共查询到20条相似文献,搜索用时 156 毫秒
1.
利用高效液相色谱-二极管阵列检测法(HPLC-DAD)研究了不同含水量、不同样品浓度及不同反应时间对原花青素降解(正丁醇/HCl法)产物花青定及反应副产物的影响.木榄花样品经70%丙酮溶液提取,利用Sephadex LH-20柱纯化后得到原花青素样品.配制不同含水量和不同样品浓度的反应溶液,充分震荡后进行正丁醇/HCl法降解.用HPLC-DAD分析不同实验条件下得到的反应产物及副产物.结果表明,反应体系在含水量5%~15%的条件下,转化产物随着反应体系含水量的增加,花青定的转化率也随之增加,副产物的转化率却随之减少,总转化率(即花青定加上副产物的总转化量)呈增加趋势;在反应体系含水量大于15%时,随含水量的增加,转化产物含量呈现下降的趋势;增加反应体系中样品含量并没有明显增加转化产物的转化率,副产物的转化率相对稳定;不同反应时间处理得到的转化产物经HPLC-DAD分析并未发现转化产物花青定和副产物表现出明显的变化规律,总转化率相对稳定. 相似文献
2.
吡啶气相光氯化反应机理的理论研究──夺氢机理过渡态和IRC解析 总被引:5,自引:1,他引:4
氯自由基与吡啶分子发生夺氢反应生成2-氯吡啶、3-氯吡啶和4-氯吡啶等不同产物主要由两个连续的基元反应组成.研究了生成不同氯代产物的每一个基元反应过渡态,计算比较了不同反应路径活化能的高低,结果表明,不同产物以生成2-氯吡啶的活化能最低,生成2-氯吡啶两个连续基元反应的活化能分别为8.33kJ/mol和1.51kJ/mol,反应优先生成2-氯吡啶,并对邻位反应路径进行了键级、净电荷密度和IRC解析. 相似文献
3.
4.
5.
研究了在不同碱性条件下,对羟基苯甲醛与4-溴异戊烯的烷基化反应。通过调节反应条件可选择性地合成C-烷基化产物、O-烷基化产物或C-烷基化-O-烷基化产物。产物的结构经1H NMR,IR和MS表征。 相似文献
6.
7.
8.
9.
催化剂对CaO固硫反应活性的影响研究 总被引:4,自引:0,他引:4
用热天平研究了在CaO中添加不同催化剂对固硫反应进程及固硫反应转化率的影响,并采用等效粒子模型处理实验数据,计算了固硫反应两个阶段(表面化学反应控制阶段及产物层扩散控制阶段)的动力学参数。实验表明不同的催化剂对CaO固硫的影响效果和机制不同:催化剂KNO3,NaNO3使表面化学反应活化能和产物层扩散控制阶段反应活化能降低,但同时也使表面化学反应指前因子和扩散系数指前因子降低;而催化剂Fe2O,V2O5增大了表面化学活化能和产物层扩散控制阶段反应活化能,但同时也增大了表面化学反应指前因子和扩散系数指前因子。并发现几种催化剂对活化能和指前因子的影响都具有耦合性,因此单以表面化学反应活化能或产物层扩散控制阶段反应活化能来判断固硫反应活性是不够全面的,应计算出具体温度下的反应速率常数和产物层扩散系数值,才能准确地反映固硫反应的活性。 相似文献
10.
2,5-二甲氧基苯基烷基酮1_(a-d)(烷基分别为甲基、乙基、异丙基和叔丁基)与t-BuMgCl反应后,主要生成了1,2-加成产物、1.6-共轭加成产物及还原产物,产物及其分布在不同程度上受酮的结构、反应介质以及金属镁中过渡金属杂质的含量等因素的影响。据此,提出了反应的可能机理。 相似文献
11.
F. van Bolhuis 《Journal of organometallic chemistry》1979,170(3):299-308
The crystal structure of Cp2TiC6H5CN-2,6-(CH3)2C6H3 is reported. The iminoacyl ligand is η2-coordinated at the metal (Ti---C 2.096(4), Ti---N 2.149(4) Å). The cyclopentadienyl ligands show the normal bent Cp2Ti structure. 相似文献
12.
