Shizen Sekiguchi

Aromatic nucleophilic substitution reactions of 1-dialkylamino-substituted activated benzenes with various amines in dimethyl sulfoxide

Abstract In the reactions of 1-d1a1kylamino-2,4,6-trinitro- and 1-dialkylam1no-2, 4-dinitrobenzenes with various amines in dimethyl sulfoxide, 1-dialkylamino group is easily replaced with primary n-alkylamines at room temperature, and in a low yield with pyrrolidine only among secondary amines.

Proton-transfer reactions in the excited state of phenanthrylamines by nanosecond spectroscopy and fluorimetry

Proton-transfer reactions in the excited singlet state of phenanthrylamines at 300 K have been studied by means of nanosecond time-resolved spectroscopy and fluorimetry. On the basis of dynamic analyses involving proton-induced fluorescence quenching, the proton dissociation (k1) and association (k2) rate constants and the acidity constants pK*a in the excited singlet state of phenanthrylamines were determined. The pK*a values are discussed theoretically by taking account of their electronic structures. An empirical equation to estimate approximately the correct pK*a values of aromatic amines using data from Stokes shifts and (pK*a)FC values (determined by the Forster cycle) is proposed. Isotope effects on the rate constants and pK*a values have also been examined.

Aromatic nucleophilic substitution—II : Intermediates in the reactions of 2,4-dinitro- or 2,4,5-trinitro-1-naphthyl ethyl ether with secondary amines and preparation of a spiro meisenheimer complex

Abstract The intermediates in the reactions of 2,4-dinitro-(2) or 2,4,5-trinitro-1-naphthyl ethyl ether (11) with secondary amines have been studied. In the reaction of 2 with piperidine, the NMR spectrum of the reaction system indicated the coexistence of the three species-starting material, Meisenheimer complex, and substituted product. In the reaction of 11 with piperidine or N-methyl-n-butylamine, the the NMR spectra of the reaction system indicated the presence of a Meisenheimer complex, but did not indicate the formation of a substituted product. In addition, the spiro Meisenheimer complex (9) was prepared from 1-[N-methyl-(2′-hydroxy)ethylamino]-2,4,5-trinitronaphthalene (8) and sodium methoxide.

Reactions of Aromatic Compounds in Molten Salts. I. Dimerization of Aromatic Amines in a Molten Mixture of AlCl3–NaCl–KCl

Aromatic amines underwent dimerization in a molten salt consisting of a mixture of AlCl3–NaCl–KCl. The reaction is an oxidative cationic polymerization but, in contrast with the reactions of the ordinary aromatic compounds which gave the corresponding polyaryls, in the cases of aromatic amines the reaction was regiospecific and stopped at the stage of biaryl to yield benzidine derivatives.

The reactions of 2-substituted 4-chloro-6-(2-hydroxy-1-naphthyl)-1,3,5-triazines with several nucleophiles.

The nucleophilic substitution reactions of 2-methoxy- and 2-diethylamino-4-chloro-6-(2-hydroxy-1-naphthyl)-1,3,5-triazines (1) with aniline, diethylamine, sodium azide, and sodium methoxide were carried out and compared with the reactions of the corresponding derivatives of 4-chloro-6-(4-hydroxy-1-naphthyl)-1,3,5-triazine (2) and 4-chloro-6-(1-naphthyl)-1,3,5-triazine (3). Compound 1 was found to be more reactive than the corresponding (2) and (3), not only in the reactions of a neutral molecule, but also in those of anionic species. The results of the reactions of neutral species are interpreted in terms of the difference in solvation toward the substrates; however, the loss of coplanarity between the naphthalene and triazine nuclei may be responsible for the high reactivity of Compound 1 in the reactions of anionic species.

