20633-06-1Relevant articles and documents
Exploring the Subtle Effect of Aliphatic Ring Size on Minor Actinide-Extraction Properties and Metal Ion Speciation in Bis-1,2,4-Triazine Ligands
Zaytsev, Andrey V.,Bulmer, Rachel,Kozhevnikov, Valery N.,Sims, Mark,Modolo, Giuseppe,Wilden, Andreas,Waddell, Paul G.,Geist, Andreas,Panak, Petra J.,Wessling, Patrik,Lewis, Frank W.
, p. 428 - 437 (2020)
The synthesis and evaluation of three novel bis-1,2,4-triazine ligands containing five-membered aliphatic rings are reported. Compared to the more hydrophobic ligands 1–3 containing six-membered aliphatic rings, the distribution ratios for relevant f-block metal ions were approximately one order of magnitude lower in each case. Ligand 10 showed an efficient, selective and rapid separation of AmIII and CmIII from nitric acid. The speciation of the ligands with trivalent f-block metal ions was probed using NMR titrations and competition experiments, time-resolved laser fluorescence spectroscopy and X-ray crystallography. While the tetradentate ligands 8 and 10 formed LnIII complexes of the same stoichiometry as their more hydrophobic analogues 2 and 3, significant differences in speciation were observed between the two classes of ligand, with a lower percentage of the extracted 1:2 complexes being formed for ligands 8 and 10. The structures of the solid state 1:1 and 1:2 complexes formed by 8 and 10 with YIII, LuIII and PrIII are very similar to those formed by 2 and 3 with LnIII. Ligand 10 forms CmIII and EuIII 1:2 complexes that are thermodynamically less stable than those formed by ligand 3, suggesting that less hydrophobic ligands form less stable AnIII complexes. Thus, it has been shown for the first time how tuning the cyclic aliphatic part of these ligands leads to subtle changes in their metal ion speciation, complex stability and metal extraction affinity.
Photochemistry of α-oxo oximes. Part 10. Photochemistry of three cyclic α-oxo oxime methyl ethers and their acyclic analogue at λ 254 nm
Buys, Theo S. V.,Cerfontain, Hans,Geenevasen, Jan A. J.,Stunnenberg, Frank
, p. 491 - 501 (2007/10/02)
The (E)- and (Z)-isomers of the 3,3,n,n-tetramethyl-2-(methoxyimino)-1-cycloalkanones (n=5 to 7) (3a-c) and their analogue (Z)-4-(methoxyimino)-2,2,5,5-tetramethyl-3-hexanone have been irridated at λ 254 nm in acetonitrile as solvent in order to study the influence of ring size on product formation.The dependence of product composition on irridation time revealed that the (E)-isomers of 3a-c undergo both E-Z isomerization and photodecomposition, whereas the (Z)-isomers undergo only Z-E isomerization.The primary step in photodecomposition is homolysis of the N-O bond.The observed products result from the various possible reactions of initially formed methoxy and cyclic iminyl radicals 17, cyanoacyl radicals 18 formed by ring opening of 17, cyanoalkyl radicals 19 formed from 18 by decarbonylation and cyclopentaniminyl radical 20b, formed by cyclization of the 5-cyano-2-hexyl radical 19b.Mechanisms for the formation of the various products are proposed and the relative importance of the various steps is discussed, also in relation to the results obtained using carbon tetrachloride as radical scavenger.Irridation of (Z)-4 at λ 254 nm leads to decomposition with formation of 2,2-dimethylpropanenitrile, methanol, isobutane and isobutene.
Formation of 1,3-Oxaselenoles via Pummerer Reaction in Selenium Dioxide Oxidation of Cyclic 1,2- and 1,3-Diketones, and the Preparation of 1,5,5-Trimethyl-7-selenabicycloheptane-2,3-dione
Laitalainen, Tarja,Simonen, Tapio,Kivekaes, Raikko,Klinga, Martti
, p. 333 - 340 (2007/10/02)
4,5,6,7-Tetrahydro-4',4',6,6-tetramethylspiro-2',4,6'-trione and related 1,3-oxaselenole derivatives, and not the previously reported selenoxides of type (1), are formed in the selenium dioxide oxidation of cyclohexane-1,3-diones.The structural assignments were made on the basis of n.m.r. spectroscopy, and in the case of (5), X-ray analysis was undertaken.Oxidation of 3,3,5,5-tetramethylcyclohexane-1,2-dione with selenium dioxide yielded the bis-selenide (9) and the 1,3-oxaselenole (10) along with the usual oxidation products, whereas the oxidation of 3,5,5-trimethylcyclohexane-1,2-dione gave the title, bridged selenabicyclic compound.
INDANE-1,2,3-TRIONE ; A HIGHLY REACTIVE ENOPHILE
Gill, G. Bryon,Kirollos, Kirollos S.
, p. 1399 - 1402 (2007/10/02)
Among the 1,2,3-tricarbonyl systems investigated, indane-1,2,3-trione has been found to be a particularly reactive enophile.Cleavage of the adducts with periodic acid affords allyl carboxylic acids.Both addition and cleavage reactions are essentially quantitative.
Ring inversion in some fully α-methylated cycloalkane-1,2-diones
Verheidt, Paul L.,Kruk, Cor,Cerfontain, Hans
, p. 85 - 87 (2007/10/02)
Variable-temperature NMR spectra of 3,5,5,5-tetramethylcyclopentane-1,2-dione (1a) and its 6-, 7- and 8-membered homologues (1b-d) showed conformational isomerization for the letter three compounds, the barrier to their ring inversion being 37.5, 38.9 and 62.7 kJ/mol, respectively.
