摘要:

AbstractThe formation constants of ternary mixed ligand complex compounds formed from Cu(II)‐2,2′‐bipyridyl (bipy) withN‐(para‐substituted phenyl) glycines (pRPhG), Cu(II)‐1,10‐phenanthroline (phen) withN‐(meta‐substituted phenyl) glycines (mRPhG), Cu(II)‐bipy/phen with some α‐aminoacids (αA) have been determined by pH method at 25°C in the presence of 0.10 M NaClO4. It was found that linear free energy relationships do exist between the stability of ternary complex compounds and the base strengths of the ligands in all four ternary systems investigated. The stability of the ternary complex compounds was discussed in terms of ΔlogKMand logXvalues. It was found again that linear relationships exist between Δ logKM, logXand pK2in the Cu(II)

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040302

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe results of chemical reaction of carvone (1) initiated by the irradiation of XeCl excimer laser were reported in this paper. According to the relations of the products of carvonecamphor (2) and 1‐exo, 5‐dimethyl‐syn‐2 [(ethoxycarbonyl)‐methyl] bicyclo [2, 1, 1]hexane (3) to the irradiation energy of the laser, the reaction process of 1→2→3 can be defined. The experiments showed that the production rates of 2 or 3 per joule of the irradiation energy was increasing with the increase of the incident laser beam intensities at low light intensity and had a tendency to saturate at high intensity. Besides, the concentration effect of the sample and luminescence phenomenon could also be observed during the laser irradi

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040303

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe triplet energy migration of polymers and copolymers of vinyl benzophenone (VBP) and vinyl naphthalene (VN) has been studied by measuring delayed fluorescence and polarization spectra in glassy dilute solution at 77 K. Strong delayed fluorescence of PVN proves the existence of triplet energy migration and T‐T annihilation in the polymer chain. Efficient intersystem crossing of “BP” and efficient energy migration and transfer between chromophores along the polymer chain result in the absence of delayed fluorescence for copolymer P (VN‐VBP) studied in this work. The order of benzophenone phosphorescence intensity: BP>Co (VBP‐St)>PVBP indicates the T‐T annihilation decreasing the phosphorescence of PVBP. Fluorescence and phosphorescence polarization data of polymers are smaller than that of their model compounds. It is evident that energy migration exists in the po

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040304

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThrough the reactions of ferrous thiolates with tetrathiomolybdate, we discussed the reaction pathways and possible intermediates during the formation of double‐cubane type Mo‐Fe‐S cluster compounds. We also reported the synthesis, crystal structure, IR and magnetic susceptibility measurements of the title compound 2. The crystal of 2 belongs to triclinic system,Mr= 2670.3;\documentclass{article}\pagestyle{empty}\begin{document}$$ P\bar 1 $$\end{document};a= 12.755(4) Å,b= 13.076(3) Å,c= 20.576(4) Å; α = 80.00 (2)°, β = 81.39(2)°, γ = 61.51(2)°;V= 2966.3(14) Å3;Z= 1;Dc= 1.495 g/cm2. FinalRfactor is 0.077 for 4031 observed reflections. The compound was obtained through the reaction of (Et4N)2[Fe4(SPh)10] (1) with (Et4N)2MoS4in acetonitrile solution. The structure of anion 2 is two cubane clusters bridged by a Fe(SPh)6group. The Mo… Mo' distance of 7.188 Å is the longest among all double‐cubane cluster compounds

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040305

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractHydrolytic rate constants ofp‐substituted phenol esters of carboxylic acids with various chain lengths were measured in 1:1 (v/v) Me2SO‐H2O. Amylose accelerates the hydrolytic rates of all substrates, but the catalytic patterns are different for long and short chain substrates,i.e., acetates (2‐X) show 2nd order kinetics, dodecanoates, (12‐X) and hexadecanoates (16‐X) follow Michaelis‐Menten saturation kinetics. The dissociation constantsKdof inclusion complexes are dependent on the chain length of substrates. The rate constantskun,Kobs,k2andkoof 12‐X and 2‐X conform to the Hammett relation, the ρ values are almost the same, whether in the presence or absence of amylose. Butkun,kobsandkcvalues of 16‐X all cannot be correlated by the Hammett equation because of the aggregation and self‐coiling of 16‐X in this poor solvent. Thermodynamic parameters ΔHiand ΔSiof the inclusion process and activation parameters ΔHc≠and ΔSc≠were obtained from the temperature dependence ofKdandkc. The results indicate that the formation of inclusion complexes between amylose and substrates is an entropy disfavored and enthalpy favored process. Comparison of ΔHc≠, ΔSc≠with ΔHun≠and ΔSun≠shows that the acceleration of hydrolysis of long chain substrates by amylose is caused by th

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040306

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractFrom a long‐stored hydrochloric acid extract of the Chinese toxic plant Kou‐Wen (Gelsemium elegansBenth), hydrakouminol, C20H24N2O2(M+ 324.1814) has been isolated. It has been assigned a structure 2 according to spectroscopic analysis, and considered to be resulting from an extremely slow process of proton‐induced hydration of koumine, 1, via two consecutive Wagner‐Meerwein rearrangements, as shown in Scheme 1. The proposed structure 2 has been supported by its reduction with borane complex in hydrochloric acid intoneo‐dihydrokoumine 3, the structure of which has been determined by1H and13C NMR analyses and confirmed by X‐ray crystallography. The probable mechanism for the formation of 2 and 3 has bee

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040307

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThis paper deals with the synthesis of two new (±)‐3‐oxa‐A‐nor steroids 1a and 1 b. The conjugated addition of 5′‐methylfurandithane anion 8b to the CD‐ring synthon 9 in HMPA‐THF afforded 9, 10‐seco‐3‐oxa‐A‐nor steroid 22. The intramolecular cyclization of 22 in acidic medium gave 23, which underwent hydrolytic desulfurization at elevated temperature in acidic medium to give 1b. The desulfurization of 23

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040308

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractIn this paper, the kinetics, the product distributions and the corresponding reactions of some products of zeolite‐catalyzed hydration of α‐pinene have been studied. The results indicate: 1. α‐Pinene is hydrated mainly to borneol, but isomerizations always accompany the hydration and camphene and limonene are the main olefines formed. 2. The disappearance of α‐pinene follows the first‐order kinetics, of which the rate constants, the activation energy as well as the activation entropies have been calculated. 3. A probable mechanism has been proposed, in which the hydration of α‐pinene through two equilibrating adsorbed intermediates, which, via three pathways, lead to derivatives of fenchane, bornane andp‐menthane respectively. The distributions of the three pathways have been examined and appear to be determined by the stability of the adsorbed interm

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040309

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe fluorocarbanion [n‐C3F7OCF (CF3)−] generated by decarbomethoxylation of methyl perfluoro‐2‐methyl‐3‐oxa‐hexanoate(1)can be trapped in many cases with substituted benzoyl chlorides (YArCOCl). In this way, a simple, convenient method for the preparation of aryl β‐oxa‐fluoroalkylketones has been developed. The mechanistic consideration of the ester decomposition induced by the lithium chloride/hexamethylphosphoric triamide complex (LiCl/HMPA) and KI/CH3CN involves nucleophilic attack by halides on the methoxy car

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040310

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe key intermediate (2S, 3R)‐2‐citronellyl‐6‐methylene‐heptan‐2,3,7‐triol (8) of analogues of zoapatanol was synthesized in seven steps from the chiral synthon 2. The absolute configuration of the new chiral centre in compounds 5a‐8 was identified as S by Muk

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040311

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY