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41.
Compounds of general formulatrans-ArNi(PR3)2OAr' (R = Et, cyclohexyl; Ar = 2-MeC6H4, 2-FC6H4; Ar' = 4-FC6H4, 4-NO2C6H4) were synthesized by the reaction of Ar'OK with cationic nickel complexes generated by treatment of ArNi(PR3)2Cl with TlBF4. Syntheses of 4-fluorophenoxide complexes, ArNi(PR3)2OC6H4F-4, additionally give some quantities oftrans-[ArNi(PR3)2OC6H4F-4][HOC6H4F-4] adducts. Exchange reactions MeC6H4Ni(PEt3)2OC6H4F-4 + XC6H4OH 2-MeC6H4Ni(PEt3)2OC6H4X + 4-FC6H4OH were studied in THF. The equilibrium is shifted to the right as the acidity of ArOH increases. A linear relationship between lgK
eq and pK
a of XC6H4OH in DMSO was found. A conclusion concerning the strong polarization of the Ni-O bond was made on the basis of an analysis of the chemical shifts of fluorine atoms in 2-MeC6H4Ni(PEt3)2OC6H4F-4.Translated fromIvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2266–2271, November, 1995. 相似文献
42.
1 INTRODUCTION Tri-butyl phosphate (TBP) has been widely used as the extraction reagent in U-Th fuel to separate uranium from thorium. But di-butyl phos- phate (DBP) and butyl phosphate (MBP), the radio- lytic products of TBP, exhibit some coordinated ability to the fission elements, such as Zr and Nb. The substitutes for TBP have being studied for several decades[1~4]. The physical and chemical properties of amides are similar to those of TBP and they selectively extract U(Ⅵ… 相似文献
43.
I. Goba B. Turovska J. Stradins I. Turovskis E. Liepinsh S. Belyakov 《Chemistry of Heterocyclic Compounds》2007,43(2):175-186
It has been shown that chemical oxidation of the methyl ester of 3,4,5-trimethoxycarbonyl-1,2,6-trimethyl-1,4-dihydropyridine
to the pyridinium salt, requiring forcing experimental conditions, may be replaced by electrochemical oxidation. On electrochemical
reduction of 3,4,5-trimethoxycarbonyl-1,2,6-trimethylpyridinium perchlorate in the presence of alkylating agents 1,2,3,4,4,5,6-substituted
1,4-dihydropyridines are obtained.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 226–237, February, 2007. 相似文献
44.
本文报道了金属置换碳酸酐酶的活性研究。指出了离子半径的大小,配位构型的要求,热力学稳定性和配位体交换动力学是决定各种金属置换碳酸酐酶活性的重要因素。并用金属置换法测定了Ni(Ⅱ)与apo-CA形成金属酶的反应动力学速率常数。在25℃、pH7.47时,K_(fNi(Ⅱ)-CA)为14.01·mol~(-1)sec~(-1),较之于Zn(Ⅱ)-CA的速率常数小10~3倍。Cd(Ⅱ)-CA的生成动力学为一快反应,采用配位竞争法,在邻菲罗啉配位剂存在下,测得了Cd(Ⅱ)-CA生成动力学的条件速率常数在o-phen浓度为1.96和2.92×10~(-4)mol·1~(-1)时分别为137.1和114.61·mol~(-1)sec~(-1)。这一研究提示了镉对生物体的毒性作用的一个重要方面是使锌酶失活。而配位剂的存在大大降低了镉与脱辅基锌酶的反应动力学,这也是它们显示解毒功能所在。 相似文献
45.
The behavior of hexafluoroacetone ethoxycarbonylimine in cyclocondensation with different binucleophiles of the amidine type, viz., amino derivatives of N- and N,S-heterocycles, was studied. A preparative method for the synthesis of previously unknown annelated 2,2-bis(trifluoromethyl)-1,3,5-triazinones was developed. 相似文献
46.
