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The dianthrimide method for the determination of boron in iron and low-alloy steels may be applied to nickel-base materials. The sample is dissolved, without any loss of boron, by hydrochloric and sulphuric acids and the resulting boric acid determined spectrophotometrically with dianthrimide. Background corrections are necessary to compensate for the absorbance from ions such as nickel and iron. 相似文献
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Virgil I. Stenberg Nand K. Narain S. P. Singh Ralph H. Obenauf M. J. Albright 《Journal of heterocyclic chemistry》1977,14(3):407-410
The 15N and 13C nmr spectra of physostigmine are discussed along with complete assignment of the signals. This alkaloid 15 N nmr spectrum is notable because it contains nitrogens in three different environments. 相似文献
5.
Carlo Mealli Stefano Midollini Simonetta Moneti Thomas A. Albright 《Helvetica chimica acta》1983,66(2):557-569
The reaction of [(C3Ph3)Ni(PPh3)2]ClO4 with P(CH2CH2PPh2)3(pp3) and NaBPh4 yields the [(C3Ph3)Ni(pp3)]BPh4-complex. After long exposure of the solution of this compound in acetone/butanol to the air a new derivative [(C3Ph3)-Ni(pp2po)]BPh4· 0.5 C4H9OH, where pp2po is (Ph2PCH2CH2)2P(CH2 CH2POPh2), is obtained. Complete X-ray analysis has been carried out for the latter complex: a=18.303 (5); b=29.445 (6), c=13.305 (5) Å, β=112.70 (9)°; space group monoclinic, P21/a, Z=4. Disorder problems were encountered in the refinement of the structure. The best R is 0.093. One of the arms of the parent pp3-molecule, not coordinated to the metal, undergoes oxidation. The Ni-atom, coordinated by the three remaining P-atoms of the ligand, is also linked in a roughly η3-mode to the cyclopropenium ligand. The geometry of the molecule is examined in detail. Extended HMO-calculations were performed to interpret how the variation of P? Ni? P angles affects the bonding between the NiP3- and C3H3-fragments. The conclusion is that the overall energy of the complex may be lowered in spite of a weakening of the Ni-cyclopropenium linkage. Extensions are made to other systems containing a linkage between a metal and a X3-ring (X=P,As). 相似文献
6.
Daniel B. Moran George O. Morton J. Donald Albright 《Journal of heterocyclic chemistry》1986,23(4):1071-1077
Methods for the synthesis of (pyridinyl)-1,2,4-triazolo[4,3-a]pyridines were developed. The principal route to the required intermediate 2-chloropyridines was based on rearrangements of mono N-oxides of 2,2′-bipyridine, 2,3′-bipyridine, 3,3′-bipyridine, 2,4′-bipyridine and 4,4′-bipyridine with phosphorus oxychloride. Reaction of 3,3′-bipyridine 1-oxide or 2,2′-bipyridine 1-oxide with phosphorus oxychloride gave mixtures of chloro isomers. Reaction with acetic anhydride, 3,3′-bipyridine 1-oxide and 2,2′-bipyridine 1-oxide gave exclusively [3,3′-bipyridine]-2(1H)-one and [2,2′-bipyridine]-6(1H)-one, respectively. 1,2,4-Triazolo[4,3-a]pyridines with pyridinyl groups at the 5,6,7 and 8 positions were synthesized. 相似文献
7.
Ronald I. Trust J. Donald Albright F. M. Lovell N. A. Perkinson 《Journal of heterocyclic chemistry》1979,16(7):1393-1403
Synthetic methods for the preparation of 6-aryl-1,2,4-triazolo[4,3-b]-1,2,4-triazines ( 1 ) and the 7-aryl isomers ( 2 ) are described. Compounds 1 were prepared from aryl glyoxaldoximes 76 via 6-aryl-1,2,4-triazin-3(2H)ones ( 75 ). A simple procedure for the preparation of the 7-aryl isomers was effected using arylglyoxals 11 and the triazoles ( 4, 12a and 12b ). However, complete regioselectivity was not realized in all cases, especially when the triazoles were substituted at the C-5 position. A regiospecific synthesis of the 7-aryl isomers 2 was developed via the 3-methylthio-5-aryl-1,2,4-triazines ( 61 ). The structure of the parent 6-phenyl derivative 5 was confirmed by x-ray crystallography. 相似文献
8.
In two papers Zavitsas described a model for the thermodynamic properties of aqueous solutions of a single electrolyte or nonelectrolyte (Zavitsas, J Phys Chem B 105:7805–7817, 2001; J Solution Chem 39:301–317, 2010) in which he assumed that part of the water is so strongly bound to the solute that it can be considered as part of it, and thus only the remaining unbound water is considered to be the solvent. He showed that when the usual water mole fraction was replaced by the resulting mole fraction of unbound water, obtained by optimizing an effective hydration number, basically linear relations were obtained to fairly high molalities for the freezing temperature lowering, boiling temperature elevation, and the water activity/vapor pressure of water. However, Zavitsas only considered the properties of the solvent, not the solute. In this paper we derive the corresponding expressions for the activity coefficient of the solute for the usual molality scale based on 1 kg of water, for the modified molality scale based on 1 kg of unbound water, for the mole fraction scale based on the total number of moles of water, and for the modified mole fraction scale based on the number of moles of unbound water. These equations show that if the hydration number is larger than the stoichiometric ionization number of the electrolyte, then all four types of mean activity coefficients are predicted to always be >1 (nearly all hydration numbers reported by Zavitsas for electrolyte solutions are greater than the corresponding ionization numbers), which directly conflicts with extensive experimental and theoretical evidence that the mean activity coefficients of electrolytes in aqueous solutions always initially decrease below unity. In contrast, for nonelectrolyte solutions, the hydration model of Zavitsas gives more realistic values of the activity coefficients. 相似文献
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