离子交换树脂在高参数水汽系统中的分解特性研究

通过高压釜模拟高温高压的水汽环境,研究了离子交换树脂在温度为230℃和300℃下的分解特性,全面检测了离子交换树脂的各种分解产物和树脂分解前后的结构变化,结合树脂的化学结构,分析了离子交换树脂的分解机理,并通过高压釜挂片试验,探究了离子交换树脂的分解产物对TA16合金的影响。试验结果表明,离子交换树脂的分解包括具有离子交换能力的活性基团的脱离和树脂骨架的分解,H型阳树脂分解产生了H2SO4,Na型阳树脂分解生成了NaHSO4,OH型阴树脂分解生成了三甲胺,Cl型阴树脂分解产生氯化三甲铵,4种树脂分解都有苯及苯的同系物生成,且分解产物对TA16合金没有明显的腐蚀。     

微酸性条件下环己基过氧化氢分解制备环己酮工艺研究

针对传统碱性分解的不足,以有机铬酸酯为催化剂,对环己烷氧化液中的环己基过氧化氢分解制备环己酮工艺进行了探索,考察了在催化剂铬离子浓度150 ppm时,分解温度及时间对环己烷氧化液分解产物的影响,得出最佳的微酸性分解工艺条件。并在连续分解实验装置对前面得到的微酸性分解工艺条件进行验证。     

热力学抑制剂作用下甲烷水合物分解过程的分子动力学模拟

采用正则系综(NVT)分子动力学方法模拟研究277.0 K、11.45 mol·L-1的热力学抑制剂乙二醇(EG)溶液作用下甲烷水合物分解微观过程. 模拟显示甲烷水合物的分解从甲烷水合物固体表面开始, 逐渐向内部推移, 固态水合物在分解过程中逐渐缩小, 直至消失. 固态水合物的分解从晶格扭曲变形开始, 之后笼形框架结构破裂, 最后形成笼形结构碎片. 同时已经分解的甲烷水合物在外层形成水膜, 包裹里层正在分解的甲烷水合物, 增大里层甲烷水合物分解传质阻力.     

硫酸铝晶体热分解行为及分解反应动力学研究

针对酸法制备氧化铝过程中Al2(SO4)3.18H2O焙烧分解工艺,通过TG-DTA曲线,研究其分解行为和分解过程的动力学.结果表明:Al2(SO4)3.18H2O的脱水分解过程分两步进行,首先脱掉15个层间水,其次脱掉3个结构水;分解过程一步完成.利用Doyle-Ozawa微分法和Kissinger积分法计算出各吸热峰反应的活化能、指前因子,得到Al2(SO4)3.18H2O分解反应的速率方程.     

溶液中氢氧化铜分解问题的实验探究

实验教学中制取的氢氧化铜,在室温条件下放置时会变黑。通过实验探究,验证了溶液中氢氧化铜分解的反应机理和影响氢氧化铜分解快慢的因素。得出了温度越高、碱性越强,氢氧化铜分解越快的结论。总结了氢氧化铜分解的特点。     

用硷法分解独居石的研究

用热液球磨分解法进行分解国产独居石的研究,在独居石矿砂(不必粉碎)与氢氧化钠的比例1:1,硷液浓度为50％,反应温度为160±2℃,反应时间为6小间的条件下,矿砂的分解率在95％以上。文中列出了常压分解,压热分解等分解独居石的方法的较好操作条件,也将热液球磨分解法、常压分解法和压热分解法进行了比较,认为热液球磨分解法是其中较好的方法。     

氮化硅的酸分解研究

基于化学动力学原理,采用增加分解压力,提高分解温度的手段,使原在常压下无法用酸分解的氮化硅实现了用酸分解。并研究了提高分解效率的诸条件,从而改革了原有的用碱性熔剂熔融氮化硅的方法。     

稀土尾矿中氟碳铈矿分解反应动力学研究

分解反应动力学可以深入分析氟碳铈矿分解反应过程,基于程序升温热重和质谱数据,采用Li Chung-Hsiung方法和Malek方法确定了氟碳铈矿分解反应过程的最概然机理函数、活化能和指前因子。热重实验结果表明,氟碳铈矿在空气和N₂气氛围下400～600℃温度范围内分解,空气氛围更有利于氟碳铈矿分解反应的进行,分解过程可用A模型很好地描述,即氟碳铈矿分解反应的速率控制步骤包含产物成核、核增长和核吸收长大。空气氛围下,氟碳铈矿分解反应过程活化能和指前因子分别为17.657～24.885 kJ·mol^-1和6.223～29.653 min^-1;N₂气氛围下,氟碳铈矿分解反应过程活化能和指前因子分别为25.532～30.236 kJ·mol^-1和36.882～64.250 min^-1,基于最概然机理函数、活化能和指前因子,建立了N₂气和空气氛围下的稀土尾矿中氟碳铈矿的分解反应动力学模型。     

复合离子液体中纤维素的催化分解

通过将酸性功能化离子液体与对纤维素具有溶解作用的离子液体进行复合, 构建了一类新型的高效催化纤维素分解的体系, 并采用热重(TG)分析方法, 研究了复合离子液体中纤维素的分解行为. 结果表明: 复合离子液体中纤维素的分解温度明显降低, 溶于离子液体中的纤维素可被酸性离子液体原位催化分解. 纤维素的分解温度受离子液体催化剂的酸性及纤维素在复合离子液体中的溶解度影响明显: 酸性越强, 溶解度越大, 纤维素的分解温度越低.     

