Preparative method of obtaining L- and D-2-hydroxy-3-methylbutyric acids

Summary A preparative method was developed for obtaining L-and D-2-hydroxy-3-methylbutyric acids by the separation of racemic 2-hydroxy-3-methylbutyric acid with the aid of D-and L-threo-2-amino-1-p-nitrophenyl-1,3-propanediols.     

Über die Bromierung von 9-Vinylcarbazol

Zusammenfassung Bei der Bromierung von N-Vinylcarbazol wird unter verschiedenen Reaktionsbedingungen 3.6-Dibromcarbazol, 3.6-Dibrom-9-(1.2-dibromäthyl)carbazol, 3.6-Dibrom-9-(1-methoxy-2-bromäthyl)-carbazol und 3.6-Dibrom-9-(1-äthoxy-2-bromäthyl)-carbazol erhalten. Aus 9-Äthylcarbazol wurde 3.6-Dibrom-9-äthylcarbazol, aus 1.2-Bis(9-carbazyl)cyclobutan 1.2-Bis[9-(3.6-dibromcarbazyl)]cyclobutan und aus Poly-N-vinylcarbazol Poly-3.6-dibrom-9-vinylcarbazol dargestellt. Der Bromierungsmechanismus wird diskutiert.

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Bromination of N-vinylcarbazole

Bromination of N-vinylcarbazole under various conditions gives 3.6-dibromocarbazole, 3.6-dibromo-9-(1.2-dibromoethyl)-carbazole, 3.6-dibromo-9-(1-methoxy-2-bromoethyl)carbazole, and 3.6-dibromo-9-(1-ethoxy-2-bromoethyl)carbazole. 3.6-Dibromo-9-ethylcarbazole and 1.2-bis[9-(3.6-dibromocarbazyl)]-cyclobutane have been obtained from the corresponding carbazole derivatives, and poly-N-vinylcarbazole was brominated to poly-3.6-dibromo-9-vinylcarbazole. The bromination mechanism is discussed.

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An dieser Arbeit nahm ich als UNO-Stipendiat teil, wofür ich der UNO sehr zu Dank verpflichtet bin.     

Determination of cadmium by substoichiometric thermal neutron activation analysis

A rapid and selective method has been developed for the determination of cadmium in environmental samples by thermal neutron activation analysis, employing substoichiometric solvent extraction technique. Alcoholic solution of 2-mercaptobenzothiazole /2-HMBT/ has been used for the substoichiometric extraction of Cd/II/ from an aqueous solution of pH 7.0 into methyl iso-butyl ketone /MIBK/.     

Quantum-chemical analysis of the features of the electronic structure of model bis(imidazole)iron porphyrins as compared to data from Mössbauer spectroscopy

A quantum-chemical analysis of the electronic structure of two low-spin complexes, viz., bis(imidazole)hemichrome [Fe(III)P]2Im (S = 1.2) and bis(imidazole)hemochrome [Fe(II)P]·2Im (S = 0), which simulate hemi- and hemoproteins (P denotes porphyrin, Im denotes imidazole, and S is the spin of the iron ion), has been carried out by the extended Hückel method with SCF convergence with respect to the charges of the atoms. The data on the electronic structure of the complexes have been used for calculations of the quadrupole splitting in the⁵⁷Fe Mössbauer spectra of these compounds. An analysis of the contributions of the valence electrons of the Fe atom and the ligands to the quadrupole splitting as a function of the structure of the iron ion, its electronic environment, and the parameters of the first coordination sphere has been carried out. Good agreement between the calculated and experimental values of the quadrupole splitting has been obtained. An analysis of the orbital interactions has been carried out, and data on the classification and composition of the MO's have been presented.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 2, pp. 146–153, March–April, 1985.     

Solute absorption into molten polystyrene

The equilibrium volatilities at near infinite dilution of various solutes absorbed in molten polystyrene have been determined by a gas chromatographic technique. This method is much more rapid, although, with the present apparatus, probably less accurate than conventional static techniques. The primary parameters obtained from measurements of retention volumes are the Henry's law constants, from which are derived the weight and volume fraction activity coefficients, the Flory-Huggins interaction parameters, and the heats of dilution and solution. Of the solutes investigated, 2-butanone (MEK) was the least, and benzene the most compatible (highest and lowest volume fraction activity coefficients, respectively) with molten polystyrene. A small, but definite, variation of the activity coefficients with polystyrene molecular weight was observed.     

Reactions of azirines with sulfur nucleophiles. 2. Reactions of 2H-azirine with β,γ-dihydroxy thiols and β-dithiols. a new route to the synthesis of cyclic sulfides

The reaction of 2H-azirine with a number of dihydroxy thiols and dithiols leads to aziridin-2-yl alkyl sulfides. The latter readily isomerize to cyclic sulfides the size of the ring of which is determined by the length of the alkyl sulfide chain.For Communication 1, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 623–627, May, 1985.