The dilithio compound (E)‐1‐lithio‐2‐(o‐lithiophenyl)‐1‐trimethylsilylethene (5) was synthesized from 2‐trimethylsilylbenzo‐[b]tellurophene (6) with lithium‐6 and a detailed analysis of its 1H, 6Li, 13C, and 29Si NMR spectra showed 5 to form a dimer 52 in tetrahydrofuran and diethylether, while addition of tetramethylethylenediamine stabilizes a monomer 51. A monomer–dimer equilibrium exists with K at 230 K = 1.25 and ΔG230o  = −0.43 kJ mol−1. Homonuclear 6Li,6Li coupling of 0.25 ± 0.07 Hz in the dimer was detected by a 1D‐6Li,6Li INADEQUATE experiment, and scalar 6Li,13C coupling constants were obtained from 13C satellites in the 6Li spectrum, from 13C multiplet simulation and 6Li,13C‐HMQC spectra. In addition, structures and coupling constants of 51 and 52 were calculated by density functional theory (DFT) methods. It was found that the magnitude of the 6Li,13C spin–spin interactions shows an inverse correlation with the C‐Li bond lengths. The intra‐aggregate exchange in the dimer, caused by 180° rotation of one monomer unit within the solvent cage, was studied by 6Li DNMR and line shape analysis and yielded ΔG298≠  = 60 ± 3 kJ mol−1; ΔH≠ = 84 ± 3 kJ mol−1; ΔS≠ = 80 ± 3 J mol−1 K−1 for this process. Copyright © 2015 John Wiley & Sons, Ltd.

A simple testis proposed for short-lived organopotassium and organosodium intermediates formed during some organic processes. It is based on the use of 15-crown-5 or 18-crown-6 as the additional reagent and identification of its ring opening product, i.e. alkali metal tetraethylene glycoxide vinyl ether or alkali metal pentaethylene glycoxide vinyl ether, respectively.

Alkalides are salts containing alkali metal anions and complexed metal cations. These unusual species discovered by Dye ( Dye, J. L.; Andrews, C. W.; Mathews, S. E. J. Phys. Chem., 1975, 79, 3065) are strong reductants of many organic and inorganic compounds. These reactions occur rapidly under mild homogeneous conditions. In this paper we discuss new data concerning the application of potassium potassides selected from the group of alkalides to polymerization processes. Their new and corrected mechanisms for some vinyl and oxacyclic monomers are presented.

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The objectives of this review are mainly reactions of alkalides with various classes of organic compounds. Mechanisms of these processes are discussed taking into account our present stage of knowledge. A new method for the preparation of crystalline nanomaterials via homogeneous reduction of transition and post-transition metal salts is also presented.

The potassium anion possesses two valence electrons in its outer orbital. These two electrons might be transferred to an acceptor molecule simultaneously or stepwise. The stepwise mechanism had been stated till now experimentally only for the reaction of alkalide K-, K+(18-crown-6) with phenylacetylperoxide. A concept of this review was to ascertain if that mechanism has a more general character. Reactions of potassium anions of alkalide K-, K+(15-crown-5)(2) with some cyclic ethers and lactones of different ring size were selected for that purpose.

Angewandte ChemieVolume 94, Issue 4 p. 314-317 Zuschriften Hochfeld-bedingte NMR-Spin-Entkopplung bei Organoquecksilber-Verbindungen Dr. Reinhard Benn, Dr. Reinhard Benn Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1, D-4330 Mülheim an der RuhrSearch for more papers by this authorProf. Dr. Harald Günther, Prof. Dr. Harald Günther FB 8, Organische Chemie, Universität-Gesamthochschule Postfach 210209, D-5900 Siegen 21Search for more papers by this authorProf. Dr. Adalbert Maercker, Prof. Dr. Adalbert Maercker FB 8, Organische Chemie, Universität-Gesamthochschule Postfach 210209, D-5900 Siegen 21Search for more papers by this authorVolkmar Menger, Volkmar Menger FB 8, Organische Chemie, Universität-Gesamthochschule Postfach 210209, D-5900 Siegen 21Search for more papers by this authorPeter Schmitt, Peter Schmitt FB 8, Organische Chemie, Universität-Gesamthochschule Postfach 210209, D-5900 Siegen 21Search for more papers by this author Dr. Reinhard Benn, Dr. Reinhard Benn Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1, D-4330 Mülheim an der RuhrSearch for more papers by this authorProf. Dr. Harald Günther, Prof. Dr. Harald Günther FB 8, Organische Chemie, Universität-Gesamthochschule Postfach 210209, D-5900 Siegen 21Search for more papers by this authorProf. Dr. Adalbert Maercker, Prof. Dr. Adalbert Maercker FB 8, Organische Chemie, Universität-Gesamthochschule Postfach 210209, D-5900 Siegen 21Search for more papers by this authorVolkmar Menger, Volkmar Menger FB 8, Organische Chemie, Universität-Gesamthochschule Postfach 210209, D-5900 Siegen 21Search for more papers by this authorPeter Schmitt, Peter Schmitt FB 8, Organische Chemie, Universität-Gesamthochschule Postfach 210209, D-5900 Siegen 21Search for more papers by this author First published: April 1982 https://doi.org/10.1002/ange.19820940435Citations: 10AboutPDF ToolsRequest permissionAdd to favorites ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume94, Issue4April 1982Pages 314-317 This is the German version of Angewandte Chemie. Note for articles published since 1962: Do not cite this version alone. Take me to the International Edition version with citable page numbers, DOI, and citation export. We apologize for the inconvenience. RelatedInformation

