盐酸滴定碳酸钠第二化学计量点碳酸浓度的探讨

盐酸滴定碳酸钠第二化学计量点碳酸的浓度是溶液的pH值的计算依据，碳酸的浓度应该根据等物质的量反应原理，利用反应溶液的浓度具体计算得出，同时，应该明确说明计算时忽略碳酸的分解这一前提条件。     

Alpha-Carbonic Acid Revisited: Carbonic Acid Monomethyl Ester as a Solid and its Conformational Isomerism in the Gas Phase

In this work, earlier studies reporting α-H₂CO₃ are revised. The cryo-technique pioneered by Hage, Hallbrucker, and Mayer (HHM) is adapted to supposedly prepare carbonic acid from KHCO₃. In methanolic solution, methylation of the salt is found, which upon acidification transforms to the monomethyl ester of carbonic acid (CAME, HO-CO-OCH₃). Infrared spectroscopy data both of the solid at 210 K and of the evaporated molecules trapped and isolated in argon matrix at 10 K are presented. The interpretation of the observed bands on the basis of carbonic acid [as suggested originally by HHM in their publications from 1993–1997 and taken over by Winkel et al., J. Am. Chem. Soc. 2007 and Bernard et al., Angew. Chem. Int. Ed. 2011] is inferior compared with the interpretation on the basis of CAME. The assignment relies on isotope substitution experiments, including deuteration of the OH- and CH₃- groups as well as ¹²C and ¹³C isotope exchange and on variation of the solvents in both preparation steps. The interpretation of the single molecule spectroscopy experiments is aided by a comprehensive calculation of high-level ab initio frequencies for gas-phase molecules and clusters in the harmonic approximation. This analysis provides evidence for the existence of not only single CAME molecules but also CAME dimers and water complexes in the argon matrix. Furthermore, different conformational CAME isomers are identified, where conformational isomerism is triggered in experiments through UV irradiation. In contrast to earlier studies, this analysis allows explanation of almost every single band of the complex spectra in the range between 4000 and 600 cm⁻¹.     

关于7种含氧酸结构与酸性的讨论

含氧酸是无机化学授课的一个重要内容，讨论了含氧酸中亚硫酸、硼酸、次磷酸、亚磷酸、溴酸、亚溴酸、碳酸的结构与酸性。研究表明，SO2溶液中存在着2种异构体；硼酸在不同条件下存在Lewis酸和Brönsted酸2种形式；次磷酸、亚磷酸、溴酸、亚溴酸都存在着异构化倾向；在一定条件下，碳酸具有一定的动力学稳定性。     

Synthesis of macrocyclic tris-cis-tris-trans- dodeca[(phenyl)(hydroxy)]cyclododecasiloxane in carbonic acid solution

The possibility to synthesize stereoregular tris-cis-tris-trans- dodeca[(phenyl)(hydroxy)]cyclododecasiloxane (tris-cis-tris-trans-[PhSi(O)OH]12) in an inorganic liquid medium – aqueous carbonic acid solution – was shown. The interaction of polyhedral phenylcoppersodiumsiloxane, {[(C₆H₅Si(O)O^?]₁₂(Cu₂⁺)₄(Na⁺)₄}*(L)_m (L?=?Buⁿ OH, H₂O), with carbonic acid can be considered as a new ‘green’ method to obtain functional organosiloxane macrocycles. In contrast to the known methods, no organic solvents were used during the reaction. The identification of the structure of the end compound was performed by means of NMR and Infrared spectroscopy as well as X-ray crystallography.     

Evaluation of vanillic acid as inhibitor of carbonic anhydrase isozyme III by using a modified Hummel–Dreyer method: approach for drug discovery

α‐3 carbonic anhydrase isozyme (CAIII) is the most abundant protein in adipocytes and considered insensitive to sulfonamide inhibitors. It was reported recently that the knock‐down of CAIII is attributed with controlling lipogenesis. Thus inhibition of this target may lead to the discovery of new therapies against obesity and insulin resistance. Vanillic acid as a small molecule with coordinating groups and has a potential to bind zinc atoms in CA binding sites. Inhibition of CAIII by vanillic acid was evaluated by Hummel–Dreyer chromatography because it provides free interaction between ligand and macromolecule and introduces solution for faulty results obtained by current colorimetric assays. HPLC system of vanillic acid produces vacancy (negative) peak representing the amount of attached vanillic acid with CAIII. It was found that vanillic acid is able to bind with CAIII through two equilibria, one at equimolar ratio and another at 2:1 (vanillic acid–CAIII) ratio. The affinity constant of equimolar binding between CAIII and vanillic acid was found to be 14,400 m ^?1. It was found that vanillic acid binding with CAIII is much stronger than phenol and acetazolamide (positive controls). Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis,crystal structure,spectroscopy, thermal properties and carbonic anhydrase activities of new metal(II) complexes with mefenamic acid and picoline derivatives

The mononuclear six metal(II) complexes ([Co(mef)₂(3-pic)₂(CH₃OH)₂] (1), [Ni(mef)₂(3-pic)₂(CH₃OH)₂] (2), [Cu(mef)₂(3-pic)₂] (3), [Co(mef)₂(4-pic)₂] (4), [Ni(mef)₂(4-pic)₂] (5), and [Cu(mef)₂(4-pic)₂] (6) with mefenamic acid and picoline ligands were synthesized, characterized, and their carbonic anhydrase inhibitory activities were evaluated. The six complexes were characterized by elemental analysis, FT-IR spectroscopy, and thermal analyses. The crystal structures of 1, 3, and 6 were determined by X-ray crystallography. The complexes have octahedral geometry. In 1, the mefenamato ligand behaved as monodentate whereas in 3 and 6, the mefenamato ligand acted as a bidentate ligand. Complexes 3 and 6 consist of the mefenamate and 4-picoline ligands. In 1, unlike the other complexes, methanol acted as a ligand and was involved in the coordination. Carbonic anhydrase I and II isoenzymes were purified from human erythrocytes. The in vitro effects of mefenamic acid, 3-picoline, 4-picoline, and the six metal(II) complexes on these isoenzymes were evaluated.     

COMPLEXES OF BINUCLEATING LIGANDS. XIII. SOLUBLE COMPLEXES OF A LIGAND WITH A BRIDGING THIOPHENOXIDE COMPONENT AND PERIPHERAL n-OCTYL SUBSTITUENTS

Abstract

The trianionic binucleating ligands formally derived from the condensation products of S-n-octyldithiocarbazate with either 2-hydroxy- or 2-mercapto-5-methylisophthalaldehyde (hereafter (L″)^3- and L^3- respectively) gave the binuclear complexes L″Ni₂ (CH₃ O), L″Ni₂ (C₆ H₅ CH₂ O), LNi₂ (C₃ H₃ N₂), LCu₂ (C₃ H₃ N₂) and LNi₂ (SR) where R=C₈H_{1 7} of CH₃.C₆ H₄ and C₃ H₃ N₂ ^?=the pyrazolate anion. These complexes were soluble in chloroform and ¹H n.m.r. data for some of them are presented. There was no evidence for significant magnetic exchange within LCu₂ (C₃ H₃ N₂). Attempts to generate LNi₂ (X) where X^?=Cl^?, Br^? or I^? gave L₂ Ni₃ in which L^3- fails to impose the intended molecular arrangement. Attempts to generate L(Pd(II))₂ (X) unexpectedly gave materials containing additional palladium, i.e. LPd₄ (CH₃ CO₂) and LPd₄ (C₃ H₃ N₂).