不饱和醇电还原质谱-电化学循环伏安(MSCV)法研究:I.烯丙醇的电还原

用MSCV法研究了烯丙醇在多孔Pt电极上0.5ol.dm^-3HCLO4中的电还原。烯丙醇电还原时主要涉及二类反应:烯丙基上C-OH断键生成丙烯; 丙烯进一步氢化生成丙烷。表征丙烯及丙烷的诸碎片M/Z的质谱电流(IM)-电极电位(Φ)扫描曲线线详细描绘了各分步反应的状况。在一定电位范围, 各M/Z的lgIM-Φ呈线性; 求得各有关M/Z的Tafel斜率。根据实验结果对反应机理进行了详细分析。     

不饱和醇电还原的质谱-电化学循环伏安(MSCV)法研究 Ⅰ.烯丙醇的电还原

用MSCV法研究了烯丙醇在多孔Pt电极上0.5mol·dm~(-3)KClO_4中的电还原.烯丙醇电还原时主要涉及二类反应:烯丙基上C—OH断键生成丙烯;丙烯进一步氢化生成丙烷.表征丙烯及丙烷的诸碎片m/z的质谱电流(I_M)-电极电位(φ)扫描曲线详细描绘了各分步反应的状况.在一定电位范围,各m/z的IgI_M-φ呈线性;求得各有关m/z的Tafel斜率.根据实验结果对反应机理进得了详细分析.     

不饱和醇电还原的质谱-电化学循环伏安(MSCV)法研究:II.炔丙醇的电还原

炔丙醇在多孔Pt黑电极上, 0.5mol.dm^-3HCLO4溶液中电还原的MSCV研究结果表明炔丙醇电还原时既涉及烯丙基C-OH断键反应亦涉及炔丙基上C-OH断键反应生成烃类。此外有少量炔丙醇直接质子化生成部分饱和的烯丙醇。表征各种反应产物的M/Z的质谱电流-电极电位扫描曲线(IM-Φ)详细描绘了各分步反应的图象。各M/Z的1gIM-Φ曲线在一空电位范围内呈线性, 并求得它们的Tafel斜率。依据实验结果对反应机理进行了详细分析。     

不饱和醇电还原的质谱-电化学循环伏安(MSCV)法研究:II.炔丙醇的电还原

炔丙醇在多孔Pt黑电极上, 0.5mol.dm^-3HCLO4溶液中电还原的MSCV研究结果表明炔丙醇电还原时既涉及烯丙基C-OH断键反应亦涉及炔丙基上C-OH断键反应生成烃类。此外有少量炔丙醇直接质子化生成部分饱和的烯丙醇。表征各种反应产物的M/Z的质谱电流-电极电位扫描曲线(IM-Φ)详细描绘了各分步反应的图象。各M/Z的1gIM-Φ曲线在一空电位范围内呈线性, 并求得它们的Tafel斜率。依据实验结果对反应机理进行了详细分析。     

不饱和醇电还原的质谱-电化学循环伏安(MSCV)法研究 Ⅱ.炔丙醇的电还原

炔丙醇在多孔Pt黑电极上,0.5mol·dm~(-3)HClO_4溶液中电还原的MSCV研究结果表明炔丙醇电还原时既涉及烯丙基上C—OH断键反应亦涉及炔丙基上C—OH断键反应生成烃类.此外有少量炔丙醇直接质子化生成部分饱和的烯丙醇.表征各种反应产物的m/z的质谱电流-电极电位扫描曲线(I_(M-φ))详细描绘了各分步反应的图象.各m/z的lgI_(M-φ)曲线在一定电位范围内呈线性,并求得它们的Tafel斜率.依据实验结果对反应机理进行了详细分析.     

