- Benzpyrylium squarylium and croconylium dyes, and processes for their preparation and use
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Dyes comprising an inner salt of a compound of the formula: wherein: Q1 is a 4-(benz[b]-4H-pyrylium)methylidene, 4-(benz[b]-4H-thiopyrylium)methylidene or 4-(benz[b]-4H-selenopyrylium)methylidene grouping; Z is a 1,3-(2-hydroxy-4-oxo-2-cyclobutylidene) hydroxide or 1,3-(2-hydroxy-4,5-dioxo-2-cyclopentylidene) hydroxide ring; and Q2 is a 4-(benz[b]-4H-pyran-4-ylidene)methyl, 4-(benz[b]-4H-thiopyran-4-ylidene)methyl or 4-(benz[b]-4H-selenopyran-4-ylidene)methyl grouping; wherein at least one of the groupings Q1 and Q2 carries at its 2-position a substituent in which a non-aromatic carbon atom is bonded directly to the benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus, subject to the proviso that if this 2-substituent contains an aromatic nucleus, this aromatic nucleus is not conjugated with the benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus to which it is attached, are useful as visible and near infra-red absorbers, having high extinction coefficients and improved solubility in polymeric media.
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- NONCONVENTIONAL FRIEDEL-CRAFTS CHEMISTRY II. ON THE CATALYTIC ACTION OF TRIFLIC ACID AND ALUMINIUM CHLORIDE IN SELECTED ARYL THIOESTERS
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The catalytic action of triflic acid and/or aluminium chloride on seven selected aryl thioesters (1-7) gave in all cases aryl thiols, diaryl sulfides, diaryl disulfide, and thianthrene derivatives in addition to the corresponding aryl carboxylic acids.Thioester 5 gave thiochromanone derovatives in good yield under the same conditions.Plausible mechanism were suggested to rationalize the obtained results. Key words: Aryl thioesters; Friedel-Crafts reactions; triflic acid; aluminium chloride.
- El-Zohry, M. F.,El-Khawaga, A. M.,Ismail, M. T.,Abdel-Wahab, A. A.
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p. 373 - 380
(2007/10/02)
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- A general route to the synthesis of 3-alkylidene derivatives of 4-thiochromanone 1,1-dioxide
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The reactions of the trimethylsilyl enol ethers of both 4-thiochromanone and 4-thiochromanone 1,1-dioxide with various carbonyl compounds complexed with titanium tetrachloride give moderate yields of the previously unknown 3-alkylidene condensation products under mild conditions.Other Lewis acids, with the exception of boron trifluoride, were found to be ineffective in this transformation.
- Still, Ian W. J.,Ablenas, Fred J.
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p. 2535 - 2539
(2007/10/02)
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