Influence of carbonyl stress on rheological alterations of blood materials and decarbonylation effect of glutathione

The effects of various toxic carbonyls such as malondialdehyde(MDA),a secondary product of lipid peroxidation,and other aldehydes on rheological parameters and their relationship with aging-associated alterations were studied.Both MDA and glutaraldehyde(Glu) in different concentrations significantly increase viscosity,plastic viscosity and yield stress of human plasma and erythrocyte suspensions.MDA(20 mmol/L) reduces sharply the typical fluorescence of proteins(excitation 280 nm/emission 350 nm),and produces age pigment-like fluorescence with a strong emission peak at 460 nm when excites at 395 nm by only being incubated for some hours.In contrast,Glu decreases merely the fluorescence of proteins without producing age pigment-like fluorescence.These data suggest interestingly that the MDA-induced gradual protein cross linking seems to form from different mechanisms compared to the fast rheological changes of blood materials which may take place either in acute and chronic diseases or during aging.On the other hand,MDA induces various deleterious alterations of erythrocytes whereas glutathione(GSH) inhibits the MDA-related carbonyl stress in a concentration-dependent manner.The results indicate that carbonyl-amino reaction exists in the blood widely and GSH has the ability to interrupt or reverse this reaction in a certain way.It implies that carbonyl stress may be one of the important factors in blood stasis and suggests a theoretical and practical approach in anti-stresses and anti-aging.

Adsorption and Decarbonylation Reaction of Furfural on the Pd(111) and M/Pd(111)(M=Ni, Cu and Ru) Surfaces

By performing with density functional theory(DFT) method, the detailed adsorption process and the catalytic decarbonylation mechanisms of furfural over Pd(111) and M/Pd(111)(M = Ni, Cu, Ru) surfaces toward furan were clarified. The results of atomic size factor, formation energy and d-band center showed that Ru/Pd(111) surface was the most stable and active. The adsorption energies of furfural on the different surfaces followed the order Ru/Pd(111) > Cu/Pd(111) > Pd(111) > Ni/Pd(111). After analyzing Mulliken atomic charge population and the deformation density, we can find that on Ru/Pd(111) surface, the number of charge transfer was the most and the interaction was the strongest. Therefore, its adsorption energy was the highest. Furthermore, the furfural decarbonylation pathway is more kinetically feasible on bimetallic surface, and the reaction is the most likely to occur on Ru/Pd(111).

Theoretical Study on the C-H Activation in Decarbonylation of Acetaldehyde by NiL_2(L=SO_3CH_3) Using Density Functional Theory

Density functional theory calculations were carried out to explore the potential energy surface（PES） associated with the gas-phase reaction of Ni L2（L=SO3CH3） with acetone. The geometries and energies of the reactants, intermediates, products and transition states of the triplet ground potential energy surfaces of [Ni, O, C2, H4] were obtained at the B3LYP/6-311＋＋G（d,p） levels in C,H,O atoms and B3LYP/ Lanl2 dz in Ni atom. It was found through our calculations that the decabonylation of acetaldehyde contains four steps including encounter complexation, C-C activation, aldehyde H-shift and nonreactive dissociation. The results revealed that C-C activation induced by Ni L2（L=SO3CH3） led to the decarbonylation of acetaldehyde.

Ligand enabled none-oxidative decarbonylation of aliphatic aldehydes

Decarbonylation of aldehydes is a basic organic transformation, which has been developed for more than six-decade. However, as comparing to well-studied aromatic aldehydes, fewer examples for catalytic decarbonylation of aliphatic aldehydes were reported, mainly on simple or special substrates.For α-bulky or highly functionalized ones, stoichiometric Rh(I) were usually required for decent yields.Herein, we present a rare example of Ir(I)-catalyzed direct decarbonylation of α-quaternary aldehydes with broad substrate scope and good functional group compatibility via judicious selection of ligand. Theα-chirality is memorized in this decarbonylation process. In addition, we report a broad-spectrum decarbonylation of α-secondary and α-tertiary aldehydes containing multifunctional groups with an improved Rh(I)/DPPP recipe. Finally, we realized selective decarbonylation of α-tertiary aldehydes in the presence of α-quaternary one via the reactivity differences.

