Showing papers on "Xanthene published in 1976"
01 Jan 1976-Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry
TL;DR: The fluorescence efficiency of xanthene dyes, oxazine dyes and 7-aminocoumarins is discussed in this article, and several new fluorescence standards are suggested.
Abstract: The fluorescence efficiency of xanthene dyes, oxazine dyes, and 7-aminocoumarins is discussed. Relations with the molecular structure are pointed out and dependence on solvent and temperature is explained. Several new fluorescence standards are suggested.
174 citations
TL;DR: The 14H-Dibenzo[a,j]xanthene was easily synthesized by heating alkali (K or Na) 2-naphthyloxide under CO and CO2 pressure as discussed by the authors.
Abstract: 14H-Dibenzo[a,j]xanthene was easily synthesized by heating alkali (K or Na) 2-naphthyloxide under CO and CO2 pressure.
75 citations
TL;DR: In this article, the 1H-CIDNP technique was used to investigate the structure of the unstable intermediates of the 9,10-o-benzeno-4a,9,9a,10,tetrahydro-1,4-anthraquinone 1 and xanthene 2 in benzene gave dihydro-monomer 3 and dihydrodimer 4 of 1.
Abstract: Irradiation of 9,10-o-benzeno-4a,9,9a,10-tetrahydro-1,4-anthraquinone 1 and xanthene 2 in benzene gave dihydro-monomer 3 and dihydrodimer 4 of 1 as the final products. The course of the reaction and the structure of the unstable intermediates were investigated by means of 1H-CIDNP technique.
14 citations
TL;DR: The temperature dependence of fluorescence yield and the radiative lifetime of a fluorescein derivative (6-hydroxy-9phenyl-fluoron) was determined in alkaline solutions in this article.
13 citations
TL;DR: The measurement of triplet decay time (τ p ) and the relative yields of phosphorescence to fluorescence (φ p /φ f ) have been made in solutions of xanthene dyes.
9 citations
TL;DR: In this article, Salicylaldehyde 1 and pyrrolidine enamines 2 give 1,2-dihydro-3H-xanthenes 5, the amino alcohols 3 being the first and unsaturated amino ketals 7 and 10 being the secondary intermediates.
8 citations
TL;DR: In this article, the ion-pair formation of carbanions of xanthene (XH) and thioxanthene with alkali metal cations has been investigated by optical absorption and emission spectroscopy.
Abstract: The ion-pair formation of the carbanions of xanthene (XH–) and thioxanthene (TxH–) with alkali metal cations has been investigated by optical absorption and emission spectroscopy. The absorption spectra depend on solvent, counter ion and temperature in the same way as has been found for other carbanions. The XH– fluorescence spectrum exhibits an unexpected dependence on temperature; from TxH– no fluorescence has been observed.The absorption spectra have been analysed by deconvolution into Gaussian curves and are interpreted with the aid of the results of π-electron SCF-MO calculations. The enthalpies and entropies of the conversion of the contact ion pairs into the solvent-separated ion pairs of both carbanions have been calculated from the spectral data at different temperatures. The excited state acidity of XH2 has been determined from the absorption and fluorescence spectra. The experimental results are discussed in connection with those of some related systems.
3 citations
TL;DR: In this article, the photochemical reaction of 1,1,4,4tetramethyl-2,3-tetralindione, 1, with hydrogen donors, such as xanthene and aldehyde, in the liquid phase has been investigated.
Abstract: The photochemical reaction of 1,1,4,4-tetramethyl-2,3-tetralindione, 1, with hydrogen donors, such as xanthene and aldehyde, in the liquid phase has been investigated. When xanthene was selected as the hydrogen donor, the main products were the “1,2-adduct,” photo-reduced α-keto alcohol, and 9,9′-bixanthenyl. The photolysis of 1 and an aldehyde gave the mixture of the “1,2-adduct” and the “1,4-adduct.” However, in the reaction with isobutyraldehyde another type of “1,2-adduct” was obtained, i.e., a combination product between the semidione radical and the isopropyl radical resulting from the decarbonylation of the isobutyryl radical, together with propene and carbon monoxide. The usual type of “1,2-adduct,” the “1,4-adduct,” and the photo-reduced product (α-keto alcohol) were the minor products in the reaction. It was also confirmed that the original “1,4-adduct” obtained from 1 and acetaldehyde rearranged photochemically to a different type of “1,2-adduct,” but no reverse rearrangement was observed under...
