The metal complex catalyzed reactions of anils. I. The reaction of acetone with anilines

1976 ◽  
Vol 54 (24) ◽  
pp. 3895-3908 ◽  
Author(s):  
A. R. Boate ◽  
D. R. Eaton
Keyword(s):  
Proton Transfer ◽  
Metal Complex ◽  
Metal Complexes ◽  
Ligand Exchange ◽  
Equilibrium Constants ◽  
Catalytic Reactions ◽  
Rate Data ◽  
Aliphatic Ketones ◽  
Synthetic Routes ◽  
Catalyzed Reactions

It has been shown that the formation of anils from anilines and aliphatic ketones is homogeneously catalyzed by a variety of metal complexes. The products of the reactions have been unambiguously identified by preparing the anils using other synthetic routes. The catalysis is quite general and the system is therefore suitable for a systematic catalytic study varying both the catalysts and the substrates. The related reactions of anil hydrolysis and transimination may also be studied. The catalysts used, thiourea complexes of Co(II), Ni(II), and Zn(II), vary in their effectiveness by more than two orders of magnitude. In the present paper experiments defining the catalytic system are described. The equilibrium constants for the complexation of all the substrate molecules have been determined. Qualitative rate data on various ligand exchange and proton transfer steps is presented to demonstrate that such reactions cannot be rate determining in the overall catalytic reactions.

CYCLOBUTADIENE–METAL COMPLEXES: PART VIII. SYNTHESIS OF TETRAPHENYLCYCLOBUTADIENE NICKEL HALIDES BY LIGAND-EXCHANGE REACTIONS

1966 ◽  
Vol 44 (22) ◽  
pp. 2673-2677 ◽  
Author(s):  
D. F. Pollock ◽  
P. M. Maitlis
Keyword(s):  
Metal Complex ◽  
Metal Complexes ◽  
Ligand Exchange ◽  
Palladium Complexes ◽  
Exchange Reactions ◽  
Reaction Proceeds ◽  
Halide Complexes

The preparation of cyclobutadiene nickel halide complexes (R4C4NiX2)2, where R is phenyl or substituted phenyl, by reaction of the palladium complexes, [R4C4PdX2]2, with a tert-phosphine metal complex, e.g. (n-Bu3P)2NiX2, is described. The reaction proceeds according to the equation[Formula: see text]Possible mechanisms are suggested.

Metal complex catalyzed reactions of anils. II. Transimination

1977 ◽  
Vol 55 (12) ◽  
pp. 2426-2431 ◽  
Author(s):  
A. R. Boate ◽  
D. R. Eaton
Keyword(s):  
Metal Complex ◽  
Metal Complexes ◽  
Equal Probability ◽  
Methyl Groups ◽  
Free Rotation ◽  
Saturation Transfer ◽  
Aromatic Residues ◽  
Methyl Group ◽  
Catalyzed Reactions

The exchange of aromatic residues between anilines and anils (transimination) has been shown to be efficiently catalyzed by metal complexes of thiourea. This reaction can be conveniently studied by nmr spin saturation transfer techniques. Experiments of this type using both CW and FT nmr spectrometers are reported. The rate of the reaction is about two orders of magnitude greater than the rates of reactions involving anil formation and hydrolysis with the same substrates and catalysts. The effectiveness of the catalysts vary in the same manner as they do for anil formation and the reaction is similarly subject to inhibition by competing ligands. The rate of exchange of the two inequivalent methyl groups in acetone anils is similarly catalyzed and may be studied by spin saturation transfer experiments. The lifetime of an anil molecule for methyl group exchange is approximately twice that for transimination suggesting that the rate determining process for transimination results in free rotation about the C—N bond so that the methyl groups have an equal probability of retaining or exchanging their environments.

Chemistry of Unsymmetrical C1-Substituted Oxabenzonorbornadienes

2021 ◽  
Vol 17 ◽  
Author(s):  
Austin Pounder ◽  
Angel Ho ◽  
Matthew Macleod ◽  
William Tam
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Substituent Effects ◽  
Face Selectivity ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Synthetic Intermediate

: Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate which can be readily activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain on the alkene. To date, the understanding of transition-metal catalyzed reactions of OBD itself has burgeoned; however, this has not been the case for unsymmetrical OBDs. Throughout the development of these reactions, the nature of C1-substituent has proven to have a profound effect on both the reactivity and selectivity of the outcome of the reaction. Upon substitution, different modes of reactivity arise, contributing to the possibility of multiple stereo-, regio-, and in extreme cases, constitutional isomers which can provide unique means of constructing a variety of synthetically useful cyclic frameworks. To maximize selectivity, an understanding of bridgehead substituent effects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

scholarly journals Stability of Metal Complexes with a Ligand of Biological Interest: Noradrenaline

