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A pH dependence of absorption spectra of carthamin in aqueous solution was investigated by the principal component method. In aqueous solution near to neutral condition, the spectral change showed the existence of two components, A and B, the maximum absorption of which were at 520 and 500 nm, respectively. They seemed to correspond to F0 and Fx0 in silk cloth dyed from the neutral dye bath, as reported previously. The following equilibrium was set up between the components of A and B : A B + H+ (.log K = 6.9). In acidic conditions, a small amount of the third component existed. On the other hand, the other components (D and D') existed in alkaline conditions. On the basis of the examination results, the acid-base equilibriums between these components were supposed, and the chemical species having different number of dissociated hydroxyl groups of carthamin were tentatively assigned to these components.

The dyeing of silk cloth with carthamin extracted from safflower (Benibana) gave different shade with three organic acids, even though all dye baths were adjusted to pH=6.9. The cause of this color difference was studied by analyzing Kubelka-Munk function (KM-function) spectra of dyed silk cloth. The KM-function spectra were found to be composed by two spectral components, F0 and F0x. Theirmaximal absorptions were at 520 and 510 nm, respectively. The shade of dyed silk cloth depended on the both of relative strengths of the spectral components and the dyeing concentrations. The relative strength of the spectral component (F0) was arranged by the used organic acids as citric acid > acetic acid > Ubai, while the dyeing concentrations were arranged as acetic acid > Ubai and citric acid. The difference between the spectral components, F0 and F0x, was suggested to be caused by the degree dissociation of hydroxyl groups in carthamin. The dependence of the color difference of dyed silk cloth on the used organic acid, therefore, was considered to be attributed to the difference in acidity on the silk cloth.

1-Hydroxyanthraquinone derivatives and some pH indicators showed thermochromism on silica gel, based on the shift in the acid-base equilibrium. In a lower temperature range, the degree of acid dissociation of the dyes increased with a rise in temperature, mainly based on the increase in the basic sites on silica gel resulting from the decreasing amount of water adhering on it. In a higher temperature range, on the other hand, the acid dissociation of the dyes with a rise in temperature was promoted by the increase in acidity of the dyes.

Photofading of crystal violet (CV) in nylon and polyester films is suppressed with the progress of decay. Photofading of the dye in polymer substrates is explained on the basis of two models: a distribution of photochemical reactivity sites for the dye, and a bimolecular reaction mechanism for fading. Simulation results using the first model are compatible with experimental results for nylon, whereas the simulation derived by combining both models corresponds well to the photofading behavior of CV in polyester. Results from the fluorescence measurements by pulse fluorometry also support the first model.

The UV/VIS spectra of a series of stilbazolium merocyanine-type dyes containing a benzoquinolizinium ring have been recorded in seven solvents. The dyes with a hydroxyl group showed hypsochromic shifts (less than 50 nm) on changing the solvent from 3-methylbutan-1-ol to water. On the other hand, the azonia betaine-type dyes formed by deprotonation of the hydroxy-substituted dyes exhibited a large hypsochromic shift (about 200 nm) as the solvent polarity increased. The transition energies (ET) of the dyes having a hydroxyl group did not correlate well with solvent polarity scales such as Brooker's χR and χB, Kosower's Z, and Dimroth and Reichardt's ET(30), while good correlations were observed between ET of the azonia betaine-type dyes and the scales χB, Z, and ET(30). The solvatochromism was analyzed by the linear solvation energy relationship with the multi-parameter proposed by the Kamlet, Abboud, and Taft group and showed excellent correlations for the azonia betaine-type dyes. The inherent wave-number (ν0) and the susceptibility of the absorption maximum (νmax) to solvent polarity-polarizability ( π ∗ ), to solvent hydrogen-bond donating acidity (α), and to solvent hydrogen-bond accepting basicity (β) are discussed.

Core potentials required for self-consistent field (scf) molecular orbital calculations of the spectra of π-electron systems can be expressed by functions of the Slater nuclear charge and the apparent core charge. The core potentials of a perturbed π-electron system are reasonably evaluated using these functions. A novel first order perturbation method is suggested to analyze spectral change by small variations of the core. The spectra of aza and azonia aromatic compounds can be estimated by this perturbation method. The spectra of azobenzene, anthraquinone and its diimine are discussed on the basis of the spectra of their corresponding hydrocarbons. An unusual effect on the spectrum of azulene by a methyl substituent can be successfully explained by the first order perturbation method.

