- Orthoamides and iminium salts LXXIV [1]. Reactions of N,N,N',N'- Tetramethyl-chloroformamidiniumChloride with metals
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N,N,N',N'-Tetramethyl-formamidinium chloride (2a) reacts with elemental sodium in various solvents to give N,N,N',N',N'',N''-hexamethyl-guanidinium chloride (4a). The reaction of 2a with potassium affords N,N,N',N',N'',N'',N''', N'''-octamethyl-oxamidinium dichloride (3a). From the reaction of 2a with magnesium in different solvents in general result mixtures of the salts 4a, 3a and N,N,N',N'-tetramethyl-formamidinium chloride (10a). The composition of these mixtures depends on the solvent and the reaction temperature. Similar results are obtained, when a zinc'copper couple is used instead of magnesium. Very likely from 2a and magnesium or zinc, respectively, organometallic intermediates 11, 12 are formed which could be trapped by aromatic aldehydes and phenylisocyanate. The salt 2a can be reductively coupled by a low-valent titanium reagent to give the oxamidinium salt 3a.
- Kantlehner, Willi,Aichholz, Reiner,Karl, Martin
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p. 305 - 319
(2012/07/13)
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- Tetra(amino)methanes: Implications of their structure and reactivity pattern for hypothetical carbon nitride frameworks
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Because of their possible role as model compounds for the structural units of carbon nitride C3N4, the preparation, structural chemistry, and some representative reactions of tetra(amino)methanes have been (re)investigated. In the crystal, C(NMe2)4 (1) has a molecular geometry close to D2d symmetry as proposed by theoretical calculations using state-of-the-art density functional methods. The coordination of the central carbon atom is distorted tetrahedral and the configuration of the nitrogen atoms is strongly pyramidal, as opposed to almost planar in the tetra(amino)silanes. Tetra(pyrrolidinyljmethane has a similar core structure, with all heterocyclic substituents in an envelop conformation flexible in solution. Tetra(piperidinyl)methane is more rigid in solution, owing to a more congested structure, with much higher inversion barriers for the six-membered rings. Hydrolysis of 1 leads to Me2NH and hexamethylguanidinium hydroxide, and treatment of 1 with HAuCl4(aq) affords crystalline [C(NMe2)3]+ AuCl4-, the structure of which has also been determined. Compound 1 is a strong nucleophile and can be used as an aminating agent, converting e.g. halosilanes into dimethylaminosilanes, with the guanidinium cation as the leaving group. The experimental results are discussed in the light of recent predictions regarding bulk carbon nitrides. WILEY-VCH Verlag GmbH, 1997.
- Jockisch, Alexander,Schier, Annette,Schmidbaur, Hubert
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p. 1739 - 1744
(2007/10/03)
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- Orthoamides, XXXIX. - Preparation of Ketene Aminals from CH-acidic Compounds and Ethoxy-N,N,N',N',N'',N''-hexamethylmethanetriamine
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The orthocarbonic acid derivative 5 reacts with the weakly CH-acidic compounds 4a-h to give the ketene aminals 6a-h.The compound 6i has been obtained from 4i and N,N,N',N',N'',N''-hexamethylguanidinium chloride in the presence of sodium hydride.Acetone re
- Kantlehner, Willi,Mergen, Walter W.,Haug, Erwin
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p. 290 - 298
(2007/10/02)
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- Reaction of Guanidinium Salts with Alkyl Bromides and Acid Chlorides
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The guanidinium salt 1a reacts with alkyl bromides 2a-g and acid chlorides 2h-k to give the nitriles 3a-g and the acyl cyanides 3h-k, respectively.Acyl isocyanates 4a,b have been obtained from the guanidinium cyanate 1d and the acid chlorides 2h,l.Reaction of the alkyl bromides 2b,c,m,n and acid chlorides 2h,l with the guanidinium thiocyanate 1e affords alkyl thiocyanates 5a-d and acyl isothiocyanates 6a,b, respectively.
- Kantlehner, Willi,Kapassakalidis, Johannis J.,Speh, Peter,Braeuner, Hans-Juergen
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p. 389 - 393
(2007/10/02)
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