衰荡信号接近单指数衰减（R2=0.998 39）,符合朗伯-比尔定律。探究了不同信号平均次数对衰荡信号稳定性的影响,综合考虑衰荡信号的稳定性和分析仪的响应时间,采用128次作为实验过程中的信号平均次数。对呼气异戊二烯分析仪的性能进行了测试,为了表征分析仪的稳定性,持续测量了分析仪16 min的真空衰荡时间。使用氮气、空气和呼吸样本,测量了呼气异戊二烯分析仪的重复性和响应速度。为了测试分析仪的线性度,测量了不同粒子数密度的异戊二烯标准气体（10×10-9,30×10-9,50×10-9,100×10-9,200×10-9）的衰荡时间。最后分析了在224 nm测量异戊二烯存在的光谱干扰问题（NO,N₂O和丙酮）。实验表明：分析仪具有高的灵敏度（检测极限为0.49×10-9）、良好的重复性、稳定性（0.48%）、近实时的响应速度（1秒测量一个数据）和良好的线性度（R2=0.993 13）,将检测极限提高至现有水平的1/1 000。研究证明基于CRDS的便携式呼气异戊二烯分析仪可实现对人体呼气异戊二烯的有效分析。     

New insights into the palladium-catalysed synthesis of δ-lactones from 1,3-dienes and carbon dioxide

Two-coordinate Pd(0) complexes are shown to be important intermediates in the telomerization of 1,3-dienes and CO₂ using palladium/phosphine catalysts without additives. Only one phosphorus atom is bound to palladium during the C–C bond forming steps, but the second phosphorus atom is crucial in the early stages of the catalytic cycle and for the elimination of the product. A ligand that gave an active palladium catalyst for the coupling of 1,3-butadiene and CO₂ has been designed. Use of a palladium catalyst in the reaction of isoprene with CO₂ allowed for the first time isolation and NMR spectroscopic characterization of the resulting mixture of lactones.     

“In-situ” monitoring activation and reaction on very absorbing catalytic solid by DRIFT spectrometer

The FTIR's well-known advantages are strongly shown by the use of new infrared techniques. Both advantages of FTIR and diffuse reflectance make this coupling particularly important in the development of infrared studies.Sensitivity and rapidity of the FTIR spectrometer, added to the extremely simple preparation of the sample, allowed by diffuse reflectance attachment, give a high performing tool particularly in catalysis in the view of understanding the catalytic reactions mechanisms. We have chosen thein-situ study of two catalytic systems active in selective hydrogénation of dienes: a copper-chromium oxide and Cu/Al₂O₃ .     

Insights into the Intraspecific Variability of the above and Belowground Emissions of Volatile Organic Compounds in Tomato

The in-vivo monitoring of volatile organic compound (VOC) emissions is a potential non-invasive tool in plant protection, especially in greenhouse cultivation. We studied VOC production from above and belowground organs of the eight parents of the Multi-Parent Advanced Generation Intercross population (MAGIC) tomato population, which exhibits a high genetic variability, in order to obtain more insight into the variability of constitutive VOC emissions from tomato plants under stress-free conditions. Foliage emissions were composed of terpenes, the majority of which were also stored in the leaves. Foliage emissions were very low, partly light-dependent, and differed significantly among genotypes, both in quantity and quality. Soil with roots emitted VOCs at similar, though more variable, rates than foliage. Soil emissions were characterized by terpenes, oxygenated alkanes, and alkenes and phenolic compounds, only a few of which were found in root extracts at low concentrations. Correlation analyses revealed that several VOCs emitted from foliage or soil are jointly regulated and that above and belowground sources are partially interconnected. With respect to VOC monitoring in tomato crops, our results underline that genetic variability, light-dependent de-novo synthesis, and belowground sources are factors to be considered for successful use in crop monitoring.     

Characterization of organosulfates from the photooxidation of isoprene and unsaturated fatty acids in ambient aerosol using liquid chromatography/(-) electrospray ionization mass spectrometry

In the present study, we have characterized in detail the MS(2) and MS(3) fragmentation behaviors, using electrospray ionization (ESI) in the negative ion mode, of previously identified sulfated isoprene secondary organic aerosol compounds, including 2-methyltetrols, 2-methylglyceric acid, 2-methyltetrol mononitrate derivatives, glyoxal and methylglyoxal. A major fragmentation pathway for the deprotonated molecules of the sulfate esters of 2-methyltetrols and 2-methylglyceric acid and of the sulfate derivatives of glyoxal and methylglyoxal is the formation of the bisulfate [HSO(4)](-) anion, while the deprotonated sulfate esters of 2-methyltetrol mononitrate derivatives preferentially fragment through loss of nitric acid. Rational interpretation of MS(2), MS(3) and accurate mass data led to the structural characterization of unknown polar compounds in K-puszta fine aerosol as organosulfate derivatives of photooxidation products of unsaturated fatty acids, i.e. 2-hydroxy-1,4-butanedialdehyde, 4,5- and 2,3-dihydroxypentanoic acids, and 2-hydroxyglutaric acid, and of alpha-pinene, i.e. 3-hydroxyglutaric acid. The deprotonated molecules of the sulfated hydroxyacids, 2-methylglyceric acid, 4,5- and 2,3-dihydroxypentanoic acid, and 2- and 3-hydroxyglutaric acids, showed in addition to the [HSO(4)](-) ion (m/z 97) neutral losses of water, CO(2) and/or SO(3), features that are characteristic of humic-like substances. The polar organosulfates characterized in the present work are of climatic relevance because they may contribute to the hydrophilic properties of fine ambient aerosol. In addition, these compounds probably serve as ambient tracer compounds for the occurrence of secondary organic aerosol formation under acidic conditions.     

Nd-Al双金属配合物催化双烯聚合反应动力学

以Ｎｄ－Ａｌ双金属配合物为催化剂,考察了丁二烯和异戊二烯聚合反应的动力学,得到稳态聚合速率方程为Ｒｐ＝ｋ〔Ｍ〕〔Ｎｄ〕＾ｎ（ｎ＝１）;丁二烯比异戊二烯有更大的表观增长速率常数ｋ,这些与聚合体系中是否存在过量的烷基铝无关。对多组分稀土催化剂作用下异戊二烯聚合反应动力学方程中出现较高ｎ值的现象进行了初步的探讨。