《溶胶ndSolu》ppt课件

1、溶胶凝胶化学与工程引论溶胶凝胶化学与工程引论A.C. Pierre, Introduction to Sol-gel Processing (Chemistry and Engineering)主讲：夏长荣，主讲：夏长荣，3607475，资料楼北，资料楼北217室，室， : 辅导：王运龙，辅导：王运龙， 考试考试60，不参与考试不计成果；，不参与考试不计成果；分组专题报告分组专题报告40；上课上课12周，签到周，签到8次以上，签到次以上，签到8次以下不计成果。次以下不计成果。Simplified chart of sol-ge

2、l processesThe chemistry of precursors solutionsAll types of precursors can be used, provided they are miscible.Metallic salt MmXn, AlCl3, (NH4)2Ce(NO3)6.Alkoxides, Al(OC2H5)3, Si(OCH3)4Organometallic compounds1. SolventsWaterNon aqueous solvents水是最好的极性溶剂之一，主要缘由是什么？水是最好的极性溶剂之一，主要缘由是什么？举举3个非水溶剂的例子？个非

3、水溶剂的例子？极性溶剂和非极性溶剂的主要区别是什么？极性溶剂和非极性溶剂的主要区别是什么？酸性、碱性、二性溶剂有何区别？酸性、碱性、二性溶剂有何区别？举例阐明举例阐明Protic, Aprotic, amphoteric质子性、非质子性、非质子性、两性溶剂？质子性、两性溶剂？Water, H2OThe angle HOH is 104.5o in the gaseous state, and varies from 118o to 120o in the liquid state.Dipole moment, = 1.85 D (1 Debye = 3.33610-30 Cm)3a1 is d

4、elocalized, Lewis base, donating a pair of electrons1b1 is non binding, a weak donorNegative partial charge of oxygen atom of (O) = -0.4Positive partial charge (H) = +0.2Results of polar structure IWater is an excellent liquid medium in which to dissolve ionic solutes2041rqqFr 0 = 8.8542 10-12 Fm-1,

5、 the dielectric permittivity of vacuum r, the relative dielectric constant, r,H2O = 78.4; it consequently largely attenuates the coulomb interaction between two electrical charges.Results of polar structure IIMolecules are bound by up to 4 hydrogen bonds to neighboring molecules.Further increase the

6、 ability to dissolve ionic solutes.Auto-dissociate2H2O H3O+ + HO-Kw = H3O+ HO- = 10-14 at 25oCH3O+ H9O4+ HO- H7O4-In consequence, O2- practically does not exist in water, and when a solid oxide is dissolved it immediately undergo an acid base protonation reactionNon aqueous solventsNon aqueous solve

7、nts r 40, Such moleculars have good ionizing properties and can therefore dissolve other polar solute r 20, These moleculars have a weak ionizing property and can only dissove less polar soluteClassificationProtic; exchange a proton, acidic; donate a proton or accept a pair of electronsAprotic; can

8、not exchange a proton, base; accept a proton or donate a pair of electronsA solvent is amphoteric when it can behave both as a base and as an acid.Amphoteric solventsMineral acids (HCN, HX, HNO3, H2SO4, H2S)Carboxylic acids R-COOHWater, the first alcohols (CH3OH, C2H5OH, ), and phenol C6H5OHAmmonia

9、NH3 and amines (RNH2, RRNH)Amides (R-CO-NH2, R-CO-NHR)2. Precursors transformations化学位？化学位？CH3COOH在在CH3COOH的水溶液中的化学位？的水溶液中的化学位？在在CH3COOH的水溶液中，的水溶液中，CH3COOH中的中的H与与H2O中的中的H的化学位相等吗？所带电荷一样吗？的化学位相等吗？所带电荷一样吗？实际上可以确定一个溶液体系一切不独立存在物实际上可以确定一个溶液体系一切不独立存在物种的化学位吗？主要原理是什么？种的化学位吗？主要原理是什么？什么叫络合物？举例阐明。什么叫络合物？举例阐明。络合

