Hydrolysis study of organic acid anhydrides by differential thermal analysis-I Pyromellitic dianhydride

A technique for following the hydrolysis of pyromellitic acid dianhydride (PMDA) by differential thermal analysis (DTA) is described. On exposure of PMDA to moisture, an endothennic peak is initiated between 190 and 200 degrees . As the degree of hydrolysis increases, this peak becomes more intense and shifts to higher temperatures. The formation of pyromellitic acid (PMA) during the hydrolysis of PMDA can be determined qualitatively by DTA.     

Kristallstrukturbestimmung von NaHC2O4 · H2O

NaHC₂O₄ · H₂O crystallizes in space group P 1 with a₀ = 6,51, b₀ = 6,66, c₀ = 5,70 Å, α₀ = 95,0°, β₀ = 109,8°, γ₀ = 74,9° and Z = 2. The structure was solved by direct methods. The refinement was carried out with 679 reflections to R₁ = 7,7%. The angle between the O? C? O planes is 12,6°.     

The crystal structure of iododimethyl(trimethylamine)aluminum

The crystal structure of iododimethyl(trimethylamine)aluminium has been determined from single-crystal X-ray diffraction data collected by counter methods. I(CH₃)₂Al · N(CH₃)₃ crystallizes in the othorhombic space group Pnma with cell dimensions a=12.59(1), b=10.75(1), c=7.58(1)å, and p_calc=1.58 g·cm^?3 for Z=4. Least-squares refinement gave a final weighted R Value of 0.071 for 574 independet observed reflections. Each monomeric molecule lies on a crystallographic mirror plane with the trimethylamine and iododimethylaliminium groups in a staggered configuration about the aluminum  nitrogen bond.     

The effect of a magnetic field on the singlet/triplet ratio in geminate ion recombination

Excited state formation by ion recombination in solutions of fluorene in squalene has been studied by pulse radiolysis at the center of a large electromagnet. The products of the slower part of the ion recombination are affected by an applied magnetic field. The fluorescence yield increases by a factor of about 1.5 whereas the triplet yield decreases.     

Radiation Effects on Concentrated Potassium Hexacyanoferrate(III) Solutions

The neutron irradiated potassium hexacyanoferrate(III) solutions were analyzed for Fe(CN)₆^4?, Fe(CN)₆^3?, and Prussian blue. The retention values (1.1%) were constant throughout the pH and concentration ranges studied, and did not change with the length of irradiation. The complex behavior of the radiochemical yield of the Fe(CN)₆^4? and Prussian blue was attributed to the competition of the various reactions involved in the irradiation.     

Pyrans,their analogs,and related compounds

Reaction of 4, 4-dichloroflavine (I) with sulfurylchloride affords 2, 3, 3, 4, 4-pentachloroflavan (II). Hydrolysis of II gives 2-hydroxy-3, 3-dichloro-4-flavanone (III), while alcoholysis with aqueous alcohols yields 2-alkoxy-3,3-dichloro-4-flavanones (IVa, b). Treatment of III with SOCl₂ gives 2,3,3-trlchloro-4-flavanone (V), which with caustic alkali or sodium ethoxide is converted into o-(1-phenyl-2, 2-dichlorovinyloxy)benzoic acid (VIc) or its ethyl ester (VIb), respectively.For Part XLII, see [7].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1167–1170, September, 1970.     

Calculation of Siegert eigenvalues for molecular systems: results for He(21,3S)+ H

The variational calculation of Siegert eigenvalues has previously been shown to provide reliable positions and widths for atomic resonances. This approach is herein extended to molecular problems, and the first such calculations for a molecular autoionizing system, He(2^1,3S)+H→ He+H⁺+e^?, are reported.