6,818 research outputs found
Studies on the oxidation of hexamethylbenzene 2: Preparation of dimethylpyromellitic acid
Hexamethylbenzene (HMB) was difficult to be oxidized with an alkaline potassium permanganate solution, since HMB was insoluble in an aqueous alkaline solution. But, when HMB was warmed with 50% nitric acid for a short time, and then treated with aqueous potassium permanganate, the reaction occurred readily and dimethylpyromellitic acid was obtained. When HMB was warmed with 50% nitric acid for 1 to 2 minutes, a yellow material was produced, which was soluble in hot aqueous potassium hydroxide, though free from carboxylic acids. It contained a little amount of bis-(nitromethyl)prehnitene and several unknown compounds. Further, the heat stability of polyimide prepared by the reaction of tetramethyldimethylpyromellitate with 4,4 prime-diaminodiphenylmethane turned out to be nearly equal to that of polyimide prepared from tetramethylpyromellitate
Studies on the oxidation of hexamethylbenzene 1: Oxidation of hexamethylbenzene with nitric acid
The oxidative reaction of hexamethylbenzene (HMB) with nitric acid was studied, and the hitherto unknown polymethylbenzenepolycarboxylic acids were isolated: tetramethylphthalic anhydride, tetramethylisophthalic acid, 1,3,5-, 1,2,4- and 1,2,3-trimethylbenzenetricarboxylic acids. When HMB was warmed with 50% nitric acid at about 80 C, tetramethylphthalic anhydride and tetramethylisophthalic acid were initially produced. The continued reaction led to the production of trimethylbenzenetricarboxylic acids, but only slight amounts of dimethylbenzenetetracarboxylic acids were detected in the reaction mixture. Whereas tetramethylphthalic anydride and tetramethylisophthalic acid were obtained, pentamethylbenzoic acid, a possible precursor of them, was scarcely produced. On the other hand, a yellow material extracted with ether from the initial reaction mixture contained bis-(nitromethyl)prehnitene (CH3)4C6(CH2NO2)2, which was easily converted into the phthalic anhydride
New Approach for Evaluating Incomplete and Complete Fusion Cross Sections with Continuum-Discretized Coupled-Channels Method
We propose a new method for evaluating incomplete and complete fusion cross
sections separately using the Continuum-Discretized Coupled-Channels method.
This method is applied to analysis of the deuteron induced reaction on a 7Li
target up to 50 MeV of the deuteron incident energy. Effects of deuteron
breakup on this reaction are explicitly taken into account. Results of the
method are compared with those of the Glauber model, and the difference between
the two is discussed. It is found that the energy dependence of the incomplete
fusion cross sections obtained by the present calculation is almost the same as
that obtained by the Glauber model, while for the complete fusion cross
section, the two models give markedly different energy dependence. We show also
that a prescription for evaluating incomplete fusion cross sections proposed in
a previous study gives much smaller result than an experimental value.Comment: 10 pages, 5 figure
Experience with statically-generated proxies for facilitating Java runtime specialisation
Issues pertaining to mechanisms which can be used to change the behaviour of Java classes at runtime are discussed. The proxy mechanism is compared to, and contrasted with other standard approaches to this problem. Some of the problems the proxy mechanism is subject to are expanded upon. The question of whether statically-developed proxies are a viable alternative to bytecode rewriting was investigated by means of the JavaCloak system, which uses statically-generated proxies to alter the runtime behaviour of externally-developed code. The issues addressed include ensuring the type safety, dealing with the self problem, object encapsulation, and issues of object identity and equality. Some performance figures are provided which demonstrate the load the JavaCloak proxy mechanism places on the system
Study of Field-Induced Magnetic Order in Singlet-Ground-State Magnet CsFeCl
The field-induced magnetic order in the singlet-ground-state system
CsFeCl has been studied by measuring magnetization and neutron diffraction.
The field dependence of intensity for the neutron magnetic reflection has
clearly demonstrated that the field-induced ordered phase is described by the
order parameter . A condensate growth of magnons is investigated through
the temperature dependence of and , and this ordering is
discussed in the context of a magnon Bose-Einstein condensation. Development of
the coherent state and the static correlation length has been observed in the
incommensurate phase in the field region of , a satellite peak was found in coexistence with the commensurate
peak at the phase boundary around 10 T, which indicates that the tilt of the
c-axis would be less than in the whole experiments.Comment: 5 pages, 5 figure
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