Reactions Pu

Americium - the atomic number is 95 and the chemical symbol is Am. The name derives from America where it was first synthesized in a series of successive neutron capture reactions in the element plutonium, Pu, in a nuclear reactor in 1944 by American scientists under Glenn T. Seaborg at the University of California lab in Berkeley, California, using the nuclear reaction Pu ( n, y) Y) P Am. Americium is the sixth element in the Actinide... 

Element 114 - no name has been proposed or accepted by lUPAC for element 114. This element was first synthesized in a November-December 1998 experiment by a multi-national team of scientists working at the Joint Institute for Nuclear Research (JINR), Dubna, Russia. The scientific teams were from JINR and the Lawrence Livermore Laboratory in Livermore, California, USA. The teams used the nuclear reaction Pu ( Ca, 3n) 114. The longest half-life associated with this unstable element is 21 second 114. 

The chemical and physical properties of Unq (or rutherfordium) are homologous with the element hafnium ( jHf), located just above it in group 4 (fVB) in the periodic table. It was first claimed to be produced artificially by the Joint Institute for Nuclear Research (JINR) located in Dubna, Russia. The Russian scientists used a cyclotron that smashed a target of plutonium-242 with very heavy ions of neon-22, resulting in the following reaction Pu-242 + jjjNe-22 —> jj, Unq-260 + 4 n-1 (alpha radiation). The Russians named Unq-260 kurcha-tovium (Ku-260) for the head of their center, Ivan Kurchatov. (See details in the next section, History. )... 

In 1996, Enders and coworkers reported the asymmetric epoxidation of ( )-enones 91 in the presence of stoichiometric amounts of diethylzinc and (lR,2R)-A-methylpseudo-ephedrine (120) under an oxygen atmosphere to give fraw -epoxides 92 with excellent yields (94-99%), almost complete diastereoselectivity (>98% de) and with very good enantioselectivities (61-92%) (Scheme 54) . For the same reaction Pu and coworkers utilized achiral polybinaphthyl 121 as ligand (in excess) instead of the chiral aminoalcohol. For each substrate, only one diastereomer was formed, but in most cases yields were lower than observed with the Enders system. Enders catalyst shows high asymmetric induction for alkyl-substituted enones (ee 82-92%), but for substrates bearing only aromatic substituents only modest enantioselectivity was obtained (R = R = Ph ... 

Since the isotope Am can be prepared in relatively pure form by extraction as a decay product over a pmod of years from strongly neutron-bombarded plutonium, Pu, this isotope is used for much of the chemical investigation of this element. Better suited is the isotope Am due to its longer half-life (7.37 x 10 years as compared to 432.2 years for Am). A mixture of the isotopes Am, Am, and Am can be prepared by intense neutron irradiation of Am according to the reactions Am (n, y) —> Am (n, y) —> Am. Nearly isotr ically pure Am can be prepared by a sequence of neutron bombardments and chemical separations as follows neutron bombardment of Am yields Pu by the reactions Am (n, y) Am after chemical separation the Pu can be transformed to Am via the reactions Pu (n, y) Pu Am, and the Am can... 

Pu. PuO, and PuO can all exist in equilibrium Pu is a small, highly charged ion and therefore undergoes extensive hydrolysis at low acidity and forms many stable complex ions. This tendency is a dominant feature of Pu(IV) chemistry. Pu(IV) forms a long-chain compound or polymer by hydrolytic reactions. Pu(lV) polymer is one of the more ui leasant aspects of Pu chemistry from the standpoint of the radiochemist. 

Seaborgium (Z = 106) cannot be produced directly in " Ca-induced reactions, as it would require a radon target. The 1.9-min isotope Sg occurs in the decay chains arising from Cn and Fl, best produced in the reaction " Pu(" Ca,3n) [316]. The a-decay branch of the intermediate nuclide Ds is only 10%, so the effective production cross section is reduced from 4 pb to 0.4 pb. The 0.4-s isotope Sg is the decay daughter of Hs produced in the Ra( Ca,4n) reaction [133]. A single atom of Sg has been reported in the Fl decay chain, with a decay time of 2 min [353]. The nuclides produced in the " Cm( Ne,5n)... 

The Russian scientists made spectrophotometric studies in 1-2 M NaOH solutions of the reactions Pu(vi) -l- Am(vii) -> Pu(vii) -t- Am(vi), and 2Np(vi) Am(vii)- 2Np(vii)-l-Am(v). Appearance of the characteristic spectrum of Pu(vii) provides strong evidence that the green solutions of americium prepared as described above do indeed contain a powerful oxidant such as Am(vii) is expected to be. 

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