Xanthene

About: Xanthene is a research topic. Over the lifetime, 2132 publications have been published within this topic receiving 34803 citations. The topic is also known as: Xanthene & dibenzo[a,e]pyran.

Reactions of enamines with benzaldehyde and benzylidenecyclohexanone

Abstract: Benzaldehyde reacts with 1-pyrrolidin-1-ylcyclohexene and 1-piperidin-1-ylcyclohexene to give xanthene derivatives identical to the products of reaction of dibenzylidenecyclohexanone with the enamines : 1-morpholinocyclohexene behaves differently. Benzylidenecyclohexanone with 1-pyrrolidin-1-ylcyclohexene gives an analogous adduct the hydrolysis of which has been investigated.

Novel epoxy resin and production thereof

Abstract: PURPOSE:To obtain title epoxy resin having excellent heat resistance and useful as paint, etc., by reacting specified xanthene cpd. with epihalohydrin in the presence of an alkaline cpd. CONSTITUTION:A xanthene cpd. of formula I (wherein R1, R2 are H, 1-5C alkyl) such as 3, 6-dihydroxy-9, 9-dimethylxanthene is reacted with epihalohydrin of formula II (wherein R3 is H, CH3; X is halogen) such as epichlorohydrin or beta-methylepibromohydrin in an amt. of from 0.6-10mol per one hydroxyl gp. of the xanthene cpd. in the presence of an alkaline cpd. such as sodium hydroxide, sodium silicate at a temp. of from 20-120 deg.C to produce epoxy resin of formula III (wherein n>=0).

Oxygen- and pH-Dependent Photophysics of Fluorinated Fluorescein Derivatives: Non-Symmetrical vs. Symmetrical Fluorination.

Abstract: Fluorescein, and derivatives of fluorescein, are often used as fluorescent probes and sensors. In systems where pH is a variable, protonation/deprotonation of the molecule can influence the pertinent photophysics. Fluorination of the xanthene moiety can alter the molecule’s pKa such as to render a probe whose photophysics remains invariant over a wide pH range. Di-fluorination is often sufficient to accomplish this goal, as has been demonstrated with compounds such as Oregon Green in which the xanthene moiety is symmetrically difluorinated. In this work, we synthesized a non-symmetrical difluorinated analog of Oregon Green which we call Athens Green. We ascertained that the photophysics and photochemistry of Athens Green, including the oxygen-dependent photophysics that results in the sensitized production of singlet oxygen, O2(a1Δg), can differ appreciably from the photophysics of Oregon Green. Our data indicate that Athens Green will be a more benign fluorescent probe in systems that involve the production and removal of O2(a1Δg). These results expand the available options in the toolbox of fluorescein-based fluorophores.

2-[(2,4-Dihydroxy­benzyl­idene)amino]-3′,6′-bis­(ethyl­amino)spiro­[isoindoline-1,9′-xanthen]-3-one

Abstract: The title compound, C35H36N4O4, was prepared as a spiro­lactam ring formation of rhodamine B dye for comparison with a ring-opened form. The xanthene ring system is approximately planar. The r.m.s. deviation from planarity is 0.064 (6) A for the xanthene ring. The dihedral angles formed by the spiro­lactam and 2,4-dihydroxy­benzene rings with the xanthene ring system are 86.6 (9) and 88.0 (9)°, respectively.

9H‐xanthene‐2,7‐diols as antioxidants for autoxidation of linoleic acid

Abstract: The antioxidant activities of 9H-xanthene-2,7-diols and α-tocopherol were studied during the oxidation of linoleic acid in a homogeneous solution and in an aqueous micelle dispersion. The antioxidant activities of 9H-xanthene-2,7-diols for both systems were 1.0–2.4 times greater relative to α-tocopherol. In addition, the 1,3,4,5,6,8-hexamethylxanthene-2,7-diol showed less cytotoxicity toward human fibroblasts than did 2,6-di-t-butyl-4-methylphenol.