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301.
Ethyl butylidene-bis-3-phthalimidoacetoacetate (II) was prepared by condensation of ethyl-3-phthalimido-acetoacetate and n-butyraldehyde in the presence of piperidine in benzene. Compound II was hydrolysed by hydrochloric acid followed by cyclization with potassium thiocyanate to yield bis(2-mercaptoimidazole)-4,4-butylidene (IV). 相似文献
302.
Alcoholate complexes of nickel chloride with the general formula, NiCL2 · ROH (R = CH3, C2H5, i-C3H7, n-C4H9, t-C4H9, t-C5H11, n-C6H13 and n-C8H17), synthesized either by the reaction of anhydrous nickel chloride with alcohols or by the replacement of methanol from NiCL2 · MeOH with higher alcohols, depict interesting differences when R is a secondary or tertiary alkyl group instead of a primary group. A study of the magnetic susceptibility, thermogravimetric measurement, electron spin resonance and electronic reflectance spectra has been carried out to throw light on the structure of these derivatives. 相似文献
303.
Krishna N. Mehrotra Mithlesh Chauhan Rajeev K. Shukla 《Monatshefte für Chemie / Chemical Monthly》1989,120(12):1063-1068
Summary The physico-chemical characteristics of samarium soaps (caproate and caprate) in solid state were investigated by IR, X-ray diffraction and TGA measurements. The IR results revealed that the fatty acids exist in dimeric state through hydrogen bonding and samarium soaps possess partial ionic character. The X-ray diffraction measurements were used to calculate the long spacings and the results confirmed the double layer structure of samarium soaps. The decomposition reaction was found kinetically of zero order and the values of energy of activation for the decomposition process for caproate and caprate were found to be 8.0 and 7.8 kcal mol–1, respectively.
Physikochemische Untersuchungen an Samariumseifen in festem Zustand
Zusammenfassung Die physikochemischen Charakteristika von Samariumseifen (Caproat und Caprat) wurden im festen Zustand mittels IR, Röntgendiffraktion und TGA-Messungen untersucht. Die IR-Ergebnisse zeigten, daß die Fettsäuren durch Wasserstoffbrücken dimer vorliegen und daß die Samariumseifen partiell ionischen Charakter besitzen. Die Röntgenuntersuchungen bestätigen die Doppelschichtstruktur der Seifen. Die Zersetzungsreaktion verlief nach nullter Ordnung, und die Aktivierungsenergien für den Zersetzungsprozeß für Caproat und Caprat waren 8.0 und 7.8 kcal mol–1.相似文献
304.
Summary It has been shown that Cu, Hg, Sb, Bi, Se, Te, Au, Pt and Pd precipitated from their compounds in elementary form and thus be determined gravimetrically by vanadium(II) sulphate solution.
Part II: Z. analyt. Chem.189, 406 (1962). 相似文献
Zusammenfassung Cu, Hg, Sb, Bi, Se, Te, Au, Pt und Pd können mit Vanadium(II)-sulfatlösung aus ihren Verbindungen in elementarer Form gefällt und gravimetrisch bestimmt werden.
Part II: Z. analyt. Chem.189, 406 (1962). 相似文献
305.
O. P. Singh A. Chaturvedi D. B. Saxena R. K. Mehrotra G. Srivastava 《Monatshefte für Chemie / Chemical Monthly》1994,125(6-7):607-613
Summary 2-Diphenylphosphinato-1,3,2-dioxaborolanes and -borinanes of the type (whereG = -CH2CHMe-, -CH2CH2CH2-, -CH2CH2CHMe-,-CMe2CMe2-, -CMe2CH2CHMe-,-CH2CMe2CH2-, -CH2CEt2CH2-, and -C6H4-) are obtained by the reaction of diphenylphosphinic acid with the corresponding 2,2-oxo-bis-1,3,2-dioxaborolanes and-borinanes. The products are white crystalline solids, which have sharp melting points and are hydrolytically stable. They have been characterized by elemental analysis, IR and multinuclear NMR (11B,31P, and119Sn) studies. The data suggest structures with monodentate phosphinato moieties and 3-coordinated boron atoms.
Synthesen und spektroskopische Untersuchungen von Diphenylphosphinatoderivaten von Bor
Zusammenfassung 2-Diphenylphosphinato-1,3,2-dioxaborolane und -borinane des Typs (mitG = -CH2CHMe-, -CH2CH2CH2-,-CH2CH2CHMe-, -CMe2CMe2-,-CMe2CH2CHMe-, -CH2CMe2CH2-, -CH2CEt2CH2- und C6H4) erhält man durch Reaktion von Diphenylphosphinsäure mit den entsprechenden 2,2-Oxo-bis-1,3,2-dioxaborolanen und -borinanen. Die Produkte sind weiße, kristalline, hydrolyseunempfindliche Festkörper. Sie wurden mittels Elementaranalyse, IR-Spektroskopie und multinuklearer NMR-Spektroskopie (11B,31P und119Sn) charakterisiert. Die Resultate legen Strukturen mit monodentaten Phosphinatoeinheiten und dreifach koordinierten Boratomen nahe.相似文献
306.
The crotyloxides of the general formula M(OCH2? CH ? CH-CH3)n [when M = B and Al, n = 3; M = Ti and Ge, n = 4 and M = Nb and Ta, n = 5] and BunSn(OCH2? CH ? CH? CH3)4-n [where n = 2 and 3] have been synthesized by the reaction of the corresponding metal alkoxide (ethoxide or isopropoxide) with crotyl alcohol in the appropriate molar ratios. These derivatives have been characterized by elemental analysis, i.r. and p.m.r. spectra. Their refractive indices and molecular weigths have also been measured. 相似文献
307.
Tej N. Srivastava Ashok K. S. Chauhan Gopal K. Mehrotra 《Transition Metal Chemistry》1981,6(4):252-254
Summary Coordinative interaction between tellurium tetrachloride or aryltellurium trichloride and transition metal chelates of tetradentate Schiff bases has yielded bimetallic molecular adducts of the general formula RnTeCl4–n · ML [n = 0 or 1, R = Ph,p-MeOC6H4 orp-EtOC6H4, M = nickel(II) or copper(II) and L2– dianion of the Schiff bases derived from salicylaldehyde oro-hydroxyacetophenone and ethylenediamine]. The i.r. spectral and magnetic measurements on the complexes in the solid state indicate coordination of the metal chelates to tellurium(IV)via two phenolic oxygens. Planarity about the transition metal ion is thus retained. 相似文献
308.
We describe an implementation of a primal—dual path following method for linear programming that solves symmetric indefinite augmented systems directly by Bunch—Parlett factorization, rather than reducing these systems to the positive definite normal equations that are solved by Cholesky factorization in many existing implementations. The augmented system approach is seen to avoid difficulties of numerical instability and inefficiency associated with free variables and with dense columns in the normal equations approach. Solving the indefinite systems does incur an extra overhead, whose median is about 40% in our tests; but the augmented system approach proves to be faster for a minority of cases in which the normal equations have relatively dense Cholesky factors. A detailed analysis shows that the augmented system factorization is reliable over a fairly large range of the parameter settings that control the tradeoff between sparsity and numerical stability.This paper is dedicated to Phil Wolfe on the occasion of his 65th birthday.This work has been supported in part by National Science Foundation grants DDM-8908818 (Fourer) and CCR-8810107 (Mehrotra), and by a grant from GTE Laboratories (Mehrotra). 相似文献
309.
310.