乙腈溶剂中三氯化苄在银阴极上的脱氯反应

用常规循环伏安(CV)法和恒电位电解法研究了含0.1 mol·L^-四丁基高氯酸铵(TBAP)乙腈溶剂中三氯化苄在银电极上的还原脱氯机理; 用以银和氯离子的氧化还原反应为基础的阳极区拓宽CV法探测了还原脱氯反应生成氯离子在银电极上的吸附情况. 循环伏安实验表明: (1) 银电极对三氯化苄的电还原脱氯反应具有比汞电极更优良的电催化活性; (2) 三氯化苄在低扫描速率(v)下得到的第一个还原峰对应反应受吸附控制, 电子转移系数约为0.25, 遵守协同电子转移机理; (3) 三氯化苄还原脱氯反应生成氯离子在银电极上的吸附电位为-0.75 - -1.75 V (vs Ag/Ag⁺). 电解实验表明, 通过改变银电极电位可以有效控制三氯化苄还原反应的电解产物.     

铁电极电还原溴化钠甲醇溶液反应动力学和机理

研究溴化钠（NaBr）甲醇溶液在铁电极上电还原反应动力学和机理对于二茂铁电化学制备、非水体系中二氧化碳（CO₂）的电还原和有机电合成等领域具有实际价值和科学意义, 但对此未见详细报道. 本文采用极化曲线和电化学阻抗谱等技术详细地研究了该体系的电还原动力学和机理. 结果表明: 反应物为甲醇而Na⁺只起导电作用; 电极电位是该体系中唯一状态变量, 其对甲醇电还原速率常数的影响符合阿仑尼乌斯唯象方程式; 电还原过程不受扩散极化控制, 溶液欧姆极化是主要极化形式; 甲醇电还原依法拉第定律计量地产生氢气, 反应活化能约为26.2 kJ·mol^-1.     

硝基苯在铜电极上的电还原特性研究

应用循环伏安法和线性扫描伏安法研究水溶液中硝基苯在铜电极上的电还原特性及其电还原为苯胺的中间步骤和反应机理.结果表明:铜电极上硝基苯的还原电位在-0.58V和-1.32V左右(vs.SCE),溶液的酸性和碱性均有益于该还原反应的发生;还原过程伴有反应物吸附现象,当硝基苯浓度较大时,还原过程受传质过程控制;随着厌氧程度的提高,还原速率加快.     

在TiO_2纳米阵列上电沉积RuO_2用于CO_2电还原（英文）

传统上,RuO_2/TiO_2复合电极制备是通过在TiO_2/Ti基体上多次涂覆含Ru前驱体溶液和随后热分解(TD)来实现的.为克服上述方法中Ru用量大和利用率低之不足,本工作主要基于循环伏安法(CV)在TiO_2纳米管阵列(TNA)上电沉积RuO_2制备RuO_2~(CV)/TNA复合电极.SEM、GIXRD和CV结果表明,电沉积的RuO_2为无定型结构,所制备电极中的Ru用量约为传统的RuO_2~(TD)/TNA电极中Ru用量的1/30.尽管两电极催化CO_2还原产物的法拉第效率接近,但是RuO_2~(CV)/TNA电极比RuO_2~(TD)/TNA电极展示了更高的还原电流,较正的初始还原电位和更好的稳定性.与磷酸盐缓冲溶液中电还原CO_2相比,RuO_2~(CV)/TNA电极在0.1 mol·L~(-1) KHCO_3中电还原CO_2除生成更高法拉第效率的甲酸根和甲烷外,还检测到CO的生成.     

邻碘苯甲酸电还原脱碘的原位红外光谱研究

采用循环伏安法研究了邻碘苯甲酸在NaOH溶液中的电化学还原反应,与Pt和Ti等电极相比,Ag和Cu电极对邻碘苯甲酸具有较好的电还原活性,还原电位向正电位方向移动.通过原位红外光谱技术研究了邻碘苯甲酸在Ag和Cu电极上的电还原机理.结果表明,在电位高于-800 mV时,邻碘苯甲酸在Ag电极表面先形成吸附中间态R…I…Ag,而在Cu电极表面以负离子形式存在.随着电位的进一步负移,邻碘苯甲酸在Ag和Cu电极上均发生脱碘加氢反应,经还原得到最终产物苯甲酸.     

