Photochemistry of N‐(2‐Acylphenyl)‐2‐methylprop‐2‐enamides: Competition between Photocyclization and Long‐Range Hydrogen Abstraction

The photochemical reactions of various ‘N‐methacryloyl acylanilides’ (=N‐(acylphenyl)‐2‐methylprop‐2‐enamides) have been investigated. Under irradiation, the acyl‐substituted anilides 1a – 1c and 1o afforded exclusively the corresponding quinoline‐based cyclization products of type 2 (Table 1). In contrast, irradiation of the benzoyl (Bz)‐substituted anilides 1e – 1h afforded a mixture of the open‐chain amides 4e – 4h and the cyclization products 2e – 2h . Irradiation of the para‐acyl‐substituted anilides 6a – 6e and 6h afforded the corresponding quinoline‐based cyclization products of type 5 as the sole products (Table 2). The formation of the cyclization products 2a – 2c and 2o can be rationalized in terms of 6π‐electron cyclization, followed by thermal [1,5] acyl migration, and that of compounds 3p, 5a – 5e , and 5h can be explained by a 6π‐electron cyclization only. The formation of the open‐chain amides 4e – 4h probably follows a mechanism involving a 1,7‐diradical, C and a spirolactam of type D (Scheme). Long‐range ζ‐H abstraction by the excited carbonyl O‐atom of the benzoyl group on the aniline ring is expected to proceed via a nine‐membered cyclic transition state, as proposed on the basis of X‐ray crystallographic analyses (Fig. 2).     

3]rotaxane synthesized via covalent bond formation can recognize cations forming a sandwich structure

A novel [3]rotaxane composed of two 25-membered crownophanes and one axle molecule having two anthryl end groups was successfully synthesized via covalent bond formation followed by aminolysis, and can incorporate caesium ion into the space between the two macrocycles as a 1 : 1 sandwich-type complex, whereas it makes a 1 : 2 complex with lithium ion.     

Reactor neutron activation analysis by using multi-elemental comparators: Problems of nuclear constants of128I,175Yb and several other nuclides

A simple method has been developed for evaluating the neutron spectrum and the temperature by using U, Sb, Cr, Co and Lu as monitors and successfully applied to the routine analysis. For most of nuclides, amounts determined by the method showed reasonable agreements with those added. However, there have been found several nuclides which gave erroneous results beyond the permissible limits. In the case of¹²⁸I, the reason for the deviation was found to lie on the normalization factor of -ray abundances that are in common use. This was confirmed by using I₂ doped polyacethylene which is a material highly resistant to ionizing radiations.⁴⁶Sc,¹⁷⁵Yb and several other rare earth nuclides are discussed as well.     

Trace elements in land plants: Concentration ranges and accumulators of rare earths,Ba, Ra,Mn, Fe,Co and heavy halogens

More than 2000 samales of land plant leaves, mostly of tree, have been analyzed by neutron activation analysis in order to find out macroscopic relations between distributions of chemical elements in plants and soil characteristics. The distributions of the elements in plants were also examined from the view point of botanical taxonomy or phylogeny. New species which accumulate Co, rare earths, Ba, Ra, heavy halogens and some other elements have been found. Capability or potentiality for accumulating elements could be related to higher ranks of taxonomy, that is, genus or family. The nature of soil is also found to have profound effects on the extent of accumulation of elements in plants.     

Viscosities of aqueous solutions of quaternary phosphonium bromides at 15, 25 and 35°C

The viscosities of aqueous solutions of Bu _4-n Ph _n PBr n=0–4 have been measured over the concentration range 0.01–0.2 M at 15, 25 and 35°C, to examine the differences in ion-water interactions of these quaternary cations. The viscosity data were treated by the extended Jones-Dole equation, including the square term in solute concentration, Dc². A decrease in the B coefficient with increase in the number of phenyl groups n, and with increasing temperature is observed. Nearly linear dependence of the B coefficient on n was found, in contrast with partial molal volumes for which non-linear relations with n have been found. D decreases with increasing temperature but becomes independent of n at higher temperatures.     

Theory for the upper critical field in superconducting multilayers with interface irregularities

The upper critical field in superconducting multilayers, which are composed of two kinds of superconducting layers with different diffusion constants and contain interface irregularities, investigated in the direction parallel to the layers. The interface irregularities enhance the upper critical field. The crossover temperature at which the superconducting nucleation position moves from one layer to another is increased as the effect of the irregularities becomes strong. As a result, the two-dimensional region where the nucleation position of the superconducting order is inside a layer with the larger diffusion constant is greatly reduced by the irregularities.