Kinetic studies of the reaction of 1-dialkylamino-2,4-dinitronaphthalenes with butylamine in dimethyl sulfoxide

The nucleophilic substitution reaction of butylamine with 1-pyrrolidino-2,4-dinitronaphthalene (1a) in dimethyl sulfoxide is subject to general base catalysis, whereas the reaction of the same amine with 1-piperidino-(1b) or 1-dimethylamino-2,4-dinitronaphthalene (1c) is not. General base catalysis is shown to be a consequence of rate-limiting deprotonation of the zwitterionic intermediate complex. The structures of 1a and 1b analysed by X-ray crystallography fairly tie in with the great difference in behaviour between 1a and 1b.

Aromatic nucleophilic substitution reactions of 1-dialkylamino-2,4-dinitronaphthalenes with various amines in dimethyl sulphoxide. Part 26.

The dialkylamino group (e.g., dimethyl-, diethyl-, and N-methylbutyl-amino, piperidino, and pyrrolidino) of 1-dialkylamino-2,4-dinitronaphthalenes is readily replaced by primary alkylamines in dimethyl sulphoxide. However, substitution does not occur for secondary alkylamines except in the case of pyrrolidine. Aromatic primary amines (p-methoxy-, p-methyl-, and p-nitro-anilines and aniline) are less reactive than aliphatic primary amines, probably owing to their nucleophilicity and bulkiness. Benzylamine is more reactive than aromatic primary amines, but less reactive than aliphatic primary amines. Dependence of substitution on the conformation of nucleophilic amines is discussed.

Kinetics of the reactions of nitro-substituted N-alkylacetanilides with sodium methoxide in methanol

The sodium methoxide-catalysed methanolysis of N-ethyl-(3) or N-methyl-2′,4′,6′-trinitroacetanilide (4) is found to proceed with initial formation of a 1,3-disubstituted anionic σ-complex (II), which then reverts to the reactant system, relatively slowly giving N-alkyl-4-methoxy-(main product) and N-alkyl-2′-methoxy-4′,6′-dinitroacetanilides with the amido group unchanged, via a 1,4-disubstituted anionic σ-complex (III); kinetics and absorption and 1H n.m.r. spectral data are reported.

Alkaline hydrolyses of N-alkyl-2,4-dinitroacetanilides

The alkaline hydrolysis in protium and deuterium oxides of N-alkyl-2,4-dinitroacetanilides (alkyl; methyl and hydrogen) proceeds via the rate-limiting formation of a tetrahedral intermediate, which decomposes to give products with water (k2 process) and hydroxide catalysis (k3 process), the latter process being predominant. Solvent isotope effects for both processes are ca. 3.0 (60 °C). Breakdown of the tetrahedral intermediate proceeds by two pathways with the transition states involving C–N bond breakage to give a hydrogen-bonded anilide ion intermediate.

Polymerization of Alkylene Oxides with Alkyl Orthovanadate-Zinc Chloride System

オルトバナジン酸アルキル- 塩化亜鉛系がアルキレンオキシドの重合に活性を有することを見出したので, 本研究では主としてプロピレンオキシドを用い重合を行ない考察をした。本触媒はオルトバナジン酸アルキル(OV(OR)3)のみでは重合活性を有せず,塩化亜鉛の共存により始めて重合活性を有する。OV(OR)3のアルキル基としてEt,iso-Pr,sec-Buの3種類を調製したが,重合活性はi-Pr>Et～sec-Buの順であった。OR基の影響が強く働いているものと考えられる。OV(OPri)3-ZnCl2系による重合を詳細にしらべたが,しらべた温度範囲(30～50℃)では,温度が低い程,重合度は大きいが重合率は減少する。共存する塩化物としてAlCl3, MgCl2, SnCl2, SnCl4, ZnCl2の効果をしらべたが, ZnCl2が最も有効であることを認めた。OV(OPri)3-ZnCl2系のIRスペクトルより錯体を生成しているものと推定される。エチレンオキシドの低重合体をつくり,IRスペクトルより末端基をしらべたところ,iso-Pr基の存在を認めた。本重合は配位アニオン重合によって進むと考えられる。