Summary 2-Chloroquinoline-3-carbaldehyde and 2-chloro-4-methylquinoline-3-carbaldehyde have been prepared from acetanilide and acetoacetanilidevia a Vilsmeier-Haack reaction. Upon reaction with phenyl hydrazine, hydroxylamine, urea, and thiourea in presence of acetic acid, these chloroaldehydes afforded the title compounds which exhibit a several times higher analgesic activity than noramidopyrine (NAP).
Synthese einiger neuer substituierter Chinoline als stark analgetisch wirkende Substanzen
Zusammenfassung 2-Chlorchinolin-3-carbaldehyd und 2-Chlor-4-methylchinolin-3-carbaldehyd wurden, ausgehend von Acetanilid und Acetylacetanilid, über eineVilsmeier-Haack-Reaktion hergestellt. Reaktion dieser chlorsubstituierten Aldehyde mit Phenylhydrazin, Hydroxylamin, Harnstoff und Thioharnstoff ergab die Titelverbindungen, deren analgetische Aktivität jene von Noramidopyrin (NAP) um ein Mehrfaches übertrifft.相似文献
47.
Shou‐Ri Sheng Xiao‐Ling Liu Yong‐Fen Tong Lie Chen Hong‐Li Wen Cai‐Sheng Song 《中国化学会会志》2005,52(5):943-946
Several new methyl substituted poly(aryl ether ketone)s containing sulfone linkage with inherent viscosities of 0.62–0.84 dL/g have been prepared from 4,4′‐bis(2‐methylphenoxy)diphenylsulfone and 4,4′‐bis(3‐methylphenoxy)diphenylsulfone with terephthaloyl chloride and isophthaloyl chloride by electrophilic Friedel‐Crafts acylation in the presence of DMF with anhydrous AlCl3 as a catalyst in 1,2‐dichloroethane, respectively. These polymers having weight‐average molecular weight in the range of 71,000–49,000 are all amorphous and show high glass transition temperatures ranging from 167 °C to 191 °C, excellent thermal stability at temperatures over 400 °C in air or nitrogen, high char yields of 51–58% in nitrogen and good solubility in CHCl3 and polar solvents such as DMF, DMSO and NMP at room temperature. 相似文献
48.
Rate constants for the reaction of ethyl bromoacetate with three series of substituted naphthoate ions have been measured
in an acetone-water mixture (90% v/v). Using σ
p
values rate constants at 30o correlate well with the Hammett equation yielding ρ=−0.54, −0.19 and −0.25 for (4,1−), (6,1−) and (6,2−) series, respectively.
Comparison of these ρ values with those of the reaction of phenacyl bromide reveals the failure of the reactivity-selectivity
principle RSP in these reactions. Failure of RSP has been explained in terms of isoselective temperature. 相似文献
49.
50.
Enthalpies of dilution of formamide, N-methylformamide, N-ethylformamide, N-propylformamide, N-butylformamide, N-pentylformamide, N,N-diethyl-formamide, N,N-dipropylformamide, N,N-dibutylformamide, and N,N-dipentyl-formamide dissolved in N,N-dimethylformamide as solvent have been measured calorimetrically at 25°C. The results are interpreted in terms of the McMillan-Mayer theory. Enthalpic interaction parameters are obtained for pairs, triplets, and in some cases, quadruplets of solute molecules. In general, the enthalpic pair interaction coefficients are negative, whereas the triplet coefficients are positive. The interaction enthalpies are positive only for N-methylformamide and formamide. The magnitudes of the enthalpic pair and triplet interaction coefficients increase with increasing number of C atoms in the N-alkyl groups. The results for the formamides presented in this paper are compared with those for corresponding acetamides published earlier. Although the trends are comparable, distinct differences are observed. The contribution of the -CH3 group at the CO side of the dialkylacetamides to the enthalpic interaction coefficients appears to be negligible. The same is true for -CH2 groups at the NH side of a number of amides and related compounds. The enthalpic pair interaction coefficients of the mono-N-alkylsubstituted formamides show a shift of about 100 J-kg-mol–2 as compared with isomeric N-alkylacetamides. This is discussed in terms of the difference in proton donating and accepting ability of several types of amide molecules. It is concluded that substitution effects should be incorporated in additivity models for these type of systems. 相似文献