Mechanism of electroreduction of allyl alcohol at platinized platinum electrode in acidic aqueous solution.

The electroreduction of allyl alcohol to form propene at the platinized platinum electrode in acidic aqueous solution has been studied using CV plots, IR, ESR, and MS spectra, and a semiempricial MO method (MOPAC7/AM1, PM3). From the determinations of charge-transfer coefficients, reaction orders and apparent activation energy for the given reaction, the detection of the intermediates such as C(3)H(5)(+), C(3)H(5)(*), and C(3)H(5)(-) species, and PM3 calculations of charge distribution and frontier orbital energies of the reaction species C(3)H(5)OH and C(3)H(5)(+), the authors suggest that in acidic aqueous solution the production of propene via reductive splitting of the C-OH bond situated in the allyl position of allyl alcohol obeys a carbonium ion-carbanion mechanism.     

Insight into the partial oxidation of propene: the reactions of 2-propen-1-ol on clean and O-covered Mo(110)

The reactions of 2-propen-1-ol (allyl alcohol) were studied on clean and O-covered Mo(110) to understand the effect of resonance stabilization and the presence of surface oxygen on reaction selectivity. Propene is the only gaseous hydrocarbon product evolved from allyl alcohol reaction on O-covered Mo(110). Water and dihydrogen are also produced, along with a small amount of adsorbed carbon. We estimated, using X-ray photoelectron spectroscopy, that approximately 70% of the 0.11 ML of 2-propen-1-ol that reacts forms propene. In contrast, the dominant reaction pathway on the clean surface is nonselective decomposition to adsorbed carbon and hydrogen, leading to a 23% selectivity for propene formation. On both clean and O-covered Mo(110), X-ray photoelectron spectroscopy and infrared spectroscopy identify allyloxy as the reaction intermediate yielding propene. These results are discussed in the context of propene oxidation and periodic trends in reactivity.     

Complexes de l'iridium avec le cyclooctadiène-1,5 IV. Le di-υ-chloro-bis(π-cylooctadiène-1,5)-bis(π-ether diallylique)-diiridium

Di-μ-chlorobis(π-cycloocta-1,5-diene)diiridium, (I), reacts with allyl alcohol to give a complex, (II), of (I) and diallyl ether and byproducts: propene, propanal and diallyl ether. The same complex is readily obtained by direct reaction of (I) and diallyl ether. Some physicochemical properties (II) are described (IR spectra, stability, reactivity, etc.). Its structure is discussed, and a mechanism for the transformation of allyl alcohol during the reaction is given.     

Scope of the allylation reaction with [RuCp(PP)]+ catalysts: changing the nucleophile or allylic alcohol

The scope of the dehydrative allylation reaction using allyl alcohol as allyl donor with [RuCp(PP)]⁺ complexes as catalysts is explored. Aliphatic alcohols are successfully allylated with allyl alcohol or diallyl ether, obtaining high selectivity for the alkyl allyl ether. The reactivity of aliphatic alcohols is in the order of primary > secondary ? tertiary. The tertiary alcohol 1‐adamantanol reacts extremely slowly in the absence of strong acid, but when HOTs is added, reasonable yields of 1‐adamantyl allyl ether are obtained. The alkyl allyl ether is found to be the thermodynamically favored product over diallyl ether. Apart from alcohols, thiols and indole are also efficiently allylated, while aniline acts as a catalyst inhibitor. Allylation reactions with various substituted allylic alcohols give products with retention of the substitution pattern. It is proposed that a Ru(IV) σ‐allyl species plays a key role in the mechanism of these allylation reactions. Copyright © 2010 John Wiley & Sons, Ltd.     

