Utilization of cyclotron produced fast neutrons in the activation analysis for oxygen

The possible application of cyclotron-produced fast neutrons to activation analysis for oxygen based on the¹⁶O(n, p)¹⁶N reaction has been investigated. Neutrons were produced by bombarding a thick beryllium target with 22 to 45 MeV deuterons. It was found that the sensitivity increases rapidly with the energy of the deuterons. Using 45 MeV deuterons and a 10 μA beam current a sensitivity of about 20 counts per 1 μg oxigen could be achieved, enabling the determination of less than 1 μg oxigen. In a direct comparison it was experimentally established that the sensitivity for cyclotron-produced neutrons assuming a deuteron beam of about 10 μA, is up to two orders of magnitude higher than that achievable for 14 MeV neutrons with a flux of about 10¹⁰ n/s. The interference of fluorine is at about the same level for both the cyclotron-produced and 14 MeV neutrons. Using cyclotron-produced fast neutrons in the investigated energy range, sodium and magnesium can also interfere, but only to a very much lower extent.     

First access to the spin-labelled β-amino acid POAC in an enantiopure state by resolution through its binaphthyl esters

Resolution of trans 3-(9-fluorenylmethyloxycarbonylamino)-1-oxyl-2,2,5,5-tetramethylpyrrolidine-4-carboxylic acid (Fmoc-POAC-OH) was quickly achieved upon esterification with (aR)-1,1′-binaphthyl-2,2′-diol, chromatographic separation of the obtained diastereomers, and facile saponification of the aryl ester function with removal of the chiral auxiliary.     

Does charge carrier dimensionality increase in mixed-valence salts of tetrathiafulvalene-terminated dendrimers?

[structure: see text] In four new dendrimers terminated by 12 electroactive tetrathiafulvalenyl substituents, the tridimensional character of the inter- and intradendrimeric charge and electron transfer, and hence of the electroconductivity, is evidenced by examination of the electronic spectra of their corresponding neutral state and cation radical, dication, and mixed-valence salts, including a closed-shell anion.     

Permeation liquid membrane for trace metal speciation in natural waters. Transport of liposoluble Cu(II) complexes

In this paper, the transport of Cu(II) in the presence of lipophilic Cu(II) organic complexes through permeation liquid membranes (PLMs) have been investigated. In natural waters, small organic compounds, which form liposoluble neutral complexes with Cu(II), are potentially toxic and bioavailable. Hence, to understand the role of liposoluble Cu(II) complexes in natural waters, four organic ligands: phthalic acid, bipyridyl, pyrocatechol and hydroxyquinoline, which form uncharged or lipophilic Cu(II) complexes, were tested. The results showed that the transport of lipophilic Cu(II) complexes through PLM depends on the lipophilicity of the complex. Applications of PLMs in natural waters are presented.     

[1] Benzofuro[2,3-d] pyridazines. VI. Etude des reactions de scission des acyltetrahydrobenzofuropyridazones

The cleavage of the pyridazine ring of the acyltetrahydro [1] benzofuro [2,3-d] pyridazones was carried out by hydrolysis, alcoholysis or aminolysis reactions and they affect the lactam 3,4-bond. They lead chiefly to benzofuran derivatives with acid, ester, amide or hydrazide groups in the 2-position and eventually an acylated methylhydrazine group in the 3-position. The cyclization reactions of 3-hydrazinomethylbenzofuran-2-carboxylic acid and its derivatives or ethyl 3-bromome thylbenzofuran-2-carboxylate affords tetrahydrobenzofuropyridazones. The nmr spectra were studied.     

Synthesis of phosphonocinnamic thioesters, substrate analogues of cinnamoyl-CoA reductase, a key enzyme in the lignification process

The one-pot transesterification of diethylarylvinylphosphonates with N-acetylcysteamine has been achieved using phosphonochloridates as intermediates. Reaction of phosphonodiesters with (COCl)₂ gave the corresponding chlorinated compounds, which were coupled with N-acetylcysteamine in presence of Et₃N.     

A new diphenylphosphinite ionic liquid (IL-OPPh2) as reagent and solvent for highly selective bromination, thiocyanation or isothiocyanation of alcohols and trimethylsilyl and tetrahydropyranyl ethers

A new diphenylphosphinite ionic liquid (IL-OPPh₂) is introduced. This ionic liquid is used as both a reagent and a solvent to convert alcohols and trimethylsilyl and tetrahydropyranyl (THP) ethers into their corresponding alkyl bromides, thiocyanates or isothiocyanates in the presence of Br₂ and SCN⁻ at 80 °C. In this ionic liquid, bromination and thiocyanation of alcohols occurs highly selectively in the presence of trimethylsilyl and THP-ethers and also between different classes of alcohols. The use of this ionic liquid allows easy separation of the desired products from the phosphinate by-product.     

Réactivité de spirochromènes et de mérocyanines azahétérocycliques vis-à-vis de quelques agents nucléophiles

Under the action of nucleophile reagents such as water, hydrogen sulfide and sodium borohydride, the saturated azaheterocyclic spirochromenes are opened either on the azaheterocyclic side or on the benzopyran side or on both parts simultaneously. The merocyanines are either partially reduced or decomposed by the sodium borohydride.     

Decarboxylation catalytique et quantitative d'acides arylacetiques en presence'de cuivre I

Copper(I) salts of arylacetic acids $\text{1}$ RCO₂H readily undergo a catalytic and quantitative decarboxylation in acetonitrile leading to hydrocarbons $\text{2}$ RH when the corresponding carbanions R are stabilized by resonance and/or electronwithdrawing substituents.     

Complex copper(II) fluorides. XV. The Ternary System BaF2?CuF2?ScF3

The liquid-solid phase diagram of the binary system BaF₂? ScF₃ is established by D.T.A. and radiocrystallography. Three fluorides are disclosed: Ba₃Sc₂F₁₂, Ba₅Sc₃F₁₉ and a cubic high temperature phase Ba_1?xSc_xF_2+x (x = 0.17), the structure of which derives from that of BaF₂. A solid solution between BaF₂ and ScF₃ is also evidenced at high temperature. The ternary system BaF₂? CuF₂? ScF₃ is investigated by radiocrystallography and an isothermal section at 670°C is given. It shows the existence of four phases: a complex quaternary fluoride Ba₁₀Cu₁₂ScF₄₇, two “polytypic” phases the structure of which derives from that of BaCuF₄ and a tetragonal solid solution Ba₅Sc_3?xCu_xF_19?x with 0 ≤ x ≤ 1.