Catalytic determination of selenium with a picrate-selective electrode

A method is described for the determination of selenium, based on its catalytic effect on the picrate—sulfide reaction. The determination involves a variable-time kinetic procedure using potentiometric monitoring with a picrate-selective electrode and automatic measurement of the time required for the potential to change by a preselected amount (5.0 mV). Selenium in the range 3–30 μg was determined with an average error of about 4% and relative standard deviations of about 2%. The reaction can also be followed spectrophotometrically.     

Trace analysis of fluorine by the Coulomb excitation method

The reaction¹⁹F(p, p′ γ)¹⁹F was used for the determination of fluorine concentration in biological materials such as lichen tissues and human bones. By means of this method, fluorine air contamination in the vicinity of aluminium works and the level of fluorine intoxication of exposed persons were investigated.     

Aromatic antimony compounds. Transition metal complexes of 2,5-dimethylstibacyclopentadienyl

Hydrostannation of 2,4-hexadiyne with dibutyltin dihydride gave 1,1-dibutyl-2,5-dimethylstannole, which was converted to 2,5-dimethylstibacymantrene and to bis(2,5-dimethylstibacyclopentadienyl)iron.     

Copolymerization reactivities and conductivities of some living polymers of p-substituted styrenes

A kinetic study in tetrahydrofuran of the addition of 1,1-diphenylethylene on para-substituted styrylcarbanions (with Cs⁺ as counterion) has given the reactivities of free ions and ion-pairs. For both species, the addition rate constant increased in the following sequence for the substituent of the phenyl ring: pH < p-CH₃ <p-CH₃O. It was also shown that in the same solvent, the dissociation constants of the polystyryl ion-pairs decreased with the electron-donating power of the substituent.     

Etude de la reactivite des coumarines—I : Regioselectivete des reactifs de grignard engages avec la coumarine

The various products obtained by the action of organomagnesium, compounds on coumarin result from 1.2-1.2 di-addition (phenolic alcohols) or 1.2–1.4 di-addition (ketophenols) or 1.4 mono-addition (dihydrobenzopyrones). The results show the importance of the nature of the halogen component of the Grignard reagent. A theoretical model allows regioselectivity of coumarine in relation to the group R and the halogene X to be evaluated.     

Magydardiendiol,diterpenoid with a new skeleton from magydaris panacifolia (umbelliferae).

Three new diterpenoids with a substituted α-cyclogeraniol skeleton have been isolated from the umbelliferae $\text{Magydaris panacifolia}$ (Vahl) Lange, for which the names of magydar-2,13-dien-11,17-diol, $\text{1}$, magydar-2,10 (20), 13-trien-17-ol, $\text{2}$, and magydar-2,10(20), 13-trien-17-yl acetate, $\text{3}$, are proposed. The structures of these substances have been deduced from spectroscopic and chemical data.