摘要:

AbstractHigh‐performance liquid chromatography (HPLC) coupled with the reverse‐pulse amperometric (RPA) detection method has been developed for the analysis of triorganotin compounds in aqueous solutions. The major advantage of RPA vs. conventional amperometric detection is its ‘in situ’ elimination of interference from dissolved oxygen in the chromatographic eluent; therefore, no extra chemicals or apparatus are required for oxygen removal. With a Partisil‐10 SCX column and an eluent of methanol/0.01 M sodium acetate buffer (70:30, pH 5.5), the four triorganotins, viz., trimethyl‐, triethyl‐, tripropyl‐, and tributyltin, can be totally separated. Detection by RPA was performed with a static dropping mercury electrode with an initial potential of −1.15 V and a final potential of +0.15 V. The absolute detection limit (S/N = 3) ranged from 12 ng of tributyltin (as tin) to 0.3 μg of trimethyltin (as tin). Applications of the method to the analysis of trace tributyltin in marine antifoulant leachate and sea w

ISSN:0009-4536    

DOI:10.1002/jccs.198900028

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractDiantipyrylmethane and tiron spectrophotometric determinations of Ti in the super alloys, Inconel 718 and Inconel 600, have been studied thoroughly. Both reagents formed stable yellow complexes with Ti(IV) in acidic medium. The possible interference from Ni, Fe and Cr was examined. Interference from Fe(III) was eliminated by the reduction of Fe(III) to Fe(II). Cr was removed as chromyl chloride which led to a dramatic improvement in the analytical results for Ti by the tiron photometric method. However, the removal of Cr was not necessary when the diantipyrylmethane method was employed. Consequently, lengthy manipulation of super alloys was required for the tiron determination. These two spectrophotometric methods are compared in terms of simplicity, reproducibility and accuracy.

ISSN:0009-4536    

DOI:10.1002/jccs.198900029

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractIn order to investigate the effect of structure variation upon complex dissociation rate constants, the kinetics of the dissociation of (C·rac·5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)copper(II) (red) cation has been examined spectrophotometrically at 25.0°C in 0.1–5.0 M HNO3. The cleavage of the second copper‐nitrogen bond is proposed as the rate‐determining step for this reaction. The possible pathways for the cleavages of the copper‐nitrogen bonds, the factors influencing the dissociation rates, and the factors affecting the relative importance of each of these possible pathway

ISSN:0009-4536    

DOI:10.1002/jccs.198900030

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractBy means of the addition of Ba into the Bi‐Ca‐Sr‐Cu‐O 2122 system, a series of Bi2CaSr2‐xBaxCu2O8+δ(0 ≤ × ≤ 2) quinary metal oxides were prepared by the citrate route and by the conventional powder reaction method. The samples prepared by the former method have better properties than the latter. It was found that 5 was not equal to zero for all of them and that it increased with decreasing Tc. Two phases were indentified in the oxides containing all five metal elements. One is the Bi‐Ca‐Sr‐Cu‐O 2122 phase, the other is a new insulating phase which probably contains Bi‐Ca‐Ba‐Cu‐O with undetermined stoichiometry. Superconductivity was found in those samples for which × ≤ 1.50 with their Tc onsets between 93–78 K by resistivity measurements. Superconductivity decreased monotonically with increasing x. However, residual resistance was found in those samples for which 1.00 ≤ × ≤ 1.50, The Meissner effect appears in the samples where × ≤ 1.00 with Tc onsets between 88–80 K. For x = 1.75 and 2.00, the samples were semiconductors with resistivities of 6.66 × 102and 6.96 × 103Ω cm at 290 K, and activat

ISSN:0009-4536    

DOI:10.1002/jccs.198900031

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe rates of reaction of a series of substituted naphthoxides with 1‐chloro‐2,4‐dinitrobenzene in methanol, and the pKavalues of the naphthols in 50% methanol have been measured. A linear free energy relationship applies well to these reactions. The rate constants are correlated with the pKavalues of the corresponding naphthols via the Brönsted equation giving a β values of 0.94. A linear correlation between ΔH‡and ΔS‡is indicative of single mechanism. The nmr spectra of the substituted naphthols have been measur

ISSN:0009-4536    

DOI:10.1002/jccs.198900032

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractAn investigation of benzylic oxidations with manganese dioxide supported on neutral alumina has been carried out. Isolation of intermediated products, which is possible in some cases, gives strong support for the reaction mechanism proposed. With 2,6‐di‐tert‐butyl‐4‐methylphenol, 4,4′‐dihydroxy‐3,5,3′,5′‐tetra‐tert‐butyldiphenylmethane,2,6‐di‐tert‐butylphenol and 4‐methyl‐phenol, selective formation of essentially a single prod

ISSN:0009-4536    

DOI:10.1002/jccs.198900033

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

Abstract3‐(Phenylthio)‐4‐(trimethylsilyl)‐3‐sulfolene(2)was readily prepared by chlorosulphenylation‐dehydrochlorination of 3‐(trimethylsilyl)‐3‐sulfolene(4b). Treatment of 2 with n‐butyllithium at −105 °C followed by an alkylating agent gave only C5 alkylation products 6 demonstrating the stronger carbanion stabilizing ability of phenylthio group than that of trimethylsilyl group. 2‐(Phenylthio)‐3(trimethylsilyl)‐1,3‐butadiene(3a)was readily prepared by thermal extrusion of sulfur dioxide from2. Selective oxidation of3awith MCPBA gave the sulfinyl(3b)and sulfonyl(3c)derivatives. The Diels‐Alder reactions of3a‐cwere studied, and the regiocontrolling power of the substituents follow

ISSN:0009-4536    

DOI:10.1002/jccs.198900034

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThat polystyrene and benzene as additives to gasoline increase the amount of polycyclic aromatic hydrocarbons (PAHs) has been studied previously in our laboratory. This paper describes the use of carbon disulfide as the solvent instead of benzene brings a marked reduction of the formation of polycyclic aromatic hydrocarbons.

ISSN:0009-4536    

DOI:10.1002/jccs.198900035

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe reactions of 4‐carboxyhydrazide‐5,6‐diphenyl‐3(2H)‐pyridazinone(I)with aromatic aldehydes, phenyl isothiocyanate, β dicarbonyl compounds, ethyl ethoxymethylenecyanoacetate, ethyl cyanoacetate and acylating agents have been investigated. Oxadiazolines(III)and thiazolidinones(IV)were synthesized from arylidenehydrazides(II)through appropriate routes. The thiosemicarbazide derivative(V)on reaction with malonic acid and acetyl chloride gaveVII, and on treatment with monochloroacetic acid and sodium acetate affordedIX. Some reactions with 3‐amino‐4,5‐diphenylpyrazolo [3,4‐b] pyridazine (XIVa)

ISSN:0009-4536    

DOI:10.1002/jccs.198900036

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY

摘要:

Abstract2,2′‐Bifuran was synthesized via a much more efficient way directly from fu

ISSN:0009-4536    

DOI:10.1002/jccs.198900037

出版商:WILEY‐VCH Verlag    

年代:1989

数据来源: WILEY