Dimethyl sulfoxide-aided copper(0)-catalyzed intramolecular decarbonylative rearrangement of N-aryl isatins leading to acridones

Described here is the first example of Cu(0)-catalyzed intramolecular decarbonylative rearrangements of readily available N-aryl isatins assisted by solvent dimethyl sulfoxide(DMSO)under air atmosphere and additive-free conditions leading to various biologically important acridones in good to excellent yields.This novel transformation is proposed to go through a sequential DMSO-aided Cu insertion into the amide C-N bond,CO extrusion,Cu migration,reductive elimination and DMSO-aided proton migration processes,involving multiple types of bond cleavage and formation in a single chemical step.

Theoretical studies on the mechanism of the thermal decarboxylation and decarbonylation of a number of α-keto-acids

Both processes of decarboxylation and decarbonylation of a number of acids including RCOCO2H,R=H,CH3,CH2F,CF3,CH=CH2,Ph,OH have been studied by semi-empirical MO theory AMI method to verify the reaction mechanism of each process and the effect of different substituents on them.The calculated results are consistent with the experimental reports and can be summed up as follows:(1) The decarboxylation of these acids to form aldehydes and carbon dioxide is concerted and takes place through a 4-membered ring transition state in which a partial negative charge develops on the carbon of the α-carbonyl group,so that the inductive effect of some substituents is favourable for this process.(2) Their decarbonylation into carboxylic acids and carbon monoxide however is the attack of the OH on the carbon of the alkyl portion of the acid,forming a 3-membered ring transition state.(3) The activation energy of decarbonylation is lower than that of decarboxylation,since oxygen is more nucleophilic than hydrogen and also the strong OH bond need not to be broken.

草酸二甲酯催化制备碳酸二甲酯反应过程研究

研究了草酸二甲酯脱羰生成碳酸二甲酯的反应机理,设计开发了新型脱羰催化剂,分别进行了间歇釜式、连续固定床两种反应工艺催化剂的评价筛选和反应工艺条件优化。通过对草酸二甲酯脱羰催化剂及工艺的实验研发,发明了一种含铯固体碱催化剂(主要成分为Ba-CeCs_(2)CO_(3)-Al_(2)O_(3),简称“BS-CCL”);采用该催化剂,间歇釜式反应工艺中草酸二甲酯的转化率高,生成碳酸二甲酯的选择性较好。

Three new decarbonyl prenylphloroglucinols bearing unusual spirost subunits from Hypericum scabrum and their neuronal activities

Three novel polycyclic polyprenyled acylphloroglucinols,Hyperscabins A-C,were obtained from the aerial parts of Hypericum scabrum.They featured an unprecedented 5,5-spiro ketal subunit with the loss of C-2’carbonyl in the phloroglucinol ring.Their structures were characterized by extensive spectroscopic analyses,NMR calculations with DP4+analysis,calculated electronic circular dichroism(ECD)spectra and the application of modified Mosher’s methods.In the assay of[^(3)H]-5-HT and[^(3)H]-NE reuptake inhibition,compounds 1 and 2 showed good inhibito ry activity(81.8%and 83.2%)in 10μmol/L.In addition,compound 1 significantly increased cell viability in the experiment of oxygen and glucose deprivation/deoxygenation.

Decarbonylative C-C bond forming reactions mediated by transition metals

New methods for carbon-carbon (C-C) forming reactions are constantly emerging in the field of organic synthesis. In this review, a brief history followed by recent developments of decarbonylative C-C forming reactions mediated by transition metals is described. Many different substrates are presented and the review is organized by the different carbonyl precursors, such as acyl chlorides, aldehydes, anhydrides, esters and ketones, used in the respective transformations. Furthermore, the broad scope of these reactions is exhibited by the application to several reaction types (e.g. Heck-type reactions, Suzuki cross-coupling type reactions, C-H activation, etc.) as well as a natural product synthesis (e.g. muscroride A). While several examples are provided, this review marks the beginning of a new field that is still in its infancy and for what might be a new approach to achieve highly efficient reactions that come closer to meeting the standards of chemical economies (e.g. atom, redox, step, etc.) and green chemistry.

