[en] The effects of dissolved chemicals such as NaOH, NaI, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) on solution pH after gamma irradiation were investigated. Upon irradiation with 1.6-24 kGy of gamma radiation (0.4-6 kGy h^-1), the pH of the NaOH solutions decreased, while the OH^- consumption increased with increasing initial solution pH. This was attributed to acid-base neutralization between the OH^- in the solutions and the acidic species (HO₂· and ·NO₂) formed by irradiation. The pH of the acidic NaI solution increased after irradiation with 8 kGy dose (at 2 kGy h^-1), which was attributed to I^- oxidation by the products of water and air radiolysis. The pH values of the MIBK and MEK solutions decreased from 7 to 4.5 or lower upon irradiation with 40 kGy dose (at 10 kGy h^-1), which indicates that the alkyl groups of the ketones do not significantly affect the rates of decomposition by irradiation. The pH of the mixed solution of ketone and NaI was in the range of 6.7-6.9 before irradiation but decreased to 4.5 after irradiation with 40 kGy dose. In the mixed solutions, CH₃COR and I^- competed with each other to contribute to pH change. (author)

[en] The published data on the synthesis of β-enamino ketones, δ-amino dienones and conjugated ω-amino polyenones of diverse structures are generalised. The bibliography includes 129 references.

[en] The extraction of Nd(III), Tb(III) and Lu(III) as representatives of lanthanide(III) ions with picrolonic acid (HPA) in methylisobutylketone (MIBK) has been studied from pH 1-2 buffer solutions. The composition of the organic species formed in the organic phase after extraction has been determined by slope analysis to be M(PA)₃ [M = Nd(III), Tb(III) and Lu(III)]. The equilibrium constant values, log k_ex, were deduced to be 2.96±0.02, 2.52±0.05 and 1.52±0.07 for Nd(III), Tb(III) and Lu(III), respectively. The effect of various anions and cations on the extraction of these metal ions has also been studied. Among the masking anions, fluoride, oxalate, citrate and cyanide ions lowered the extraction, whereas presence of Zn(II) Cu(II), Fe(II), Co(II) and Ni(II) has only reduced to 25.87%. The extraction of various other divalent metal ions from pH 2 buffer solution was also studied and high separation factors (10³) for the three selected rare earth metal ions were obtained with good selectivity. (author)

[en] The main advances in the chemistry of acetylene in superbasic media achieved over the last five years are analyzed. Particular emphasis is placed on the ethynylation of aldehydes and ketones and C-, N- and O-vinylation. The cascade assembly of complex molecules in which ethynylation and vinylation are consecutive steps is considered. The bibliography includes 369 references

[en] Friedel-Crafts type reactions of ninhydrin (1,2,3-indantrione) have been examined by us and other groups. Besides the common arene compounds phenolic compounds could be used to prepare the corresponding 2-(2-hydroxyaryl)-2- hydroxy-1,3-indanedione derivatives such as 1. Recently, we have reported on the unusual formation of benzo[b]indeno[2,1-d]furanone ring system 3 as well as the normally expected 2 during alkylation of 2-(2-hydroxyaryl)- 2-hydroxy-1,3-indanedione derivative 1 as shown in Scheme 1

No abstract available

[en] We disclosed the synthesis of 2-benzylidene-7a-alkyl-tetrahydropyrrolizine-3,5-dione derivatives starting from the Baylis-Hillman adducts. The synthetic method was straightforward and the synthetic applications toward some important alkaloid backbone are actively underway. Recently, 3-alkylidenedihydropyrrol-2-ones and 3-alkyl-idenedihydropyrrole derivatives were synthesized starting from the Baylis-Hillman adducts of methyl acrylate and methyl vinyl ketone, respectively. These compounds were prepared by the reductive cyclization of nitroalkane derivatives, which were synthesized from the Baylis-Hillman acetate by the S_N2' reaction with primary nitroalkane, as shown in Scheme 1

[en] It has been shown that 2-bromocyclohex-1-enecarbaldehydes, which are readily prepared from α-methylene containing cyclohexanones under the bromination conditions of Vilsmeier-Haak reaction, undergo carbonylative cyclization with aliphatic primary amines in the presence of a palladium catalyst and a bidentate phosphorus ligand to give 3-aminohydroisoindol-1-ones. The present reaction provides a promising route for the synthesis of valuable heterocycles from readily available starting ketones. Further study of synthetic applications to heterocycles using these ketones is currently under investigation. Palladium-catalyzed carbonylation of organic halides (or triflates) followed by intramolecular cyclization (carbonyl-ative cyclization) has been widely explored and used as a promising synthetic tool for the construction of the structural core of many pharmacologically and biologically active lactones and lactams

[en] α-Sulfenylation of aldehydes and ketones using N-formyl and N-acyl sulfenamides, prepared by Cu-catalyzed aerobic coupling of amides and thiols, was achieved in the presence of cyclic secondary amine⋅HCl catalysts. To obtain various sulfur-functionalized carbonyl compounds, sulfenamides containing aromatic and aliphatic organosulfur were investigated. As carbonyl compounds, cyclic and acyclic ketones, 1,3-dicarbonyl compounds, and aldehydes were investigated, affording the desired α-sulfenylation products in good yields

[en] The lifetimes of a number of biradicals produced in the photochemical Norrish type II reaction of phenyl alkyl ketones have been measured. The decay of the biradicals was followed by monitoring the competition with electron transfer to paraquat dications using nanosecond laser techniques. The lifetimes are rather insensitive to changes in temperature, substitution, and solvent, and are typically in the neighborhood of 100 ns. It is concluded that intersystem crossing is the main factor determining the biradical lifetimes. The rate constant for electron transfer to paraquat dications is 3.7 x 10⁹ M^-1s^-1 in methanol at room temperature for 1,4-ketyl--alkyl biradicals, and considerably higher for diketyl biradicals, apparently reflecting a change in path degeneracy. Oxygen behaves as a biradical scavenger with a rate constant of 6.2 x 10⁹ M^-1s^-1 in methanol. The lifetimes of the excited ketone triplets have also been determined at room temperature under the experimental conditions employed; this is an important parameter in determining the viability of the measurements of biradical lifetimes by this technique