Butyryloxymethyloxirane (glycidyl butyrate) is efficiently reduced with potassium anions of alkalide K-, K+(15-crown-5)(2). The reaction proceeds via the corresponding radical anion, which decomposes the homolytic alkyl-oxygen bond cleavage or dimerizes. The oxirane ring is not opened by K-. No organometallic is formed as an intermediate. This shows that the mechanism of the process under study differs from that proposed earlier for alkyl glycidates. The position of the ester group in the substituent influences the behavior of the oxiranes.

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The mechanism of the initiation step of beta-lactones polymerization with potassium anions of alkalide is verified, as had been suggested by Szwarc [ Szwarc, M. Ionic Polymerization Fundamentals; Carl Hanser Verlag: Munich, 1996; p 69]. Contrary to previous papers, the carbon-carbon bond scission is not observed. It is shown that indeed this kind of bond rupture does not occur, at least in beta-butyrolactone. In fact, the acyl-oxygen bond is mainly cleaved in this lactone by potassium anions. The reaction proceeds by lactone dianion as an intermediate succeeding formation of the radical anion. The latter decomposes by the alkyl-oxygen bond cleavage in a side reaction. Finally, potassium crotonate and potassium 3-hydroxybutyrate are mainly formed, and potassium butyrate is a side product. They become the real initiators of the polymerization. The same results are observed with alkalide K-, K+(15-crown-5)(2), and K-, K+(18-crown-6).

A mechanism is proposed for the reaction of gamma-butyrolactone with the potassium anion as a two-electron-transfer reagent. Potassium hydride and potassium 4-potassiobutyrate are formed in this process as intermediates. These compounds deprotonate gamma-butyrolactone. Potassium lactone enolate, potassium butyrate, and hydrogen are the final reaction products.

Transfer of one electron from potassium anion of alkalide K−, K+(15-crown-5)2 to the double bond of vinyloxirane results in the oxirane ring opening exclusively in the α-position. K0 and radical anions are formed in the process. The former transfers the second electron mainly to the next monomer molecule. The latter dimerize to potassium glycoxides, which initiate the polymerization of vinyloxirane. The introduction of two CH2 groups between the double bond and the oxirane ring changes the way of electron transfer. The oxirane ring of 3-butenyloxirane becomes the electron acceptor and its opening occurs in the β-position. In this case K0 transfers the second electron to the primarily formed radical anion giving an organopotassium intermediate. It reacts with crown ether. Potassium alkoxides are the reaction products. They become the real initiators of 3-butenyloxirane polymerization.

The course of the reaction of alkalide K-, K+(15-crown-5)(2) 1 with selected alcohols depends on the kind of alcohol and the mode of substrate delivery. In the case of methanol, potassium methoxide formed initially undergoes destruction at the excess of 1. It results in potassium oxide and methylpotassium. The latter opens the crown ether ring giving potassium tetraethylene glycoxide vinyl ether and methane. A similar course of the process is observed for propanol. Potassium glycidoxide is the main product formed in the reaction of 1 with glycidol. Its oxirane ring is opened at the excess of 1. Organopotassium alkoxides, i.e., potassium potassiomethoxide and dipotassium potassiopropane-1,2-dioxide are intermediate products of this reaction. They react then with the crown ether. Potassium methoxide, potassium enolate of acetaldehyde, dipotassium, propane-1,2-dioxide and potassium tetraethylene glycoxide vinyl ether are the final products of this process. (C) 2004 Elsevier B.V. All rights reserved.