Catalytic Elimination of Oxygenated Byproducts in the Toluene Methylation Process

Catalytic methylation of toluene with methanol is an important alternative pathway for xylene production.Previous studies have indicated that methanol always undergoes several side reactions on acidic zeolites,resulting in oxygencontaining byproducts such as dimethyl ethers,ketones,and carboxylic acids.Herein,the presence and distribution of the oxygenated compounds formed during toluene methylation were firstly examined by systematic chromatographic analysis.Plausible formation mechanisms for the various oxygenates are discussed.The most problematic byproduct is found to be acetic acid,which can lead to inferior product quality and damage downstream units.A feasible solution is presented for oxygenate removal after toluene methylation,in which acetic acid is eliminated by catalytic decomposition into low-boilingpoint acetone over a MgO catalyst.This process allows for all of the low-boiling-point oxygenates,including methanol,dimethyl ether,acetone,and butanone,to be removed from the aromatics phase,taking advantage of the temperature of the reaction effluent and standard distillation equipment.X-ray diffraction was used to characterize the crystal phase of the fresh and used MgO decarbonylation catalysts,while thermogravimetry/mass spectrometry and Fourier-transform infrared spectroscopy were applied to investigate the transformation mechanism of acetic acid over the decarbonylation catalyst.CO insertion and ketonization of acetic acid accounted for the formation and elimination of acetic acid,respectively.The combined methylation/decarbonylation process should enable the production of high-quality xylenes,an important industrial feedstock,by overcoming the main technical obstacles associated with the toluene methylation process.

对苯二甲酸的加氢精制过程 I.热力学及反应特性分析

对钯碳催化剂(Pd/AC)上对苯二甲酸(TA)加氢精制过程进行了研究,结合反应体系的热力学分析,对该体系中的反应历程、反应特性进行了探讨,并对工业过程进行取样分析验证实验结果。结果表明:加氢精制工艺过程主要发生了两类反应,即加氢反应和脱羰反应,但脱羰反应的并存并未从本质上影响最终精制目的,即降低TA中对羧基苯甲醛(4-CBA)的含量。加氢反应是一个串联反应,即先由4-CBA加氢生成对羟甲基苯甲酸(4-HM BA),反应速率非常快,而后4-HM BA进一步加氢生成对甲基苯甲酸(4-PT),相对速率较慢;脱羰反应的进行程度与反应体系中存在的微量氧密切相关,溶解的微量氧对脱羰反应有促进作用,而氢气则会抑制脱羰反应。

糠醛在Pt(111)表面的吸附和脱碳反应

采用广义梯度近似的密度泛函理论并结合平板模型的方法,优化了糠醛分子在Pt(111)面的吸附模型,并探究了糠醛脱碳反应形成呋喃的机理.结果表明:吸附后糠醛分子环上的C―H(O)键及支链―CHO相对于金属表面倾斜上翘,分子平面被扭曲,易于呋喃的形成;同时,糠醛分子向Pt表面转移电子0.765e,环中的大π键与Pt(111)表面的d轨道发生较强的相互作用,使得糠醛的芳香性被破坏,环上的碳原子呈现准sp^3杂化.此外,对糠醛脱碳反应中的各反应步骤进行过渡态搜索,通过比较各步骤的活化能,得出糠醛更易先失去支链上的H形成酰基中间体(C_4H_3O)CO,中间体继续脱碳加氢形成产物呋喃.该过程的控速步骤为(C_4H_3O)CO*+*→C_4H_3O*+CO*(*为吸附位),活化能为127.65 kJ·mol^(-1).

化学还原法制备胶体Pd/γ-Al_2O_3催化剂及其催化性能

采用化学还原法制备了高分散的胶体Pd/γ-Al2O3催化剂,考察了保护剂、还原剂和制备方法等对其催化性能的影响。实验结果表明,最佳保护剂为聚乙烯吡咯烷酮(PVP),PVP的最佳用量为n(N)∶n(Pd)=40∶1;最佳还原剂为乙醇/NaOH,NaOH的最佳用量为n(NaOH)∶n(Pd)=3∶1。X射线光电子能谱和X射线衍射表征结果显示,催化剂中的Pd以零价态存在;同时根据Debye-Scherrer公式估算,Pd在催化剂中以胶体状态存在。将胶体Pd/γ-Al2O3催化剂用于糠醛液相脱羰反应,实验结果表明,该催化剂比常规方法制备的Pd/γ-Al2O3催化剂具有更高的活性,糠醛的转化率为97.6%,呋喃的选择性为95.1%。

线型1,2-邻二萘醌-1-肟(1-nqo)钌配合物的合成

报道了含C1 6长碳链线型 1,2 邻二萘醌 1 肟 (1 nqo)钌配合物trans ,cis 及cis ,cis [Ru(1 nqo) 2 (CO) (spy) ](3)及 (4 ) ,含C1 8长碳链线型 1 nqo钌配合物cis ,cis [Ru(1 nqo) 2 (CO) (opy) ](5 ) ,trans ,trans [Ru(1 nqo) 2 (opy) 2 ](6 )的合成 .利用红外、FAB质谱、核磁共振氢谱及紫外 -可见吸收光谱表征配合物的结构 ,利用1 H 1

