- A new member of tetranuclear dinitrosyl iron complexes (DNICs) with 2-mercaptothiazoline ligand: Synthesis, structure and properties
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A new tetranuclear dinitrosyliron complex [(μ-SC3H 4SN)Fe(NO)2]4 (2), each of a Fe center coordinated with two S or two N, was prepared by CO replacement from the reduced precursor (CO)2Fe(NO)2 with 1 equiv of HSC 3H4SN (2-mercaptothiazoline) in the presence of O 2(g). The structure of 2 is similar to [(Imid-iPr)Fe(NO) 2]4 (Imid-iPr = 2-isopropylimidazole) (Hess et al. J Am Chem Soc 133:20426-20434, 2011), and both complexes comprise a quadrilateral plane of irons with corresponding ligands, SC3H4SN - or Imid-iPr-, bridging the edges and two nitrosyl ligands capping the irons at the corners. An additional equiv of SC 3H4SN- was added to 2, which results in the mononuclear {Fe(NO)2}9 (SC3H 4SN)2Fe(NO) 2 - (3), in the manner of N bound-[SC3H4SN]. Reaction of (TMEDA)IFe(NO) 2 (TMEDA = tetramethylethylenediamine) and complex 3 leads to the formation of complex 2. Dinuclear complex [(μ-C5H 7N2)Fe(NO)2]2 (4) can be synthesized by the ligand displacement of SC3H4SN- to C5H7N2 - (3,5-dimethylpyrazolate) of 2 (Chong et al. Can J Chem 57:3119-3125, 1979). Complexes 2-4 were characterized by IR and UV-Vis. The molecular structures of 2 and 3 were determined by X-ray single crystal diffraction.
- Chen, Chien-Hong,Wang, Jheng-Hong,Huang, Jing-Yi,Hsieh, Chung-Hung
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- INTERPRETATION OF HYDROXYLIC SOLVENT EFFECTS BASED ON CORRELATIONS WITH SOLVENT PARAMETERS. REACTION OF Et3N WITH EtI
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Hydroxylic solvent effects on 20 rate constants, k, of the Menschutkin reaction of Et3N with EtI are unravelled and rationalized by means of multiple linear regression equations.To perform this analysis new k values in 2 mono- and 9 dialcohols are obtained.New values are also presented for the Kamlet and Taft solvatochromic parameters ?*, α and β of 1-hexanol.The results show that the solvent dipolarity, polarizability and cohesive energy density are main properties influencing the reactivity, for the set of studied solvents.
- Calado, Antonio R. T.,Pinheiro, Lidia M. V.,Albuquerque, Lidia M. P. C.,Goncalves, Raquel M. C.,Roses, Marti,et al.
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- PRESSURE AND SOLVENT EFFECTS ON THE KINETICS OF A MENSHUTKIN REACTION IN ALIPHATIC ALCOHOLS
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The kinetics of the Menshutkin reaction between triethylamine and iodomethane was studied at 313 K in seven primary and secondary alcanols.An accurate conductometric method was employed to obtain second-order rate constants at pressures of 0.1-200 MPa.Volumes and isothermal compressions of activation were calculated by different model-based equations which are compared.Activation volumes at 0.1 MPa are in the range -26 to -33 cm3mol-1.Procedures for dissecting intra- and intermolecular contributions to the volume of activation are discussed.A clear dependence of model parameters on the solvent volumetric properties was found.
- Viana, Cesar A. N.,Calado, Antonio R. T.,Pinherio, Lidia M. V.
