Acyclic Triene Metathesis Polymerization with Chain‐Stoppers: Molecular Weight Control in the Synthesis of Branched Polymers

The synthesis of branched macromolecules from renewable resources via olefin metathesis is described. We observed that it is possible to control the molecular weight during the acyclic triene metathesis (ATMET) of a triglyceride by the application of methyl acrylate as a chain stopper for this straightforward one step one pot polymerization. The resulting branched materials were characterized by GPC, NMR as well as ESI‐MS and the combination of these techniques provided valuable insights into the polymer structure as well as occurring side reactions during this olefin metathesis polymerization reaction.

     

醇溶性聚酰胺树脂的制备

醇溶性聚酰胺树脂的制备邢存章，徐新国，董铭章（山东轻工业学院化工系济南２５０１００）关键词醇溶聚酰胺，羟基丙二肢，聚合脂肪酸，二聚酸，制备热塑聚酰胺树脂是由植物油聚合脂肪酸与乙二胺制得的分子量３０００～９０００的线型缩聚物。早期的树脂溶于芳烃用作柔性...     

深黄被孢霉催化转化脂肪醇合成不饱和脂肪酸的初步研究

The unsaturated fatty acids were biosynthesized by Mortierella isabellina grown on fatty alcohols (butanol, hexadecanol, octadecanol, etc) at 28 ℃ for 5 d and the fatty acid composition was analyzed by gas chromatography. The results showed that more lipid and higher content of the corresponding unsaturated fatty acids could be biosynthesized by the fungi grown on the long chain alcohols. Meanwhile, long chain alcohols were converted more quickly and had higher conversion. It suggests that long chain alcohols are more practical substrates.     

Divergent Dendrimer Synthesis via the Passerini Three‐Component Reaction and Olefin Cross‐Metathesis

The combination of the Passerini reaction and olefin cross‐metathesis is shown to be a very useful approach for the divergent synthesis of dendrimers. Castor oil‐derived platform chemicals, such as 10‐undecenoic acid and 10‐undecenal, are reacted in a Passerini reaction with an unsaturated isocyanide to obtain a core unit having three terminal double bonds. Subsequent olefin cross‐metathesis with tert‐butyl acrylate, followed by hydrogenation of the double bonds and hydrolysis of the tert‐butyl ester, leads to an active core unit bearing three carboxylic acid groups as reactive sites. Iterative steps of the Passerini reaction with 10‐undecenal and 10‐isocyanodec‐1‐ene for branching, and olefin cross‐metathesis with tert‐butyl acrylate, followed by hydrogenation and hydrolysis allow the synthesis of a third‐generation dendrimer. All steps of the synthesis are carefully characterized by NMR, GPC, MS, and IR.

     

苦味酸在聚酰胺树脂上的吸附热力学及动力学

在静态下,考察了温度对聚酰胺树脂吸附水溶液中苦味酸的影响,探讨了吸附的热力学、动力学规律.结果表明:温度对吸附的影响较小,等温吸附规律可用Freundlich或Langmuir方程表示;吸附过程为熵驱动的吸热、熵增的自发过程;属物理吸附范畴;吸附动力学规律可用q=aeb/t吸附速率方程表示,属颗粒内扩散控制.     

Fatty Acid Derived Monomers and Related Polymers Via Thiol‐ene (Click) Additions

Thiol‐ene additions of methyl 10‐undecenoate, a castor oil derived renewable platform chemical, were studied with the goal of preparing a set of renewable monomers. Good to excellent yields were obtained for these solvent and initiator free thiol‐ene additions. The resulting monomers were then polymerized using TBD as a catalyst, to linear as well as hyperbranched polyesters that also contain thio‐ether linkages. All thus prepared polymers were fully characterized (NMR, GPC, DSC, and TGA) and the results of these investigations will be discussed within this contribution. The thermal analysis of these polymers revealed melting points in the range from 50 to 71 °C. Moreover, no significant weight loss was observed below 300 °C.

     

Renewable Non‐Isocyanate Based Thermoplastic Polyurethanes via Polycondensation of Dimethyl Carbamate Monomers with Diols

1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene (TBD)‐catalyzed polycondensation reactions of fatty acid derived dimethyl dicarbamates and diols are introduced as a versatile, non‐isocyanate route to renewable polyurethanes. The key step for the synthesis of dimethyl carbamate monomers from plant‐oil‐derived dicarboxylic acids is based on a sustainable base‐catalyzed Lossen rearrangement. The formed polyurethanes with molecular weights up to 25 kDa are characterized by SEC, DSC, and NMR analysis.