10、物的构成过程主要有几种？络合物的构成过程主要有几种？第一电离能和电子亲和势第一电离能和电子亲和势22121)() 1(eenEnEzEzEIThe first ionization energy, I12221) 1()(eenEnEzEzEAThe electron affinity, AChemical potential of the electrons and electronegativity of an isolated atomThe chemical potential of the electrons in a atom;eaenEThe electronegativity

11、of an isolated atom;eanEAI)(211Therefore,aeaPartial charge model The partial charge model is based on the electrical interactions between the partial electric charges, , carried by each atom and molecule.)()()()()(eaiaieaiaeeninii22121)(21eanEAIWhere, a is the atom hardnessElectronegativity scalesTh

12、e absolute electronegativity ia and hardness ia concern an isolated atom I.The Mulliken iM and iM, the electronic state of an atom in its average valence structure.The Pauling iP and iP, the average structure configuration in which the atoms are engaged.The Allred and Rochow iO and iO for the partia

13、l charge model, both the valence state and the shape of an atom X in its average polariztion.Allred-Rochows electronegativityOiOi36. 1iOiOii)(OiOi36. 1iizComplex C such as M(OH)y(H2O)N-y(z-y)+iOiiOiZC136. 1)( (C) = (H+) = (H2O)Water as an examplepH 7, water is partial charged, (H+) = o (H+) 0.06pH(H

14、+) = (H2O) = 2.631 0.02pHComplex transformationCo(NH3)6Cl3Nucleophilic additionCo(NH3)53+ + NH3 = Co(NH3)63+The direct addition of a new ligand occurs when the coordination number of the cation in the complex is not fully satisfied.Dissociative mechanismNi(OH2)62+ Ni(OH2)52+ + H2ONi(OH2)52+ + NH3 Ni

15、(OH2)5(NH3)2+Since the rate constant of such a reaction does not depend on the concentration of the entering Y ligand, this dissociative mechanism is a unimolecular nucleophilic substitution, SN1.Associative substitutionIt is a bimolecular nucleophilic substitution, SN2 since the rate constant depen

16、ds on the concentration of both the entering and the leaving groups.Interchange substitutionThe reaction proceeds in only one step and this is a SN2 substitutionBidentateTypical chelating ligands (2; bidentate, 3; tridentate, 4; tetradentate, and 6; hexadentate)Typical chelating ligands (2; bidentat

17、e, 3; tridentate, 4; tetradentate, and 6; hexadentate)3. 金属盐溶液4. 假设水合物不稳定，能够发生的反响是什么？假设水合物不稳定，能够发生的反响是什么？主要产物？反响进展的条件是什么？主要产物？反响进展的条件是什么？1. Al(NO3)3溶于水后，电离，构成溶于水后，电离，构成Al3和和NO3?2. Al3在水中稳定存在吗？在水中稳定存在吗？3. 假设构成水合物，即假设构成水合物，即Al3的络合物，它稳定吗？的络合物，它稳定吗？Metal Salts SolutionIONS SOLVATATIONMX = M(H2O)nz+ + X(

18、H2O)mz-, Z = 48, frequently 6, Al(H2O)63+, H9O4+HydrolysisHydrolysis is the deprotonation of a salvated metal cation.The aquo ligand, H2O is transformed into an hydroxo ligand, OH-, if only one proton leaves.Into an oxo ligand, O2-, if two protons detaches.Formation of hydroxo ligandsThe first depro

19、tonationThe successive deprotonationsThe equivalent forms of the reactionDeprotonation mechanism with hydroxo ligandThe deprotonation reaction occur as long as (O) free water (O) complex 0Formation of hydroxo ligands from oxo ligandsThe reaction continues as long as 0 (H) complex -1, or (X) 1 (X-) (M-(OH2)N-1z+Rewrite using electronegativitiesWith a molecular group HXIf only (HX) 0, or (X-) -1Fe(OH)2(OH2)4+ with bidentate anionsWith X = CH3COO-X- separates