Ph_4PCl催化合成碳酸二苯酯研究

研究了以Ph4PCl为催化剂 ,草酸二苯酯脱羰基合成碳酸二苯酯反应。考察了催化剂的催化性能及影响反应的因素 ,得到了最佳的反应条件为反应温度 2 6 0℃ ,反应时间 3h ,草酸二苯酯和催化剂用量的摩比为 10 0∶1。在此条件下DPO转化率、DPC选择性、DPC收率分别为 99 5 %、98 3%、97 8%。Ph4PCl催化剂具有催化活性高 ,选择性好 ,反应时间短 。

糠醛制呋喃用 Pd/C 催化剂的制备研究

对由糠醛生产呋喃的负载型Ｐｄ催化剂的制备进行了研究，利用浸渍法对Ｐｄ／Ｃ催化剂制备中的浸渍、焙烧、活化等条件进行了考察，通过正交实验和平行实验得出了糠醛液相脱羰基用Ｐｄ／Ｃ催化剂的最佳制备条件。

丙烯醛及其衍生物基态脱羰反应机理的理论研究

用从头算自洽场分子轨道方法和能量梯度技术，研究丙烯醛及其衍生物基态脱羰反应的机理，用二级微扰方法考虑电子相关效应．结果表明基态丙烯醛脱羰为一简单反应，反应涉及三中心过渡态．取代基对丙烯醛脱羰反应仅有较小的影响，从计算的势垒可以推得基态丙烯醛及其衍生物热脱羰是很困难的，但是，光激发得到的丙烯醛很可能首先通过内转换成系间窜跃回到基态，然后发生脱羰反应，即基态脱羰很可能在其光解离反应机理中起着重要作用．

丁醇醛和丁醇酸热解形成CO和CO_2机理的密度泛函理论研究

采用密度泛函理论方法B3LYP/cc-pVTZ,对模型化合物2,3,4-羟基丁醛的脱羰基和2,3,4-羟基丁酸的脱羧基反应机理进行了量子化学理论研究。对两种模型化合物分别设计了三种热解反应途径,计算了不同温度下各热解反应途径的标准热力学及动力学参数。计算结果表明,纤维素热解过程中CO2和CO的逸出分别与脱羧基和脱羰基反应相对应,脱羧基和脱羰基反应均为分子内氢原子转移的协同过程。脱羰基反应是吸热反应,而脱羧基反应是放热反应。饱和丁醇醛的脱羰基反应反应能垒为288.8 kJ/mol,脱水后的不饱和烯醇醛的脱羰基反应能垒增大;饱和丁醇酸的脱羧基反应能垒较高,为303.4 kJ/mol,脱水后的不饱和烯醇酸的脱羧基反应能垒明显减小,这说明脱水有利于CO2的生成。

Zn(OAc)2·2H_2O催化草酸二苯酯脱羰基合成碳酸二苯酯反应的研究

研究了Zn(OAc)2·2H2O催化草酸二苯酯(DPO)脱羰基合成碳酸二苯酯(DPC)反应,考察了反应温度、反应时间、DPO和催化剂用量物质的量配比对DPC选择性、DPC收率和DPO转化率的影响。确定的较佳反应条件是反应温度260℃,反应时间3h,DPO和催化剂用量物质的量配比是100∶15。运用MXXC、Benson等基团贡献法,对草酸二苯酯脱羰基反应的平衡常数进行了估算,得到ΔrH533=2707kJ/mol,KP=13×109。DPO脱羰基合成DPC反应体系中存在副反应。

基态丙酮酸单分子反应的机理

运用MP2和B3LYP方法,对基态丙酮酸的8个可能的单分子反应的反应机理进行了详细的理论计算.研究发现,氢键相互作用及两个羰基的相对空间取向在丙酮酸异构体的稳定性中起着重要的作用.并且由最稳定的异构体Tc旋转为其它异构体的能垒都比较高,旋转异构反应在室温下是难于进行的.经由质子迁移过程可实现Ct和Tt异构体之间的转化,但反应能垒比内旋转过程高得多,说明质子迁移无法与内旋转过程相竞争.对基态丙酮酸脱羧和脱羰反应途径的研究均表明,脱羧反应是经由五中心过渡态首先生成甲基羟基卡宾中间体,然后中间体再进一步异构得到产物.四中心协同反应机理是不利的.