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- Silver (I) activated quaternization of tertiary amines by alkyl iodides: Overall analysis coupling homogeneous and heterogeneous processes
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Kinetic data for the silver (I) activated homogeneous and heterogeneous quaternization of tributylamine by alkyl iodides in toluene is presented. Silver iodide was used as a solid catalyst. Solution and surface parameters were obtained applying the multistep kinetic model, previously proposed by Santos and Barbosa. A scrutiny of the derived quantities evidences competing structural and electronic effects. The solution reaction is dominated by structural factors while electronic effects govern the surface process. An overall analysis considering data from triethylamine systems, earlier investigated, allowed the establishment of a parallelism between the homogeneous and heterogeneous processes. A molecular level study involving size, shape and orientation of the chemical species on the surface, lead to estimates of interfacial layer thicknesses. A combination of surface parameters superficial reacting monolayer thicknesses and, the parallelism between homogeneous and heterogeneous catalysis consented the evaluation of "volumetric surface rate constants" which are directly comparable with their solution counterparts.
- Santos, M. Soledade C.S.,Barbosa, Ester F.G.
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experimental part
p. 106 - 113
(2012/04/17)
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- An unusual Michael addition-dealkylation or elimination via the reaction of tertiary or secondary amines with a (Z)-iodoacrylate
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A series of (E)-ammonium or amino acrylates have been prepared via the Michael addition of methyl (Z)-iodoacrylate and several secondary and tertiary alkylamines. Tertiary amines undergo concomitant addition-dealkylation, almost quantitatively producing (
- Maw, Graham,Thirsk, Carl,Whiting, Andrew
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p. 8387 - 8390
(2007/10/03)
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- Arrhenius-like Behaviour of Menschutkin Reactions in Solution
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Rate constants for Menschutkin reactions were obtained in both primary and secondary alcohols.A very accurate method of determining the rate constants was developed on the basis of concentration-time curves obtained from standard conductivity concentration curves.The results showed a standard deviation generally less than 1percent.Several equations were tested and all of them lead to a very close Arrhenius behaviour with a clear exception for methanolic solutions.The results are more conclusive where the free energies of activation and the volumes of activation were calculated as a function of the carbon chain length and other physical properties of the solvents.
- Viana, C. A. N.,Calado, A. R. T.,Pinheiro, L. M. V.
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p. 173 - 185
(2007/10/02)
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- A STUDY OF EFFECT OF TEMPERATURE ON THE INFLUENCE OF MEDIUM ON THE REACTION OF TRIETHYLAMINE WITH ETHYL IODIDE
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The rate constants of the reaction of triethylamine with ethyliodide have been measured in 15 solvents at the temperatures of 293, 313, 333 and 373 K.The solvent characteristics by Kamlet and Taft and those by Pytela have been found to be excellently applicable to evaluation of influence of medium on this reaction at all the temperatures mentioned.However, these methods give different results with regard to the proton-donor effects of solvents on the reaction.
- Bekarek, Vojtech,Nevecna, Tatjana
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p. 874 - 879
(2007/10/02)
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- New Synthetic Routes to B4H10 and B5H9
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The boron hydride B4H10 is prepared in high yields (90 percent) through hydride-ion abstraction reactions when a mixture of BH4(-)/B3H8(-) is treated with CH3I or I2, respectively.A high yield (96 percent) method for the conversion of B3H8(-) to B4H10 is the reaction of B3H8(-) with AlCl3 in solvents which do not have any Lewis base character.The solvents are assumed to react as electron acceptors with the intermediate to form B4H10, R(-) and H2 (R-H = solvent).A 1:1 mixture of B4H10 and B5H9 is obtained when B3H8(-) is treated with CH3I or I2.The reaction can be viewed to involve an initial step in which unstable B3H7 is generated which immediately undergoes decomposition to give B4H10, B5H9 and H2.Treatment of B4H10 with (n-Bu)4NBr results in the formation of B3H-Br(-) which decomposes slowly at 0 deg C to form B5H9.An alternative synthesis of B5H9 via hydride-ion abstraction is possible through the reaction of (n-Bu)2O-BF3 with B3H8(-) in ether solvents. - Keywords: Syntheses of B4H10 and B5H9
- Brellochs, Bernd,Binder, Herbert
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p. 648 - 653
(2007/10/02)
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- A STUDY OF THE MEDIUM EFFECT OF MIXED SOLVENTS; THE CYCLOHEXANE-NITROBENZENE SYSTEM
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Rate constants of the reaction of triethylamine with ethyl iodide (at 293.15, 313.15, 323.15, and 333.45 K) and wavenumbers of the longest wavelength band maxima of 4-nitroso-N,N-dimethylaniline and 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenoxide were measured in nitrobenzene and thirteen mixtures of nitrobenzene with cyclohexane.The activation characteristics of the reaction of triethylamine with ethyl iodide in these media were calculated and the correlations of rate constants and spectral data were carried out with functions of relative permitivity and refractive index of the media used and mutually with each other.
