Concentration levels and behavior of transuranium nuclides in Japanese coastal marine environment

The concentration of^239,240Pu and²⁴¹Am in different samples collected from the coastal marine environment of Ibaraki Prefecture, Japan facing the Pacific Ocean have been studied. Seawater samples have been collected since 1975 and sea-biota since 1981. The mean concentration levels of^239,240Pu and²⁴¹Am were 0.51, 0.20 for anchovy, 0.22, 0.11 for flounder, 4.9, 0.77 for brown algae, 2.0, 2.4 for shellfish, and 0.022, 0.0028 for seawater (in mBq/kl), respectively. The chronological change of^239,240Pu in seawater was influence by fallout amounts. The activity ratio between the nuclides showed steady levels after two years from the end of atmospheric nuclear explosion tests. Activity levels and the ratios for each type of sample are briefly discussed.     

Synthesis and ion selectivity of macrocyclic metacyclophanes analogous to spherand-type calixarenes

Novel macrocyclic compounds, hexahydroxy[1.0.1.0.1.0]- (2b) and octahydroxy[1.0.1.0.1.0.1.0]metacyclophane (2c) have been prepared in 50–70% yield by base-catalyzed condensation of 5,5-di-tert-butyl-2,2-dihydroxybiphenyl (1) with formaldehyde in refluxing xylene. An attempted alkylation of the flexible macrocycles2b and2c with ethyl bromoacetate in the presence of Cs₂CO₃ under acetonitrile reflux gave only one pure stereoisomer3 and4, respectively, while other possible isomers were not observed. The structural characterization of these products is also discussed. The two-phase solvent extraction data indicated that hexaethyl ester3 and octaethyl ester4 show strong metal affinity, comparable with that of the corresponding calix[n]arenes, and a high K⁺ selectivity was observed for octaethyl ester4.¹H-NMR titration of hexaethyl ester3 and octaethyl ester4 with KSCN clearly demonstrate that a 11 complex is formed which is stable on the NMR time scale.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes.     

Benzolactams. 4. Reaction of 3',4'- or 4',5'-dialkoxy-substituted 1-(2'-Bromobenzyl)-2-ethoxycarbonyl-1,2,3,4-tetrahydroisoquinolines with alkyllithium. 1,2 and 1,4 additions of alkyllithium to benzolactams

Treatment of 1-(2'-bromo-3',4'-dialkoxybenzyl)-1,2,3, 4-tetrahydroisoquinoline carbamates, 1a,c, with excess alkyllithium gave 8-oxoberbines, 2a,c, which were successively attacked in situ with another molecule of alkyllithium to give 1,2 and/or 1,4 addition products. A primary alkyllithium, such as MeLi or BuLi, gave a 1,2 addition product, 8-methyleneberbine 9a or 8-butylideneberbine 3a. t-BuLi preferred 1,4 addition, followed by elimination of the alkoxy group, to give 9-tert-butyl-8-oxoberbine 6a or 7c. s-BuLi gave a mixture of 1,2 and 1,4 addition products, 1-[2'-(2' '-methylbutyryl)benzyl]-1,2,3,4-tetrahydroisoquinoline 4a and 9-s-butyl-8-oxoberbine 5a. Similar treatments of carbamate 1b having no alkoxy group at its 3' position gave 1,2 addition products, 8-butylideneberbine 3b, 1-[2'-(2' '-methylbutyryl)benzyl]-1,2,3, 4-tetrahydroisoquinoline 4b, and 1-(2'-pivaloylbenzyl)-1,2,3, 4-tetrahydroisoquinoline 6b, in all cases. Reactions of 1a with s-BuMgCl and isoPrMgCl also gave the 1,4 adduct, 5a, and its 9-isoPr analogue, 12a. Treatment of 9a with excess NaBH(4) in AcOH gave (+/-)-coralydine (10b).     

Conformation of drawn poly(trimethylene terephthalate) studied by solid-state 13C NMR

The change in the conformation of the flexible O-CH2-CH2-CH2-O segment of poly(trimethylene terephthalate) (PTT) monofilament caused by drawing was investigated by means of the gamma-gauche effect on the 13C solid-state NMR chemical shift of the internal methylene carbon, combined with the NMR relaxations. The conformation around the O-CH2 and CH2-O bonds for as-spun fiber was trans/trans. On drawing, followed by heat treatment, the conformation changed to gauche/gauche. The ratio of gauche/gauche to trans/trans for the drawn PTT fiber was determined quantitatively.     

Synthesis of spirodienones by intramolecular ipso-cyclization of N-methoxy-(4-halogenophenyl)amides using [hydroxy(tosyloxy)iodo]benzene in trifluoroethanol

Spirodienones bearing the 1-azaspiro[4.5]decane ring system have been synthesized from N-methoxy-(4-halogenophenyl)amides by the intramolecular ipso attack of a nitrenium ion generated with [hydroxy(tosyloxy)iodo]benzene in trifluoroethanol.     

Second-order perturbational treatment of normal coordinates in the string model for the hydration reaction of formaldehyde

A perturbation theory for normal coordinates of nonadiabatic solvation is presented by means of the “string model” of chemical reactions. The dynamic normal coordinate is introduced for the perturbational treatment of the “intrinsic” normal coordinates that are orthogonal to the reaction path. The reaction is defined as the intrinsic reaction coordinate (IRC ) that is treated as a string. The string is thrown in the external force field that acts as a nonadiabatic source of perturbation. As an application of the present treatment, the effect of a water molecule for hydration reaction of formaldehyde is calculated. A second-order perturbation effect for the enhancement of the reaction rate is found.     

Theoretical prediction of optical absorption maxima for photosensory receptor mutants

We found a linear correlation between the theoretically predicted shifts and experimentally observed absorption spectra for various mutants of photoactive yellow protein, a photosensory receptor. Excitation energies of mutants were evaluated by the combination of the high level ab initio calculation for the chromophore inside and the low level ab initio calculation for the surrounding protein environment. Importantly, the electronic states of these two regions were treated both as variables and they are solved consistently to each other. The protein–chromophore interaction has been accurately reproduced by this method.     

Synthesis and polymerization of 4-o-vinylbenzyl-2,2,6,6-tetramethylpiperidine

Some hindered amine polymers containing 2,2,6,6-tetramethylpiperidine structure were synthesized. A new monomer, 4-O-vinylbenzyl-2,2,6,6-tetramethylpiperidine, was homopolymerized and copolymerized with some vinyl monomers in the presence of AIBN as an initiator. The obtained amine polymers were oxidized with hydrogen peroxide to obtain the polymers having nitroxyl radical moiety.