1999 ◽  
Vol 23 (2) ◽  
pp. 90-91
Author(s):  
Christian Gérard ◽  
Hanane Chehhal ◽  
Michel Aplincourt
Keyword(s):  
Metal Complexes ◽  
Equilibrium Constants ◽  
Biological Interest ◽  
Potentiometric Measurements

Stoichiometry, equilibrium constants and spectra of iron(III) complexes with noradrenaline have been determined from spectrophotometric measurements; in addition equilibrium constants of complexes with MgII, CdII and PbII have been determined from potentiometric measurements.

scholarly journals The fundamental flaw of the HSAB principle is revealed by a complete speciation analysis of the [PtCl6−nBrn]2−(n = 0–6) system

2015 ◽  
Vol 17 (8) ◽  
pp. 5712-5724 ◽  
Author(s):  
W. J. Gerber ◽  
P.-H. van Wyk ◽  
D. M. E. van Niekerk ◽  
K. R. Koch
Keyword(s):  
Exchange Reaction ◽  
Ligand Exchange ◽  
Equilibrium Constants ◽  
Reaction Network ◽  
Speciation Analysis ◽  
Hsab Principle ◽  
Speciation Diagram ◽  
System P

Bjerrum's model of step-wise ligand exchange is extended to compute a complete speciation diagram for the [PtCl6−nBrn]2−(n= 0–6) system including all 17 equilibrium constants concerning the PtIVchlorido–bromido exchange reaction network (HERN).

A Potentiometric Study on Proton-Transfer Equilibria and Cationic Conjugation in Pyridine N-Oxide Systems in Acetone and Methanol

1996 ◽  
Vol 49 (9) ◽  
pp. 931 ◽  
Author(s):  
L Chmurzynski ◽  
E Kaczmarczyk ◽  
M Nesterowicz ◽  
G Wawrzyniak ◽  
Z Warnke
Keyword(s):  
Proton Transfer ◽  
Equilibrium Constants ◽  
Proton Donor ◽  
Heterocyclic Amines ◽  
Transfer Reactions ◽  
Oxide Systems ◽  
Experimental Systems ◽  
Proton Transfer Reactions ◽  
Potentiometric Titration Method

The potentiometric titration method has been used to study the equilibria of cationic in sytems formed by substituted pyridine N-oxides in the polar, non-aqueous solvents acetone and methanol. For comparison, the systems with trimethylamine N-oxide as a representative of aliphatic amine N-oxides and pyridine representing parent heterocyclic amines were also studied. The cationic heteroconjugation constants, i.e. the equilibrium constants for conjugation reactions between free and protonated N-bases leading to the formation of unsymmetric BHB'+ cations, were determined in experimental systems with and without proton transfer. It was found that there were significant differences in the values of the cationic heteroconjugation constants determined in these two acid-base systems. The proton-transfer reactions limit and even preclude the determination of the cationic heteroconjugation constants. On this basis it was concluded that the heteroconjugation constants should be determined in systems without proton transfer. In such systems, in the amphiprotic solvent methanol, cationic heteroconjugation was ascertained in all substituted pyridine N-oxide systems, the values of heteroconjugation constants being relatively low (logarithms of their values of the order of 2-2.5), and only negligible in systems involving trimethylamine N-oxide. A more pronounced tendency towards cationic heteroconjugation of the [OHO]+ type was observed in the aprotic protophobic acetone, where heteroconjugation constants were determined for all amine N-oxide systems studied including those containing protonated trimethylamine N-oxide as a proton donor. However, the values of the cationic heteroconjugation constants were found to be, in methanol likewise, relatively low (log KBHB'+ of the order of 2-3). On the contrary, a greater extent of cationic heteroconjugation equilibria was observed in methanol than in acetone in the case of systems containing pyridine, i.e. [NHO]+ type bridges formed by amine N-oxides and heterocyclic amines. In methanol the heteroconjugation constants turned out to be determinable for all such systems studied (logarithms of the equilibrium constants being of the same order as for N-oxide systems), whereas in acetone the hetero constants were indeterminable for all systems.

Sign in / Sign up

Export Citation Format

Share Document