The reaction of phenyl substituted cyclopropanes phenylcyclopropane and 1,1-diphenylcyclopropane, phenyl substituted bicyclobutanes 1-phenylbicyclobutane, 1-methyl-3-phenylbicyclobutane, 1-methyl-2,2-diphenylbicyclobutane, as well as phenyl substituted spiropentanes phenylspiropentane and 1,1-diphenylspiropentane with lithium metal or lithium di-t-butylbiphenyl (LiDBB) was investigated. Under suitable reaction conditions and choice of solvent in all cases cleavage of the single bond next to the activating phenyl group was observed. The dilithiumorganic compounds thus obtained are sufficiently stable and can be trapped with electrophiles. Lithium hydride elimination is observed as follow-up reaction only in a few cases. The corresponding anions of the strained ring systems 1-lithio-2,2-diphenylcyclopropane, 1-lithio-3-phenylbicyclobutane, 1-lithio-3-methyl-2,2-diphenylbicyclobutane, and 1-lithio-4-phenylspiropentane, which can be obtained by lithium bromine exchange or by metalation of the unsubstituted carbocycle, do not show any cleavage upon reaction with lithium metal.

The structure of vinyl ethers determines the direction of the C-O bond cleavage by alkalide K-, K-divided by(15-crown-5)(2) 1. Highly reactive organopotassium compounds are intermediate products formed in the system containing phenyl vinyl ether, butyl vinyl ether, ethylene glycol butyl vinyl ether or triethylene glycol methyl vinyl ether. Vinylpotassium and butylpotassium react with 15-crown-5. The oxacyclic ring of the latter is opened in this case. Organopotassium ethers possessing CH2CH2O units eliminate ethylene. It results in various potassium alkoxides. The reaction of 1 with butyl vinyl ether occurs very slow as compared to other vinyl ethers and most of other reagents used till now. (C) 2004 Elsevier B.V. All rights reserved.

The electron from potassium anion of K−, K+(15-crown-5)2 (1) is initially transferred to the aromatic ring of phenyloxirane and (phenylmethyl)oxirane. The oxirane ring is then opened exclusively in the α-position. Two dimeric products, i.e. dipotassium 2,3-diphenylbutane-1,4-dioxide and dipotassium 1,3-diphenylbutane-1,4-dioxide are formed in the case of phenyloxirane. A mixture of several potassium alkoxides involving 3-phenylpropoxide, 3-phenylallyloxide, tetraethylene glycoxide vinyl ether, and appropriate alcohols, i.e. 3-phenyl-1-propanol, 3-phenylallyl alcohol, and tetraethylene glycol vinyl ether, is obtained in the reaction of 1 with (phenylmethyl)oxirane. However, introduction of the second CH2 group into the substituent results in the β-opening of the oxirane ring in (2-phenylethyl)oxirane. Potassium 4-phenylbutane-2-oxide, and potassium tetraethylene glycoxide vinyl ether are the main reaction products in this case. Organometallic intermediates take part in all these processes.

Several reactions occur during the initiation of 2-(9-carbazolyl)ethyl glycidyl ether polymerization by K−, K+ (15-crown-5)2. At first the oxirane ring is opened mainly in the β-position. An organometallic intermediate obtained cleaved then the linear ether bond in the substituent and the cyclic one in crown ether. Various potassium alkoxides are finally formed. They are the real initiators of the polymerization. 9-Vinylcarbazole being another reaction product is inactive in this process.

The reaction of allene (3a) and alkyl substituted allenes 1,2-hexadiene (3b), cyclopropylallene (3c), and vinylidene cyclopropane (3d) with lithium metal was investigated in order to access 2,3-dilithioalkenes 4a–d. These dilithioalkenes 4a–d are very reactive in polar solvents like THF and act as strong bases, either metalation of the starting allene 3a–d, the solvent, or sufficiently acidic intermediates like 8 a–d is observed. The metalation products 5–7 show follow-up reactions like 1,3-H shift to the corresponding 1-lithio-1-alkynes 8 and subsequent metalation to the dilithioalkynes 9. Additionally, lithium hydride elimination and ring-chain rearrangement (for 5c) are observed. 1,2-Hexadiene (3b) can be brought to reaction with lithium metal in the apolar solvent pentane, here the follow-up reactions are much slower due to the insolubility of 4b. In all cases the elucidation of the reaction pathways is hampered by the formation of complex mixtures of, amongst others, regio- and stereoisomeric products upon quenching with simple electrophiles.

The kind of substituent in alkyl glycidyl ethers affects the course of their reaction with K−, K+(15-crown-5)2. The cyclic oxirane ring is exclusively cleaved in the case of butyl glycidyl ether whereas the presence of the unsaturated allyl group in the glycidyl ether molecule unexpectedly prefers the scission of the linear ether bond. In both the systems organometallic intermediates are formed. They react with crown ether causing its ring opening. Allylpotassium formed from allyl glycidyl ether reacts also with another glycidyl ether molecule; the oxirane ring is opened in this case.