     

Grubbs Catalysts Immobilized on Merrifield Resin for Metathesis of Leaf Alcohols by using a Convenient Recycling Approach

Three new types of heterogeneous catalysts were prepared using a facile approach by the immobilization of Grubbs catalysts on PEGylated Merrifield resin. One of the immobilized catalysts was more efficient than the free catalyst for the metathesis of leaf alcohols in conversion and selectivity and was reused repeatedly (up to 5 cycles) with only a slight loss of activity (10.5 %). The long-chain PEGylated linker provided an appropriate distance between the resin and the catalytic center so that the ruthenium catalysts acted as the free catalyst.     

Cross‐metathesis of biorenewable dioxalates and diols to film‐forming degradable polyoxalates

Starting from commonly available sugar derivatives, a single step protocol to access a small family of isohexide‐dioxalates ( 2a–c ) has been established. The synthetic competence of 2a–c has been demonstrated by subjecting them to condensation polymerization. Quite surprisingly, the proton NMR of poly(isomannide‐co‐hexane)oxalate revealed a 1:2 ratio between isomannide‐dioxalate ( 2a ) and 1,6‐hexanediol ( 3a ) in the polymer backbone. This intriguing reactivity was found to be an outcome of a cross metathesis reaction between 2a and 3a . The cross metathesis products 3a ”[2‐(2‐methoxyacetoxy)ethyl 2‐(2‐hydroxyethoxy)‐2‐(λ3‐oxydanylidene)acetate] and 2a ‘(3R,6R)‐6‐hydroxyhexahydrofuro[3,2‐b]‐furan‐3‐yl methyl oxalate were isolated in a control experiment. Based on direct and indirect evidence, and control experiments, an alternative polymerization mechanism is proposed. Polymerization conditions were optimized to obtain polyoxalates P1(2a‐3a)‐P9(2c‐3c) with molecular weights in the range of 14,000–68,000 g/mol, and narrow polydispersities. The identity of the polyoxalates was unambiguously established using 1‐2D NMR spectroscopy, MALDI‐ToF‐MS, and GPC measurements. The practical implication of these polymers is demonstrated by preparing transparent, mechanically robust films. The environmental footprint of the selected polyoxalates was investigated by subjecting them to solution and solid‐state degradation. The polyoxalates were found to be amenable to degradation. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1584–1592     

直链饱和一元胺物理性质递变规律研究

以直链饱和一元胺同系物结构重复单元数值连续变化为模型假定 ,获得了描述直链饱和一元胺同系物物理性质递变规律的数学表达式 :P =a +bnc,其中a、b、c均为常数 ,n为结构重复单元数值 ,P为直链饱和一元胺同系物的物理性质 .通过非线性回归分析 ,得到回归方程 ,结果表明直链饱和一元胺同系物的物理性质与重复单元数值之间满足上述关系式 ,均显示优良的相关性     

直链饱和一元醇物理性质递变规律研究

以直链饱和一元醇同系物结构重复单元数值连续变化为模型假定 ,获得了描述直链饱和一元醇同系物物理性质递变规律的数学表达式 :P =(a0 +a1n) / (1+b1n) ,其中a0 ,a1,b1均为常数 ,n为结构重复单元数值 ,P为直链饱和一元醇同系物的物理性质 .通过非线性回归分析 ,得到回归方程 ,结果表明直链饱和一元醇同系物的物理性质与重复单元数值之间满足上述关系式 ,均显示优良的相关性     

Olefin Metathesis at the Dawn of Implementation in Pharmaceutical and Specialty‐Chemicals Manufacturing

The recent uptake of molecular metathesis catalysts in specialty‐chemicals and pharmaceutical manufacturing is reviewed.     

脂肪醇的生物毒性与结构参数的相关性研究

应用量子化学从头算HF/3-21G方法得到了14种脂肪醇分子的优势构象,利用HF/3-21G法和分子图形学技术获得其电子结构、几何结构参数和连接性指数,并将这些参数与脂肪醇对番茄和红蜘蛛的毒性相关联.结果表明,脂肪醇对番茄的生物毒性与一阶分子连接性指数1X和羟基电荷QOH之间存在良好的二元线性相关性,而脂肪醇对红蜘蛛的生物毒性与一阶分子连接性指数1X和分子最高已占轨道能EH之间存在良好的二元线性相关性,成功地建立脂肪醇对番茄和红蜘蛛毒性的构效关系式.     

Cross‐Metathesis/Isomerization/Allylboration Sequence for a Diastereoselective Synthesis of Anti‐Homoallylic Alcohols from Allylbenzene Derivatives and Aldehydes

We describe a highly diastereoselective approach to anti‐homoallylic alcohols from allylbenzene derivatives and aldehydes. The strategy is based on a cross‐metathesis/isomerization/allylboration sequence catalyzed successively by ruthenium and iridium. This methodology provides another way to access this class of compounds, which leads to the preparation of hitherto‐unknown homoallylic alcohols without the requirement to control the stereochemistry of the 1‐alkenyl boronate intermediates. Our study towards an enantioselective version of this sequential reaction is also reported.     

