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991.
N-(2-Bromoethyl)phthalimide (1) was reacted with sodium imidazolate in DMF to give the novel aminal N-[1-(1H-imidazol-1-yl)ethyl]phthalimide (4a) as well as N-vinylphthalimide (3) and the desired Gabriel intermediate 2. Aminal 4a as well as heterologues 4b - d form directly from reaction of 3 with the appropriate heterocyclic sodium salt. 相似文献
992.
993.
H. ter Meulen H. J. Raavensway M. Ohmasa St. Z. Bartosiewicz Ch. T. Gayley Ch. -L. Tseng F. Wei E. V. White G. F. Wright F. Arndt F. Neumann H. Doehring E. Ochiai K. Tsuda S. Sakamoto Ch. B. Medinski I. W. Kosstrow und W. L. Ruigh 《Fresenius' Journal of Analytical Chemistry》1943,125(5-6):199-204
Ohne Zusammenfassung 相似文献
994.
Steric Effects on the Structures,Reactivity, and Coordination Chemistry of Tris(2‐pyridyl)aluminates 下载免费PDF全文
Dr. Raúl García‐Rodríguez Prof. Dominic S. Wright 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14949-14957
Introducing substituents in the 6‐position of the 2‐pyridyl rings of tris(pyridyl)aluminate anions, of the type [EtAl(2‐py′)3]? (py′=a substituted 2‐pyridyl group), has a large impact on their metal coordination characteristics. This is seen most remarkably in the desolvation of the THF solvate [EtAl(6‐Me‐2‐py)3Li?THF] to give the monomer [EtAl(6‐Me‐2‐py)3Li] ( 1 ), containing a pyramidal, three‐coordinate Li+ cation. Similar monomeric complexes are observed for [EtAl(6‐CF3‐2‐py)3Li] ( 2 ) and [EtAl(6‐Br‐2‐py)3Li] ( 3 ), which contain CF3 and Br substituents (R). This steric influence can be exploited in the synthesis of a new class of terminal Al?OH complexes, as is seen in the controlled hydrolysis of 2 and 3 to give [EtAl(OH)(6‐R‐2‐py)2]? anions, as in the dimer [EtAl(OH)(6‐Br‐2‐py)2Li]2 ( 5 ). Attempts to deprotonate the Al?OH group of 5 using Et2Zn led only to the formation of the zincate complex [LiZn(6‐Br‐py)3]2 ( 6 ), while reactions of the 6‐Br substituted 3 and the unsubstituted complex [EtAl(2‐py)3Li] with MeOH give [EtAl(OMe)(6‐Br‐2‐py)2Li]2 ( 7 ) and [EtAl(OMe)(2‐py)2Li]2 ( 8 ), respectively, having similar dimeric arrangements to 5 . The combined studies presented provide key synthetic methods for the functionalization and elaboration of tris(pyridyl)aluminate ligands. 相似文献
995.
Lewis M. Broomfield Manfred Bochmann Joseph A. Wright 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(3):m79-m82
The title phosphine oxide–phosphine, 0.43C17H16NOP·0.57C17H16NP, (I)/(II), was obtained as a 0.861 (6):1.139 (6) cocrystallized mixture. Hydrogen bonding between the two constituents leads to the formation of 2:2 solid‐state assemblies. Instead of forming the expected simple N,P‐chelated system via loss of the N‐bound H atom, reaction of 2‐(diphenylphosphinomethyl)pyrrole, (II), with TiCl4 leads to the formation of the title titanium(IV) complex, [TiCl4(C17H16NP)], (IV), containing a rearranged neutral ligand in which the N‐bound H atom moves to one of the pyrrole C atoms, giving a partially unsaturated ring. 相似文献
996.
The thermal stability of some hydroxyl-terminated poly(bisphenol A tere- or isophthalates) and their corresponding poly(ester carbonates) made by subsequent coupling with phosgene has been investigated by thermogravimetry. Samples have been studied in nitrogen or air using constant rates of temperature rise or isothermal conditions.The isophthalate-containing polyesters are more thermo-oxidatively stable than their terephthalate analogues and molecular weight has a significant effect on stability. In contrast, there is little difference in the thermal stability of the poly (isophthalate carbonates) and the poly(terephthalate carbonates) and the stability of the latter is relatively independent of the ratio of the diester to carbonate group content. The stability of the poly(terephthalate carbonates) is also relatively insensitive to end-group modifications. 相似文献
997.
Bartholomew's statistics for testing homogeneity of normal means with ordered alternatives have null distributions which are mixtures of chisquared or beta distributions depending on whether the variances are known or not. The mixing coefficients depend on the sample sizes and the order restriction. If a researcher knows which mean is smallest and which is largest, but does not know how the other means are ordered, then a loop ordering is appropriate. Exact expressions for the mixing coefficients for a loop ordering and arbitrary sample sizes are given for five or fewer populations and approximations are developed for more than five populations. Also, the mixing coefficients for a loop ordering with equal sample sizes are computed. These mixing coefficients also arise in testing the ordering as the null hypothesis, in testing order restrictions in exponential families and in testing order restrictions nonparametrically.This research was supported by the National Institutes of Health under Grant 1 R01 GM42584-01A1 相似文献
998.
García F Kowenicki RA Kuzu I Riera L McPartlin M Wright DS 《Dalton transactions (Cambridge, England : 2003)》2004,(18):2904-2909
The dimeric macrocycles [[P(mu-NtBu)]2.LL]2 [LL = OCH2C(Me)2CH2O (1), 2,6-(NH)2C5H3N (2), 1,2-(NH)2C6H4(3)] have been obtained by the reactions of the appropriate diols and diamines (LLH2) with the dimeric phosph(III)azane [ClP(mu-NtBu)]2. Under different conditions the reaction of 1,2-(NH2)2C6H4 with [ClP(mu-NtBu)]2 gives the monomer [[P(mu-NtBu)]2.[1,2-(NH)2C6H4]] (4) (instead of the dimer 3). Contrary to the literature, the results illustrate that the formation of dimeric macrocycles is common in these reactions and dependent among other factors on the steric demands and length of the organic spacer (LL) as well as the reaction conditions. 相似文献
999.
Experimental Techniques - 相似文献
1000.
A two wavelength extinction technique is used to quantitatively measure the temporal fuel vapor field produced by pulsed
automotive fuel injectors. Line-of-sight measurements are spatially deconvoluted to yield a picture of the overall, cycle-averaged,
radial vapor concentration profiles. Vapor measurements are also given for single, consecutive, injection pulses, showing
cycle-to-cycle variations in the vapor field. Methods to characterize the cyclic variability in the vapor field of a pulsed
spray are discussed. As an illustrative example, the differences between an air assist and a non-air assist injector are shown
as a function of duty cycle and axial location.
Received: 11 August 1997/Accepted: 10 February 1998 相似文献