The use of several cells of different length is required for the analysis of dye aggregation by the spectral method, and the length of the cell must be calibrated before measurement of the absorption spectra of the dye solution. A new analytical method for dye aggregation in solution using the principal component analytical (PCA) method is suggested. Since calibration of the length of cell is not required, this new spectral method can be more easily used for the analysis of the aggregation of a dye in solution.

Transfers of dyes into micelles of anionic, cationic or nonionic surfactants from water have been investigated by means of spectroscopy. The dyes used were ortho or para hydroxy-2-styrylbenzo |a| quinolizium salts |A (OH), B (OH)| and B (OH) with methyl radical |C (OH)| and their phenolate derivatives | A (O-), B (O-), and C (O-)| and 4-nitrophenole (NPh), 4-nitroaniline (NA) and N, N-dimethyl-4-nitroaniline (NMA), The dyes of A (OH), B (OH), and C (OH) and NPh were not transfered into micelles of these three surfactants from water. The dyes of phenolate from, A (O-), B (O-), and C (O-), NA and NMA, could not be incorporated into the anionic surfactant micelles, but were incorporated into cationic and nonionic surfactant micelles. The equilibrium constants of these surfactant micelles were close to each other, and were in the order of NMA>NA>C (O-)>A (O-)_??_B (O-). The polarity of the inside of micelles was estimated on basis of the spectral shifts of the dyes.

Photocyclization provided a good route to prepare azonia derivatives of fused polycyclic aromatic compounds such as benzo [c] phenanthrene, benzo [ghi] perylene, benzo [a] coronene, picene, and [6] helicene. The photoreactions could be classified into four types; (A) photocyclization of 1-styrylpyridinium salts to benzo [a] quinolizinium derivatives, (B) photocyclizaiton of styrylquinolizinium salts to fused azonia compounds, (C) photocyclization of 2-styrylpyridine derivatives to benzo [c] quinolizinium salts, and (D) photocyclization of 1, 2-diarylpyridinium salts.The photocyclization occurred when the bond order (Prs*) between atoms r and s, involved in the cyclization in the excited state, has a negative value.

The reaction of 1-aminoanthraquinone with benzyl chloride in KOH-DMSO system afforded 3,11b-dibenzyl-2-phenyl-2,3,7,11b-tetrahydroanthra[1,9-de][1,3]oxazin-7-one (5; 78% yield), whose structure was determined by single-crystal X-ray diffraction. The reaction of compound 5 with aluminium chloride gave 1-phenyl-2,6-di-hydronaphth[1,2,3-cd]indol-6-one (52% yield) having strong fluorescence.

The 2-styrylbenzo[a]quinolizinium salt was photocyclized to afford 12a-azoniabenzo[ghi]perylene salt in 66% yield. The 2a-azoniabenzo[a]coronene salt was obtained by the photocyclization of 2-[2-(4-biphenylyl)vinyl]benzo[a]-quinolizinium salt and 2-styryl-10-phenylbenzo[a]quinolizinium salt in 80% and 75% yields, respectively.

Asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with sodium salt of acetamidomalonate ester has been carried out in the presence of a palladium catalyst containing ( S )-BINAP to give a chiral α-allyl-αacetamidomalonate ester derivative of high optical purity (94±1% ee).

Highly fluorescent 1-phenylnaphth[1,2,3-cd]indol-6(2H)-one (3b) and its 7-chloro and 7-amino derivatives were synthesized by reaction of 1-aminoanthraquinones with benzyl chloride in KOH–DMSO system, followed by treatment with aluminium chloride. The compound 3b was easily N-alkylated with various alkyl halides in KOH–DMSO system. The fluorescence quantum yields (Qf) of naphth[1,2,3-cd]indol-6(2H)-one derivatives 3 were high (0.5–0.7), except for 7-amino derivatives which did not fluoresce. The Qf of 7-chloro derivative (3d) was strongly dependent on solvent: 0.37 in ethanol; 0.02 in acetonitrile; 0 in benzene. The compounds 3 were demonstrated to be efficient laser dyes for 500–550 nm region.

Palladlum-catalyzed asymmetric allylic alkylatlon of 1,3-dlphenyl-2-propenyl acetate with sodium salt of dimethyl malonate and its derivatives has been successfully carried out in the presence of optically active diphosphine, such as (S)-BINAP. High enantioselectivity of up to 90% ee was obtained with dimethyl malonate.

The photocyclization of 2-[2-(2-chlorophenyl)vinyl]-6-methylpyridine and 2-[2-(2-chlorophenyl)vinyl]quinoline in acetonitrile afforded new compounds 1-methylbenzo[c]quinolizinium salt and dibenzo[c,f]quinolizinium salt in 56% and 41% yields, respectively.