A highly rigid diamine monomer derived from naturally occurring myo‐inositol and its use for polyamide synthesis

A rigid diamine was synthesized from myo‐inositol, a naturally occurring cyclic hexaol, and used as a monomer to synthesize polyamides. myo‐Inositol was treated with 1,1‐dimethoxycyclohexane to yield a bisketal bearing two hydroxyl groups, and from this bisketal, the target diamine was synthesized in three steps: (1) derivation of the diol into the corresponding bistriflate, (2) nucleophilic substitution of the bistriflate with sodium azide yielding a diazide, and (3) reduction of the diazide to the target diamine. The target diamine readily underwent polycondensation with dicarboxylic acid chloride in solution. The resulting polyamides, whose main chain inherited the rigid 5‐6‐5 system from the diamine monomers, have high glass transition temperatures. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3436–3443     

Refining of plant oils to chemicals by olefin metathesis

Plant oils are attractive substrates for the chemical industry. Their scope for the production of chemicals can be expanded by sophisticated catalytic conversions. Olefin metathesis is an example, which also illustrates generic issues of "biorefining" to chemicals. Utilization on a large scale requires high catalyst activities, which influences the choice of the metathesis reaction. The mixture of different fatty acids composing a technical-grade plant oil substrate gives rise to a range of products. This decisively determines possible process schemes, and potentially provides novel chemicals and intermediates not employed to date.     

共反应剂法合成纤维素高级脂肪酸酯

采用乙酸酐为共反应剂合成了纤维素高级脂及酸酯。运用IR,^1H NMR对合成产物的结构进行了表征。结果表明,在纤维素分子骨架上同时接技了高级脂肪酸酯基以及乙酸酯基,产物为纤维素混合酸酯。产物的酯化度值通过^1H NMR确定,可达到1.66。研究了纤维素与系列高级脂肪酸的酯化反应,结果表明,随着高级脂肪酸中碳原子数目的增加,产物的酯化度逐渐减小,而产物质量有一个先增加后减小的趋势。     

脂肪族聚酯弹性体的合成及其性能研究

介绍了一种以癸二酸、乙二醇和甘油为原料合成可降解脂肪族聚酯的方法,并利用红外光谱、光电子能谱、示差扫描量热法、X射线衍射和力学测试等方法对聚酯的性质进行了研究.结果显示,产物表现出典型的高弹性,随着原料中癸二酸/乙二醇的比值增加,产物的弹性模量呈增加趋势,微观结构由局部有序向无序转变.产物具有良好的生物降解能力,37℃下在含猪胰脂肪酶的磷酸缓冲溶液里72h失重率在6.1%～14.4%之间.     

Cascade Metathesis Reactions for the Synthesis of Taxane and Isotaxane Derivatives

Tricyclic isotaxane and taxane derivatives have been synthesized by a very efficient cascade ring‐closing dienyne metathesis (RCDEYM) reaction, which formed the A and B rings in one operation. When the alkyne is present at C13 (with no neighboring gem‐dimethyl group), the RCEDYM reaction leads to 14,15‐isotaxanes 16 a , b and 18 b with the gem‐dimethyl group on the A ring. If the alkyne is at the C11 position (and thus flanked by a gem‐dimethyl group), RCEDYM reaction only proceeds in the presence of a trisubstituted olefin at C13, which disfavors the competing diene ring‐closing metathesis reaction, to give the tricyclic core of Taxol 44 .     

Impact of Ethylene on Efficiency and Stereocontrol in Olefin Metathesis: When to Add It,When to Remove It,and When to Avoid It

Ethylene is the byproduct of olefin metathesis reactions that involve one or more terminal alkenes. Its volatility is one reason why many cross-metathesis or ring-closing metathesis processes, which are reversible transformations, are efficient. However, because ethylene can be converted to a methylidene complex, which is a highly reactive but relatively unstable species, its concentration can impact olefin metathesis in other ways. In some cases, introducing excess ethylene can increase reaction rate owing to faster catalyst initiation. Ethylene and a derived methylidene complex can also advantageously inhibit substrate or product homocoupling, and/or divert a less selective pathway. In other instances, a methylidene's low stability and high activity may lead to erosion of efficiency and/or kinetic selectivity, making it preferable that ethylene is removed while being generated. If methylidene decomposition is so fast that there is little or no product formation, it is best that ethylene and methylidene complex formation is avoided altogether. This is accomplished by the use of di- or trisubstituted alkenes in stereoretentive processes, which includes adopting methylene capping strategy. Here, we analyze the different scenarios through which ethylene and the involvement of methylidene complexes can be manipulated and managed so that an olefin metathesis reaction may occur more efficiently and/or more stereoselectively.