The reaction of the metallocene dichlorides Cp2MCl2 (Cp = η5-C5H5; M = Ti, Zr, Hf, Mo, W) and Cp2′TiCl2 (Cp′ = η5-C5H4CH3) with equimolar amounts of dilithium-benzene-o-diselenolate, 1,2-(LiSe)2C6H4, gives the chelate complexes Cp2M(Se2C6H4) (M = Ti (I), Zr (II), Hf (III), Mo (IV), W (V)) and Cp2′Ti(Se2C6H4) (VI). CpTiCl3 reacts with 1,2-(LiSe)2C6H4 to give CpTiCl(Se2C6H4) (VII). The ring inversion activation parameters for I–VI can be determined by means of temperature-dependent 1H NMR spectroscopy in solution. The fragmentation behaviour of I–VII in the mass spectrometer has been investigated by pursuing metastable transitions, using linked-scan techniques. 相似文献
13.
二(甲基环戊二烯基)二氯化钛[(MeCp)2TiCl2](Ⅰ),Wilkinson等人[1]曾用四氯化钛和甲基环戊二烯基钠反应来制备,产率26%.后来Brantly[2]用四氯化钛和MeC5H4MgCl在乙醚-苯混合溶液中于-70℃反应.以上两种方法不但操作复杂,且条件苛刻,产率低.最近吴绍祖等[3]用二乙胺作为氯化氢的接受体,四氢呋喃作溶剂,由TiCl4和甲基环戊二烯直接反应来合成.产率43%.我们采用甲基环戊二烯基锂与TiCl4反应来合成,产率为63%. 相似文献
14.
Syed A.A Shah Hendrik Dorn Judith Gindl Mathias Noltemeyer Hans-Georg Schmidt Herbert W Roesky 《Journal of organometallic chemistry》1998,550(1-2):1-6
Reaction of [Cp*TiF3] (Cp* = (ν5-C5Me5)) with Me3SiOSO2- p-C6H4CH3, Me3SiOPOPh2 and 1,2-(Me3SiOCO)2C6H4 yields the dinuclear complexes [{Cp*TiF(μ-F)(μ-OSO2-p-C6H4CH4)}2] (1), [{Cp*TiF(μ-F)(μ-OPOPh2)}2] (2) and [{Cp*TiF(μ-F)(μ-OCO-o-C6H4CO2SiMe3)}2] (3). The molecular structures of 1 and 2 have been determined by single-crystal X-ray analysis. In complexes 1-3, the two titanium atoms are connected by bridging fluorine atoms as well as bridging sulfonate, phosphinate and carboxylate groups respectively. Each titanium atom is also bonded to a terminal fluorine atom. Reaction of [Cp2*ZrF2] with 1,2-(Me3SiOCO)2C6H4 leads to the mononuclear pentacoordinate 18-electron species [Cp2*ZrF(μ-OCO-o-C6H4CO2SiMe3)] (4) and its structure was determined by X-ray crystallographic methods. 相似文献
15.
Eugenijus Urnezius Kin-Chung Lam Arnold L. Rheingold John D. Protasiewicz 《Journal of organometallic chemistry》2001,630(2):193-197
The new terminal phosphinidene complex [Cp2Zr=PDmp(PMe3)] (Dmp=2,6-Mes2C6H3; 1) was prepared in 81% yield by the reaction of [Li(Et2O)][P(H)Dmp] with [Cp2Zr(Me)Cl] in the presence of excess PMe3. Compound 1 reacts with Ph2PCl to produce selectively the sterically congested triphosphane DmpP(PPh2)2 (2) and [Cp2ZrCl2] in high yields. The structure of 2 obtained by X-ray diffraction analysis of a single crystal reveals phosphorus–phosphorus bond lengths of 2.251(2) and 2.234(2) Å and a PPP bond angle of 105.46(6)°. 相似文献
16.
Shogo Sakai 《Journal of Molecular Structure》2001,540(1-3):157-169
The potential energy surfaces for reactions of ethylene with Cp2Ti+R, Cp2Ti(Cl)R, and Cp2Ti(Cl:AlH2Cl)R (R=H and CH3) were calculated by ab initio molecular orbital methods. These six reaction mechanisms were compared. Of the two possible reaction paths, attack of ethylene at Ti and the Cl and R ligands (path IN) and that from the opposite side of the Cl ligand (path OUT), the former is found to be more favorable, with a very low activation energy for reaction of ethylene with Cp2Ti(Cl)H. For reaction of ethylene with Cp2Ti(Cl)CH3, the insertion transition states on both paths have almost the same energy barrier height above the reactants. For reaction of ethylene with Cp2Ti(Cl:AlH2Cl)R, the bond alternation between Ti–Cl and Cl–Al plays an important role in the mechanisms. 相似文献
17.