Publisher Summary This chapter presents the synthesis of polycyclic aromatic nitrogen cations, as well as their chemical and physicochemical properties. The chemistry of bicyclic and tricyclic compounds is also discussed from a theoretical standpoint. The chapter discusses that there are two general types of polycyclic aromatic nitrogen cations: N-Alkyl quinolinium salts (Type A) and quinolizinium salts (Type B). Since the prefix azonia designates the cationic nitrogen, which is a part of cyclic structures, these two types of compounds are categorized as the azonia derivatives of polycyclic aromatic hydrocarbons. It reviews that the replacement of a bridgehead carbon of polycyclic aromatic hydrocarbons with nitrogen gives the azonia derivatives. Of the six possible tetracyclic benzenoid aromatic hydrocarbons, one can predict a total of 18 aromatic cations having bridgehead nitrogen. In case of compounds without symmetry, this happens because many isomeric compounds are possible due to the position of quaternary nitrogen.

Six isomers of the methylbenzo[c]quinolizinium salt 3 including four new monomethyl derivatives were synthesized by thermal-intramolecular quaternization of the cis-methyl-substituted 2-[2-(2-chlorophenyl)-vinyl]pyridines 4 or by the irradiation of trans-4 with selected wavelengths (290 400 nm) in acetonitrile. Among the regioisomeric monomethyl derivatives 3, the 1-, 3-, and 6-methyl derivatives 3b, 3d, and 3g reacted with p-methoxybenzaldehyde in the presence of bis(l-piperidino)-(p-methoxyphenyl)-methane 7 to yield trans-(p-methoxystyryl)benzo[c]quinolizinium salts 6. The reactivity of 3 and methylbenzo[a]quinolizinium salts 1 was discussed on the basis of their π-electron energy.

Photocyclization provided a good route to prepare azonia derivatives of fused polycyclic aromatic compounds such as benzo [c] phenanthrene, benzo [ghi] perylene, benzo [a] coronene, picene, and [6] helicene. The photoreactions could be classified into four types; (A) photocyclization of 1-styrylpyridinium salts to benzo [a] quinolizinium derivatives, (B) photocyclizaiton of styrylquinolizinium salts to fused azonia compounds, (C) photocyclization of 2-styrylpyridine derivatives to benzo [c] quinolizinium salts, and (D) photocyclization of 1, 2-diarylpyridinium salts.The photocyclization occurred when the bond order (Prs*) between atoms r and s, involved in the cyclization in the excited state, has a negative value.

Visible light irradiation to the reaction mixture of metalloporphyrins such as antimony (V), phosphorus(V), tin(IV) and germanium(IV) tetraphenylporphyrins with methylviologen (MV 2+ ), hydroxide ion (OH − ), alkene in degassed acetonitrile—water induced reduction of MV 2+ into its cation radical (MV -+ and epoxidation of the alkene. The oxygen atom of water was confirmed to be incorporated in the oxidation product epoxide by experiment using H 2 18 O. Detailed laser flash photolysis studies of the antimony(V) tetraphenylporphyrin system revealed that the hydroxy-coordinated antimony(V) tetraphenylporphyrin deprotonated in the triplet excited states followed by an electron transfer to MV 2+ to produce MV -+ and oxo-type porphyrin complex which could transfer the oxygen atom to alkene to form the corresponding epoxide.

The effect of dye and water on the molecular motions of poly (ethylene terephthalate) (PET) was investigated by dynamic viscoelastic measurements and thermal analysis of dyed PET films. Both α and β loss modulus peaks of dry films shifted to lower temperature side with the increase of dye concentration, accompanied by a decrease of their apparent activation energy. The results suggested that dye molecules in the films enhanced the segmental mobility of PET as a result of plasticizing effect. The number of segments per unit cross section derived from the relaxation intensity of β dispersion, which was associated with local mode relaxation of PET. depended on dye concentration in the films. It is expected that higher dye concentration brings about a different mode of dye adsorption in PET substrates. The apparent activation energy of α dispersion due to glass transition of PET decreased markedly in the presence of water. The segmental mobility of PET chains seem to be much sensitive to moisture content in the film as compared with plasticizing effects by dye molecules.