负载钯催化剂上亚硝酸乙酯的催化分解

 研究了亚硝酸乙酯在不同载体及负载钯催化剂上的分解行为．结果显示，固体酸性中心和金属钯中心都可以催化亚硝酸乙酯的分解反应．在C2H5ONO与CO合成草酸二乙酯的反应中，亚硝酸乙酯是在固体催化剂表面发生分解，而不是在气相发生热裂解．并且，该反应的活性与亚硝酸乙酯的分解程度不存在正比关系．通过对分解产物的分析，提出了亚硝酸乙酯在固体催化剂上分解的连续脱氢机理．     

二苯胺-4-偶氮磺酸盐及其树脂的制备和光、热分解性质

从二苯胺 4 重氮盐(DS)和3 甲氧基二苯胺 4 重氮盐(MDS)以及重氮树脂(DR)和硝基重氮树脂(NDR)与亚硫酸钠反应,在水溶液中制备了相应的二苯胺 4 偶氮磺酸盐DSS和MDSS(简称偶氮磺酸盐)及相应的重氮树脂的偶氮磺酸盐DRS和NDRS(简称偶氮磺酸盐树脂).对它们在水溶液和固相膜中的光、热反应进行了研究.结果表明偶氮磺酸盐与偶氮磺酸盐树脂有很好的感光性能,而热稳定性比相应的重氮盐和重氮树脂好很多,其中二苯胺上有硝基取代的偶氮磺酸盐树脂具有突出的热稳定性,其水溶液在70℃加热6h,其固相膜在100℃加热11天几乎观察不到分解.对偶氮磺酸盐及偶氮磺酸盐树脂的光、热分解机理作了初步分析.     

不同结构二苯胺重氮盐及重氮树脂的光,热分解

对二苯胺-4-重氮盐(DS)、邻-甲氧基二苯胺-4-重氮盐(MDS)和N-甲基-间硝基二苯胺-4-重氮盐(NDS)及它们的重氮树脂(DR,MDR,NDR)在水溶液中的光,热分解研究表明,这些重氮盐和树脂的光分解性质,即感光灵敏性差别不大,而热分解性质,即热稳定性差别很大.MDS的热稳定性最好.固相膜中3种树脂的光分解亦差别不大,但N-甲基-间硝基二苯胺-4-重氮树脂(NDR)固相膜的热稳定性出乎预料地好.从疏水性的角度对NDR固相膜突出的热稳定性作了初步解释.     

有机负离子重氮树脂

重氮树脂作为阴图ＰＳ版的感光剂已有很多专利［１～４］．它是由二苯胺－４－重氮盐或取代二苯胺－４－重氮盐与多聚甲醛在浓硫酸中缩聚制得，由于耐候性与亲油墨性差，实际应用时，需将ＨＳＯ－４转换为有机负离子，如与十二烷基苯磺酸钠反应，但常导致热分解温度（Ｔｄ...     

3-甲氧基二苯胺-4-重氮盐的制备及其光、热分解性质

３－甲氧基二苯胺－４－重氮盐（ＭＤＤＳ）与甲醛或４,４－二甲氧次甲基二苯醚的缩合物用作阴图ＰＳ版感光剂,Ｈｏｅｃｈｓｔ等公司［１～５］已有很多专利．可能是出于商业利益,关于ＭＤＤＳ的制备方法未见报道．我们［６］从苯胺钾与３－甲氧基氯苯出发,制备了这...     

Thermal and photochemical solvolysis of (E)- and (Z)-2-phenyl-1-propenyl(phenyl)iodonium tetrafluoroborate: benzenium and primary vinylic cation intermediates

The thermal and photochemical solvolysis of the two stereoisomeric 2-phenyl-1-propenyl(phenyl)iodonium tetrafluoroborates has been investigated in alcoholic solvents of varying nucleophilicity. The product profiles and rates of product formation in the thermal reaction are all compatible with a mechanism involving cleavage of the vinylic C-I bond assisted by the group in the trans position (methyl or phenyl), always leading to rearranged products. Depending on the nucleophilicity of the solvent, the primarily formed cations may or may not further rearrange to more stable isomers. The less reactive Z compound also yields some unrearranged vinyl ether product in the more nucleophilic solvents via an in-plane S(N)2 mechanism. The mechanism of the photolysis involves direct, unassisted cleavage of the vinylic, and aromatic, C-I bond in an S(N)1 mechanism. This produces a primary vinyl cation, which is partially trapped prior to rearrangement in methanol. The unrearranged vinyl ethers are mainly formed with retention of configuration via a lambda3-iodonium/solvent complex in an S(N)i mechanism. Thermal and photochemical solvolyses of iodonium salts are complementary techniques for the generation of different cation intermediates from the same substrate.     