Main stages of unusual allyl coupling involving nickel bis-η3-allyl complexes in the presence of dichlorobutenes

The reactions of nickel bis-η³-allyl complexes with dichlorobutenes were studied. The overall process includes several stages, each characterized by substantially different reactions: traditional allyl coupling, substrate insertion between recombining allyl ligands, and the trimerization of allyl fragments accompanied by hydride transfer (unusual allyl coupling). Unusual allyl coupling occurs at a final stage preceded by the formation of oligomeric nickel intermediates with the mean composition Ni₄(C₃H₅)₆(C₄H₆)₃Cl₇. Their decomposition gives nonadiene and nonatriene isomers and propene. Trace amounts of molecular hydrogen were found indicating the formation of nickel hydride complexes at the final stage. Nickel bis-η³-allyl complexes react similarly with different dichlorobutenes.     

苯氧乙酸烯丙酯的合成

对苯酚和氯乙酸的Williamson反应加以改进,使苯氧乙酸的收率达到95．4％。并以苯氧乙酸和烯丙醇为原料,活性碳负载磷钨酸为催化剂,合成了苯氧乙酸烯丙酯。考察了两个反应的主要影响因素。     

FTIR matrix-isolation study of the reaction products of vanadium atoms with propene: observation of allylvanadium hydride as a precursor to sacrificial hydrogenation of propene

Vanadium atoms have been reacted with different partial pressures of propene in Ar under matrix-isolation conditions, and the products have been observed using Fourier transform infrared (FTIR) spectroscopy. Under dilute propene in Ar conditions, new features are observed in the IR spectra corresponding to a C-H insertion product, identified here as H-V-(η(3)-allyl). Use of d(3)-propene (CD(3)-CH═CH(2)) demonstrates that the initial V-atom insertion occurs at the methyl group of the propene molecule, and DFT calculations have been used to support the identity of the initial product. Upon increasing the partial pressure of propene, additional features corresponding to propane (C(3)H(8)) are observed, with the hydrogen-atom source for the observed hydrogenation demonstrated to be additional propene units. Analysis of a systematic increase in the partial pressure of propene in the system demonstrates that the yield of propane correlates with the decrease of the allyl product, demonstrating the H-V(allyl) species as a reactive intermediate in the overall hydrogenation process. An overall mechanism is proposed to rationalize the formation of the insertion product and ultimately the products of hydrogenation, which agrees with previous gas-phase and matrix-isolation work involving propene and the related system, ethene.     

A DFT Study on the Reaction Pathways for Carbon?Carbon Bond‐Forming Reactions between Propargylic Alcohols and Alkenes or Ketones Catalyzed by Thiolate‐Bridged Diruthenium Complexes

The reaction pathways of two types of the carbon? carbon bond‐forming reactions catalyzed by thiolate‐bridged diruthenium complexes have been investigated by density‐functional‐theory calculations. It is clarified that both carbon? carbon bond‐forming reactions proceed through a ruthenium–allenylidene complex as a common reactive intermediate. The attack of π electrons on propene or the vinyl alcohol on the ruthenium–allenylidene complex is the first step of the reaction pathways. The reaction pathways are different after the attack of nucleophiles on the ruthenium–alkynyl complex. In the reaction with propene, the carbon? carbon bond‐forming reaction proceeds through a stepwise process, whereas in the reaction with vinyl alcohol, it proceeds through a concerted process. The interactions between the ruthenium–allenylidene complex and propene or vinyl alcohol have been investigated by applying a simple way of looking at orbital interactions.     

Si-disubstituted diallylsilanes in homolytic thiylation and electrophilic fragmentation reactions

Approaches to Si-disubstituted 1-thia-5-silacyclooctanes based on homolytic addition of hydrogen sulfide to diallylsilanes R₂Si(CH₂CH=CH₂)₂ and on intramolecular cyclization of Si-disubstituted (allyl)(γ-sulfanylpropyl)silanes have been studied. In the former case the reactivity of the silanes decreases in the order R = MeO > F > Me > Ph, whereas in the latter case the reactivity order is slightly different: Me > MeO ≈ F ? Ph. The reactions of diphenyl-and dimethyldiallylsilanes with the complex BF₃·2AcOH occur in a different manner: The former involves rearrangement to form fluoro(2-methylpent-4-enyl)diphenylsilane, while the latter, elimination of the two allyl groups to fluorodimethylsilane and propene.