Six isomers of the methylbenzo[c]quinolizinium salt 3 including four new monomethyl derivatives were synthesized by thermal-intramolecular quaternization of the cis-methyl-substituted 2-[2-(2-chlorophenyl)-vinyl]pyridines 4 or by the irradiation of trans-4 with selected wavelengths (290 400 nm) in acetonitrile. Among the regioisomeric monomethyl derivatives 3, the 1-, 3-, and 6-methyl derivatives 3b, 3d, and 3g reacted with p-methoxybenzaldehyde in the presence of bis(l-piperidino)-(p-methoxyphenyl)-methane 7 to yield trans-(p-methoxystyryl)benzo[c]quinolizinium salts 6. The reactivity of 3 and methylbenzo[a]quinolizinium salts 1 was discussed on the basis of their π-electron energy.

Formation of inclusion compounds between azoniabetain dyes (2-styryl benzo [a] quinoliziniums, A, B and C) and α-, β- and γ-cyclodextrins (CD) has been investigated from the absorption spectra accompanied by negative solvatochromism. As reference, 4-nitrophenol, potassium 4-nitrophenolate and 4-nitroaniline were used as indicator of the inclusion. The latter three compounds formed inclusion compounds only with α-CD, but not with β- and γ-CD's because of their larger cavity radii. Dye A in OH 0-forms was not included by the three CD's by the steric hindrance of oxygen at o-position of the dye. Dyes, B and C in OH form were not included by α-CD but formed 1:1 inclusion compounds with β- and γ-CD's, and in 0- form, they formed 1:1 incusion compounds with the three CD's. The formation constants were found to be in the order; β-CD > γ-CD > α-CD. Structures of the inclusion compounds were suggested based on their spectra.

Highly fluorescent 1-phenylnaphth[1,2,3-cd]indol-6(2H)-one (3b) and its 7-chloro and 7-amino derivatives were synthesized by reaction of 1-aminoanthraquinones with benzyl chloride in KOH–DMSO system, followed by treatment with aluminium chloride. The compound 3b was easily N-alkylated with various alkyl halides in KOH–DMSO system. The fluorescence quantum yields (Qf) of naphth[1,2,3-cd]indol-6(2H)-one derivatives 3 were high (0.5–0.7), except for 7-amino derivatives which did not fluoresce. The Qf of 7-chloro derivative (3d) was strongly dependent on solvent: 0.37 in ethanol; 0.02 in acetonitrile; 0 in benzene. The compounds 3 were demonstrated to be efficient laser dyes for 500–550 nm region.

Palladlum-catalyzed asymmetric allylic alkylatlon of 1,3-dlphenyl-2-propenyl acetate with sodium salt of dimethyl malonate and its derivatives has been successfully carried out in the presence of optically active diphosphine, such as (S)-BINAP. High enantioselectivity of up to 90% ee was obtained with dimethyl malonate.

All isomers of (monomethyl)benzo[a]quinolizinium salts including five new monomethyl derivatives were prepared by photocyclization, sulfur extrusion, or cyclodehydration reaction, and their aldol-type condensation was examined. The 2- and 4-methyl derivatives 3b and 3c reacted with p-methoxybenzaldehyde in the presence of piperidine to yield trans-(p-methoxystyryl)benzo[a]quinolizinium salts 11. The other methyl derivatives did not react with the aldehyde. The methyl group was reactive at the 2- and 4-positions, located para and ortho to the azonia ring nitrogen, respectively; however, it was unreactive at the 6-position located at another ortho position.

The effects of humidity and oxygen on the photofading of Crystal Violet (CV) in nylon 6 film were studied in detail. Both moisture and oxygen were necessasy for the formation of Michler's Ketone. The effects of temperature and humidity on the photofading of CV in nylon 6 and polyester films were discussed in terms of kinetics. The fading rate was accelerated with rises in temperature and humidity for both films, and the rate was lower in polyester film than in nylon. The quantum yield in film decreased with the progress of decay, whereas it was almost unchanged in solution. The relationship between relative quantum yield (φ) in film and absorbance (A) at λmax was expressed by the equation, φ=β(A-a0)m. The parameter m indicates the ease of decrease of the rate with the progress of decay. The influences of temperature and humidity on the value of m were compared. The value of m depends on the initial absorbance in some cases. At elevated temperatures m has smaller value in almost all the cases.

Asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with sodium salt of acetamidomalonate ester has been carried out in the presence of a palladium catalyst containing ( S )-BINAP to give a chiral α-allyl-αacetamidomalonate ester derivative of high optical purity (94±1% ee).