二苯胺重氮盐在乙醇中的光、热分解动力学

二苯胺-4-重氮盐与甲醛的缩聚产物-重氮树脂是制备阴图PS版最重要的感光剂,用它制备阴图PS版已有很多专利^[1-7],但二苯胺重氮盐(包括有类似结构的咔唑重氮盐)光、热分解,文献上还未见有报导。     

Photosolvolysis of (E)-styryl(phenyl)iodonium tetrafluoroborate. Generation and reactivity of a primary vinyl Cation

The photochemistry of (E)-styryl(phenyl)iodonium tetrafluoroborate in methanol and 2,2,2-trifluoroethanol as well as in dichloromethane and toluene has been investigated. In all solvents the vinylic C [bond] I bond is more photoreactive than the aromatic C [bond] I bond. Homolysis as well as heterolysis of both bonds occurs, but the latter type of cleavage predominates. In alcoholic solvents, the incipient phenyl cation produces a nucleophilic substitution product. The primary styryl cation gives nucleophilic substitution, elimination, and rearrangement products. The dependence of the photoreaction on the nucleophilicity of the solvent indicates that in the presence of good nucleophiles a 10-I-3 compound is the reactive iodonium species. In this case the reaction proceeds via an S(N)i mechanism. In the absence of good nucleophiles an 8-I-2 species gives photoreaction via an S(N)1 mechanism. This is corroborated by the solvent dependence of the UV spectra, and the product composition upon photoreaction with bromide in varying concentration. Photoreaction of the iodonium salt in a chlorinated alkane yields (E)- and (Z)-beta-fluorostyrene in a Schiemann-type reaction. Reaction in toluene yields Friedel-Crafts products. The results of the photochemical reactions are compared to those of the thermal ones, and the implications of the differences are discussed.     

Effects of an electron-withdrawing group on thermal decomposition of 4-alkylidene-1-pyrazolines: a novel stereoselective formation of alkylidenecyclopropane due to participation of pi-electrons on the methylene carbon in decomposition

Thermal decomposition of 4-alkylidenepyrazolines 14 bearing a methoxycarbonyl group at C-3, prepared by 1,3-dipolar cycloaddition between allenecarboxylates 12 and diazoalkanes 13, was carried out. Unlike normal 4-alkylidenepyrazolines, which decompose in stepwise mechanisms at high temperatures, 14 decomposed concertedly at moderately low temperatures (45-110 degrees C), resulting in selective formation of the two isomeric alkylidenecyclopropanes 7 arising from the bond formation between the exo-methylene carbon and the 5-carbon. The selective formation and the configurations of the products are rationalized in terms of the concerted process via the folded conformation of the pyrazolines. Introduction of an electron-withdrawing group at the 3-position of the 4-alkylidenepyrazoline system causes the polarization of the C(3)-N(2) bond inducing the properties of intramolecular diazonium salt 8, in which the pi-electrons on the methylene carbon become more nucleophilic and participate in the cleavage of the C(5)-N(1) bond. The X-ray crystal structure of the typical normal alkylidenepyrazoline 14a with only small steric interactions between the substituents was determined to be a nearly planar ring structure.     

N-甲基二苯胺-4-重氮盐制备及性质

二苯胺重氮盐(C₆H₅NHC₆H₄N₂⁺ X^-)与甲醛的缩合物重氮树脂,在光照下易与带侧链羟基的线型高分子形成亲墨性好的交联产物,被广泛用于阴图PS版的制备^{[1 5]}。用于PS版感光剂,最重要的一项性能是热稳定性要好,即制备重氮树脂用的重氮盐热分解温度要高,热分解速度要慢。     

A new disilene with π-accepting groups from the reaction of disilyne RSi≡SiR (R = Si(i)Pr[CH(SiMe3)2]) with isocyanides

The reaction of 1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4-diisopropyltetrasila-2-yne (1) with tert-butylisocyanide or tert-octylisocyanide produced the corresponding disilyne-isocyanide adducts [RSiSiR(CNR')(2)] (R = Si(i)Pr[CH(SiMe(3))(2)](2), R' = (t)Bu (2a) or CMe(2)CH(2)(t)Bu (2b)), which are stable below -30 °C and were characterized by spectroscopic data and, in the case of 2a, X-ray crystallography. Upon warming to room temperature, 2 underwent thermal decomposition to produce 1,2-dicyanodisilene R(NC)Si═Si(CN)R (3) and 1,2-dicyanodisilane R(NC)HSiSiH(CN)R (4) via C-N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative 3 was characterized by X-ray crystallography.