About ScienceDirect 《Journal of organometallic chemistry》1987,320(3):C39-C43
Elementary sulfur and selenium combine (in boiling heptane) with [(tBuCp)2-Zr(C6H4R)2] (Cp = η5-C5H4; R = OCH3) to give the corresponding dichalcogenophenylenezirconocene. With tellurium, the reaction proceeds only at lower temperature (in boiling hexane), affording the first ditellurophenylenezirconocene. As no metallacycle was obtained with the Cp ligand or when the metal is Hf, complexes of the general type [(RCp)2MSe2C6H4-o] (M = Ti, Zr, Hf; R = H, t-Bu, (CH3)5) have been synthesized by allowing metallocene dichlorides to react with potassium benzenediselenolate, prepared by cleaving [(t-BuCp)2ZrSe2C6H4-o] with t-BuOK. 相似文献
18.
Cp2Zr(-N=CHR)Cl compounds (9a–9c: R = CH3, C6H5, CH2Ph,respectively) are formed upon hydrozirconation of nitriles. Subsequent reaction with an aryllithium reagent yields Cp2Zr(-N=CHR)Ar (14). The (alkylidene amido)zirconocene complexes are characterized by a linear heteroallene-type structure possessing an sp-hybridized nitrogen atom. 9 reacts with the oligomeric metallocene dihydrides (Cp2ZrH2)x (15) and (Cp2HfH2)c, (17), respectively, to form the binuclear compounds Cp2Zr(μ-N=CHR)(μ-Cl)MCp2 (16, M = Zr) and (18, M = Hf). The formation of these thermally very stable metal complexes is discussed. 相似文献
19.
The synthesis and reactivity of {(η5-C5H4SiMe3)2Ti(CCSiMe3)2} MCl2 (M = Fe: 3a; M = Co: 3b; M = Ni: 3c) is described. The complexes 3 are accessible by the reaction of (η5-C5H4SiMe3) 2Ti(CSiMe3)2 (1) with equimolar amounts of MCl2 (2) (M = Fe, Co, Ni). 3a reacts with the organic chelat ligands 2,2′-dipyridyl (dipy) (4a) or 1,10-phenanthroline (phen) (4b) in THF at 25°C to afford in quantitative yields (η5-C5H4SiMe3)2Ti(CSiMe3)2 (1) and [Fe(dipy)2]Cl2 (5a) or [Fe(phen)2]Cl2 (5b). 1/n[CuIHal]n (6) or 1/n[AgIHal]n (7) (Hal = Cl, Br) react with {(η5 -C5H4SiMe3)2Ti(CCSiMe3)2}FeCl2 (3a), by replacement of the FeCl2 building block in 3a, to yield the compounds {(η5-C5H4SiMe3)2Ti(C CSiMe3)2}CuIHal (8) or {(η5-C5H4SiMe3)2Ti(CSiMe3)2}AgIHal (9) (Hal = Cl, Br), respectively. In 8 and 9 each of the two Me3SiCC-units is η2-coordinated to monomeric CuI Hal or AgIHal moieties. Compounds 8 and 9 can also be synthesized by the reaction of (η5-C5H4SiMe3)2 Ti(CSiMe3)2 (1) with 1/n[CuIHal]n (6) or 1/n [AgIHal]n (7) in excellent yields. All new compounds have been characterized by analytical and spectroscopic data (IR, 1H-NMR, MS). The magnetic moments of compounds 3 were measured. 相似文献
20.
Nine complexes(RC_5H_4)_2Ti(O_2CC_6H_4X)_2(R=H,CH_3;X=H,o-Cl,o-OH,o-NH_2,o-NHPh)have been conveniently prepared by the reaction of(RC_5H_4)_2TiCl_2 with 2 equiv.sodium salts of corresponding carboxylic acidin aqueous solution containing acetylacetone.The carboxylate ligands inthe complexes coordinate to titanium atom in monodentate mode. 相似文献