A marked greening observed in some foods such as sweet potato, burdock, and others during food processing was shown to be due to green pigment formation by the condensation reaction of two molecules of chlorogenic acid or caffeic acid ester with one molecule of a primary amino compound under aeration in alkaline solution. Reduction of the green pigment by ascorbic acid or NaBH4 gave a yellow product, which readily turn green and then blue in air. The reduced and acetylated product of the green pigment was identified to be a novel trihydroxy benzacridine derivative, and the yellowish ethanol solution of this product immediately turned green upon addition of butyl amine or diluted alkali. Therefore, the green pigment was assumed to be an oxidized quinone type product of trihydroxy benzacridine. This identification of the structure was supported by the correspondence of the measured absorption spectra with those calculated by the molecular orbital method. A possible charge transfer complex between products of different oxidation steps in green solution was proposed.

The 2-styrylbenzo[a]quinolizinium salt was photocyclized to afford 12a-azoniabenzo[ghi]perylene salt in 66% yield. The 2a-azoniabenzo[a]coronene salt was obtained by the photocyclization of 2-[2-(4-biphenylyl)vinyl]benzo[a]-quinolizinium salt and 2-styryl-10-phenylbenzo[a]quinolizinium salt in 80% and 75% yields, respectively.

The reaction of 1-aminoanthraquinone with benzyl chloride in KOH-DMSO system afforded 3,11b-dibenzyl-2-phenyl-2,3,7,11b-tetrahydroanthra[1,9-de][1,3]oxazin-7-one (5; 78% yield), whose structure was determined by single-crystal X-ray diffraction. The reaction of compound 5 with aluminium chloride gave 1-phenyl-2,6-di-hydronaphth[1,2,3-cd]indol-6-one (52% yield) having strong fluorescence.

A chiral diphosphinite ligand having dicyclohexylphosphinooxy and dimethylamino moieties (Cy-POP-AE) was effective for the asymmetric hydrogenation of N-(benzoylformyl) amino acids by a Rh(I) catalyst under mild conditions. A neutral rhodium(I) precursor enabled a double asymmetric induction in methanol, while a cationic precursor caused an asymmetric induction controlled mainly by the substrate chirality.

Publisher Summary This chapter presents the synthesis of polycyclic aromatic nitrogen cations, as well as their chemical and physicochemical properties. The chemistry of bicyclic and tricyclic compounds is also discussed from a theoretical standpoint. The chapter discusses that there are two general types of polycyclic aromatic nitrogen cations: N-Alkyl quinolinium salts (Type A) and quinolizinium salts (Type B). Since the prefix azonia designates the cationic nitrogen, which is a part of cyclic structures, these two types of compounds are categorized as the azonia derivatives of polycyclic aromatic hydrocarbons. It reviews that the replacement of a bridgehead carbon of polycyclic aromatic hydrocarbons with nitrogen gives the azonia derivatives. Of the six possible tetracyclic benzenoid aromatic hydrocarbons, one can predict a total of 18 aromatic cations having bridgehead nitrogen. In case of compounds without symmetry, this happens because many isomeric compounds are possible due to the position of quaternary nitrogen.

All isomers of (monomethyl)benzo[a]quinolizinium salts including five new monomethyl derivatives were prepared by photocyclization, sulfur extrusion, or cyclodehydration reaction, and their aldol-type condensation was examined. The 2- and 4-methyl derivatives 3b and 3c reacted with p-methoxybenzaldehyde in the presence of piperidine to yield trans-(p-methoxystyryl)benzo[a]quinolizinium salts 11. The other methyl derivatives did not react with the aldehyde. The methyl group was reactive at the 2- and 4-positions, located para and ortho to the azonia ring nitrogen, respectively; however, it was unreactive at the 6-position located at another ortho position.

New stilbazolium cyanine-type dyes were synthesized by the base-catalysed aldol-type condensation of 2-methylbenzo[a]quinolizinium perchlorate with hydroxy-substituted benzaldehyde derivatives. The long wavelength absorption band of the deprotonated form of the dyes underwent a remarkable hypsochromic shift as the solvent polarity increased, and the pronounced negative solvato-chromism extended over the whole visible region.

The photocyclization of 2-[2-(2-chlorophenyl)vinyl]-6-methylpyridine and 2-[2-(2-chlorophenyl)vinyl]quinoline in acetonitrile afforded new compounds 1-methylbenzo[c]quinolizinium salt and dibenzo[c,f]quinolizinium salt in 56% and 41% yields, respectively.

