Seika Corporation

Wakayama-shi, Japan

Seika Corporation

Wakayama-shi, Japan

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Imoto M.,Seika Corporation | Takeda M.,Seika Corporation | Tamaki A.,Seika Corporation | Taniguchi H.,Seika Corporation | And 2 more authors.
Journal of Organic Chemistry | Year: 2011

Observations show that nitroanilines exhibit an unusually high S NAr reactivity with OH- in aqueous media in reactions that produce nitrophenols. SNAr reaction of 4-nitroaniline (2a) in aqueous NaOH for 16 h yields 4-nitrophenol (4a) quantitatively, whereas a similar reaction of 4-nitrochlorobenzene (1a) gave 4a in 2% yield together with recovered 1a in 97%, suggesting that the leaving ability of the NH2 group far surpasses that of Cl under these conditions. An essential feature of SNAr reactions of nitroanilines is probably that the NH2 leaving group participates in a hydrogen-bonding interaction with H 2O. Density functional theory (DFT) calculations for a set of 4-nitroaniline, OH-, and H2O suggest a possible formation of a Meisenheimer complex stabilized by hydrogen-bonding interactions and a six-membered ring structure. The results obtained here contrast with conventional SNAr reactivity profiles in which nitroanilines are nearly unreactive with nucleophiles in organic solvents. © 2011 American Chemical Society.


Imoto M.,Osaka Prefecture University | Ikeda H.,Seika Corporation | Tamaki A.,Osaka Prefecture University | Takeda M.,Osaka Prefecture University | Mizuno K.,Seika Corporation
Organic Letters | Year: 2010

Figure presented An intramolecular exciplex is formed upon excitation of the cyclohexane solution of the 1,4-dicyano-2-methylnaphthalene-N,N-dimethyl-p- toluidine dyad, but little if any intramolecular CT complex exists in the ground state of this substance in solution. In contrast, in the crystalline state, the dyad forms an intermolecular mixed-stack CT complex in the ground state and an intermolecular exciplex when it is photoexcited. © 2010 American Chemical Society.


Nomoto A.,Osaka Prefecture University | Taniguchi T.,Osaka Prefecture University | Taniguchi T.,Seika Corporation | Minatobe Y.,Osaka Prefecture University | And 4 more authors.
Molecules | Year: 2015

A novel cysteine-incorporated anthraquinone derivative was synthesized, and its molecular structure was determined by X-ray crystal analysis. Each mercapto group was located separately and did not form a disulfide bond, and hydrogen bondings and Π-Π interaction were observed from the packing structure. © 2015 by the authors; licensee.


Imoto M.,Osaka Prefecture University | Imoto M.,Seika Corporation | Ikeda H.,Osaka Prefecture University | Ohashi M.,Osaka Prefecture University | And 4 more authors.
Tetrahedron Letters | Year: 2010

Colorless crystals of 1,4-dicyano-2-(4′-methoxybenzyloxy) methylnaphthalene (2), which is a 1,4-dicyano-2-methylnaphthalene (DCMN)-4-methylanisole (MA) dyad linked by an ether unit, selectively form a fluorescent intermolecular DCMN-MA exciplex (greenish blue, λ f exciplex=456nm). In contrast, 1,4-dicyano-2-(4′- methylbenzyloxy)methylnaphthalene (3), which is a DCMN-p-xylene dyad, forms a fluorescent intermolecular DCMN-DCMN excimer in the crystalline state (blue, λf excimer=404nm). These findings demonstrate that a moderate charge transfer interaction takes place between the DCMN moiety of 2 and MA moieties of the adjacent molecules of 2, which successfully facilitates the preparation of light-emissive organic crystals. © 2010 Elsevier Ltd. All rights reserved.


Taniguchi T.,Seika Corporation | Taniguchi T.,Osaka Prefecture University | Imoto M.,Seika Corporation | Takeda M.,Seika Corporation | And 6 more authors.
Tetrahedron | Year: 2016

A direct C–H arylation of aminoheterocycles with arylhydrazine hydrochlorides was developed. The reaction proceeds via a homolytic aromatic substitution mechanism involving aryl radicals as the intermediates. The new reaction takes place readily at room temperature in air and in the presence of an inexpensive base. Moreover, the reactivity of this radical arylation correlated with the HOMO energy of aminoheterocycles. This method provides not only a rapid access to diverse arylated heterocycles, but also an atom-efficient alternative to conventional transition-metal-catalyzed cross-coupling between halides and organometallics. © 2016 Elsevier Ltd


PubMed | Seika Corporation
Type: Journal Article | Journal: The Journal of organic chemistry | Year: 2011

Observations show that nitroanilines exhibit an unusually high S(N)Ar reactivity with OH(-) in aqueous media in reactions that produce nitrophenols. S(N)Ar reaction of 4-nitroaniline (2a) in aqueous NaOH for 16 h yields 4-nitrophenol (4a) quantitatively, whereas a similar reaction of 4-nitrochlorobenzene (1a) gave 4a in 2% yield together with recovered 1a in 97%, suggesting that the leaving ability of the NH(2) group far surpasses that of Cl under these conditions. An essential feature of S(N)Ar reactions of nitroanilines is probably that the NH(2) leaving group participates in a hydrogen-bonding interaction with H(2)O. Density functional theory (DFT) calculations for a set of 4-nitroaniline, OH(-), and H(2)O suggest a possible formation of a Meisenheimer complex stabilized by hydrogen-bonding interactions and a six-membered ring structure. The results obtained here contrast with conventional S(N)Ar reactivity profiles in which nitroanilines are nearly unreactive with nucleophiles in organic solvents.

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