- Nevecna, Tatjana,Bekarek, Vojtech
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p. 1942 - 1947
(2007/10/02)
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- A STUDY OF THE MEDIUM EFFECT OF MIXED SOLVENTS; THE BENZENE-ACETONITRILE SYSTEM
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Rate constants of the reaction of triethylamine with ethyl iodide (at 293.15, 313.15, 323.15, and 333.15 K) and wave numbers of the longest wavelength band maxima of 4-nitroso-N,N-dimethylaniline, 3-nitro-N,N-dimethylaniline, and 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenoxide were measured in benzene, acetonitrile, and their eleven mixtures.Activation characteristics of the reaction of triethylamine with ethyl iodide in these media were calculated, and the correlations of rate constants and spectral data with the functions of relative permitivity and refractive index of the media used and mutually with each other were carried out.
- Nevecna, Tatjana,Vymetalova, Jitka,Bekarek, Vojtech
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p. 2071 - 2076
(2007/10/02)
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- A STUDY OF THE MEDIUM EFFECT OF MIXED SOLVENTS; THE CYCLOHEXANE-ACETONE SYSTEM
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Wavenumbers of the S-O bond valence vibration of dimethyl sulphoxide, wavenumbers of the longest wavelength maxima of 3-nitro-N,N-dimethylaniline and 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenoxide and rate constants of the reaction of triethylamine with ethyl iodide measured in mixtures ox cyclohexane and acetone were correlated with functions of relative permitivity and refractive index these media and mutually with each other.
- Bekarek, Vojtech,Nevecna, Tatjana
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p. 1928 - 1934
(2007/10/02)
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- Proximity as a Component of Organic Reactivity
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Neither the SN2 reaction of methyl iodide in 100percent pyridine, nor the SN2 reaction of triethylamine in 100percent ethyl iodide, nor the elimination reaction of 4-(4-nitrophenoxy)-2-butanone in 100percent piperidine displays special reactivity ascribable to the continuous bimolecular contact.It is concluded that proximity, by itself, cannot explain the fast rates characteristic of many intramolecular reactions.Two parameters, time and distance, must be incorporated into the proximity concept to make it viable.
- Menger, F. M.,Venkataram, U. V.
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p. 4706 - 4709
(2007/10/02)
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- THE DEGRADATION OF CARBOXYLIC ACIDS INTO ALDEHYDES. REGIOSELECTIVE α-ACETOXYLATION OF 1,2,4-TRIAZOLIUM SALTS WITH DIACETOXYIODATE(1)ANION
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A novel method was developed for degradation of carboxylic acid into aldehydes containing one C atom less whose key step consists in α-acetoxylation of 5-alkyl-3-methylthio-1,4-diphenyl-1,2,4-triazolium iodides by (diacetoxyiodo)benzene.The mechanism of the regioselective α-acetoxylation was studied and the diacetoxy-iodate(1)anion was shown to be the actual oxidising agent.Further oxidation reactions of tetraethylammonium diacetoxyiodate(1) were investigated.A novel method was developed for the oxidation of primary alkyl amines into aldehydes by the novel heterocyclic reagent 5-bromo-3-methylthio-1,4-diphenyl-1,2,4-triazolium bromide and diethyl azodicarboxylate.
- Doleschall, Gabor,Toth, Gabor
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p. 1649 - 1666
(2007/10/02)
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