Visible light irradiation of a reaction mixture involving tetraphenylporphyrinatoantimony(V)(SbVTPP){[SbVTPP(OMe)Br]Br 1 or [SbVTPP(OH)2]OH 2}, methylviologen (MV2+), hydroxide ion and cyclohexene 6 in acetonitrile–water (95:5) under degassed conditions induced formation of MV˙+(one-electron reduced product of MV2+), and oxidation of cyclohexene (with cyclohexene oxide 7 and cyclohex-2-enol 8 as major products and cyclohexane-1, 2-diol 9 in small amounts in the case of 1, and cyclohexene oxide 7 as the sole product in the case of 2). One third of the obtained diol was cis isomer. The oxygen atom of the water molecule in the reaction system was confirmed as being incorporated in the oxidized products of cyclohexene by an experiment using H218O. The overall quantum yield of the photochemical epoxidation was in the order of 10–3, while that of MV˙+ production were in the order of 10–1. Hydroxide ion was shown to have both a negative effect on radical anion formation by reductive quenching of the excited triplet state of SbVTPP, and also a positive effect by acting as an oxygen source itself for the epoxidation. A key intermediate for the epoxidation was presumed to be an antimony(VI) oxo-type porphyrin complex generated by an electron transfer to MV2+ from a singly and doubly deprotonated excited triplet SbVTPP. The different product distributions obtained for 1 and 2 are discussed in relation to the geometrical structures of the presumed key intermediate oxo-complexes.

New stilbazolium cyanine-type dyes were synthesized by the base-catalysed aldol-type condensation of 2-methylbenzo[a]quinolizinium perchlorate with hydroxy-substituted benzaldehyde derivatives. The long wavelength absorption band of the deprotonated form of the dyes underwent a remarkable hypsochromic shift as the solvent polarity increased, and the pronounced negative solvato-chromism extended over the whole visible region.

The ESR spectra of the Ullmann condensation reaction system of 1-bromoanthraquinone-2-aminoethanol-CuBr showed that copper(II) species and 1-bromoanthraquinone radical anion were formed by an electron transfer from copper(I) species to 1-bromoanthraquinone. Although copper(II) species alone had little catalytic activity, the resulting copper(II) species increased the catalytic activity of the copper(I) species, and a pseudo-first order rate constant could be expressed as follows: k=k1[CuI]+k2[CuI][CuII]. According to the magnitude of k1 and k2C0, where C0 is the initial concentration of copper(I) catalyst, the reaction of haloanthraquinone with 2-aminoethanol by copper(I) catalyst can be classified into three modes. When k1

The multiplicity of the photo-excited state responsible for the dechlorination reaction of monochlorobiphenyls was determined in 2-propanol. Linear Stern-Volmer plots were obtained by the use of 1,3-cyclohexadiene for the dechlorination reactions of 2- and 3-chlorobiphenyl; the slopes were 35.7 and 11.0 dm3 mol−1 respectively. Fluorescence emissions were also quenched, and the quenching constants for 2- and 3-chlorobiphenyls were in accord with the respective values of the slope obtained from the Stern-Volmer plot for the reaction. The reaction of 4-chlorobiphenyl was quenched by cis-1,3-pentadiene, but was accelerated by 1,3-cyclohexadiene. Photosensitized dechlorinations of monochlorobiphenyls took place with several ketones, such as acetone and acetophenonc. These sensitized reactions were, however, very inefficient compared with the reactions in the direct excitations, except in the case of 4-chlorobiphenyl. It was, then, concluded that the dechlorinations of 2- and 3-chlorobiphenyl occurred only from...

An irreversible electron transport from hydroxide ion to organic molecules via sodium anthraquinone-2-sulfonate was observed in a reversed micellar system by stepwise UV (λ=365 nm) and visible light (λ>450 nm) irradiations.

Rh(I)-new chiral diphosphinite systems with terminal amino groups were very effective for asymmetric hydrogenation of dehydrodipeptides with free carboxyl group and a chiral carbon. The effectiveness of the diphosphinite catalysts strongly suggests the contribution of electrostatic effect to asymmetric induction.

Lightfastness of basic dyes and cationic dyes depends on substrates surrounding dyes. In order to learn origin we studied the photoreaction of Crystal Violet (CV) in alcohol and acetonitrile solutions as a model of substrate. Under degassed condition the photoreaction of CV was reduction to give its leuco compound in all used solvents. The photoreaction showed a remarkable dependence on wavelength of irradiated light, and CV excited state with ultraviolet irradiation is more active than that with visible light. In aerated solvents the photoreaction of CV was oxidation in acetonitrile, while reduction in alcohol.