Hiroki Horiuchi

Rearrangement of alkyl phenyl ethers to alkylphenols in the presence of cation-exchanged montmorillonite (Mn+-mont)

The rearrangement of alkyl phenyl ethers such as 4-phenoxybutan-2-one 1,1-phenoxybutane 2a, 2-phenoxybutane 2b, 2-methyl-2-phenoxypropane 2c and phenoxycyclohexane 2d have been investigated in the presence of cation-exchanged montmorillonite (Mn+-mont; Mn+= Zr4+, Al3+, Fe3+ and Zn2+). The ether 1 rearranged to 4-(4-hydroxyphenyl)butan-2-one 3(raspberry ketone), the odour source of raspberry, in 16–34% GLC yield, where Zn2+-mont was the most effective catalyst. Similarly, other ethers 2a–d rearranged to the corresponding alkylphenols in up to 75% isolated yield with good product selectivity, Al3+-mont being the catalyst of choice. Al3+-Mont was regenerated and reused in the rearrangement of 2b, 2c and 2d.

Cation-exchanged fluorotetrasilicic mica (Mn+–TSM; Mn+= Mn2+, Cr3+, Co2+ and Cu2+)-catalysed oxidation of alkanes with tert-butyl hydroperoxide

Oxidation of alkanes such as cyclohexane 1, cyclooctane 4, cyclododecane 7, adamantane 10, octane 14, methylcyclohexane 18 and 2,5-dimethylhexane 23 with 70% aqueous tert-butyl hydroperoxide has been investigated in benzene in the presence of cation-exchanged fluorotetrasilicic mica (Mnn+–TSM; Mn+= Mn2+, Cr3+, Co2+ and Cu2+) and molecular sieves 4 A. Compound 1 was oxidised to cyclohexanone 2(a major product) and cyclohexanol 3 in 9.7–13.4% GLC yield with turnover numbers 154–205, where Mn2+–TSM gave the highest turnover number. Similarly, other alkanes 4, 7, 10, 14, 18 and 23 were oxidised mainly to the corresponding ketones in the presence of Mn2+–TSM with a turnover number up to 435. It was confirmed in the cyclohexane oxidation that Mn2+–TSM was regenerated and reused. Compounds 1, 4 and 10 were shape-selectively oxidised in teh presence of Cr3+–TSM.

ALPHA CLUSTERING AND CONDENSATION IN NUCLEI

Low density states near the 3α and 4α breakup threshold in 12C and 16O, respectively, are discussed in terms of the α-particle condensation. Calculations are performed in OCM (Orthogonality Condition Model) and THSR (Tohsaki-Horiuchi-Schuck-Ropke) approaches. The state in 12C and the state in 16O are shown to have dilute density structures and give strong enhancement of the occupation of the S-state c.o.m. orbital of the α-particles. The possibility of the existence of α-particle condensed states in heavier nα nuclei is also discussed.

Alpha Cluster Condensation in Threshold States of Self-Conjugate 4n Nuclei

It is a well known fact that in light nuclei many states are of the cluster type [1-4]. In the case of cluster states of stable nuclei where we have only very few excess nucleons in addition to the clusters, they are all located close to or above the threshold energy of breakup into constituent clusters. This fact which is known as the threshold rule [5] means that the inter-cluster binding is weak in cluster states. The threshold rule can be considered as a necessary condition for the formation of the cluster structure, because if the inter-cluster binding is strong the clusters overlap strongly and the clusters will loose their identities.

α-CLUSTER STATES AND 4α-PARTICLE BOSE CONDENSATE IN 16O

In order to explore the 4α-particle condensate state in 16O, we solve a full four-body equation of motion based on the 4α OCM (Orthogonality Condition Model) in a large 4α model space spanned by Gaussian basis functions. A full spectrum up to the state is reproduced consistently with the lowest six 0+ states of experimental spectrum. The state is obtained at 2 MeV above the 4α breakup threshold and has a dilute density structure, where the rms radius is more than 5 fm. The state has an appreciably large α condensate fraction 61 %, and a highly amount of components, both of which are strong pieces of evidence of the state being the 4α condensate state.

Microscopic description of deformed α‐particle condensation

A spatial deformation is introduced into the model wave function of the α‐cluster condensate in order to study non‐zero spin excitations of the α‐particle condensate type. Application to 8Be shows that the binding energies of the 0+ and 2+ states are nicely reproduced. Our 0+ wave function is found to be exactly equal to the 0+ wave function obtained by the full microscopic calculation of two α particles.

Mn2+-exchanged clay-catalysed oxidation of alkanes with tert-butyl hydroperoxide

Oxidation of alkanes such as cyclohexane, cyclooctane, adamantane and octane with 70% aqueous tert-butyl hydroperoxide in benzene in the presence of Mn2+-exchanged clay catalyst and molecular sieves 4 A produces mainly the corresponding ketones with high turnover numbers.