3 citations
Patent•
14 Oct 1976TL;DR: The disclosure relates to xanthene derivatives which possess analgesic activity, to processes for the manufacture of said derivatives and to pharmaceutical compositions containing them as mentioned in this paper, and typical of the xanthen derivatives disclosed is 6-chloro-4-hydroxy-1'-methylxanthene-9-spiro-4'-piperidine.
Abstract: The disclosure relates to xanthene derivatives which possess analgesic activity, to processes for the manufacture of said derivatives and to pharmaceutical compositions containing them. Typical of the xanthene derivatives disclosed is 6-chloro-4-hydroxy-1'-methylxanthene-9-spiro-4'-piperidine.
3 citations
TL;DR: In this paper, the stereochemical isomers of the 1,2-adducts of xanthene to carbonyl groups were isolated as the reaction products CIDNP technique was applied for the examination of the course of the reactions.
Abstract: Photochemical reduction of 2,3-dihydro-2-methyl-2,3-methano-1,4-naphthoquinone (1a) and 2,3-dihydro-2,3-dimethyl-2,3-methano-1,4-naphthoquinone (1b) with xanthene was investigated 6,7,8,9-Tetrahydrobenzocycloheptene-5,9-dione derivatives and stereochemical isomers of the so-called “1,2-adducts” of xanthene to carbonyl groups were isolated as the reaction products CIDNP technique was applied for the examination of the course of the reactions
2 citations
TL;DR: The 14H-Dibenzo[a,j]xanthene was easily synthesized by heating alkali (K or Na) 2-naphthyloxide under CO and CO2 pressure as discussed by the authors.
Abstract: 14H-Dibenzo[a,j]xanthene was easily synthesized by heating alkali (K or Na) 2-naphthyloxide under CO and CO2 pressure.
TL;DR: In this article, the photochemical reduction of 2,3-dihydro-2-methyl-2,3methano-1,4-naphthoquinone with xanthene was investigated.
Abstract: Photochemical reduction of 2,3-dihydro-2-methyl-2,3-methano-1,4-naphthoquinone (1a) and 2,3-dihydro-2,3-dimethyl-2,3-methano-1,4-naphthoquinone (1b) with xanthene was investigated. 6,7,8,9-Tetrahydrobenzocycloheptene-5,9-dione derivatives and stereochemical isomers of the so-called “1,2-adducts” of xanthene to carbonyl groups were isolated as the reaction products. CIDNP technique was applied for the examination of the course of the reactions.
Patent•
01 Mar 1976
TL;DR: In this paper, the present invention relates to novel xanthene and thioxanthene derivatives of the following general formula: where Y represents sulfur or oxygen, R 1 represents hydrogen, chlorine, trifluoromethyl or dimethylsulfamoyl, R 2 represents hydrogen or fluorine; and R 3 and R 4 each represent hydrogen or methyl.
Abstract: The present invention relates to novel xanthene and thioxanthene derivatives of the following general formula: ##STR1## wherein Y represents sulfur or oxygen, R 1 represents hydrogen, chlorine, trifluoromethyl or dimethylsulfamoyl, R 2 represents hydrogen or fluorine; and R 3 and R 4 each represents hydrogen or methyl, provided that R 3 and R 4 may not both represent hydrogen, or R 3 and R 4 taken together with the nitrogen atom form a piperazine or piperidine ring optionally substituted in the 4-position by a methyl group or a 2-hydroxyethyl group, if desired, esterified with an aliphatic carboxylic acid having from one to seventeen carbon atoms inclusive, as well as non-toxic acid addition salts thereof.